We are now in a time of transition; moving from cold weather to warm weather.
You can look at your lawn and see a little bit of green starting to show on some of our grasses. The trees are blooming and starting to put on new leaves.
But one thing that is always with us is insects. They are active even during the coldest parts of the winter. This past week, I saw collards that were covered with aphids. Also, I have had plenty of hollies and camellias brought in that the back of the leaves are covered with a white substance -- an insect called scale.
There are many different types of scale insects. However, they can be placed into two groups: armored scales and soft scales. Although there are two groups of scale, the life cycle begins the same for all of them. The female scale produces eggs that she keeps under the protective coating around her. When the young scale, called crawlers, emerge from the egg, they move a short distance and begin feeding by sucking the sap from the plant.
At this point, they become immobile and spend the rest of their lives feeding at this site. Once they start feeding, they produce a waxy coating that protects them. This covering is the reason that scale is so hard to control. The hard, waxy coating of scale can repel most insecticides.
Both types of scale have one generation of young per year. The crawlers will emerge in our area in March or April. The warmer the weather, the sooner they emerge. The crawler stage is when a control program should be started.
Scout your plants to determine when the scales are crawling. There are a couple of ways to determine when the crawlers are active. The first is to find a limb or leaf that has an infestation of scale and shake this part of the plant over a piece of paper. Some of the crawlers are light in color and some are dark, so it is best to use a light-colored and a dark-colored piece of paper to make it easier to see the crawlers.
Another way to check is to take a double-sided piece of tape and put it around the leaf or limb.
There are a number of ways to control scale while in the crawler stage. If we could get some hard rains, like we did last weekend, the rain would wash the crawlers off the plant. But a water hose will work.
Insecticidal soaps and horticultural oil sprays also can be used to control the crawlers. The horticultural oil spray will control the adults of soft scale, but does very little to armored scale. Horticultural oils should be used before the weather gets too warm or they can burn the plant.
There are some natural predators that feed on soft scale but very few that feed on armored scale. Many birds prey heavily on soft scales, particularly when birds are fledging young and are seeking foods high in protein.
There are many insects that feed on soft scale. Parasitic wasps, predatory bugs, predatory mites and green lacewing larvae are some of the beneficial insects that feed on scale. Reducing the amount of insecticides or applying these insecticides as late in the day as possible will increase the number of beneficial insects. Another way to increase these insects is to plant plenty of flowers, because the adults of these insects are nectar-feeders.
If the infestation of scale insects is limited to one or two branches, prune these limbs. For you gardeners who have a little more time and have a light infestation, they may be picked off by hand. A plastic kitchen scrub pad or similar object can be used to scrub off armored scale.
There are a couple of insecticides that will give control of scale while they are in the crawler stage. Malathion is one insecticide, and Sevin 50WP is the other. With any of these products, spray the interior of the plant or underside of the leaf. These products have to get on the insect to work.
A systemic insecticide, imidacloprid, can be mixed with water and poured around the root system. It is then moved throughout the plant, and will give control for the season. Imidacloprid works best on soft scale, but can give some control of armored scale.
To do a good job of controlling scale, start scouting your plants now.
Columbia County Extension Agent Charles Phillips can be reached at (706) 868-3413 or by e-mail at email@example.com. The Extension Web address is www.ugaextension.com/columbia.
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