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June 1 Pest Alert


June 1, 2021.  

It’s getting closer to apply the first generation Codling moth spray.     Spinosad or neem are some least-toxic options. Malathion, acetamiprid , permethrin is the hard pesticide option. Spray in the evening and add 1 tbsp/gallon each of insecticidal soap and molasses to the mix. Some sprays have a short residual, so you will need to spray several times per generation. If you have had problems with currents and gooseberries with worms inside it is time to spray for them now. Spinosad or pyrethrin every 7-10 days.

Elm and birch leafminers are in the tan colored blotches they have made on elm and birch leaves. Tent caterpillars are present in increasing numbers. They are nearing the stage where they will be too large to effectively treat them with Bt (Bacillus thuriengensis). Grasshoppers are hatching in grassy, south-facing areas. Cones, screened boxes, floating row covers, and other protective covers provide some protection if the number of pests isn't high. However, if they are hungry enough, grasshoppers will eat through cloth or plastic row covers, so try using metal window screening.

It is time to apply treatments to healthy pine trees to prevent Mountain Pine Beetle attack. You can apply the pheromone called Verbenone or spray the trunks of pine trees with carbaryl up to where the trunk diameter is LESS THAN 5” around. Put on the verbenone packets June 15th to 1st of July. Keep pine trees well watered when the weather is hot and dry. It’s time to apply preventative Bronze Birch borer sprays now. Spray trunks of healthy birch trees as high as possible with a liquid carbaryl spray. This treatment is not effective on trees that are already infested. Poplar borer adults are starting to emerge from aspen trees and will soon be laying eggs in new aspen trees. This is the time to apply trunk insecticide sprays to healthy aspen to prevent poplar borer attack. Aphid populations are increasing. Check trees and shrubs, such as plum, cherry, caragana, maples, and roses now. Treat aphids with insecticidal soap or neem plus insecticidal soap if populations are high. Leafhoppers are still present on roses, apples, and Virginia creeper causing white stippling of leaves. Check leaf undersides for aphid-like leafhoppers. Insecticidal soap plus Pyrethrin is the least toxic option.

If you are seeing globs of frothy spit on stems and flowers of plants, no worry it’s just the spittlebug, they do little harm to the plant itself. You can wash them off with soapy water if they are in large numbers.

We’re seeing some disease problems now as a result of recent disease infection periods, including Western Gall rust on pines, aspen leaf spot and blight, fire blight, black knot, peach leaf curl, bacterial blights, on stone fruits and prunus species and powdery mildew. Sulfur is the least toxic option for aspen leaf spot and blight and other fungal diseases. Keep irrigation water off of leaves, branches and stems to avoid further disease infection when the weather dries. Copper is the least toxic option for bacterial diseases such as Fire blight and bacterial blight. Hot weather ends most disease problems. Also most fungicides are a preventative spray not a curative, meaning you have to spray fungicides before disease happens. The wet weather has caused fungal and bacterial disease symptoms on garden plants. Check tomato, potato, cuk. and squash leaves for circular, brown spots or irregular dark spots and dark, curled leaf margins. If present, keep irrigation water off of leaves and stems. Flea beetles are active now. Keep flea-beetle-eaten plants well watered and fertilize weekly with nitrogen to help them outgrow flea beetle attacks.

Sawflies are showing up in the landscape and garden. If you see these ¼ “, greenish worm-like larvae, Leaving trails, holes, and brown areas in leaves, spray them with spinosad or neem.