Indiana Plant Diseases, 1921 167 



normal growth of the fruit, resulting in cracks and the entrance of 

 rot-proclucing fungi. 



Observation this year on black rot, caused by Physalospora cydoniae, 

 gave convincing evidence of the destructiveness of the canker stage of 

 the disease. Complaints accompanied by specimens were received from 

 Fulton and Marshall counties and the serious effects of black rot cankers 

 on Ben Davis trees in an orchard near Peru were very striking inas- 

 much as many of the larger limbs were being killed. It seemed likely 

 that the fungus might be following winter injury in this case. Black 

 rot was also found causing cankers around 17-year-locust injury on 

 1918 wood of young Grimes trees near Paoli. The black rot fungus 

 also is a very common secondary invader of blotch cankers. 



The frog-eye leaf-spot caused by the black rot fungTis was exceed- 

 ingly prevalent this year throughout the state. The lesions were larger 

 than usual, showing a zone of secondary enlargement around the orig- 

 inal circular spot. Frog-eye was noted as eai'ly as April 28 at Vin- 

 cennes. In one orchard in Orange County, much of the yellowing and 

 defoliation during the drouth of June and July was attributable to this 

 disease and the same holds true for unsprayed orchards in general. In 

 an orchard of mixed varieties near Mooresville, observations made on 

 Sept. 15 showed frog-eye to be severe on Ben Davis, Maiden Blush, 

 Pewaukee, Yellow Transparent, Chenango, Wealthy, Winter Maiden 

 Blush, and Northwestern, less prevalent on Benoni, Grimes, Stark, and 

 Jonathan, and absent on Indiana Favorite and York. Near Peru, frog- 

 eye was noted to be much less common on Grimes than on Ben Davis 

 foliage. In this orchard there was not much difference between un- 

 sprayed and sprayed trees in the prevalence of frog-eye leaf-spot. 

 Counts were made on the leaves of Ben Davis trees sprayed with Bor- 

 deaux for blotch control in Clark county and it was found that 60 per 

 cent of the unsprayed leaves showed frog-eye leaf-spot as compared 

 with 45 per cent of the sprayed leaves. This shows that a 2-4-6 weeks 

 spray schedule does not control this disease. 



Fruit infection with black rot was much worse than usual this 

 year, owing probably to the wet August and September. Calyx-end 

 rot of young fruit was observed in Henry County, on July 20 and on 

 Sept. 15 the same type of rot was noted on York in Morgan county. 

 Black rot was also noted on Grimes and Jonathan in the latter orchard. 

 Culiinan reported serious losses due to black rot of Grimes and other 

 varieties in orchards in Franklin, Henry, and Miami counties due to 

 the wet weather. The prevalence of growth cracks, especially in Stay- 

 man, also increased the losses throughout the state from black rot, 

 according to the same observer. Windfalls were in general a total loss. 



Fire blight, due to Bacillus amylovorns, was in general less severe 

 than usual this year. Gregory observed destructive blight in Floyd, 

 Decatur, and Shelby counties and Culiinan reported fire blight severe 

 on Jonathan in an orchard in Franklin county, while Grimes, King 

 David, Stayman, Delicious, and Winesap in the same orchard v/ere not 

 affected. Burkholder noted fire-blight in Adams County and in Elkhart 

 County the disease was found prevalent in a small orchard containing 



