May 10, 2022. Plum, apricot & pear trees are blooming. Some caterpillars are showing up in the landscape, such as eyespotted bud moth, leaf rollers, tent caterpillars and one that looks like a caterpillar but is sawfly larva. Spinosad or Neem oil will control them when they are young. Bt(bacillus thuringensis) will control caterpillars but not sawfly larva. Most are not a serious pest. It is time to hang out the pheromone traps when apple trees bloom to monitor the codling moth. It is too early to spray for Codling moth, the wormy apple culprit. These traps will NOT control the pest, but will show you how high a population you have. It is also too early to spray for Cherry fruit worm, the wormy cherry culprit..
If rainy days occur followed by temperatures above 75°F are ideal for fire blight infection and old cankers are beginning to seep bacteria as the pathogen grows. Fire blight is a bacterial pathogen that infects flowers of pear, apple, crab apple and other members of the Rosaceae family. Symptoms include dead branches, water-soaked blossoms, light brown to blackened leaves, discolored bark, black "shepherd's crook" twigs. The initial symptom of shoot infection is flagging or wilting of the shoot tips. If trees are infected, early identification to prune out infections is crucial.
Grasshoppers are just starting to hatch in grassy south facing areas. The best time to apply (Nosema Locusta), the least toxic grasshopper bran bait is when grasshoppers are hatching.
If you had problems with Ash leaf aphids curling green ash tree leaves last year, now is the time to check for powdery-white aphids at the base of newly expanding ash leaves. If you find aphids, treat ASAP. The least-toxic option is neem oil or a mixture of insecticidal soap and pyrethrum. Check the undersides of Virginia Creeper leaves now for tiny, aphid-like leaf hopper larvae. If leaf hoppers turned Virginia Creeper leaves brown last year, spray insecticidal soap plus Pyrethrin as soon as you find leaf hopper larvae on leaf undersides. Leafminers are causing tan blotches on spinach & swiss chard leaves now, remove and destroy leaves. Spray with neem or spinosad preventatively.
Aphids are present now on roses, dogwood, plum tree, maple leaves and on other aphid-prone shrubs. If aphids were a problem last year, you can spray with insecticidal soap or a mixture of insecticidal soap and pyrethrum. Lacewings and lady bugs can be released in the evening instead of spraying.
Cottony, white woolly aphid eggs are present on Spruce and Douglas Fir trees now. If you had pine-cone-like galls on spruce trees last year, now is the time to treat this woolly aphid stage of the Spruce gall adelgid. Treat branch terminals infested with the white, cottony egg masses now with insecticidal soap or permethrin.
Blister and rust mites are just starting to cause yellow to brownish, puckered blisters or spots on Mountain Ash, apple, and pear leaves. You can still spray for blister mites. Use insecticidal soap or add pyrethrum to the insecticidal soap spray if you had a serious blister mite infestation last year.
Soil temperatures are averaging 47 F. The last several nights have been below freezing so cautiously put out transplants, even after hardening them off. Plant out cool season garden vegetables such as lettuce, peas, broccoli, onions, and cabbage now. It’s close to time to plant frost-susceptible garden plants such as tomatoes or basil, or plant and protect them with a row cover or wall of water. Our last average frost date is not until the 20th of May. When warm season crops like cucumber are planted in soils that are too cool, we see greater susceptibility to root maggot damage.
Annual weeds are germinating now. It is a good time to treat them with vinegar sprays. White and cider vinegar can be used on tender succulent annuals; but newly sprouting perennial weeds, such as quackgrass and knapweed are not affected by these low acetic acid concentrations of vinegar. Tillage can also be used to kill newly germinating annual weeds. Till on a warm, dry day so weeds dry out and die.