Landscape & Garden Alerts

2020 Peach Twig Borer

General Landscape and Garden    Treasure Valley

Peach Twig Borer (Anarsia lineatella)

Posted on: June 4, 2020 by Nic Usabel

Management of the peach twig borer, based on degree days and trap catches, will take place June 5 – June 10. 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

» Flagging cause by borer

2020 Western Cherry Fruit Fly - ISDA

Tree Fruits    Treasure Valley

Western Cherry Fruit Fly (Rhagoletis indifferens)

Posted on: May 29, 2020 by Paul Castrovillo, Ph.D.

On May 28 the first 2020 Western Cherry Fruit Fly captured in an Idaho State
Department of Agriculture WCFF trap was reported from Canyon County.
Historically we expect to find WCFF in Gem County traps about a week after
the first one is found in Canyon County.

Online phenology and degree-day models for WCFF predicted first flight on
May 24 in Ontario, May 27 in Caldwell and Emmett, May 28 in Parma and Boise
and May 30 in Nampa.

If treatment for WCFF is not already underway it should begin now.

For more information contact Paul Castrovillo at
paul.castrovillo@isda.idaho.gov or call 208-332-8627.

2020 Sequoia Pitch Moth in Pines

General Landscape and Garden    Treasure Valley

Sequoia Pitch Moth in Pines (Synanthedon sequoia)

Posted on: May 28, 2020 by Nic Usabel

The sequoia pitch moth (SPM) has been found in traps. Austrian pine, scotch pine, and other ornamental pines serve as host for the SPM. Primarily found in the truck and large branches where larvae feed on cambium tissue and sapwood. Larvae are found within large resin masses on bark or in a bark notch behind the resin mass.

Damage is primarily aesthetic causing unsightly resin masses on trees. Some trees may experience limb dieback, tree stress or tree death in severe cases. Trees under attack are almost always previously stressed.

There are no recommended insecticide control options for SPM. Management is gained with cultural control; properly plant and keep trees healthy, pick resin masses from the tree and crush larvae within. Avoid pruning or injuring trees April through August while adults are active.

» http://ipm.ucanr.edu/PMG/PESTNOTES/pn7479.html

» https://utahpests.usu.edu/ipm/ornamental-pest-guide/arthropods/wood-borers/sequoia-pitch-moth

» Sequoia Pitch Moth in Pines

2020 Western Cherry Fruit Fly

General Landscape and Garden    Treasure Valley

Western Cherry Fruit Fly (Rhagoletis indifferens)

Posted on: May 22, 2020 by Nic Usabel

A western cherry fruit fly sample was identified during the University of Idaho Extension, Canyon County Master Gardener plant clinic on May 22. 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. Follow label directions for application. For additional control options see the links below.

Current models indicate the degree days, as of May 21, between 1007 DD and 1030 DD depending on location. Forecasted degree days at 1060 DD is predicted to be May 24.

» 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

2020 Leafminer in Leafy Greens

General Landscape and Garden    Treasure Valley

Leafminer (Liriomyza spp.)

Posted on: May 14, 2020 by Nic Usabel

The leafminer (Liriomyza spp.) can be destructive to beets, spinach, chard, and other leafy greens. Leafminer describes the larval stage of various insects but are most commonly those that feed on vegetables. The adults are small black to gray flies with yellow markings in order Diptera.

Leafminer larvae form visible tunnels (mines) as they feed within the leaf tissue affecting the market value of vegetables harvested for edible foliage. Larvae are nearly translucent white or yellow color and about 0.25 inch long when mature.

To control regularly check leaves for mines which are sometimes more visible on the underside. For home gardeners using floating row covers to exclude egg-laying females, removing and destroying infested leaves and preserving natural enemies (parasitic wasps) which help control leafminer populations. See links for additional management options for home and commercial use.

» https://pnwhandbooks.org/insect/vegetable/vegetable-pests/hosts-pests/spinach-leafminer

» https://pnwhandbooks.org/insect/vegetable/vegetable-pests/hosts-pests/beet-table-leafminer

» https://pnwhandbooks.org/insect/vegetable/vegetable-pests/hosts-pests/chard-swiss-leafminer

» Leafminer in Chard

» Leafminer in Beet

» Exposed leafminer larvae

2020 Peach Leaf Curl Detected

General Landscape and Garden    Treasure Valley

Peach Leaf Curl (Taphrina deformans)

Posted on: May 4, 2020 by Nic Usabel

The Master Gardeners operating the University of Idaho Extension, Canyon County plant diagnostic clinic have identified samples of peach leaf curl. Peach leaf curl is caused by a fungus (Taphrina deformans) and there are no management options after infection has set in. Dispose of symptomatic leaves which fall to the ground. Control can be achieved in the fall with a single application of fungicides after 90% of leaves have fallen. A follow-up alert with control options will be sent in the fall.

Spores of this fungus overwinter on bark, twigs, and old infected leaves. Infection occurs through bud scales in mid- to late winter just as buds begin to swell. Slow growing shoots and leaves can be infected during cool and wet growing seasons. Maximum susceptibility is between bud break and petal fall.

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

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

» peach leaf curl1

» peach leaf curl2

» peach leaf curl3

2020 Lilac-Ash Borer

General Landscape and Garden    Treasure Valley

Lilac-Ash Borer Podosesia syringae

Posted on: April 29, 2020 by Nic Usabel

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 been caught in traps. 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 5, 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

Fall and Winter Watering

Landscape and Garden    All Locations

Posted on: November 18, 2019 by Maria Held

With no rainfall for a few weeks and none in the forecast make sure to water you landscape at least one more time before winter. It is important for anything planted this year especially trees and shrubs. This will give your plants the best possible start next spring and make them less susceptible to pests and diseases.

» https://extension.colostate.edu/topic-areas/yard-garden/fall-and-winter-watering-7-211/

Fall spray for shothole disease and peach leaf curl

Landscape and Garden    Treasure Valley

Coryneum blight (shothole disease), Taphrina deformans (peach leaf curl)

Posted on: October 22, 2019 by Maria Held

Prevent new coryneum blight (shothole) infections this fall by applying copper to trees when 50% of the leaves have fallen. The disease affects all stone fruits but is mainly a concern in apricot, nectarine and peach.

As peach trees lose their leaves you need to spray for peach leaf curl if you experienced the disease this spring.

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

» http://extension.colostate.edu/topic-areas/agriculture/coryneum-blight-2-914/

» https://extension.usu.edu/files/publications/factsheet/peach-leafcurl.pdf

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

Tomato Fruit Issues

Landscape and Garden    All Locations

Posted on: August 19, 2019 by Maria Held

Are you experiencing issues with you tomato fruit like blossom end rot, catfacing, splitting, zippering and such? Below are some links to help you determine what is going on with your tomatoes. Remember that variety selection and consistent watering are important in preventing some of these problems.

» http://vegetablemdonline.ppath.cornell.edu/NewsArticles/Tom_ComDis.htm

» http://blogs.cornell.edu/livegpath/gallery/tomato/zippering-fruit-disorder-on-tomatoes

» http://blogs.cornell.edu/livegpath/gallery/tomato/thrips-and-their-feeding-injury/

» http://blogs.cornell.edu/livegpath/gallery/tomato/feeding-injury-caused-by-stink-bugs/

Blossom End Rot on Summer Squash and Tomato

Landscape and Garden    Treasure Valley

Blossom End Rot on Squash and Tomato

Posted on: July 31, 2019 by Maria Held

Blossom end rot is showing up on summer squash. Tomatoes, peppers, eggplant and even watermelon may be affected. It occurs in the first fruits formed on the plants and is caused by a lack of calcium in the fruit. Most garden soils a sufficient supply of calcium; refer to your soil test results. However, uneven watering may cause symptoms in fast growing plants.

» https://pender.ces.ncsu.edu/2013/05/why-are-my-squash-rotting/

» https://www.canr.msu.edu/resources/blossom_end_rot_tip_sheet

» Blossom_End_Rot_Fact_Sheet_Cornell_Univeristy_86509.pdf

Blossom Drop on Tomatoes and Peppers

Landscape and Garden    Treasure Valley

Blossom Drop

Posted on: July 29, 2019 by Maria Held

Gardeners are experiencing blossom drop on their tomatoes and other vegetables. This is due to high daytime > 90 F and low nighttime <55 F temperatures we have been experiencing. Pollen becomes sterile during hot weather. Fertilizer high in nitrogen and lots of water lead to growth of leaves instead of fruit set.

» https://extension.oregonstate.edu/news/why-vegetables-drop-blossoms

» Tomato blossom drop