Twigleaf blight

The pathogen kills the one-year-old wood on infected uprights. No crop is produced on blighted uprights. Infected leaves turn from dark brown to bleached tan in late winter and spring and remain attached to the dead uprights. Blighted uprights may be scattered, or they can be in areas ranging from a few feet in diameter to the entire bed. Ascomata begin to form on the lower surfaces of infected leaves in spring. As they mature, they open along a median slit to release spores from early June until harvest in October. These spores are ejected forcibly into the air during mornings and early afternoons on days following rain or irrigation, where wind disperses them. New growth is infected between late June and mid-August, though exactly when varies from year to year. Twig blight may be severe the year after planting. Plants should be checked in the second year and new growth protected if necessary. The disease can slow the establishment of new beds. Yield on infected uprights can be lowered by one third, and the following year’s crop can also be affected as infected uprights are less likely to set a mixed bud for the next crop year.