Gardening Tips by John Begeman
College of Agriculture and Life Sciences, The University
of Arizona
What's Bugging Your Garden?True, most people don't like really hot weather, but lots of bugs love it! Particularly the pesky kinds that feed on all sorts of plants in our gardens and landscapes. They particularly like the fact that little rain has come to wash them off the leaves. They also enjoy the fact that plants stressed by hot weather are easier to attack. The biggest fans of hot, dry weather are spider mites. If you've noticed your Italian cypress or junipers turning brown, it's from the feeding of these tiny pests, related to true spiders. In fact, if you look closely, you can see the webs they spin over the needles. The size of a pin head, mites can only be seen well with the aid of a magnifying glass. I look for them by taking a white sheet of paper and holding it under suspicious looking branches. Giving the branch a hard shake over the paper will cause the mites to fall off, appearing as tiny black or red specks crawling about on the white background. Spider mites also feed on pyracantha. If your's have developed coppery colored leaves you can bet mites are present. The best way to control mites is to provide them with what nature hasn't, a good washing off with water. Use a strong jet from your garden hose to spray the plant. This will knock off a great percentage of the mites. Doing this on a weekly basis will keep the plants nearly free of mites. If infestations are severe, you can also use a soap spray to really clean them up! Make your soap spray by mixing 1/4 teaspoon of dawn or palmolive dish washing liquid in one gallon of water. Spray in the morning when temperatures are cool. Follow the initial spray with one a week later. The second spray will kill young mites newly hatched from the eggs left by the adults. Many types of worms are also now feeding on trees, shrubs and vegetables. Tomato horn worms, by far the biggest caterpillar, can be seen russeling through tomato plants. The size of a big, big thumb, this ravenous green caterpillar can devour hole plants in no time flat. The tomato hornworm is also called the tobacco worm, probably because the pupa resembles a cigar with a large looped handle. If you have grapes, you've probably noticed many of the leaves turning into lacy skeletons. Look closely and you'll find some beautiful little black and yellow stripped caterpillars. These are the grape leaf skeletonizer caterpillars. They emerge each June from eggs layed by the a small grey moth. The best way to control caterpillars is to hand pick and destroy them. Sometimes this is not always possible. If a spray is required use an organic product such as B.T. (Bacillus thurigiensis). B.T. is most commonly sold under the trade names Dipel or Thuricide. Because it's a bacteria that must be ingested and grow inside the caterpillar, it takes a few days to kill. By the way, the bacteria has no effect on humans or pets or wildlife, only caterpillars. Another type of caterpillar, called a webworm, has been spotted feeding on a number of trees, including mesquites. They are tiny compared to the tomato hornworm. Hard to see, these little green worms spin themselves inside the leaves, where they feed in relative comfort. Webworms do so little damage, no control is required. They feed for only a short time and then disappear to pupate and develop into their adult counterpart. A number of beetles are also out and about in the garden at this time of year. The spotted cucumber beetle can be found on cucumbers, squash, and melons. It's about 1/5 inch long with a yellow body and black spots. The striped cucumber beetle has black stripes instead of spots. Both feed on leaves, stems, and fruit. Flea beetles are another common garden pest. They love eggplants; but will settle for peppers, beets, turnips or radishes. If you see vegetable plants that look like they've been used for target practice with a BB gun you've got flea beetles. Besides vegetables, flea beetles also are fond of Mexican primrose. I wish there was an easy way to control cucumber and flea beetles. Soap sprays don't seem to work very well. The best thing that I've found to use is the garden insecticide sevin'. I prefer the liquid form that can be sprayed on, but the dust is also effective. Sevin is a very mild insecticide and very safe to use. A few days should pass before harvesting and eating the vegetables. The label will tell you the exact number of days to wait before harvesting. Written by John Begeman, College of Agriculture and Life Sciences, the
University of Arizona, 520-626-5161. |