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Garden Help Desk: Weevil damage bugging you? Time for an insecticide

By USU Extension - | Aug 7, 2022
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Root weevil feeding damage is most easily seen along the margins (edges) of leaves.
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Root weevils are small, shiny and usually black or dark brown. They aren't easy to see because they will often hide during the day or quickly drop down to the ground if disturbed at night.
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Root weevils will feed on the roots and leaves of a wide variety of woody plants and sometimes on other plants if their populations are very high.
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White flies show up during hot weather. They can cause yellowing leaves and poor vigor if their populations are high, but for outdoor gardeners they're usually just a nuisance while working in the garden.

Our peonies and roses are being consumed by some unseen insect.

Earwigs or grasshoppers are two possibilities. Grasshoppers may be seen any time of day, but earwigs are most active in the late evening and in the very early morning. If you go out quietly with a flashlight after dark, or just before dawn and check the plants you may see them.

We did as you suggested. Here is what we found. It’s a beetle … many beetles! Can you suggest a remedy?

Excellent detective work! This looks like a root weevil. I didn’t mention root weevils as a possibility because the damage they cause isn’t usually as extensive as the damage in your first photos. These beetles live in the soil as larvae, feeding on the roots of shrubs and the adults feed on the foliage.

The are several options, but the easiest option is a soil drench with a systemic insecticide. The insecticide is applied as a granule that is watered in or as a liquid, with a small amount of the chemical mixed with a gallon of water and poured slowly around the base of the plant. The best time to do the drench is after the plants are done blooming for the season. These products are usually sold as a tree and shrub insect control.

These tiny, minute flying white bugs are all over the leaves of my squash and pumpkin plants. I find them every time I go out to remove squash bugs and their eggs.

These look like whiteflies. They’re most often seen on plants in the squash/cucumber family and on tomatoes and peppers. I’ve also seen them on bean plants. They can be a serious pest in greenhouses, where their populations can get quite high, but outdoors where there are many natural predators to help control their numbers, they are mostly a nuisance, flying around when disturbed by gardeners.

Whiteflies can develop insecticide resistance easily, so it’s best to avoid conventional insecticides. You can hose them off daily, or you can spray insecticidal soap, which doesn’t cause insecticide resistance. Apply insecticidal soap as often as recommended on the label for a couple of weeks, making sure you get good coverage on the undersides of leaves. Do your spraying in the evening or early morning, as the insecticidal soap can scorch the leaves if temperatures are high while the spray is wet.

My garden is having the worst year ever! I’ve been vegetable gardening for years and never had so many problems. Any ideas why?

It’s been a rough year in the garden for lots of us. Right from the start we’ve had challenges.

In early May, it seemed like we could get our summer gardens started, so we did. And then very cold weather moved through, more than once, causing chilling injury to tender plants. Some plants bounced back, some died and others remain stunted or struggling.

Once the cold spells left for good, we had a pretty short spring before the heat arrived.

As we’ve talked about before, extreme heat can also cause problems for plants. Poor fruit set, slower growth and more pests than usual are just some of the troubles our gardens have seen.

With all the struggles in our yards and gardens this year, new gardeners and even some experienced gardeners are learning a few lessons to use in future years. Here are some things to keep in mind.

  • Keep an eye on the forecast. Check the 10-day, or even just the five-day forecast before you plant but be prepared for surprises. Don’t rush your transplants into the garden if you can’t give them protection from chilly overnights.
  • Every neighborhood, even individual yards, can have microclimates that are warmer or cooler than predicted. Don’t expect your own garden temperature to perfectly match the forecast.
  • Be prepared with cold protection for tender plants if the overnight low is supposed to drop below 40.
  • Have things on hand to help your plants deal with extreme heat — mulch to help keep the soil a little cooler and 20%-40% shade fabric to cool the foliage a few degrees. You may have to make an online purchase to get what you need, but there are lots of options available.
  • When it’s time to order your garden seeds, select heat-tolerant varieties. There are heat-tolerant varieties for most of our popular vegetables. Start browsing the catalogs in January for the best selections.
  • Make notes about what happened this year and what did and didn’t work for you in your garden and landscape. That will help you to be proactive and avoid surprises in your garden next year.

Don’t give up on your gardens; we’ll all have a fresh start in 2023!


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