We are receiving reports of aphids and potential issues of Barley Yellow Dwarf (BYD) showing up in wheat in SD. There are several aphid species that can be present across the Wheat Growers service area in wheat fields, but the target species right now for Barley Yellow Dwarf virus (BYDV) concerns is the Bird Cherry Oat Aphid (BCOA). Barley Yellow Dwarf, remember, is characterized by yellow to purple coloration at the leaf tips and extending backward from the leaf tip. This is different from Wheat Streak Mosaic Virus (WSMV), in which the wheat leaves have a mottled yellow streaky (thus mosaic) pattern to the leaves. Below is a wheat aphid species photo guide for reference.
If you have not scouted your wheat fields for aphids, please contact your Wheat Growers Sales Agronomist for crop scouting. You should be scouting all cereal grains (winter wheat, spring wheat, barley, oat) for cereal aphids, because the greatest risk is in the vegetative to boot stages. Look on the underside of leaves and near the base of the plant for small, green, and pear-shaped aphids. The most common aphids on cereal grains in this area are greenbugs, English grain aphids and bird cherry oat aphids. The greenbug is pale green with a darker stripe down the back. The Bird Cherry Oat Aphid is olive green, with a brownish patch at the base of cornicles (“tailpipes”). English Grain Aphids are bright green with long black cornicles. The greenbug injects a toxin with its saliva during feeding, so can be injurious prior to heading, the English grain aphid is more common at heading. The BCOA feeds primarily on leaves in the lower part of the small grain plant, and can transmit barley yellow dwarf virus. If BYDV infected heads are noticeable, the feeding has been going on for a couple weeks. Later-planted spring wheat fields are at high risk to attract migrating aphids that are moving from more mature fields, like winter wheat. If diseased heads are present, the disease can continue to spread throughout a field, hurting grain fill.