Dead spots from 1 to 6 metres in diameter may appear in fields where aphids were abundant early in the season. Streak leaves, plants that appear flattened and dead spots in fields are symptoms of Russian wheat aphid infestation. Cultural Control Do not seed spring cereals next to heavily infested winter wheat or fall rye. Seed spring cereals as early as possible so that they mature before aphid populations increase. Use oats as a nurse crop for grasses.
Oats are more tolerant of aphid damage than barley and wheat.
The economic threshold is the density of insects or the level of insect damage at which the cost of control becomes justifiable. The threshold for Russian wheat aphid is measured in terms of the percentage of plants showing damage. Economic thresholds for the application of insecticides have been adopted from aphid control recommendations in the United States. The goal of insecticide treatment is to protect the flag leaf because of its major contribution to yield. Most damage is done in the time between the appearance of the flag leaf and the head.