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2021 Hard Frost Forecasted
General Landscape and Garden Treasure Valley
Posted on: March 29, 2021 by Ruth Givens
Hard frost is forecasted for Monday 3/29 and Tuesday 3/30 nights. If fruit trees are blooming cover to protect fruit. Uncover during the day. For more details see the link below.
» https://www.extension.iastate.edu/smallfarms/frost-protection-high-density-orchards
2021 Mosquito Management Webinar
General Landscape and 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
2021 Spring Lawn Fertilization & Care
General Landscape and 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://www.extension.uidaho.edu/publishing/pdf/CIS/CIS1182.pdf
» https://www.extension.uidaho.edu/publishing/pdf/CIS/CIS0846.pdf
2021 Peach Leaf Curl Delayed-Dormant Spring Application
General Landscape and 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
2021 Pruning Deciduous Trees & Shrubs
General Landscape and 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
2021 Delayed-Dormant Oil Application
General Landscape and Garden Treasure Valley
Posted on: January 30, 2021 by Nic Usabel
The use of horticultural oil as a dormant spray can target many insect pests at a time when beneficial insects are not yet active. Even though we refer to it as dormant oil, the application is not when trees are still dormant. A better term is a delayed-dormant application because the oil should be applied after bud swell. This coincides with the increasing activity of the overwintering insect stages, such as aphid eggs, scale nymphs, and peach twig borer larvae.
WHEN TO SPRAY: Two factors must correspond – temperature and bud stage.
TEMPERATURE: Only apply oil if temperatures remain above 40°F for 24 hours after application. With ideal conditions oil should be applied 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 first link below for pictures of bud stage.
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 second link for chemical products listed by pest. Read and follow label instructions for preparation and application.
If you have additional questions, contact your local UI Extension office. Reference the third link to search by county.
» https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=1643&context=extension_curall
» https://www.extension.uidaho.edu/find.aspx
» https://extension.colostate.edu/topic-areas/insects/insect-control-horticultural-oils-5-569/
2020 Protecting Trees from Sunscald
General Landscape and Garden Treasure Valley
Posted on: November 18, 2020 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 percent 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.
Have you completed the annual survey for the Landscape & Garden section of the PNW Pest Alert Network? Complete the survey by November 20th to be entered into a drawing for an Amazon gift card. See link 3 below to access the survey.
» http://pubs.cahnrs.wsu.edu/publications/wp-content/uploads/sites/2/publications/fs197e.pdf
» https://uidaho.co1.qualtrics.com/jfe/form/SV_3KvC6BV1KQ4zSPr
2020 Fall Control for Coryneum Blight & Peach Leaf Curl
General Landscape and Garden Treasure Valley
Coryneum blight (Thyrostroma carpophilum) & Peach leaf curl (Taphrina deformans)
Posted on: October 28, 2020 by Nic Usabel
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.
» https://pnwhandbooks.org/plantdisease/host-disease/peach-prunus-persica-leaf-curl
» https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=1736&context=extension_curall
» https://pnwhandbooks.org/plantdisease/host-disease/peach-prunus-persica-shothole
» http://ipm.ucanr.edu/PMG/GARDEN/FRUIT/DISEASE/shothole.html
2020 Frost Alert
General Landscape and Garden Treasure Valley
Posted on: October 14, 2020 by Nic Usabel
Many locations across the Treasure Valley could experience a frost this evening. To review more details about frost tolerance for common vegetables view the first link below. To understand more about cold weather and frost protection reference the second link.
Have you enjoyed landscape and garden insect pest alerts this season? If so, consider donating to the “2C Master Gardener: Growing Skills & Expertise for Local Outreach” crowdfunding campaign by clicking the third link. Master Gardener volunteers in Canyon County help to monitor and report insect pests to the PNW Pest Alert Network. A donation of $5 will help maintain one trapping station for the upcoming year.
» https://extension.sdstate.edu/fall-frost-tolerance-common-vegetables
» https://extension.arizona.edu/sites/extension.arizona.edu/files/pubs/az1002.pdf
2020 Idaho Master Gardener Programs in the Treasure Valley
General Landscape and 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.
2020 Brown Marmorated Stink Bug
General Landscape and 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://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=2785&context=extension_curall
2020 Master Gardener Fall Perennial Plant Sale
General Landscape and 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.
2020 Fall Lawn Fertilization & Care
General Landscape and 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
2020 Reduce Watering Frequency During Fall
General Landscape and 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
2020 Apple Codling Moth, Third Generation
General Landscape and Garden Treasure Valley
Codling Moth Cydia pomonella
Posted on: August 27, 2020 by Nic Usabel
The third generation of codling moth egg hatch has begun. Current degree day models indicate 2168 DD as of August 26. Third generation egg hatch begins at 2160-2200 DD.
Continue to keep fruit protected through approximately September 15. Protection of fruit can stop after that time, even if fruit has not been harvested. By mid-September there is not enough day length to signal n eggs in the fruit to hatch.
Follow label directions for harvest or post-harvest requirements.
» 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/
2020 Blossom-End Rot
General Landscape and Garden Treasure Valley - Idaho
Blossom-end rot
Posted on: August 19, 2020 by Nic Usabel
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://pnwhandbooks.org/plantdisease/host-disease/tomato-solanum-lycopersicum-blossom-end-rot
» https://utahpests.usu.edu/ipm/notes_ag/veg-blossom-end-rot
» https://vegetableguide.usu.edu/diseases/tomato-pepper-eggplant/blossom-end-rot
Pesticide Math Online Training
General Landscape and 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.
2020 Blossom Drop on Tomatoes and Peppers
General Landscape and Garden Treasure Valley
Blossom Drop
Posted on: August 3, 2020 by Nic Usabel
Blossom drop during this time of year is generally associated with temperature changes. Pollen becomes sterile during hot weather. Blossom drop and/or lack of fruit set can also be caused by too much nitrogen and water stimulating leaf growth over fruit set.
Tomatoes will experience blossom drop when evening temperature drop below 55 degrees or daytime temperatures exceed 90 degrees for an extended period. Cherry type tomatoes can set fruit over a wider range of temperatures as compared to larger fruited types.
Pepper blossoms are found to be more sensitive to temperature fluctuations during the stage of pollination. Blossoms can fall off before pollination when temperatures fall below 58 degrees and daytime temperatures rise above 85 degrees.
Remember that deep and infrequent watering is best.
» https://extension.oregonstate.edu/news/why-vegetables-drop-blossoms
2020 Peach Twig Borer, Second Generation
General Landscape and Garden Treasure Valley
Peach Twig Borer (Anarsia lineatella)
Posted on: July 24, 2020 by Nic Usabel
The second generation of peach twig borer will begin egg hatch today. Current degree day models indicate 1182 as of July 23. Second generation cover sprays begin at 1200 DD, currently forecasted for today. First cover sprays for second generation should be applied now.
For management control options review the PNW Handbook link below to select a control option appropriate for the operation. Apply according to label directions.
» https://pnwhandbooks.org/insect/tree-fruit/peach-nectarine/peach-nectarine-peach-twig-borer
» https://climate.usu.edu//includes/pestFactSheets/Peach-Twig-Borer.pdf
2020 Apple Codling Moth, Second Generation
General Landscape and Garden Treasure Valley
Codling Moth (Cydia pomonella)
Posted on: July 14, 2020 by Nic Usabel
The second generation of codling moth will begin egg hatch this week. Current degree day models report 1072 DD as of July 12. Beginning egg hatch begins at 1100 DD, currently forecasted for July 14.
Rotate among insecticide classes between generations to prevent development of insecticide resistance. 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/
2020 Squash Bug
General Landscape and Garden Treasure Valley
Squash Bug (Anasa tristis)
Posted on: July 8, 2020 by Nic Usabel
Squash bugs have been reported in Canyon County by an Idaho Master Gardener and University of Idaho personnel. It is time to check the underside of cucurbit (pumpkins and squash are most attractive) leaves for the bronze colored egg clusters. In addition, monitor plants for nymphs, adults and plants wilting.
MANAGEMENT
Wooden boards, shingles, or heavy cardboard can be placed on the ground next to the host plant. Squash bugs tend to move under the board/object at night. In the morning, turn the boards over and destroy the pest.
Hand-pick and destroy adults, nymphs, or egg clusters. Other options include rolled duct tape around fingers to pull off egg clusters, cutting off the egg part of the leaf or applying petroleum jelly directly to the eggs. Increased success is achieved when started early in the season and done every 2 to 3 days to keep numbers low.
Cultural methods include sanitation, plating squash varieties that are more tolerant of squash bug feeding, crop rotation, and time of planting.
Additional control methods can be found in the publications linked below.
» https://pnwhandbooks.org/insect/vegetable/vegetable-pests/common-vegetable/vegetable-crop-squash-bug
» https://extension.usu.edu/juab/ou-files/ENT-120-08.pdf
2020 Turfgrass Mowing Height & Watering
General Landscape and 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
2020 Fire Blight on Ornamental Trees
General Landscape and Garden Treasure Valley
Caused by bacterium Erwinia amylovora
Posted on: July 1, 2020 by Nic Usabel
Spring conditions have amplified the effects of fire blight bacterium in not only pear fruit and apple fruit, but ornamental plants in the Rose family. Plants which may show damage include crabapple, flowering pear, pyracantha, hawthorn, cotoneaster, mountain ash, and other related plants. Current observations note widespread affects in the ornamental apples and ornamental pears.
Damage is typically noticed when twigs wilt and die. The tip of the plant growth exhibits a shepherd’s crook. Symptoms seen later in the season include progressive wilting of the branch as the bacterial canker advances down the stem.
For cultural control immediately prune out and destroy infected tissues. Make pruning cuts at least 6-8 inches below the infected tissues. Sterilize pruning tool(s) between cuts using 70% alcohol or 10% bleach solution.
Other control methods to reduce inflammation of fire blight are to avoid over fertilizing with nitrogen, to not sprinkle irrigate susceptible plants, and inspect plants carefully for cankers or blighted twigs during dormancy.
The best management of fire blight is to select ornamental trees which are resistant to the bacterium. Reference the Pacific Northwest Handbook links below for additional information.
https://pnwhandbooks.org/plantdisease/cultivar-tables/crabapple-cultivar-susceptibility
» https://pnwhandbooks.org/plantdisease/host-disease/pyracantha-firethorn-fire-blight
» https://pnwhandbooks.org/plantdisease/host-disease/hawthorn-crataegus-spp-fire-blight
» https://pnwhandbooks.org/plantdisease/host-disease/mountain-ash-sorbus-spp-fire-blight
» https://pnwhandbooks.org/plantdisease/host-disease/crabapple-malus-spp-fire-blight
2020 Fruit Thinning
General Landscape and 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
2020 Peachtree Borer
General Landscape and Garden Treasure Valley
Peachtree Borer (Synanthedon exitiosa)
Posted on: June 10, 2020 by Nic Usabel
Peachtree bores have been caught in traps, maintained by Idaho Master Gardeners, in Middleton and Nampa. 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.
» https://pnwhandbooks.org/insect/tree-fruit/peach-nectarine/peach-nectarine-peachtree-borer
» https://extension.colostate.edu/topic-areas/insects/peach-tree-borer-5-566/
