All Landscape & Garden Alerts

2023 Pruning Deciduous Trees & Shrubs

Landscape & Garden    Treasure Valley, Treasure Valley - Idaho

Tree & Shrub Pruning

Posted on: March 17, 2023 by Ruth Givens

The dormant season is a great time to prune deciduous trees (landscape & fruit) and shrubs. As a general guide remove no more than one-third of the tree when pruning. Below are a few resources on how to prune. 

·       Training Young Shade Trees, University of Idaho

·       Pruning Deciduous Shade Trees, University of Arizona  

·       Pruning Deciduous Trees, University of New Hampshire 

·       Deciduous Fruit Tree Pruning Videos, University of Arizona (https://extension.arizona.edu/deciduous-fruit-tree-pruning-videos)

·       How to Prune Trees Video, Colorado State University 

Prune shrub species which grow on the current season’s growth during the dormant period, usually late winter early spring. A few examples of flowering shrubs in this grouping including butterfly bush, heather, heavenly bamboo, hydrangea, shrubby roses and rose of sharon. Reference the third link for more information. 

For shrub species which form buds on last season’s growth prune these species within about two months after the flowers fade. On these species, flower buds form in late summer and early fall. Winter pruning decreases the number of flowers the following spring as branches containing flower buds are removed. A few examples of flowering shrubs in this grouping include azaleas, lilac, magnolia, mockorange, serviceberry, and witchhazel. Reference Pruning Ornamental Trees & Shrubs, from Purdue University. (https://www.extension.purdue.edu/extmedia/HO/HO-4-W.pdf)

For most areas of Idaho, plants that bloom before June 1 formed the flowers the previous year on old wood. Those that bloom after June 1 form flowers on new growth. Keep in mind that this is rough guideline.

The City of Nampa Parks & Forestry Department will offer tree pruning classes. See the attached file for more details. 

If you have additional questions, contact your local University of Idaho Extension office. To search by county visit https://www.uidaho.edu/extension/directory/counties

Additional Resource 

PNW 400 Training & Pruning Your Home Orchard – 

https://extension.oregonstate.edu/pub/pnw-400

Ornamental Pesticide Applicators Pre-License Training

Landscape & Garden    Treasure Valley, Treasure Valley - Idaho

Pesticide Pre-license Training

Posted on: January 5, 2023 by Ruth Givens

The University of Idaho (UI) Extension Pesticide Safety Education Program (PSEP) will be offering pre-license training during the 2023 Idaho Horticulture Expo in Boise. This training will be in-person with a two-day agenda. Focus will be on the following categories: Ornamental Insecticide (OI), Ornamental Herbicide (OH), General Pest (GP), and Core (CO). 

Registration includes access to online modules and study materials housed on the National Extension Foundation website. These materials prepare students for the 2-day class and the statewide exams. ALL materials will be available to each registered student with continued access until three weeks after the training. 

January 19 – 20, 2023, daily at 9am – 4pm (MST)

Boise Centre, 850 W Front St., Boise 83702

The cost is $75 per student. To register, visit our website https://www.uidaho.edu/extension/ipm/pesticide.

For more information, contact UI Extension Sr. Instructor, Kimberly Tate at (208) 364-4581 or email ktate@uidaho.edu. 

Note: We will be offering two prelicense hybrid courses this spring; one in March and the other in April. More information will be available in February.

PNW PestAlert Landscape & Garden Survey

Landscape & Garden    Treasure Valley, Treasure Valley - Idaho

Home Garden & Landscape Survey

Posted on: November 21, 2022 by Ruth Givens

Ruth Givens from the University of Idaho Extension, Canyon County is conducting a research study. The purpose of the research is to evaluate the effectiveness of the PNW Pest Alert Network with respect to Landscape & Garden. You are being asked to participate in this study because you are a subscriber to the landscape and garden alerts.

Your participation will involve completing a voluntary survey which will provide feedback to the principal investigator. The survey should take about 3 minutes to complete. The survey includes questions such as indicate how you have used the information in the past year? How did you access the PNW Pest Alert Network alerts? How useful were the landscape and garden alerts? Your involvement in the study is voluntary, and you may choose not to participate. You can refuse to answer any of the questions at any time. There are no names or identifying information associated with your responses. There are no known risks in this study, but some individuals may experience discomfort or loss of privacy when answering questions. Data will be housed on a password protected server and deleted upon completion of the study.

The findings from this project will provide information on providing better outreach programming to control landscape and garden pests. If published, results will be presented in summary form only.

Special Incentive: Surveys completed by December 11 will be entered into a drawing for one of three $75 certificates to Texas Roadhouse.  Three lucky winners will be announced on the website and the gift cards will be sent out later in December.

If you have any questions about this research project, please feel free to call Ruth Givens at 208-459-6003. By submitting this survey, you certify that you are at least 18 years of age and agree to participate in the above described research study.

Start Survey HERE.

Fall Control for Coryneum Blight & Peach Leaf Curl

Landscape & Garden    Treasure Valley, Treasure Valley - Idaho

Coryneum Blight & Peach Leaf Curl

Posted on: October 28, 2022 by Ruth Givens

Coryneum blight (Thyrostroma carpophilum) & Peach leaf curl (Taphrina deformans)

Coryneum blight or commonly known as shothole disease which is caused by fungus Thyrostroma carpophilum. Trees which have been affected develop small, round, tan-to-purpleish spots which then dry and fall out of the leaf producing a shothole effect. Most cultivars of peach, nectarine, apricot, and almond are very susceptible while cherry and plum are less susceptible. In addition, ornamental plant species can show damage. Beyond the leaf, symptoms can also be seen on the current season and 1-year old fruiting wood. Infections consist of round, reddish spots which are slightly sunken.

Chemical control will occur at 50% leaf drop in late autumn by spraying with a copper-based fungicide, chlorothalonil, or Bordeaux mixture. Follow the label instructions for rate and application procedure. Prune out affected twigs when practical. Culturally control shothole disease by not allowing irrigation sprinklers to wet the tree foliage, select cultivars which are disease resistant when available, and remove and dispose of affected foliage and twigs. 

Peach leaf curl caused by fungus Taphrina deformans and is specific to peaches and nectarines. Trees that are infected will have leaves that are distorted or curl, appear blistered, and develop a yellow or red color.   

Control can be achieved by a single fungicide application in the fall after 90% of the leaves have fallen. Chemicals used for control are copper products or chlorothalonil. Follow the label instructions for rate and application procedure. Homeowners should also remove and dispose of infected leaves that have fallen to the ground, to remove as much inoculum as possible. Resistant varieties can be selected for additional cultural control.

Link:

Peach Leaf 

PNW Handbook: https://pnwhandbooks.org/plantdisease/host-disease/peach-prunus-persica-leaf-curl

USU: https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=1736&context=extension_curall

Shothole

PNW Handbook: https://pnwhandbooks.org/plantdisease/host-disease/peach-prunus-persica-shothole

UC IPM: http://ipm.ucanr.edu/PMG/GARDEN/FRUIT/DISEASE/shothole.html

2022 Fall Lawn Fertilization & Care

Landscape & Garden    Treasure Valley, Treasure Valley - Idaho, Northern Idaho

2022 Fall Lawn Fertilization & Care

Posted on: September 16, 2022 by Ruth Givens

University of Idaho turf specialists recommended splitting the application of lawn fertilization into three (3) applications; early May, early September, and late October/November. Review the first reference below to identify fertilization application amounts using a soil test result or the second reference for general recommendations for southern Idaho. Apply according to label directions.

If your lawn is suffering from soil compaction or development of a thick thatch layer fall is the optimal time to core aerate.  For more information on core aeration review Lawn Aeration.

Fall is a great time to control perennial weeds in the landscape if opting to use herbicides. Perennials will begin storing carbohydrates in the roots promoting herbicides to be drawn deeper into the root system and allowing for better control.

If there are additional questions on lawn care or weed management reach out to a local University of Idaho Extension office.

References:

Using Soil Test for Garden Fertilization

https://drive.google.com/file/d/16svAaPIqRcsN8VyGMc_p5SMoOO-hImv8/view

Southern Idaho Lawns

https://drive.google.com/file/d/1EcuP1OErzgRMMHN8l4fugN0VEXkLI-gv/view

Lawn Aeration

https://planttalk.colostate.edu/topics/lawns/1505-lawn-aeration/

Find University of Idaho Extension

https://www.uidaho.edu/extension/directory/counties

2022 Reduce Watering Frequency During Fall

Landscape & Garden    Treasure Valley, Treasure Valley - Idaho, Northern Idaho

Reduced Watering

Posted on: September 9, 2022 by Ruth Givens

The days are shortening, and evening temperatures are cooling. Now is the time to adjust the frequency between irrigation days for the landscape and garden.

Lawn irrigation systems can be set to increase the number of days between irrigation based on soil texture. Adjusting the frequency of watering versus the run time allows for replenishment of the water holding capacity and usable water in the soil profile. Review reference links one and two below for greater explanation. This deep and infrequent method encourages a deeper root growth of plants.

A reminder to deep water trees and shrubs prior to shutoff of irrigation water.

References:

Watering Home Lawns and Landscape, University of Idaho

https://www.extension.uidaho.edu/publishing/pdf/CIS/CIS1098.pdf

Watering Home Lawns: How Much and How Often, University of Idaho

https://www.extension.uidaho.edu/publishing/pdf/CIS/CIS1157.pdf

2022 Apple Codling Moth, Third Generation

Landscape & Garden    Treasure Valley, Treasure Valley - Idaho, Northern Idaho

Apple Codling Moth

Posted on: August 22, 2022 by Ruth Givens

The third generation of codling moth egg hatch is forecasted to begin August 24. Current degree day models indicate 2096 DD as of August 22. Third generation egg hatch begins at 2160-2200 DD.

Continue to keep fruit protected through September 15. Protection of fruit can stop after this time even if fruit has not been harvested. By mid-September there is not enough day length to signal eggs on the fruit to hatch.

Follow label directions for harvest and post-harvest requirements.

Reference Materials:

https://pnwhandbooks.org/insect/tree-fruit/apple/apple-codling-moth

https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=1879&context=extension_curall

https://extension.colostate.edu/topic-areas/insects/codling-moth-control-in-home-plantings-5-613/

2022 Blossom End Rot

Landscape & Garden    Treasure Valley, Treasure Valley - Idaho, Northern Idaho

Blossom End Rot

Posted on: August 8, 2022 by Ruth Givens

Blossom-end rot is showing up on tomato plants. Pepper, eggplant, squash, and watermelon can also be affected.

Blossom-end rot is a physiological disorder due to a shortage of calcium in young fruit. Blossom-end rot often occurs when soil moisture fluctuates as water stress interferes with calcium uptake in the plant.  Most Treasure Valley garden soils have enough calcium and additions are not recommended. Refer to soil test results.

Cultural control practices: Use infrequent deep irrigation to keep the soil uniformly moist and avoid water stress or fluctuating soil moisture. Organic mulch can be used to prevent wide fluctuations in soil moisture. Avoid over fertilizing and hoeing or cultivating near the roots.

https://utahpests.usu.edu/ipm/notes_ag/veg-blossom-end-rot

https://pnwhandbooks.org/plantdisease/host-disease/tomato-solanum-lycopersicum-blossom-end-rot

https://extension.usu.edu/vegetableguide/tomato-pepper-eggplant/blossom-end-rot

2022 Turfgrass Mowing Height & Watering

Landscape & Garden    Treasure Valley, Treasure Valley - Idaho, Northern Idaho

Turfgrass Mowing Height & Watering

Posted on: July 6, 2022 by Ruth Givens

MOWING

The weather is warming and now is the time to check the mowing height at which your turfgrass is cut. Increasing the length of grass blade encourages a deeper root growth and provides more shade cover of the soil surface reducing water evaporation.

For summer mowing height Kentucky bluegrass and fine fescue are recommended to be maintained at 3 inches, perennial ryegrass at 2 inches, and tall fescue at 4 inches. Ensure that the mower blade is sharp and follow the one-third rule; remove no more than one-third of the leaf growth each mowing.

Grass clipping which are left on the lawn by mulching decompose quickly, feed soil organisms, recycle plant nutrients, and increase organic matter in the soil.

WATERING

The goal of irrigation is to keep the lawn healthy when rainfall is not dependable. The key is to moisten the top 12 inches of the root zone. Watering deeply (10 to 12 inches) but infrequently produces healthy turf. Practicing deep watering reduces weed populations, benefits landscape trees and shrubs, increases water use efficiency, and forces an exchange of soil atmosphere with each irrigation. Early morning is the best time to water.

Determining how deep irrigation water goes can be done by using a soil probe or shovel to check soil moisture the day after irrigation. At 10 to 12 inches deep the soil should feel slightly damp. If the soil feels dry at the 10- to 12-inch depth increase the duration of water application to fill the root zone. As weather conditions change adjust the frequency of irrigation to maintain plant available water in the root zone.

Identifying or knowing soil type will help to determine the frequency of water application, rate of water infiltration, and the soils water holding capacity. For example, heavy clay soils have a greater water holding capacity, but have a slower infiltration rate (speed at which water enters the soil). These soils can be watered less frequently (once a week or less) and may need multiple application of water on day of watering to allow water to move into the soil.  Sandy soils have less water holding capacity and a greater infiltration rate. These soils need to be watered more frequently to maintain comparable turf.

For a more calculated approach to water application reference the publication links below.

https://www.extension.uidaho.edu/publishing/pdf/CIS/CIS1098.pdf

https://www.extension.uidaho.edu/publishing/pdf/CIS/CIS1157.pdf

2022 Peachtree Borer

Landscape & Garden    Treasure Valley, Treasure Valley - Idaho, Northern Idaho

Peachtree Borer

Posted on: June 29, 2022 by Ruth Givens

Peachtree bores are predicted to emerge between July 2 and July 5. This pest is a concern for stone fruits: Peach, nectarine, apricot, cherry, and plum. Key symptoms of peachtree borer infestation is the presence of sawdust and frass mixed with the gummy substance near the base of the trunk. Prevention is the best method of control.

Larvae injure the fruit tree primarily by burrowing into the tree trunks just at or below the soil line but may enter trunk up to 12” above the soil line. Larvae feed in the cambium beneath the bark girdling the tree.

Chemical Control, Home Use: For orchards less than 1 acre, or for home yard trees, preventative trunk sprays are the primary control. Apply the first application immediately after first trap catch and repeat application based on product label guidelines. Follow the required pre-harvest interval (time between last application and allowed harvest of fruit) of insecticide product. Apply insecticide as a bark drench at a rate of ½ to 1 gallon of spray mix per tree. Thoroughly cover the lower 12 inches of trunk and soak the ground at the base of tree. Do not allow the sprays to contact fruit. For chemical option review the PNW handbook link below.

Chemical Control, Commercial: Reference the PNW handbook link below to see spring and summer application recommendations.

Cultural Control: Larvae inside the trunks can be killed by inserting a wire into entry holes. Kill larvae in the late summer and fall before they spend the winter and inflict their most extensive feeding damage the following spring. Keep base of tree free of vegetation – heat and dryness reduce the survival of eggs and larvae.

The following links have information about the life cycle of peachtree borer and control methods.

https://pnwhandbooks.org/insect/tree-fruit/peach-nectarine/peach-nectarine-peachtree-borer

https://extension.colostate.edu/topic-areas/insects/peach-tree-borer-5-566/

https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=1651&context=extension_curall

2022 Peach Twig Borer

Landscape & Garden    Treasure Valley, Treasure Valley - Idaho, Northern Idaho

Peach Twig Borer

Posted on: June 22, 2022 by Ruth Givens

It is time for management of the peach twig borer, based on degree days. This pest is a concern for those growing peach, nectarine, apricot, plum and prune. Adult moths are 0.3 – 0.5 inches long, with light and dark gray mottled wings. Scales on the front of head cause the head to appear pointed. The larva is a caterpillar, about 0.5 inch long, with a dark brown head and distinctive, alternating light and dark bands on the body. 

Larvae injure fruit trees by feeding on the buds and twigs early in the season, then the larvae bore into the shoots, causing a characteristic "flagging" or wilting of the new growth. Later generations of larvae feed within shoots or even on the fruit itself. Flagging of twigs indicates an infestation.

For chemical control management options review the PNW Handbook link below to select a control option appropriate for operation. Apply according to label directions.

For cultural controls prune out shoot strikes in the late spring and early summer as soon as they are detected to prevent these larvae from completing development and contributing to summer generations of the pest. If old shoot strikes are observed during pruning in late winter to early spring, plan to apply early season controls. Old strikes hold onto the dead leaves and appear as “flagged” terminals.

https://pnwhandbooks.org/insect/tree-fruit/peach-nectarine/peach-nectarine-peach-twig-borer

https://climate.usu.edu//includes/pestFactSheets/Peach-Twig-Borer.pdf

2022 Western Cherry Fruit Fly

Landscape & Garden    Treasure Valley, Treasure Valley - Idaho, Northern Idaho

Western Cherry Fruit Fly

Posted on: June 3, 2022 by Ruth Givens

Western cherry fruit fly adults are about 0.2 inch long. They have brownish to black wings with dark bands. White maggots infest cherries. The mature maggot makes a hole in the cherry as it exits. Flies overwinter as pupae in the soil.

Once the cherries start to blush (ripen to a salmon blush color) the fruits are susceptible to egg-laying by the adult females. Consider the maturity of the ripest fruit in the orchard when determining control methods. Spraying a product with the active ingredient kaolin can create a physical barrier that prevents females from laying eggs into the developing fruit. For additional control options see the links below.

Forecasted degree days at 1060 DD is predicted to be June 4.

http://treefruit.wsu.edu/crop-protection/opm/western-cherry-fruit-fly/

https://climate.usu.edu//includes/pestFactSheets/WC-Fruit-Fly.pdf

https://pnwhandbooks.org/insect/tree-fruit/cherry/cherry-western-cherry-fruit-fly

2022 Apple Codling Moth, First Notification

Landscape & Garden    Treasure Valley, Treasure Valley - Idaho, Northern Idaho

Apple Codling Moth

Posted on: May 25, 2022 by Ruth Givens

The first apple codling moths were trapped in mid May . Currently the degree day model is reporting 201 degree days (DD) as of May 25. There are different management options to consider when controlling this pest.

Option A: Starting at 200 DD, forecasted to be May 25, apply a mixture of water and horticultural oil at 1% concentration to smother egg infestation. Follow with first application of insecticide at 350 DD. Reapply insecticides based on the protection interval stated on the label.

Option B: Starting at 220-250 DD, forecasted to be May 28, apply insecticides that target newly hatched larvae. Reapply insecticides based on the protection interval stated on the label.

Reference publication links to view insecticide options for commercial or residential sites. Commercial products with the active ingredients including; spinetoram, acetamiprid, chlorantraniliprole, etc. Residential products with active ingredients including; lambda-cyhalothrin (restricted use pesticide), or esfenvalerate and Spinosad (general-use pesticides). Non-spray option is to bag the fruit.

This pest needs prevention all season long for clean fruit.

https://pnwhandbooks.org/insect/tree-fruit/apple/apple-codling-moth

https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=1879&context=extension_curall

https://extension.colostate.edu/topic-areas/insects/codling-moth-control-in-home-plantings-5-613/

2022 Lilac-Ash Borer Control

Landscape & Garden    Treasure Valley, Treasure Valley - Idaho, Northern Idaho

Lilac-Ash Borer

Posted on: May 23, 2022 by Ruth Givens

The lilac-ash borer (Podosesia syringae), a clear-wing moth, can be a destructive pest of many species of ash (Fraxinus spp.), previt (Ligustrum spp.), lilac (Sryinga spp.).

The Lilac-ash borers have reached the degree days sufficient for emergence. Adults are short-lived and typically deposit all eggs within a week after emergence. The first spray should be applied 10-20 days after adult emergence, approximately May 25- June 15, before the larvae bore into the trunk. Spray should be applied to the trunk and larger limbs, follow label instructions for application and reapplication depending insecticide selected.

Primary insecticides include permethrin (group 3A), bifenthrin (group 3A) and endosulfan (restricted use; group 2A). Please note that imidacloprid (group 4A), a systemic insecticide, is ineffective against lilac-ash borer and should not be used.

Diversifying species in the landscape, maintaining optimum plant health, monitoring, and preventive sprays (if necessary) are the best methods for preventing infestations. Only preventative treatments exist.

https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=1920&context=extension_curall

https://extension.colostate.edu/docs/pubs/insect/05614.pdf

https://pnwhandbooks.org/insect/hort/landscape/hosts-pests-landscape-plants/ash-fraxinus-ash-borer

https://pnwhandbooks.org/insect/hort/landscape/hosts-pests-landscape-plants/lilac-syringa-ash-borer

2022 Plant Diagnostic Clinics

Landscape & Garden    Treasure Valley, Treasure Valley - Idaho

Posted on: April 28, 2022 by Nic Usabel

Many University of Idaho Extension office locations offer a free plant diagnostic clinic where certified Idaho Master Gardener volunteers help answer clientele questions. Here are the details that were shared with the PNW Pest Alert Network for those locations in the Treasure Valley.

UI Extension, Ada County (Boise, ID): The plant diagnostic clinic operates April through September and is staffed Monday and Wednesday from 10 AM to 3 PM. Ada County residents should contact 208-287-5900 or email adamg@uidaho.edu with landscape and garden questions. For additional details visit https://www.uidaho.edu/extension/county/ada/horticulture 

UI Extension, Canyon County (Caldwell, ID): The free plant diagnostic clinic operates May through September and is staffed Monday and Wednesday 1 PM to 4 PM and Friday 9 AM to 12 PM. Canyon County residents should contact 208-459-6003 or email ccmg@uidaho.edu with landscape and garden questions. For additional details visit https://www.uidaho.edu/extension/county/canyon/horticulture. 

UI Extension, Owyhee County (Marsing, ID): Landscape and garden questions for Owyhee County residents can be directed to UI Extension Canyon County at 208-459-6003 or ccmg@uidaho.edu. Contact information for Owyhee County is 208-896-4104 or owyhee@uidaho.edu. For additional details visit https://www.uidaho.edu/extension/county/owyhee.  

Don’t see your county listed? Visit https://www.uidaho.edu/extension/directory/counties to find contact information for your county office.

2022 Spring Plant Sales

Landscape & Garden    Treasure Valley, Treasure Valley - Idaho

Posted on: April 27, 2022 by Nic Usabel

Spring Garden Plant Sale

UI Extension, Canyon County (Caldwell, ID): Searching for new plants to add to your garden or landscape? The University of Idaho Canyon County Master Gardener Spring Garden Plant Sale will be held on Saturday, April 30 from 9:00 AM to Noon, at Canyon County Extension Office, 501 Main Street, Caldwell. Preorders can be made at https://bit.ly/ccmgstore and are available for pick up Saturday, April 30 from 9:30 AM to 11:30 AM. Additional inventory will be available that is not provided for preorder. Available plants include vegetables, herbs, houseplants, succulents, flowering perennials, native plants, and so much more. Join in the fun! For More information, call UI Extension, Canyon County at (208) 459-6003.

UI Extension, Ada County (Boise, ID): Let’s get growing! The University of Idaho Annual Master Gardener Plant Sale will be held Saturday, May 7 from 9:00 AM to Noon, at the Ada County Extension Office, 5880 Glenwood Street, Boise. Offerings include houseplants, herbs, vegetables, and berries, flowering perennials, gardening books, and so much more. Cash or check only. Please no early birds. For more information, call the Master Gardeners at (208) 287-5900. Come join the fun!

There are several local groups and organizations that are hosting plant sales around the Treasure Valley. Check in with your local church groups, high schools, colleges/universities, and civic groups. Here are those we have been alerted to. 

• Idaho Botanical Garden Online Plant Sale, Boise, (member only April 22, public April 29)
• Vallivue High School, Caldwell, April 30
• Ridgevue High School, Nampa, April 30
• Marsing FFA Chapter, Marsing, May 4
• Canyon Springs Garden Outreach, Middleton, May 7
• Catholic Women’s League St. Paul’s Catholic Church, Nampa, May 7
• Middleton Boy Scout Troop, Middleton, May 7

2022 Extension Drought Resources

Landscape & Garden    Treasure Valley

Posted on: April 24, 2022 by Nic Usabel

If you are looking for ways to conserve water during this growing season here are a number or resources available from various Extension programs. 

• University of Idaho Extension Drought Resources
• Utah State University Extension Drought Resources
• Watering a Home Landscape During a Drought, Colorado State University
• Native Plant Landscaping: Curb Appeal and Low Water Use, University of Idaho
• Landscaping with Native Plants, University of Idaho
• Idaho Climate & Weather Resources, University of Idaho
• U.S. Drought Monitor for Idaho, National Drought Mitigation Center

For additional questions reach out to a local Extension office. Find a local University of Idaho Extension Office.

2022 Dry Spring Conditions

Landscape & Garden    Treasure Valley - Idaho

Posted on: March 25, 2022 by Nic Usabel

Much of Idaho has experienced below average precipitation this past winter and it continues into early spring. The Treasure Valley is no different. During periods with low water resources, it is important to prioritize watering needs. While some lawn conditions appear dry it is not yet time to begin the watering of residential lawns. Consider the following as a prioritization to follow during times of low water resources:

• Young or newly transplanted trees which have a limited root system. Ensure to proper application of water and water deeply and infrequently based on soil texture.
• Established trees and shrubs should also be given consideration to priority watering as established plants are high value and take many years to replace. When applying water to trees and shrubs apply at an appropriate rate that allows water to soak into the soil to a depth of 12 inches. Frequency of water depends on soil texture and if water restrictions are in place. General guides are as follows: April once per month, May through September up to twice per month.
• Fruit gardens, vegetables gardens, and flowers are generally next on the list of prioritizations. Consider using a wood mulch or organic matter around trees, small fruits, and plants to reduce water evaporation from the soil. Avoid direct stem to mulch contact. Fruit trees and small berries may benefit from an early water now if soil conditions are dry. Early spring bulbs may also benefit from an early water if dry conditions are present. 
• Lawns finish out the priority list. If watering the lawn, ensure that sprinklers are operating correctly and applying water to desired location. Make water applications so that water is applied deeply and infrequently. Increase the mowing height of the grass and consider mulching the clippings versus bag removal. 

Resources:

• Watering a Home Landscape During Drought, Colorado State University Extension
• Watering Home Lawns and Landscapes, University of Idaho Extension 
• Watering Home Lawns: How Much and How Often, University of Idaho Extension

» Idaho SNOTEL Current Snow Water Equivalent

2022 Rose & Grapevine Pruning

Landscape & Garden    Treasure Valley - Idaho

Posted on: March 25, 2022 by Nic Usabel

Across the Treasure Valley it’s time to prune grapevines and roses. See below for more resources for pruning these landscape & garden plants.

ROSES:

Rose pruning should occur when the buds are starting to swell in early spring. Below are a few resources that can be read or viewed for rose pruning.

• How to Prune Roses, Utah State University Extension video
• Early Spring Pruning of Roses, University of Maryland Extension video
• Guide to Pruning Roses, University of Maryland Extension
• Pruning Roses, Colorado State University

GRAPEVINES:

The University of Idaho Research & Extension Center in Parma recommends pruning grapevines in the Treasure Valley no sooner than mid-March to ensure that low temperatures do not kill buds after pruning. Grapevines can “bleed”, movement of sap from the cut, heavily when pruned in spring. This does not harm the vines. Below are a few resources that can be read or viewed for grape pruning.

• Grape Pruning Four Cane System, Utah State University Extension video
• Grape Pruning, USU Garden Guys & Gal video
• Pruning Grapevines, University of Nebraska Lincoln Extension video
• Yard and Garden: How to Prune Grapevines, Iowa State University 
  
• Grape Vine Management, Utah State University Extension
• Grape Trellising and Training Basics, Utah State University Extension

2022 Spring Lawn Fertilization & Care

Landscape & Garden    Treasure Valley - Idaho

Posted on: March 22, 2022 by Nic Usabel

Spring lawn fertilization for cool season grasses recommend that fertilization be made while energy is being directed to root growth, which is followed by leaf growth. This timeframe for cool season turf in the Treasure Valley traditionally March thru early May. If mulching is a practice in your lawn maintenance plan, nitrogen can be reduced by ½ pound annually. 

The proper rate of fertilizer application is best achieved when using a soil test result to identify the fertilizer needs of the soil. UI Extension publication Using Soil Test Results for Garden Fertilization will help guide the steps.  Applications should be split between spring and fall. Application rates should not exceed 1 pound of nitrogen per 1,000 square feet in any one application, access Southern Idaho Lawns Fertilizer Guide to identify additional time(s) for application if rate would exceed the 1 pound of nitrogen per 1,000 square feet limit with only and spring and fall application. Always follow label directions.

For more information on how to obtain a soil sample to a soil test submission contact your local University of Idaho Extension office. 

Another method of identifying application rate is based on the level of turf maintenance from low to high traffic. Application rates should not exceed 1 pound of nitrogen per 1,000 square feet in any fertilizer application and always follow label directions. Review descriptions, timing, and rate of application below.

1. Light use: Classified as occasional foot traffic or little to no play from children. Annual turfgrass recommendation is 0-1 pound of nitrogen per 1,000 square feet. Split the application between a spring and fall application. 
2. Moderate Use: Typical children’s play and occasional garden parties. Annual turfgrass recommendation is 2-3 pounds of nitrogen per 1,000 square feet. Split the application equally between a spring, early fall (late September) and late fall (Mid October to Late November) 
3. Heavy Use: Frequently used sports field play, heavy traffic and/or frequent garden parties. Annual turfgrass recommendation is 4-6 pounds of nitrogen per 1,000 square feet. Apply 1 pound of nitrogen per 1,000 square feet in spring, 0.5 pound of nitrogen per 1,000 square feet late May/early June, 0.5 pound of nitrogen per 1,000 square feet late June/early July, 1 pound of nitrogen per 1,000 square feet early fall (late September) and 1 pound of nitrogen per 1,000 square feet late fall (Mid October to Late November).

If your lawn is suffering from soil compaction or development of a thick thatch layer core aeration can be completed in the spring but is preferred in fall while weed pressure will be reduced. For more information visit UI Extension publication Core Aeration of Lawns-Benefits & Procedures.

Spring provides the opportunity to seed new turfgrass areas or to over-seed areas that may have been damaged over the winter. Cool temperatures will promote germination and growth of cool season turf species, tall and fine fescues, perennial ryegrass, and Kentucky bluegrass. Weed pressure can be higher during the spring as compared to the fall when seeding or over-seeding.

If there are additional questions on lawn care or weed management reach out to a local University of Idaho Extension office.

2022 Delayed-Dormant Oil Application

Landscape & Garden    Treasure Valley - Idaho

Posted on: February 27, 2022 by Nic Usabel

In the coming weeks areas across the Treasure Valley could reach temperatures desirable for applying a delayed-dormant oil spray. The use of horticultural oil as a delayed-dormant spray can target many insect pests at a time when beneficial insects are not yet active. Use of the term “delayed-dormant” indicates that the oil should be applied after bud swell. This timeframe coincides with the increasing activity of the overwintering insect stages, such as aphid eggs, scale nymphs, and peach twig borer larvae.

The two factors of temperature and bud stage must correspond before application of horticultural oil is made.

TEMPERATURE: 

Only apply oil if temperatures remain above freezing (ideal is above 40°F) for 24 hours after application and on a clear, non-windy day in the 50 to 70°F temperature range. 

BUD STAGE: 

The window of application extends from bud swell to when the leaves just start emerging. The last point you can safely apply oil based on fruit tree crop are:

• Apple: Half-inch green, but ideal application at green tip stage. 
• Pear: Cluster bud. 
• Cherry: White bud. 
• Peach/nectarine: pre-bloom. 

Refer to the Critical Temperatures for Frost Damage on Fruit Trees by Utah State University to view images of each bud stage mentioned.

Oil should be applied at a rate of 2% (5 Tbs in 1 gallon water) and thoroughly cover all cracks and crevices. 

If aphids and scale have been a serious problem in previous years an insecticide could be added, see Chemical Control of Landscape Pests for chemical products available by pest. Read and follow label instructions for preparation and application.

If fire blight was an issue in the previous year add in a copper product for fire blight. 

If you have additional questions, contact your localUniversity of Idaho Extension office. 

Additional Resource:

• Insect Control: Horticultural Oils, Colorado State University

2022 Pruning Deciduous Trees & Shrubs

Landscape & Garden    Treasure Valley

Posted on: January 25, 2022 by Nic Usabel

The dormant season is a great time to prune deciduous trees (landscape & fruit) and shrubs. It is not recommended to prune grapevines at this time.  As a general guide remove no more than one-third of the tree when pruning. Below are a few resources on how to prune. 

• Training Young Shade Trees, University of Idaho
• Pruning Deciduous Shade Trees, University of Arizona
• Pruning Deciduous Trees, University of New Hampshire
• Deciduous Fruit Tree Pruning Videos, University of Arizona
• How to Prune Trees Video, Colorado State University

Prune shrub species which grow on the current season’s growth during the dormant period, usually late winter early spring. A few examples of flowering shrubs in this grouping including butterfly bush, heather, heavenly bamboo, hydrangea, shrubby roses and rose of sharon. Reference the third link for more information. 

For shrub species which form buds on last season’s growth prune these species within about two months after the flowers fade. On these species, flower buds form in late summer and early fall. Winter pruning decreases the number of flowers the following spring as branches containing flower buds are removed. A few examples of flowering shrubs in this grouping include azaleas, lilac, magnolia, mockorange, serviceberry, and witchhazel. Reference Pruning Ornamental Trees & Shrubs, from Purdue University. 

For most areas of Idaho, plants that bloom before June 1 formed the flowers the previous year on old wood. Those that bloom after June 1 form flowers on new growth. Keep in mind that this is rough guideline.

The City of Nampa Parks & Forestry Department will offer tree pruning classes. See the attached file Horticulture Workshops for more details. 

If you have additional questions, contact your local UI Extension office. To search by county visit https://www.uidaho.edu/extension/directory/counties

» Horticulture Workshops

2022 Idaho Horticulture Expo

Landscape & Garden    Treasure Valley

Posted on: December 14, 2021 by Nic Usabel

The Idaho Nursery and Landscape Association will host the Idaho Horticulture Expo January 19-20 at the Boise Center. 

Here is a peak at just some speakers:

• Stepahnie Adams, Morton Arboretum
• Amanda Thompsen, author of Kiss My Aster
• Tim Prather, University of Idaho
• Dr. Brent Bean, BYU Idaho
• See the full schedule

Credits available:

• 11 continuing education credits for Arborists. 
• 11 recertification credits for Pesticide Applicators

Register today at inlagrow.org.

» https://inlagrow.org/event-4572799

2021 Live Evergreen Trees as Indoor Holiday Decoration

Landscape & Garden    Treasure Valley

Posted on: December 10, 2021 by Nic Usabel

If using a live, with roots attached, evergreen tree for your indoor holiday decoration here are some items to consider. 

First, consider where in the landscape you will plant your tree. Select an open area which lacks overhanging tree branches or wires. If you don't have such a site, consider a dwarf conifer or evergreen shrub. Choose a tree that will thrive in your soil condition and climatic condition. Proper planning now will save you time and money later. 

When you visit a nursery or garden center, you will find a variety of evergreens to choose from. Evergreens are commonly available as containerized trees grown in a pot or balled and burlapped trees. 

Before the ground freezes, dig a hole 2-3 times wider than the root ball, but only as deep as the root ball itself. The soil which is removed from the hole will need to be stored where it will not freeze. This soil will be used in planting the tree after the holiday. 

Trees have a better chance of survival if they are not displayed in the house for more than a 7 to 10 days. If purchasing the tree early keep the tree in a cool location before moving it indoors and water as necessary. Extended exposure to the indoor temperatures can counteract the winter dormancy in conifers. A short display period and prompt planting is the best way to insure the survival of the tree in the landscape. 

When you are ready to plant position and level the tree. If the root ball is wrapped remove any cover or wires. Inspect the tree root ball for circling roots and straighten, cut, or remove them. Identify the trunk flare, where the trunk widens near the root zone, and ensure that the root flare is viable at ground level once planted. With the reserved soil fill the hole and gently but firmly apply pressure. Water thoroughly and apply a woodchip mulch. For more detailed planting instructions of trees visit treesaregood.org. 

With appropriate care, planting, and management you will be able to enjoy your tree in the landscape for years to come.

Resources:

Selection and Care of Living Christmas Trees, NC State Extension

2021 Protecting Trees from Sunscald

Landscape & Garden    Treasure Valley

Posted on: November 19, 2021 by Nic Usabel

Sunscald or southwest winter injury happens during the winter. Intense direct and reflected sunlight will activate tissues under the bark. At night, temperatures fall, and cells freeze, causing cell death. This damage is often not noticed for a few years until the bark has split open exposing the damage below. The damaged sites are prone to attack by wood-boring insects and fungal pathogens.

Recently planted trees, young trees, and trees with thin bark are more susceptible to sunscald. Trees species which are susceptible include maple, linden, mountain-ash, honeylocust, birch, walnut, crabapple, flowering cherry, fruit trees, aspen, ash, tuliptree, and willow. 

To prevent sunscald damage from occurring keep the lower trunk insulated or shaded in winter. Susceptible trees can be protected by wrapping the trunk with paper tree wrap, overlapping about 33% with each turn. Wrap trunks upward from the base of the tree to a point just above the lowest branch. Wrap should be removed in early spring after the risk of a hard frost has passed. If not removed the wraps can harbor insects and disease.  Trunks can also be protected by placing a light-colored board to the south and west of the tree trunk. In large applications white latex paint can be diluted 1:1 with water and applied on the southwest side of the lower trunk. Landscape design and planting susceptible trees to the north and east of buildings or evergreens can help to shade the lower trunk. 

References:

• Sunscald of Trees, Colorado State University
• Environmental Injury: Sunscald and Sunburn of Trees, Washington State University
• Sunscald Injury or Southwest Winter Injury on Deciduous Trees, Utah State University

» Sunscald on Tree

2021 Pesticide Fall Recertification Webinar Series

Landscape & Garden    All Locations

Posted on: October 22, 2021 by Nic Usabel

The UI Extension Pesticide Safety Education Program (PSEP) will be conducting 6-webinars on Tuesdays from Nov. 2 - Dec. 14. Completed webinars receive one-pesticide credit*. These webinars are synchronous and held from 10 AM - 11:15 AM (MST). The cost is $10 per applicator/webinar. Enroll now on our UI Marketplace HERE. Check out the details in the attached UIPSEP Fall Recertification Webinars poster. For more information, contact Kimberly Tate at ktate@uidaho.edu.

*For pesticide credit: Pesticide applicators must answer questions throughout the webinar session. This requires individual computer and internet access for each user. Answers will be collected to confirm attendance was maintained for the entire webinar.

2021 Idaho Master Gardener Programs in the Treasure Valley

Landscape & Garden    Treasure Valley

Posted on: October 13, 2021 by Nic Usabel

Interested in becoming an Idaho Master Gardener. See below for program information offered by University of Idaho Extension. 

UI Extension, Ada County (Boise, ID): Be added to the interest list by calling 208-287-5900 or email ada@uidaho.edu indicating your interest in the Idaho Master Gardener Program. Additional information can be found at uidaho.edu/ada.

UI Extension, Canyon County (Caldwell, ID): This location serves Canyon and Owyhee counties. Class to meet weekly Wednesday morning from 9am - noon January 12 – May 4. Be added to the interest list by emailing canyon@uidaho.edu or calling 208-459-6003. Registration packet will be released to interest list mid-October. Additional information can be found at uidaho.edu/canyon. 

UI Extension, Elmore County (Mountain Home, ID): Be added to the interest list for the 2023 class by calling 208-587-2136 ext. 1250 or email elmore@uidaho.edu. Additional information can be found at uidaho.edu/elmore. 

UI Extension, Washington County (Weiser, ID): This location serves the Payette River Valley (Gem, Payette, Washington, Adams counties). Additional information can be found at uidaho.edu/washington or by calling 208-414-0415. 

Don’t see your county listed? Use the Idaho Master Gardener webpage to find all program options across Idaho.

» https://www.uidaho.edu/extension/master-gardener

2021 Fall Lawn Fertilization & Care

Landscape & Garden    Treasure Valley

Posted on: September 15, 2021 by Nic Usabel

University of Idaho turf specialists recommended splitting the application of lawn fertilization into three (3) applications; early May, early September, and late October/November. Review the first reference below to identify fertilization application amounts using a soil test result or the second reference for general recommendations for southern Idaho.  Apply according to label directions. 

If your lawn is suffering from soil compaction or development of a thick thatch layer fall is the optimal time to core aerate.  For more information on core aeration review Core Aeration of Lawns. 

Fall is a great time to control perennial weeds in the landscape if opting to use herbicides. Perennials will begin storing carbohydrates in the roots promoting herbicides to be drawn deeper into the root system and allowing for better control. 

If there are additional questions on lawn care or weed management reach out to a local University of Idaho Extension office. 

Canyon County Master Gardeners are holding an online Fall Perennial Plant Sale. View the inventory selection at https://bit.ly/ccmgstore. 

References: 

• Using Soil Test for Garden Fertilization 
• Southern Idaho Lawns  
• Core Aeration of Lawns 
• Find University of Idaho Extension

2021 Reduce Watering Frequency During Fall

Landscape & Garden    Treasure Valley

Posted on: September 14, 2021 by Nic Usabel

The days are shortening, and evening temperatures are cooling. Now is the time to adjust the frequency between irrigation days for the landscape and garden. 

Lawn irrigation systems can be set to increase the number of days between irrigation based on soil texture. Adjusting the frequency of watering versus the run time allows for replenishment of the water holding capacity and usable water in the soil profile. See publication links below for greater explanation. This deep and infrequent method encourages a deeper root growth of plants. 

A reminder to deep water trees and shrubs prior to shutoff of irrigation water. See our previous alert, 2021 Deep Water Trees & Shrubs.

Canyon County Master Gardeners are holding an online Fall Perennial Plant Sale. View the store today at https://bit.ly/ccmgstore.

Reference:

• Watering Home Lawns and Landscape, University of Idaho
• Watering Home Lawns: How Much and How Often, University of Idaho
• 2021 Deep Water Trees & Shrubs, PNW Pest Alert Network

2021 Deep Water Trees & Shrubs

Landscape & Garden    Treasure Valley

Posted on: August 31, 2021 by Nic Usabel

Many irrigation districts across the Treasure Valley have indicated that water delivery will end early this season. If your irrigation season will end soon consider deep watering your trees and shrubs before irrigation delivery has stopped. 

For established trees irrigate trees starting halfway between the trunk and the dripline  and extending well beyond the dripline. See photo linked below for a visual. For large trees this could encompass the entire lawn. For newly planted trees irrigation is best concentrated near the trunk and slightly beyond the root ball to encourage roots to move out into the surrounding soil. Shrubs can be watered in a similar fashion to ensure the roots of the shrub have received water. Evergreen trees and shrubs will continue to lose moisture from their needles or leaves all winter long.

Consider using mulches on the soil surface to conserve moisture. In addition, it will help with weed control and uniform soil temperature. Keep mulch 2 inches away from tree and shrub stems to discourage root and crown disease. 

References:

• Tree for southwestern Idaho landscapes: Selection & Irrigation, University of Idaho
  
• Watering Home Lawn and Landscapes, University of Idaho

» Tree Dripline Image

2021 Turfgrass Mowing Height & Watering

Landscape & Garden    Treasure Valley

Posted on: June 22, 2021 by Nic Usabel

The weather in the Treasure Valley is warming quickly! 

MOWING

Now is the time to check the mowing height at which your turfgrass is cut. Increasing the length of grass blade encourages a deeper root growth and provides more shade cover of the soil surface reducing water evaporation. 

For summer mowing height Kentucky bluegrass and fine fescue are recommended to be maintained at 3 inches, perennial ryegrass at 2 inches, and tall fescue at 4 inches. Ensure that the mower blade is sharp and follow the one-third rule; remove no more than one-third of the leaf growth each mowing. 

Grass clipping which are left on the lawn by mulching decompose quickly, feed soil organisms, recycle plant nutrients, and increase organic matter in the soil. 

WATERING

The goal of irrigation is to keep the lawn healthy when rainfall is not dependable. The key is to moisten the top 10 inches to 12 inches of the root zone. Watering deeply (10 to 12 inches) but infrequently produces healthy turf. Practicing deep watering reduces weed populations, benefits landscape trees and shrubs, increases water use efficiency, and forces an exchange of soil atmosphere with each irrigation. Early morning is the best time to water. 

Determining how deep irrigation water goes can be done by using a soil probe or shovel to check soil moisture the day after irrigation. At 10 to 12 inches deep the soil should feel slightly damp. If the soil feels dry at the 10- to 12-inch depth increase the duration of water application to fill the root zone. As weather conditions change this fall adjust the frequency of irrigation to maintain plant available water in the root zone. Frequency of irrigation refers to the number of days between each water application.

Identifying or knowing soil type will help to determine the frequency of water application, rate of water infiltration, and the soils water holding capacity. For example, heavy clay soils have a greater water holding capacity, but have a slower infiltration rate (speed at which water enters the soil). These soils can be watered less frequently and may need multiple application of water on day of watering to allow water to move into the soil.  Sandy soils have less water holding capacity and a greater infiltration rate. These soils need to be watered more frequently to maintain comparable turf. 

For a more calculated approach to water application reference the publication links below. 

• Watering Home Lawns: How Much and How Often
• Watering Home Lawns & Landscapes
• Idaho Landscapes & Garden Website: Lawn & Turf

» https://www.extension.uidaho.edu/publishing/pdf/CIS/CIS1157.pdf

» https://www.extension.uidaho.edu/publishing/pdf/CIS/CIS1098.pdf

» https://www.uidaho.edu/extension/garden/landscapes/lawn

2021 Fruit Thinning

Landscape & Garden    Treasure Valley

Posted on: June 2, 2021 by Nic Usabel

Fruits which are crowded should be thinned. Apples, pears,
Asian pears, apricots, plums, and peaches all respond positively to thinning.
Cherries and nut trees are  usually not thinned. Thinning fruit will 1) increase
fruit size, 2) improve the trees  productivity in the year to come, and 3)
reduce limb breakage as fruits begin to  size. Too many fruits on a tree
translates into small fruit that is often of poor quality.

General rules for thinning: 1) The earlier the better, 2)
remove smaller fruits and  leave the larger ones, 3) remove fruits with disease
spots, hail damage, or other  defects, 4) aim for even spacing. 

General guidelines by fruit – see links below for additional
detail.

• Apples & pears:  Almost always need thinning. Should be thinned
  to one  fruit per spur with a good spacing of one fruit per 6” of branch.  Asian pears  spaced at one fruit per 6-8” of branch. Be careful not to break off spurs  while
  thinning – spurs produce flowers and fruit for many years if not  broken.
  Recommend to thin apples within 40 days of full bloom and pears within 60 days
  of full bloom.
• Peaches & nectarines: Should be
  spaced at one fruit per 6-8” of branch.  Fruits that are joined should be
  removed. Recommend to thin peaches  about 70 days past full bloom. 
• Plums: Should be thinned to have
  spacing at 6” between fruit along the  branch.
• Apricots: If tree experiences heavy
  fruit set thin fruit spaced to 3” along  branch.

» https://extension.wsu.edu/maritimefruit/fruit-thinning-for-high-quality/

» http://homeorchard.ucdavis.edu/8047.pdf

2021 Idaho Master Gardener Plant Diagnostic Clinics & Plant Sales

Landscape & Garden    Treasure Valley

Posted on: April 16, 2021 by Nic Usabel

Plant Diagnostic Clinic:

Many University of Idaho Extension offices offer a free plant
diagnostic clinic where certified Idaho Master Gardener volunteers help answer
clientele questions. Here are the details that were shared with the PNW Pest Alert
Network.

• UI Extension, Ada County (Boise, ID): The plant diagnostic clinic
  operates April through September. Ada county residents should contact 208-287-5900
  or email adamg@uidaho.edu with landscape
  and garden questions. For additional details visit https://www.uidaho.edu/extension/county/ada/horticulture.
• UI Extension, Canyon County (Caldwell, ID): The free plant diagnostic
  clinic operates May through September and is staffed Monday and Wednesday 1 PM
  to 4 PM and Friday 9 AM to 12 PM. Canyon county residents should contact 208-459-6003
  or email ccmg@uidaho.edu with landscape
  and garden questions. For additional details visit https://www.uidaho.edu/extension/county/canyon/horticulture.
  

Don’t see your county listed? Use the first link below to
find all county locations in Idaho.

Spring Garden Plant Sale:

• UI Extension, Ada County (Boise, ID): Let’s get growing! The
  University of Idaho Annual Master Gardener Plant Sale will be held Saturday,
  May 1st from 9:00 a.m. to 12:00 p.m., at the Ada County Extension Office, 5880
  Glenwood Street, Boise. Offerings include houseplants, herbs, vegetables, and
  berries, flowering perennials, gardening books, and so much more. Cash or check
  only. Please no early birds. For more information, call the Master Gardeners at
  (208) 287-5900. Come join the fun!
• UI Extension, Canyon County (Caldwell, ID): Searching for
  new plants to add to your garden or landscape? The University of Idaho Canyon
  County Master Gardener Spring Garden Plant Sale will be held on Saturday, April
  24th from 9:00 AM to 1:00 PM, at Canyon County Extension Office, 501 Main
  Street, Caldwell. New this year will be the virtual pre-sale opening Monday,
  April 19 and closing Friday, April 23. Items can be pre-ordered at https://bit.ly/ccmgstore and are available
  for pick up Saturday, April 24 from 9:30 AM to 11:30 AM. Available plants
  include vegetables, herbs, houseplants, succulents, flowering perennials,
  native plants, and so much more. Join in the fun! For More information, call UI
  Extension, Canyon County at (208) 459-6003.

» https://www.extension.uidaho.edu/find.aspx

» https://www.uidaho.edu/extension/county/ada/horticulture

» https://www.uidaho.edu/extension/county/canyon/horticulture.

» Ada MG Plant Sale

» Canyon MG Plant Sale

2021 Rose & Grapevine Pruning

Landscape & Garden    Treasure Valley

Posted on: April 2, 2021 by Nic Usabel

It’s time to prune roses and grapevines in the Treasure Valley. The cold temperatures are milder, and the forsythia is in full bloom.

ROSES:
For a guide to pruning roses click the first link below. For a video tutorial click the second link below.

GRAPEVINES:
The University of Idaho Research & Extension Center in Parma recommends pruning grapevines in the Treasure Valley no sooner than mid-March to ensure that low temperatures do not kill buds after pruning. Grapevines can “bleed”, movement of sap from the cut, heavily when pruned in spring. This does not harm the vines. For a pruning guide on grapevines click the third link below. For a video tutorial click the fourth link below.

Additional sources not provided in the links below include Grapevine Management from Utah State University at https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=2672&context=extension_curall and Pruning Roses from Colorado State University at https://planttalk.colostate.edu/topics/trees-shrubs-vines/1763-pruning-roses/.

For additional questions on rose or grapevine pruning reach out to a local University of Idaho Extension office. Find your county office by visiting https://www.extension.uidaho.edu/find.aspx.

» https://extension.umd.edu/hgic/topics/guide-pruning-roses

» https://youtu.be/xTlrYSmSFZw

» https://www.extension.iastate.edu/news/yard-and-garden-how-prune-grapevines

» https://youtu.be/VE5Aw9Wn5F4

2021 Mosquito Management Webinar

Landscape & Garden    Treasure Valley

Posted on: March 29, 2021 by Nic Usabel

A free virtual webinar titled "Mosquito Management: An Integrated Approach" will be hosted by University of Idaho Extension, Canyon County on Tuesday, April 13 2021 at 6 PM MDT.

In this webinar James Lunders, District Director for Canyon County Mosquito Abatement District, will discuss control of larval and adult mosquitos, surveillance of mosquito borne diseases, and how to protect yourself, pets, and livestock.

Registration should be completed at https://bit.ly/2Cmosquito

To see the flyer visit http://bit.ly/2QosdEE

» https://bit.ly/2Cmosquito

» http://bit.ly/2QosdEE

2021 Spring Lawn Fertilization & Care

Landscape & Garden    Treasure Valley

Posted on: March 15, 2021 by Nic Usabel

Spring lawn fertilization for cool season grasses recommend that fertilization be made while energy is being directed to root growth, which follows with leaf growth. This timeframe for cool season turf in the Treasure Valley traditionally March thru early May. If mulching is a practice in your lawn maintenance plan, nitrogen can be reduced by ½ pound annually. Attend a “Lawn Care for Success” class to learn more about maintenance, fertilization, and watering. Click the link https://bit.ly/21Lawn2C to register for the class.

The proper rate of fertilizer application is best achieved when using a soil test result to identify the fertilizer needs of the soil. Use the second link below to access a publication to help calculate rate of fertilizer application for the lawn. Applications should be split between spring and fall. Application rates should not exceed 1 pound of nitrogen per 1,000 square feet in any one application, access the third link below to review the publication to identify additional time(s) for application if rate would exceed the 1 pound of nitrogen per 1,000 square feet limit with only and spring and fall application. Always follow label directions.

For more information on how to obtain a soil sample to a soil test submission contact your local University of Idaho Extension office. Contact information can be found at https://www.extension.uidaho.edu/find.aspx

Another method of identifying application rate is based on the level of turf maintenance from low to high traffic. Application rates should not exceed 1 pound of nitrogen per 1,000 square feet in any fertilizer application and always follow label directions. Review descriptions, timing, and rate of application below.

1. Light use is classified as occasional foot traffic or little to no play from children. Annual turfgrass recommendation is 0-1 pound of nitrogen per 1,000 square feet. Split the application between a spring and fall application.

2. Moderate Use: Typical children’s play and occasional garden parties. Annual turfgrass recommendation is 2-3 pounds of nitrogen per 1,000 square feet. Split the application equally between a spring, early fall (late September) and late fall (Mid October to Late November)

3. Heavy Use: Frequently used sports field play, heavy traffic and/or frequent garden parties. Annual turfgrass recommendation is 4-6 pounds of nitrogen per 1,000 square feet. Apply 1 pound of nitrogen per 1,000 square feet in spring, 0.5 pound of nitrogen per 1,000 square feet late May/early June, 0.5 pound of nitrogen per 1,000 square feet late June/early July, 1 pound of nitrogen per 1,000 square feet early fall (late September) and 1 pound of nitrogen per 1,000 square feet late fall (Mid October to Late November).

If your lawn is suffering from soil compaction or development of a thick thatch layer core aeration can be completed in the spring but is preferred in fall while weed pressure will be reduced. For more information on core aeration reference the fourth publication link below.

Spring provides the opportunity to seed new turfgrass areas or to over-seed areas that may have been damaged over the winter. Cool temperatures will promote germination and growth of cool season turf species, tall and fine fescues, perennial ryegrass, and Kentucky bluegrass. Weed pressure can be higher this time of year so consider your weed control options or consider overseeding in the fall. Select pest resistant or recommended turfgrass cultivars when possible.

If there are additional questions on lawn care or weed management reach out to a local University of Idaho Extension office.

» https://bit.ly/21Lawn2C

» https://www.extension.uidaho.edu/publishing/pdf/CIS/CIS1182.pdf

» https://www.extension.uidaho.edu/publishing/pdf/CIS/CIS0846.pdf

» https://www.extension.uidaho.edu/publishing/html/BUL964-Core-Aeration-of-Lawns.aspx?title=Search&category1=Search&category2=NULL

2021 Peach Leaf Curl Delayed-Dormant Spring Application

Landscape & Garden    Treasure Valley

Peach leaf curl (Taphrina deformans)

Posted on: February 6, 2021 by Nic Usabel

If you experienced peach leaf curl on peach or nectarine trees during the 2020 growing season and did not treat in the fall a delayed-dormant application before floral buds open is recommended to help with control.

DESCRIPTION: Peach leaf curl caused by fungus Taphrina deformans and is specific to peaches and nectarines. Trees that are infected will have leaves that are distorted or curl, appear blistered, and develop a yellow or red color.

CONTROL: Spray with an approved fungicide such as lime sulfur or copper-based fungicide. More chemical options listed by viewing the PNW handbook link below. Apply according to label directions and instructions. Cultural control for backyard growers includes removal of infected leaves that have fallen and selecting resistant cultivars.

If you have additional questions, contact your local University of Idaho Extension office at https://www.extension.uidaho.edu/find.aspx.

» https://pnwhandbooks.org/plantdisease/host-disease/peach-prunus-persica-leaf-curl

» https://www.extension.uidaho.edu/find.aspx

2021 Pruning Deciduous Trees & Shrubs

Landscape & Garden    Treasure Valley

Posted on: January 30, 2021 by Nic Usabel

It is time to prune deciduous trees (landscape & fruit) and shrubs. As a general guide remove no more than one-third of the tree when pruning. Reference the first and third link for pruning deciduous trees and for a video reference the fourth link. Reference the second link for fruit trees.

Prune shrub species which grow on the current season’s growth during the dormant period, usually late winter early spring. A few examples of flowering shrubs in this grouping including butterfly bush, heather, heavenly bamboo, hydrangea, shrubby roses and rose of sharon. Reference the third link for more information.

For shrub species which form buds on last season’s growth prune these species within about two months after the flowers fade. On these species, flower buds form in late summer and early fall. Winter pruning decreases the number of flowers the following spring as branches containing flower buds are removed. A few examples of flowering shrubs in this grouping include azaleas, lilac, magnolia, mockorange, serviceberry, and witchhazel. Reference the third link for more information.

For most areas of Idaho, plants that bloom before June 1 formed the flowers the previous year on old wood. Those that bloom after June 1 form flowers on new growth. Keep in mind that this is only a rough guideline.

For classes on pruning in the Treasure Valley see the attached file.

If you have additional questions, contact your local UI Extension office. To search by county visit https://www.extension.uidaho.edu/find.aspx

» https://extension.arizona.edu/sites/extension.arizona.edu/files/pubs/az1139-2015.pdf

» https://catalog.extension.oregonstate.edu/pnw400/html

» https://www.extension.purdue.edu/extmedia/HO/HO-4-W.pdf

» https://youtu.be/mF8N1thnpn8

» Treasure Valley Parks & Recreation Classes

2020 Idaho Master Gardener Programs in the Treasure Valley

Landscape & Garden    Treasure Valley

Posted on: September 25, 2020 by Nic Usabel

Interested in becoming an Idaho Master Gardener. See below for program information coming near you.

UI Extension, Ada County (Boise, ID): Currently has waiting list for class. Additional information can be found at uidaho.edu/ada or by calling 208-287-5900.

UI Extension, Canyon County (Caldwell, ID): This location serves Canyon and Owyhee counties. Class to meet weekly Wednesday morning from 9am - noon January – April. Registration to open October 1st. Additional information can be found at uidaho.edu/canyon or by calling 208-459-6003.

UI Extension, Elmore County (Mountain Home, ID): Class to meet weekly Saturday from 10am – 2pm January – April. Registration open now. Additional information can be found at uidaho.edu/elmore or by calling 208-587-2136 ext. 1250

UI Extension, Washington County (Weiser, ID): This location serves the Payette River Valley (Gem, Payette, Washington, Adams counties). Additional information can be found at uidaho.edu/Washington or by calling 208-414-0415.

Don’t see your county listed? Use the link below to find all program options in Idaho.

» https://www.uidaho.edu/extension/master-gardener/course

2020 Brown Marmorated Stink Bug

Landscape & Garden    Treasure Valley

Brown Marmorated Stink Bug (Halyomorpha halys)

Posted on: September 23, 2020 by Nic Usabel

The Brown Marmorated Stink Bug (BMSB) is an invasive insect pest from eastern Asia. Its first North America detection was in Pennsylvania in 1996. BMSB adults were first discovered in Canyon County in May 2012 and in Ada County in October 2014. This year a location with traps adjacent to orchards in Canyon and Payette counties participating in the SCRI nationwide survey has collected five (5) BMSB in two subsequent weeks.

If you believe you have found BMSB in Idaho take a specimen to your local Extension office or contact the Idaho State Department of Agriculture’s Pest Survey Program at (208) 332-8627.

BMSB has a shield-shaped body with mottled brownish-grey coloration. The adults are just over ½ inch long, and their antennae are marked with distinctive white bands. The insect’s underside is white with gray or black markings, and its legs are brown with faint white banding. Unlike most native stink bugs, BMSB has smooth “shoulders”. BMSBs have distinctive black and white “skirting” around their abdomens that protrudes from under the wings. See image.

BMSB has a broad host range that includes fruit, vegetable, ornamental, and field crop plants. The insect has a mouthpart for piercing and sucking plant sap and prefers fruits and seeds pods (reproductive structures). In Utah, the catalpa tree has shown the greatest numbers during detection and assessment of invasion risk.

» https://static1.squarespace.com/static/564b8c9ae4b0459b2b8187a3/t/5a31652a9140b743f5a90bea/1513186603464/BMSB+Fact+Sheet+December_2014.pdf

» https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=2785&context=extension_curall

» https://extension.psu.edu/brown-marmorated-stink-bug

» Brown Marmorated Stink Bug

2020 Master Gardener Fall Perennial Plant Sale

Landscape & Garden    Treasure Valley

Posted on: September 11, 2020 by Nic Usabel

Canyon County Master Gardeners are holding a Fall Perennial Plant Sale. Orders can be placed online now, see first link below, and picked up curbside Saturday, September 19th from 9 AM – Noon at the UI Extension, Canyon County location at 501 Main St. Caldwell, ID 83605.

For additional information reference the flyer link below or call UI Extension, Canyon County at 208-459-6003.

» https://canyon-county-master-gardeners.square.site/

» http://bit.ly/2CFallGardenSale

2020 Fall Lawn Fertilization & Care

Landscape & Garden    Treasure Valley

Posted on: September 10, 2020 by Nic Usabel

For lawns, University of Idaho turf specialists recommend splitting fertilizer into three (3) applications early May, early September, and later October/November. Reference the publications linked below to identify fertilization amounts using soil test results (first publication link) or general recommendations for southern Idaho (second publication link). Apply fertilizer following label directions.

If your lawn is suffering from soil compaction or development of a thick thatch layer fall is the optimal time to core aerate. For more information on core aeration reference the third publication link below.

Fall is a great time to control perennial weeds in the landscape if opting to use herbicides. Perennials will begin storing carbohydrates in the roots promoting herbicides to be drawn deeper into the root system and allowing for better control.

If there are additional questions on lawn care or weed management reach out to a local University of Idaho Extension office.

» https://www.extension.uidaho.edu/publishing/pdf/CIS/CIS1182.pdf

» https://www.extension.uidaho.edu/publishing/pdf/CIS/CIS0846.pdf

» https://www.extension.uidaho.edu/publishing/html/BUL964-Core-Aeration-of-Lawns.aspx?title=Search&category1=Search&category2=NULL

2020 Reduce Watering Frequency During Fall

Landscape & Garden    Treasure Valley

Posted on: September 9, 2020 by Nic Usabel

The days are shortening, and evening temperatures are cooling. Now is the time to adjust the frequency between irrigation days for the landscape and garden.

Lawn irrigation systems should be set to increase the number of days between irrigation according to soil texture. Adjusting the frequency of watering versus the run time allows for replenishment of the water holding capacity and usable water in the soil profile (see publication link one or two below). This deep and infrequent method encourages deeper root growth of plants.

Also consider a deep watering for trees and shrubs at the drip line (see third publication link) prior to irrigation water being turned off. Evergreen trees and shrubs will continue to lose moisture from their needles or leaves all winter long.

» https://www.extension.uidaho.edu/publishing/pdf/CIS/CIS1098.pdf

» https://www.extension.uidaho.edu/publishing/pdf/CIS/CIS1157.pdf

» https://www.extension.uidaho.edu/publishing/html/BUL884-Trees-for-Idaho-landscapes.aspx?title=Search&category1=Search&category2=NULL#Watering

Pesticide Math Online Training

Landscape & Garden    Treasure Valley - Idaho

Posted on: August 17, 2020 by Nic Usabel

The UI Extension Pesticide Safety Education Program has produced three educational online training courses available for pesticide applicators, Master Gardeners, and homeowners. The Calculate Pesticides series includes real-world pesticide calculations in the following courses:

1) General Math – review basic math concepts needed for calculating pesticides.
2) Using Sprayers – develop math skills for calibrating yourself to application equipment.
3) Application Rates – identify the math formulas necessary to calculate pesticide application rates.

Simply, create your account at the National eXtension website by using this address https://campus.extension.org/course/view.php?id=1588 (also linked below). Each user must have their own identification name and password. Once you confirm your free account, you will have unlimited access to these online educational materials. If you have any questions, please contact Kimberly Tate at ktate@uidaho.edu.

» https://campus.extension.org/course/view.php?id=1588

2020 Turfgrass Mowing Height & Watering

Landscape & Garden    Treasure Valley

Posted on: July 7, 2020 by Nic Usabel

MOWING
The weather will be warming and now is the time to check the mowing height at which your turfgrass is cut. Increasing the length of grass blade encourages a deeper root growth and provides more shade cover of the soil surface reducing water evaporation.

For summer mowing height Kentucky bluegrass and fine fescue are recommended to be maintained at 3 inches, perennial ryegrass at 2 inches, and tall fescue at 4 inches. Ensure that the mower blade is sharp and follow the one-third rule; remove no more than one-third of the leaf growth each mowing.

Grass clipping which are left on the lawn by mulching decompose quickly, feed soil organisms, recycle plant nutrients, and increase organic matter in the soil.

WATERING
The goal of irrigation is to keep the lawn healthy when rainfall is not dependable. The key is to moisten the top 12 inches of the root zone. Watering deeply (10 to 12 inches) but infrequently produces healthy turf. Practicing deep watering reduces weed populations, benefits landscape trees and shrubs, increases water use efficiency, and forces an exchange of soil atmosphere with each irrigation. Early morning is the best time to water.

Determining how deep irrigation water goes can be done by using a soil probe or shovel to check soil moisture the day after irrigation. At 10 to 12 inches deep the soil should feel slightly damp. If the soil feels dry at the 10- to 12-inch depth increase the duration of water application to fill the root zone. As weather conditions change adjust the frequency of irrigation to maintain plant available water in the root zone.

Identifying or knowing soil type will help to determine the frequency of water application, rate of water infiltration, and the soils water holding capacity. For example, heavy clay soils have a greater water holding capacity, but have a slower infiltration rate (speed at which water enters the soil). These soils can be watered less frequently (once a week or less) and may need multiple application of water on day of watering to allow water to move into the soil. Sandy soils have less water holding capacity and a greater infiltration rate. These soils need to be watered more frequently to maintain comparable turf.

For a more calculated approach to water application reference the publication links below.

» https://www.extension.uidaho.edu/publishing/pdf/CIS/CIS1098.pdf

» https://www.extension.uidaho.edu/publishing/pdf/CIS/CIS1157.pdf

» https://www.uidaho.edu/extension/garden/landscapes/lawn

2020 Fruit Thinning

Landscape & Garden    Treasure Valley

Posted on: June 11, 2020 by Nic Usabel

Fruits which are crowded should be thinned. Apples, pears, Asian pears, apricots, plums, and peaches all respond positively to thinning. Cherries and nut trees are usually not thinned. Thinning fruit will 1) increase fruit size, 2) improve the trees productivity in the year to come, and 3) reduce limb breakage as fruits begin to size. Too many fruits on a tree translates into small fruit that is often of poor quality.

General rules for thinning: 1) The earlier the better, 2) remove smaller fruits and leave the larger ones, 3) remove fruits with disease spots, hail damage, or other defects, 4) aim for even spacing.

General guidelines by fruit – see links below for additional detail.

Apples & pears: Almost always need thinning. Should be thinned to one per spur with a good spacing of one fruit per 6” of branch. Asian pears spaced at one fruit per 6-8” of branch. Be careful not to break off spurs while thinning – spurs produce flowers and fruit for many years if not broken. Recommend to thin apples within 40 days of full bloom and pears within 60 days of full bloom.

Peaches & nectarines: Should be spaced at one fruit per 6-8” of branch. Fruits that are joined should be removed. Recommend to thin peaches about 70 days past full bloom.

Plums: Should be thinned to have spacing at 6” between fruit along the branch.

Apricots: If tree experiences heavy fruit set thin fruit spaced to 3” along branch.

If you are new to the orchard, know that trees will exhibit “June Drop” which is when the tree will naturally drop fruit. Some prefer to wait until this event happens to thin, however there are great advantages to thinning early. More details can be found in the links below.

» https://extension.wsu.edu/maritimefruit/fruit-thinning-for-high-quality/

» https://extension.oregonstate.edu/gardening/berries-fruit/fruit-thinning

» Thinning Young Fruit

2020 Master Gardener Plant Giveaway - Donations Accepted

Landscape & Garden    Treasure Valley

Posted on: April 17, 2020 by Maria Held

Canyon County Master Gardeners are holding a Spring Plant Giveaway at Canyon Springs 1444 Cornell St, Middleton, and Fujishin Winery 15593 Sunny Slope Rd, Caldwell on Saturday April 25th from 9 AM to 1 PM.

Donations are appreciated and can be left at each neighborhood site in the donation jar.
Master Gardeners will not be available to interact with the public, but resource materials will be provided.
Please take only the plants that you will use.
Practice Social Distancing.
For variety information please use the link below.

» https://bit.ly/PlantGiveawayLocation

Free Victory Garden Class 2020

Landscape & Garden    Treasure Valley

Posted on: April 9, 2020 by Maria Held

Are you or people you know thinking about starting or expanding your garden? University of Idaho Extension has updated and opened this online course for free public access for the rest of the year. This popular, family-friendly program is packed with instructional videos, activities, readings and more to help you grow, eat, and preserve food at home, while saving money! This program was created with love for our Idaho communities and gardeners, please share. http://bit.ly/IDVictoryGarden

» http://bit.ly/IDVictoryGarden

» Victory_Garden_class_photo.jpg

2020 Peach Leaf Curl Delayed Dormant Spring Application

Landscape & Garden    Treasure Valley

Posted on: March 5, 2020 by Nic Usabel

If you experienced peach leaf curl during the 2019 growing season, a delayed dormant application before floral buds open is recommended. Spray with an approved copper-based fungicide at the rate listed on the product.

Selecting resistant cultivars offer the best option for backyard growers.

» https://pnwhandbooks.org/plantdisease/host-disease/peach-prunus-persica-leaf-curl