July 20, 2021.
We are still catching Codling moths now, and seeing a small amount of new codling moth feeding on the outside of apples in some sample sites. If you are finding new codling moth feeding, Spinosad is the least toxic option and malathion is the hard pesticide option. Add 1Tbsp per gallon each of molasses and insecticidal soap to any codling moth sprays. Follow your pesticide of choice spraying intervals for control of the worms in your apples. The second generation of apple skellatonizer caterpillars are out turning leaves brown. You can spray Bt(bacillus thuringenis) if they have not curled the leaf up.
Grasshopper populations are increasing in some locations. As grassy areas dry up, or if neighbors hay fields near your garden, grasshoppers may move into gardens and landscapes. If they are a serious problem, you can apply quicker-acting carbaryl-treated bran baits to affected plants. These insecticide-laced baits can injure birds if they eat them. You can also cover garden plants with polyethelene shade cloth, hardware screening or remay to decrease grasshopper feeding and shade plants to encourage more vegetative growth. Grasshoppers usually decrease towards the end of summer into early fall.
We are seeing flagging (dying branches) on many apple and crabapple species in town, some are testing positive for fire blight.
Mountain Pine Beetles are attacking pines in our area now. Unsuccessful new attacks will have pitch tubes with tiny ¼ inch long, black mountain pine beetles stuck in them. Pitch tubes are popcorn sized globes of pitch that come out of the little bore holes pine beetles make in pine tree trunks. If pine trees are healthy and given enough irrigation, they have a better chance of protecting themselves. Irrigate large pine trees with a soaker hose once a week in this hot weather while mountain pine beetles are attacking.
Aphid populations are decreasing. You may still see curled leaves from earlier aphid infestation, but few aphids are present inside curled leaves at most locations. There is no need to spray for aphids now at most sites.
Eriophyid mites are responsible for yellow to brown to red spots and blisters on apple, pear, and mountain ash leaves. It looks like disease on apple leaves sometimes. It is too late to spray for blister and rust mites.
Spider mite populations are increasing in our sample sites.
Black vine weevils are feeding on the leaf margins of lilac and rhododendron now. They feed at night and start at the base of shrubs, leaving a scalloped look to leaf margins. Damage is usually cosmetic only – no need to spray.
Browning tips of fir & spruce trees are signs that the western spruce budworm or tussock moth has been feeding on the new growth. Control measures should be applied when the new growth begins next spring.
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.
Do not fertilize your trees and shrubs any more this season, we don’t want to encourage any lush growth.
Knapweed is at full- bloom. Now is the best time to mow knapweed to diminish seed dispersal.
This is a good time to divide your bearded Iris now. Early spring blooming perennials such as bleeding hearts are turning yellow and starting to go into dormancy now.
Keep plants well-watered, but keep irrigation water off of branches and leaves to avoid new disease infection or if that’s not possible water early morning so foliage can dry.