Easy control garden pests

Cabbage butterflies make voracious caterpillars.

CORVALLIS, Ore. – You look around the garden and see aphids suck the life out of your rose buds, flea beetles chomp on the cauliflower and cabbage butterflies lay eggs that will turn into voracious caterpillars. What to do?

Don’t automatically reach for the spray can, said Heather Stoven, an entomologist for Oregon State University Extension Service. First, determine what is pestering your garden and the ways it can be controlled.

“Assess the damage,” she said, “Do an evaluation. Try to see how many insects there are and if they are spreading. Be sure to identify the insect so you know what you’re dealing with. That way you can most effectively manage the situation.”

Sometimes you won’t have to manage it at all. There will always be insects in the garden – lots of them – and they all play a part in the ecosystem. Often the “good” bugs in your garden will keep the “bad” ones at bay. After all, beneficial insects need something to eat, too.

Stoven recommends Integrated Pest Management, known more commonly as IPM, for fighting off pests. The key is to use multiple techniques. Start off with monitoring – walk through the garden daily to find pests before they become infestations. Decide how much damage you can tolerate as the beneficial insects find their prey and help stave off an outbreak. If things start to balloon, begin control measures with the least toxic methods, like spraying off aphids with a stream of water or covering the cabbage with a row cover.

Learn the lifecycles of the pest insects in your garden, Stoven said. There are weak links when it’s easier to get control of the situation. For instance, soft beetle larvae are easier to kill then hard-shelled adults. Egg masses can be squished or washed off.

Once you’ve got the ID and lifecycles down, you’re well on your way to making decisions about how to control them. To get help with all of this, call or visit your county Extension office and talk to a Master Gardener. Take a look at the hundreds of publications in the Extension catalog. Or, use Ask an Expert, a question-and-answer service where you can post your questions and photos and Extension experts and Master Gardeners find the answers.

At the low end of the IPM spectrum, try physical controls. If there aren’t too many, insects can be picked off the plant and thrown into a bucket of soapy water. Wash off aphids with a spray of water. Put up traps. Use row covers. If none of that works and the damage is past the I-can-handle-it stage, move on to biological controls like nematodes and Bt (Bacillus thuringiensis). If you decide to turn to chemicals, keep in mind even natural substances can kill pollinators and other beneficial insects. Choose the least toxic ones. Read the label to see if it is meant for the insect you’re dealing with and to find out what impact it has on other critters, including humans and pets. Always follow the directions.

Keep in mind the healthier your garden, the less likely pests will get to an unacceptable level, Stoven noted. Water correctly, practice good sanitation, keep plants from crowding each other and prune to keep good air circulation. One thing people don’t think about is over fertilization. Insects love the luscious new growth brought on by too much fertilization.

“Properly grow plants,” she said. “Keep them healthy and they’ll be able to fight off pests much easier.”

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