Recent research with cereal grain aphids has provided scouting guidelines that use different thresholds based on the value of wheat. Sampling plans designed to save time during field scouting are available. These plans require as few as 25 wheat stems to a maximum of 100 stems to make a treatment decision. Field scouting should begin at stem elongation and continue up to the heading stage of wheat. Aphid populations, at or above the thresholds, during these growth stages will result in economic injury to plants.
Economic threshold are dependent on plant size and growing conditions.
Larger plants to boot . Boot to heading . . . . . . . . . . . . Before the death of one functional leaf Heading to hard dough . When greenbug abundant enough to cause death of 2 normal-sized leaves. The critical period for injury by corn leaf aphid is during tassel emergence through pollination.