-15- 



Table 1 .Occur reiicc percent of disease incidence in random samples of 

 apple foliage and fruits as calculated during early, mid and late grow- 

 ing season. 



Foliage 



Apple scab 

 Frog eye leaf spot 

 Cedar apple rust 

 Powdery mildew 

 Alternaria leaf spot 



Apple scab 

 Black rot 



Apple scab and frog eye leaf spot were the major foliar diseases 

 Apple scab was the principal fruit disease. 



A final fruit survey of 50,000 fruits was also performed just 

 prior to harvest. The results given below show the total disease 

 incidence of the fruits to be 2.81. Apple scab again proved to be 

 the most important disease affecting 2.3% of the fruits. Other fun- 

 gal diseases such as black rot, bitter rot, white rot, and fly speck 

 accounted for 0.223%. Calcium deficiencies were responsible for the 

 remaining 0. 312% . 



Table 2. Average percent of fruits infected by disease at harvest. 



Disease Causal organism % Incidence 



Apple scab Venturia inaequalis 2.3 



Black rot Physalospora obtusa 0.2 



Bitter rot Glomerella cingulata 0.1 



Wh i t e rot Botryosphaeria ribis . 1 



Fly speck Microthyriell"a rubi 0.1 



Cork spot Calcium deficiency 0. 3 



Total fruit disease incidence 2.8 



We will be continuing our surveys in 1979. Fruit growers that 

 have disease problems that they would like to have surveyed or 

 diagnosed, should contact Dr. William J. Manning in the Department 

 of Plant Pathology or their Regional Extension Agent. 



