In the spring, their activity increases and they produce sexual spores called ascospores. With the first rains of the season, the spores are released into the air. William MacHardy, professor of plant pathology in the Plant Biology Department, has been studying apple scab since 1972. He has been involved with many research experiments to widen the knowledge on apple scab. He has also collaborated with researchers from many other countries where scab is a major problem, and has offered his findings to apple growers around the world.
Apple scab is a worldwide problem.
Although MacHardy indicates that the pathogen likes New England type conditions, with a lot of rain and moisture during the growing season, the disease is a major problem almost everywhere apples are grown. The disease causes scab lesions to occur on the fruit which, although not harmful to eat, lower the value of the fruit. The disease is mostly aesthetic, MacHardy says. The lesions decrease the market value because people only want to eat nice, clean-looking fruit. The disease is commonly controlled with fungicides timed to keep the leaves and fruit protected throughout the season.