Potato psyllid (tomato psyllid)

About

A jumping insect about the size of an aphid (about 2 mm), dark gray to black with white bands (Colorado State, Texas A&M). Its flat, oval, scale-like young sit on leaf undersides of tomatoes, potatoes and their relatives.

Spotting it

Damage

Feeding by the young causes 'psyllid yellows': top leaves curl upward and turn yellow or purplish, plants are stunted, and tomato fruit quality drops (Colorado State, Texas A&M). It also spreads a bacterium that causes zebra chip disease in potatoes, which leaves dark streaks inside the tubers (OSU).

How to find it early

Put out yellow sticky cards early in the season, and use a hand lens to check the undersides of leaves for flat nymphs and eggs (Utah State). Look also for 'psyllid sugar,' tiny white grains that look like salt (Colorado State).

When

Late spring through fall; it usually reaches Colorado in May or early June.

Life cycle

It has four or more generations a season (Colorado State), and the young go through five stages in about two to three weeks. It overwinters in southern Texas and New Mexico and flies north each spring (Texas A&M), though a newer form now survives winter in California (UC IPM) and some survive on bittersweet nightshade in the Pacific Northwest (OSU).

What to do, gentlest first

Start at the top. Sprays are a last step; always read and follow the product label.

1. Check early Prevent

   Start checking leaves and sticky cards early in the season, especially if you had psyllid yellows or zebra chip before.

   Utah State says there are no effective non-chemical controls once psyllids are established.

2. Protect natural enemies Natural enemies

   Damsel bugs and minute pirate bugs are the most important predators (Colorado State); spiders, lacewings and a tiny parasitic wasp also attack psyllids (UC IPM).

   UC IPM notes that most parasites attack too late to stop crop loss, so protecting predators matters most.

3. Spinosad, or horticultural or neem oil Organic spray

   Colorado State calls spinosad the most widely available insecticide that controls this psyllid well; oils give some control. Spray the undersides of leaves where the nymphs feed.

   Spinosad is toxic to bees for about 3 hours to a day, and horticultural oil for up to about 3 hours (PNW 591); spray in the evening, away from open flowers. Read and follow the label and observe the pre-harvest interval.

Garden friends that go after it

Predatory mites

Protect these helpers: skip broad sprays when they're around.

Plants it goes after

Eggplant, Ground cherry, Pepper (sweet and chili), Potato, Tomatillo, Tomato

Pressure by region

This is a western pest. Zebra chip has been found in Arizona, California, Colorado, Idaho, Kansas, Nebraska, Nevada, New Mexico, Oregon, Utah, Washington and Wyoming (OSU), and Colorado State says northeastern Colorado sees serious damage in about half of years. It cannot survive long freezing winters, so most northern gardens get it only from spring migrants. Eastern, Midwest, Alaska and Hawaii ratings are estimates.

Ratings come from extension sources where available; some are estimates, as noted above.