Bird Cherry-Oat Aphid
Rhopalosiphum padi (L.)
Identification / Life Cycle
The bird cherry-oat aphid is dark, olive green with a reddish-brown patch on the back of the abdomen (Figure 7.8). Under cool conditions, the color can be so dark that the reddish patch becomes difficult to see. Its antennae and cornicles are black, and it is one of the largest aphids found on wheat. They are common in the fall but also can occur in spring.
Plant Damage and Response
Direct feeding damage to wheat is negligible, but populations of 50 or more per tiller at the boot to heading stage may be damaging. Heavy populations in the spring may cause the flag leaf to roll up into a corkscrew shape that can trap the awns, resulting in “fish-hooked” heads. This aphid is also a vector of barley yellow dwarf virus.
Figure 7.8 Bird cherry-oat aphid.
Figure 7.8 Bird cherry-oat aphid population.
Establishing Level of Risk
Estimate the population based on a sample of 25 to 50 randomly selected tillers. If treatment is elected, choose products broadly labeled for aphid control on wheat.
Sample tillers for the aphid. No specific sampling techniques have been estab lished. However,sampling techniques used for greenbug or Russian wheat aphid can be used in a similar manner for bird cherry-oat aphid.
If 50 or more aphids are found per tiller as the crop approaches boot stage, control measures might be considered.
Conventional foliar sprays usually are not effective in reducing virus incidence; however, neonicotinoid seed treatments reduce BYDV infection by suppressing aphid colony establishment in the fall.
Incidental predation and parasitism can occur. It is possible that bird cherry-oat aphids act as a food source for ladybeetles and therefore might help increase predator abundance in wheat fields. As an indirect effect, increased predators could attack other aphids such as the greenbug or Russian wheat aphid. No specific biocontrol agents or programs are known to control bird cherry-oat aphid infestations.