WHEAT
White Heads - I recently received a sample of wheat with a "white head". The grain head was light tan in contrast to the green stem. No seeds had developed and the stem inside the leaf sheath was separated so that the seed head could be pulled right out. Inside the leaf sheath the break was clean and no insects were found. This case DOES NOT appear to be insect damage. If it was the wheat stem sawfly, frass and tunneling would be apparent inside the stem. The sample was referred back to the Plant Disease Clinic.
Hessian Fly - See:
http://www.ento.vt.edu/Facilities/OnCampus/IDLab/HessianFly/hessian.html
This fly is not so much of a major pest but still shows up in my lab. Look for patchy poorly developing wheat fields. At this time of year you will find the small "flax seed" pupa at the base of the plant under the leaf sheath. Two practices that reduce its presence should be continued and they are planting in mid to late October after most of the adult egg laying flies have died off and to remove any volunteer wheat found in or near where wheat is to be planted that season.
Karnal Bunt - Virginia has been surveyed for this disease and it was not found in 1996. Samples will be taken again this year.
Thrips - Thrips are very common in Virginia this spring again. Any puckering, stunting, leaf curl, or stippling on shade trees and some crops may be caused by damaging populations of thrips. Check for the thrips by looking in the buds or flowers for lemon yellow insects about 1/8" long.
>From Last Year but still appropriate for this year's crops
Vegetables
Onion Thrips - Onions with damage similar to spider mites are probably damaged instead by Onion Thrips. Like the spider mite the thrips will leave white stippling although the spots are slightly larger. The small lemon yellow thrips will be found nearby. Both Malathion and Diazinon are labeled for onion and will work well on this critter.
Ornamentals
Woolly Fold Gall - This gall is common on oak in Virginia. It causes the leaves to pucker and curl along the mid-rib of the leaf. As the name implies the gall is also woolly on the inside and small maggots may be found inside at this time of year. Rarely does this gall cause damage but if most of the leaves are injured then the trees growth may be stunted: in this case treat under the tree with a white grub treatment as this particular gall overwinters in the soil.
Boxelder Bugs - These bugs are starting to feed on female Boxelder (seed producing) trees. Boxelder bugs will not harm the tree but can be household pests in the fall when they seek overwintering sites.
Soft Scales - Many soft scales including Calico Scale, Cottony Maple Scale, Cottony Camellia Scale, and Lecanium Scales have crawler dates in June and control should be planned for June 10 + 20.
Boxwood Leafminer - Boxwoods infested with leafminers will need to be treated in Mid-June with a systemic insecticide.
Household
Blow Flies - If white maggots are found crawling across the floor particularly near fireplaces and wood stoves they might be blow flies. They are most likely from dead birds or other animals in the flue.
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