- 6 - 



sible this year due to the large crop in 1974 and in part to the 

 advancement of flower development by the unusually warm weather. 



■""I will refer frequently to Boskoop in other articles concerning 

 planting systems and pruning because trees of this variety have 

 Mcintosh vigor. The fruit are large, green and russetted. I rate 

 the fruit good for flavor and texture. 



*************** 



MUMMY BERRY DISEASE OF BLUEBERRY 



C.J. Gilgut 

 Department of Plant Pathology 



One of the most destructive diseases of highbush blueberries 

 in Massachusetts is mummy berry, caused by a fungus with the awe- 

 some name, Monilinia vaccinii corymbosi . It does not occur every 

 year and several years may pass without the disease. 



The fungus winters over in the diseased fruit, called mummies, 

 which drop to the ground during the growing season. The mummies 

 are hard, dry, pumpkin-shaped, dark grey bodies and, when moist, 

 swell to twice their size and are black. They are very resistant 

 to cold, heat, and drought and may lie dormant on or in the soil 

 under the plants for more than one season. 



When weather is wet in spring, about the time buds swell and 

 growth starts on the plants, the mummies produce brown, moist, cup- 

 shaped or funnel-shaped "mummy cups," 1/4 to 1/2 inch in diameter. 

 Clouds of dust-like spores called ascospores , are discharged from 

 the cups over a period of time - usually between mid-April and the 

 end of May. Spores that land on swelling buds and new growth at- 

 tack the new shoots causing a twig blight, spur blight and dieback 

 which often is confused with late frost injury. Later, the die- 

 back may extend down the stem and kill it, sometimes even to the 

 ground. The fungus also attacks the blossom clusters to produce 

 a blossom blight. If moist conditions continue during the spring 

 and especially during bloom, the spread of the disease is rapid 

 and the loss may be serious. 



In about 10 days to two weeks after infection, there develops 

 a greyish or brownish fuzz on the diseased shoots, spurs, and flow- 

 er clusters and the fuzz produces an abundance of secondary spores, 

 different from those produced by the mummy cups, which are called 

 conidia . It is the conidia that invade the green berries in wet 

 weather. The fungus continues to grow inside the berries as they 

 enlarge and causes them to turn salmon-colored and dry and hard as 



