Lawn & Garden
The most common and most damaging insect pests of the vegetable garden are worms, squash bugs, squash vine borers, leaf-footed bugs, and stinkbugs. Ok, so those are the most common and damaging, but needless to say, there are lots of enemies to your vegetables. Scouting at least once a week for any of these insects can greatly increase your garden success, but when scouting you need to know what you’re looking for.
Before using any insecticide, it is always best to identify the insect. In many cases you could be killing the “Good Guys” who help control the “Bad Guys.” If you don’t know, then don’t spray! Always be sure the product is labeled for that specific insect and labeled for the crop you are spraying it on. When the insect is properly identified targeting the exact type of insecticide to that pest will keep from harming the beneficial insects.
All worms in the vegetable garden come in as moths, (cabbage loopers, tomato fruitworms, armyworms, and hornworms). There are many different chemicals that will control these, but your go-to should be sprays or dusts with the active ingredient Bacillus thuringiensis. This is a bacteria that is a gut poison to worms and worms alone. It has a zero post-harvest interval, which means you can apply the product and eat the fruit the very same day. The key to success against worms is to keep this product present on the plant. The most effective control is just after eggs hatch when caterpillars are still small. Once the worms get large, the BT is usually ineffective and most of their damage has already been done.
On insects that have piercing sucking mouth parts like stinkbugs, beetles and leaf-footed bugs, you should use products that will target the nervous system of the insect. The problems with many of these is they kill not only the bad insects, but most times the beneficial insects as well. Below are active ingredients of products you will find for homeowners that control insects through nervous system interference: bifenthrin, carbaryl, spinosad, and imidacloprid. All of these belong to different chemical classes or are derived from different means. For example, spinosad is labeled and used in organic production and is derived from a soil bacterium. The post harvest interval changes depending on the active ingredient and also what plant it is applied to, so always read the label.
Neem oil will control many of the insects already listed above such as: aphids, caterpillars, and many of the beetles, along with squash bugs, and pickleworms. Neem oil is made of many components with Azadirachtin as its main active ingredient. It reduces insect feeding and acts as a repellent. It also interferes with insect hormone systems, making it harder for insects to grow and lay eggs. Azadirachtin can also repel and reduce the feeding of nematodes. Other components of neem oil kill insects by hindering their ability to feed.
If you have other gardening-related questions please call the Master Gardener Helpline at: 1877-ALA-GROW (252-4769).