Infected plants are bright yellow with considerable distortion of foliage and floral parts. Flower parts turn green, forming a rosette-like growth instead of a boll. Seeds are shriveled or do not form. There is no effective control for this disease. Dense plantings tend to reduce the incidence of disease, since the insect vector prefers plants that are not crowded.
Infected plants show a characteristic erectness of leaves about the stem.
Plants may be yellow or reddish in color and the lower leaves drop prematurely. Later, plants branch abnormally, sometimes with tops twisted. Plants affected by curly top are more susceptible to Rhizoctonia root rot. There is no effective control for this disease. The fungus can attack flax plants at any stage of growth.