In most years, the English Grain aphid has tended to be the most abundant aphid in our fields, particularly at heading. EGA also transmits BYD but is less efficient at it. Also, with late planting last year, BYD infections occurred in vegetative stages. Infections in younger plants have greater impact on yield than infections in older wheat. In the next few weeks, migrating aphids are likely to be detected in the region.
Weather plays a major role in how the populations increase once they arrive.
Temperatures from 72 to 80 o F with moderate humidity favor increases in the population. Sporadic rain showers promote the development of pathogenic fungi that infect the aphids and kill them. Numerous beneficial predators and parasites establish in fields along with the aphids. If an aggressive program is taken to manage aphids, effects of treatments in younger wheat should be scouted closely. Early treatments delay the predator and parasite populations from increasing, giving the aphid populations opportunity to increase rapidly, perhaps back to threshold levels prior to heading.