Indiana Plant Diseases, 1922 207 



Parsnip. — Leaf-spot, caused by Cercosporella ijostinacae, was found 

 in October. 



Pea. — A root-rot was found by Gregory in Vigo County in May, 

 causing a heavy loss. The roots were blackened and black cankers oc- 

 curred at the bases of the stems. 



Peach. — Bacterial spot, caused by Bacterium pi-uni, remains the 

 worst disease of this crop, owing to the premature defoliation, twig 

 blight, and fruit infection. The high temperatures of this year favored 

 the disease. Exposure of the fruit by this defoliation resulted in severe 

 sunscald in July. Defoliation had begun as early as April 27 in Knox 

 County. A trace of the disease was found in a peach nursery. 



The dormant spray controls leaf curl, due to Exoascus deformans, 

 very effectively and serious outbreaks occur only in orchards not well 

 sprayed. Peculiar, red, protuberant fruit lesions were noted. Scab, 

 caused by CladosjioHum caiyophilum, occurred rather generally in 

 southern Indiana. Brown rot, caused by Sclerotinia cinerea, was serious 

 in unsprayed orchards and on fruit affected with sunscald and caused 

 some losses in transit to market. Cankers on small limbs with which 

 Valsa leucostoma was associated were found in February by Burkholder. 

 Throughout southern Indiana the fruit suffered severely from sun- 

 scald in July, especially on trees defoliated by Bacterium ])runi, and 

 widespread alarm was occasioned among growers. Large, red-bordered 

 brown necrotic areas appeai-ed on the upper exposed surfaces usually 

 near the stem. These occurred on unsprayed as well as sprayed trees 

 and hence were not attributable to spray injury. 



Pear. — Fire-blight, due to Bacillus amylovorus, was worse than in 

 1921, owing probably to the warm wet spring, and was reported from 

 ten counties. Scab, due to Venturia pyrina, occurred on leaves and fruit 

 in northern Indiana. Black rot caused by Physalospora cydoniae was 

 c.e:;tructive. The conspicuous fruit lesions of Fabraea vmculata were 

 noted in Knox County. 



Pepper. — Mosaic was of general occurrence in market gardens. Leaf 

 infection of bacterial spot, caused by Bacterium vesicatorium (6), was 

 found in market gardens. 



Plum. — Black knot, caused by Plowrightia viorbosu, occasioned a 

 number of inquiries. Brown rot, caused by Sclerotinia cinerea, was 

 serious on unsprayed trees. Gregory noted crown gall (Bacterium tume- 

 faciens) and Burkholder noted plum pockets due to Exoascus p^-uni. 

 Gregory found the latter on wild plums also. Fruit lesions of BacteH- 

 um priini were found on Abundance, plums in Jefferson County. 



Potato, — The hot dry weather was very favorable to Fusarium wilt 

 which was prevalent in the early crop in southern Indiana and the late 

 crop in northern Indiana. Leaf-roll has proved to be the most serious 

 disease of the late crop Rurals, causing a marked decrease in yield even 

 though its symptoms cannot be recognized readily in the field. Because 

 of the spread of this disease under Indiana conditions it is advisable 

 to use certified northern-grown seed stocks. Mosaic is the most serious 

 disease of the early crop (Early Chios and Irish Cobblers) and occurs 

 occasionally in Rurals. It reduces the yield even more severely than 



