Answers to your gardening questions
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Success-Oriented Vegetable Gardener, Part 7—More
Welcome through Fred's Garden Gate! Try as we may, it is virtually impossible to prevent insect intrusion and damage. There are so many of them! Here are a few more of the pesky ones in vegetable gardens.
Cabbage Worms & Loopers
These two do the most damage to members of the Cole family - cabbage, broccoli, Brussels sprouts, kale, cauliflower and mustard. A cabbage worm is fat, velvety, jade-green, has a yellow stripe down it's back, and spends most of it's larval stage eating holes in succulent, new growth. They frequently hide deep within a cabbage head, to show up on a guest's plate - amidst a collection of dark green excrement pellets. Cabbage worms, if not controlled, will infest the entire patch.
Cabbage loopers are very similar in color, markings and destructive eating habits but are not quite as fat, and fold - or "loop" - their bodies as they move about.
Both attain 1½-inches in length at maturity but the adult stage - moths - are entirely different. Cabbage worm adults are beautiful, bright white butterflies with small, black forewing spots. Females leave about 100 eggs on leaves. Adults are pretty and fun to watch but can bring on an infestation of worms which can ruin a crop.
Looper adults, on the other hand are rather drab, mottled, gray-brown moths with small, silvery spots on the forewings. Females will deposit about 300 eggs on leaves.
One of the best tricks for avoiding worm and looper damage is to plant coles as early as possible in the season while temperatures are still too cold for adults to emerge from their winter quarters. Later, at the first sign of invasion, begin weekly applications of BT (Bacillus thuringiensis). I am absolutely opposed to using chemical insecticides on vegetable crops but, if you don't mind the danger, and must resort to their use, contact your Cooperative Extension Service office for guidance.
Adults of wireworms are the occasionally-seen "click" beetles which used to fascinate me when I was a youngster - 'bout 50-odd years ago. The larval stage - "wireworms" -are experienced and proficient tunnelers, chewing their way through virtually any root, stem, seed, bulb or tuber - carrots, corn, potatoes, beets, peas, beans, lettuce, onions and all other types which get in their way. The most common site of severe infestations are garden plots which were planted where there once was a lawn.
Wireworms are usually between ½- and 1½-inches long, are a nut brown when mature (tan or cream-colored when small), and are exceedingly tough. The "heel" test almost always fails - unless it gets caught between your boot and a stone.
Natural controls for wireworms are almost non-existent - short of spreading some pretty deadly poisons. Frequent cultivation will disrupt normal development of the insect. I never allow a click beetle or its larval stage to escape while I'm weeding or cultivating. It would be very unwise to plant a vegetable (or flower) garden in an area which was recently sodded - lawn. Burying a half of a potato with its eyes removed attracts wireworms. Mark the spuds carefully and, after a couple of days, dig them up, collect the rascals, and destroy them in soapy water. Lastly, wireworms thrive in wet soil, so adding abundant organic matter, providing thorough drainage, and frequent deep cultivation will go far towards discouraging this pest.
Corn Borers & Corn Earworms
Ah...here are two of the most distressing. The "borer" takes a significant chunk out of a corn stalk, causing it to become weak, then topple. When it goes to work on a corn ear, you'll see "shot-holes" and deposits of their droppings which look like wet sawdust. Eventually, the ear will also weaken and flop downward. It also bores into other plants like hollyhock, dahlia, zinnia, aster, chrysanthemum, gladiolus, potato, bean, pepper, onion and tomato. Wherever it bores, it leaves easy access to several plant diseases and other insect types.
Corn earworms generally limit their feeding activity to tender, developing kernels, leaving a trail of brown, yucky deposits in excavated tunnels and chambers. Oftentimes they'll go for pollen-producing tassels and "silks." (No pollen equals no kernels of corn!)
Control is two-barbed: 1. Careful garden sanitation. Never (there's that word again) allow corn stalks to remain standing in the garden over winter. That's where European Corn borers can hibernate. 2. BT, applied once every week until harvest will utterly defeat and destroy them before they can do any damage. It's also important to control the adult stage fuzzy, fat moths which congregate around lights at night. Here's that tip again: a bug-zapper will attract and destroy night-flying adult moths before they get a chance to lay their clutch of eggs. Not to worry! -- beneficials don't fly at night.
A few more insects remain to be investigated that's what we'll do next time.
Much more about vegetable garden pests can be found in your complimentary copy of Keys to the Garden Gate.
Jump to Veggies Part 8 More Insects?!
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