It also occurs in central and northern B.C. but does not appear to cause economic damage. In the 1950's the disease caused serious problems in the southern half of the province. Symptoms usually appear in the third or fourth year after planting. A yellowish brown discoloration or ring pattern is visible in the woody cylinder of the tap root. Plants are stunted and produce many yellow, spindly shoots with small, cupped, yellow to brown leaves.
Foliar symptoms are most evident on regrowth after cutting.
Infected plants are more susceptible to winter kill, particularly in southern areas such as Creston and Okanagan Falls. Foliar symptoms are similar, however with witches broom the shoots are finer and more abundant with no browning of leaves, and the tap root remains white. Accurate diagnosis usually requires a laboratory test. The stem nematode increases susceptibility to bacterial wilt and also spreads the pathogen. The use of resistant cultivars is the best control method.