Plant damage

Aphids feed in dense colonies, typically at the base and sheath of younger leaves and within leaves curled by their feeding. Aphids prefer the newest leaves of plants, and are often found on the last two leaves unfurled. At high densities they can be found on any foliar parts.

Even few aphids can cause symptoms to appear as early as 7 days after infestation. Damage symptoms are charcterised by (also see images) longitudinal rolling of leaves, forming a hollow tube inside which aphids shelter; whitish, yellowish to pink-purple chlorotic streaks along the length of leaves. Heavily infested plants are often stunted and may appear flattened, with tillers lying almost parallel to the ground. Viewed from a distance, damage may appear as a general loss of colouration across the affected crop area. Later in the crop cycle, wheat awns may become trapped by rolled leaves, resulting in hook-shaped head growth and bleaching, and reduced yield. Economic damage is mainly caused by direct feeding. The virus transmission status of RWA is unclear.

RWA feeding damage symptoms to wheat.
RWA feeding damage symptoms to wheat.
RWA on wheat leaf with distinctive striping attributable to aphid feeding
RWA on wheat leaf with distinctive striping attributable to aphid feeding
White and purple chlorotic streaks along lengths of leaves
White and purple chlorotic streaks along lengths of leaves
RW aphid colony
RW aphid colony
Stunting, flattened growth, white and purple streaks on leaves
Stunting, flattened growth, white and purple streaks on leaves
Stress, stunted growth and loss of green colouration caused by heavy infestation at Tarlee, May 2016
Stress, stunted growth and loss of green colouration caused by heavy infestation at Tarlee, May 2016

Page Last Reviewed: 03 Jun 2016
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