June 17, 2010 at 8:47 a.m.
Watch for rose chafers, tannish five-sixteenths to one-half inch long insects with long reddish legs. They are particularly common in areas with sandy soil. Rose chafers feed on the blossoms of roses, peonies, and other flowers. They will also gladly feed on fruit, such as grapes and strawberries, and skeletonize (feed between the large veins of leaves) foliage on other plants, such as roses, birch, and grapes.
Managing rose chafers is challenging. You can try handpicking the beetles and tossing them into a pail of soapy water-this is easier in small gardens. You can protect some plants by erecting a cheesecloth or similar barrier around the plants for as long as the rose chafers are active (until the end of June). You may also elect to use a residual insecticide, such as bifenthrin, esfenvalerate, or permethrin. Be sure the plant you wish to treat in on the label of the specific product you intend to use.
Apple Maggots are a major pest of apples. The adults damage the fruit when they lay eggs into the apples and the larvae further damage apples by tunneling through the flesh. They spend the winter as pupae in the soil and are active as adults starting about July 1.
There are several methods you can use to protect your apples from this pest. First, consider bagging them. Another non-chemical method is to hang sticky traps, about five in an average sized tree to capture the adult maggots as they try to lay eggs. Bag your apples or set up your traps by July 1.
You can also consider treating with an insecticide. There are not many options available to home gardeners, although carbaryl is available in a few products. Also look for products containing esfenvalerate, although read the label carefully. In one case, the product is limited to treating just dwarf and young apple trees.
There are several different schedules you can follow. Regardless of which schedule you use, do not spray before July 1. One schedule is to treat apples two days after a rain or irrigation of one-half inch or more of water. This is when the adults are most likely to emerge. You can also set up a trap in the tree and spray whenever you have trapped at least five apple maggot adults in one week. Another option is to treat apple maggots on a regular schedule, once every 10-14 days. This method is the most effective, but it also uses the most insecticide.
Be on the watch for Colorado potato beetles. Both the larvae and adults feed on potato leaves and are active throughout the summer. Handpicking adults and larvae and throwing them into a pail of soapy water is effective, especially for small gardens.
An effective insecticide with low impact to the environment is Bacillus thuringiensis var. tenebrionis. This naturally occurring bacterium is most effective against young larvae. It is less effective against older larvae and has no effect against adult beetles. Other low-impact insecticides that are reasonably effective are spinosad and azadirachtin.
Most synthetic insecticides (carbaryl and permethrin, for example) have little or no effect on Colorado potato beetles because of insecticide resistance. An exception would be esfenvalerate. This is a newer insecticide that does not yet have widespread insecticide resistance.
Fourlined plant bugs are still active-expect them to continue feeding until early July. Although they typically don't kill perennials or other plants they attack, they often do affect their appearance. Ignore them when possible. If you wish to protect the plant's appearance, apply a residual insecticide, such as bifenthrin, esfenvalerate, or permethrin. It is less important to treat these insects the closer we get to late June and early July.
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