If you see the buds on your fruit or flowering trees starting to plump, it is time to give them some protection. If you like unblemished fruit, don't put your sprayer away yet; you should continue protecting the buds on your trees until midsummer. University scientists say you should spray them every seven to 10 days until your fruit is harvested.
Look for swollen buds. That's their sign that it's time to spray with dormant oil. Actually, you can spray apples, crabapples, pears, and quince even before the buds start to plump. Some mites and scale may have been living on your tree all winter long, and this first coat of special oil will keep them under control.
Look for horticultural oil at home and garden centers. If the buds have already started to swell, you can use delayed dormant spray. Wait for a calm day when temperatures are above 50 degrees and will stay above freezing for 24 hours.
Another sign is when the tips are green. This is called the half-inch-green stage. It takes a few weeks for the buds to develop enough to start showing a bit of leaf growth, and when they are about a half an inch long you can see the green tip. Spray your trees with captan plus diazinon. Captan is a fungicide to fight fungus and bacteria and diazinon is an insecticide to fend off the scale and mites that the dormant oil missed.
Spray your tree again with the same captan/diazinon mixture when you see the buds open up and start to turn color. Spray them again about a month later when the petals have almost dropped off.
Here are some predators to watch for. Aphids might attack and cause the leaves to curl up from the ends. An infestation can weaken your trees.
Apple maggots are little flies that look like house flies and lay their eggs under the fruit's skin. They develop into larvae and tunnel through the fruit. Codling moths fly at night and will do the same thing. They lay their eggs inside a blossom and let their fat, gray grub larvae hatch inside pear and apple fruit.
Plentiful cobwebs in branches are made by caterpillars. Types such as tent, webworms, and cankerworm caterpillars will spin webs to protect their eggs and hatching larvae.
Insecticides, including Imidan or a multipurpose malathion/methoxychlor, will keep codling moth, plum curculio, and leafrollers from rounding the bases on your trees. But once the bees are in flight in the early summer, put those insecticides away. We want the bees to do their work and pollinate all they can. An insecticide can't tell the difference between a good bug and a bad bug.
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