Chemical control has not proven to be effective at preventing the appearance of aster yellows. In literature available from the Flax Council of Canada, there is reference to a major epidemic that occurred in 1957 which resulted in severe yield losses. Beyond that, information is sketchy. Symptoms of aster yellows in flax include the yellowing of the top part of the plant, malformation of flowers, and stunted growth. The flowers appear as small, yellowish green leaves.
Diseased flowers are sterile and produce no seed.
The severity of the disease depends on the growth stage at infection and the number of insects that are carrying the organism. Management of aster yellows in flax is accomplished through early seeding to avoid the migrating leafhoppers. Normally, infected leafhoppers arrive in the region in late June. This year, leafhoppers were abundant by late May. As their populations increase and aster yellow infected plants become available, more of the population becomes infected and capable of vectoring the organism.