June 8, 2021.
It’s time to apply the first generation Codling moth spray. The first hatch will start at the end of this week. Spinosad or neem are some of the least-toxic options. Malathion and permethrin are some of the hard pesticide options. Spray in the evening and add 1 tbsp/gallon each of insecticidal soap and molasses to the mix. If you live at a higher elevation you may want to wait a week or more to spray. If you had wormy cherries last year, it’s almost time to spray for cherry fruit worm (usually when cherries start to show their first color). The least toxic options are spinosad and pyrethrum. Malathion is the hard pesticide option. Check your spray of choice label to determine how often to reapply..
Elm and birch leafminers are starting to pupate and leave behind the tan colored blotches they have made on elm and birch leaves. There should be no need to treat for Leafminers now.
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).
It is time to apply treatments to healthy pine trees to prevent Mountain Pine Beetle attack. You can apply the pheromone called Verbenone (available in Missoula at Rob Dillon Distributors) or spray the trunks of pine trees with carbaryl up to where the trunk diameter is LESS THAN 5” around. Keep pine trees well watered when the weather is hot and dry. Put on the Verbenone packets on now till to July 1st.
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. 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.
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. Rose curculios may also be feeding on rose foliage. Leafminers are present on swiss chard, beets and spinach leaves, remove infected leaves and use Spinosad or neem to control them.
Wilting spruce tree terminals (top branches) can mean White Pine Weevil larvae are feeding inside the tip branch. Remove and destroy wilted, browning spruce tips as soon as you see them. Juniper scale is now hatching and in the crawler stage, now is the time to treat.
We’re seeing some disease problems now including Western Gall rust on pines, aspen leaf spot and blight, cedar apple rust, fireblight, black knot, 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 Fireblight. The wet weather has caused fungal and bacterial disease symptoms on garden plants. Check tomato, potato, cuke 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.