182 



Proci^edings of Indiana Academy of Science 



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

 very prevalent in several market gardens near Indianapolis and was 

 also noted near Goshen. As observed September 9, this disease caused a 

 conspicuous mottled or speckled appearance of the upper side of the 

 leaf owing to the yellow color of the very small, thickset, angular, in- 

 tervenous lesions. On the lower epidermis these lesions presented a 

 dusty or velvety gray surface due to the abundant sporulation of the 

 fung-us. As the lesions become older the tissue dies and turns brown 

 and frequently the lesions were so abundant that entire leaves were 

 killed. 



Pea. — Bacterial spot of field peas, caused probably by Bactermm pisi, 

 was found producing greasy, parchment-like lesions on the leaves and 

 stems in a field in Marion County on May 20. 



Peach. — Burkholder reported that leaf curl, due to E.i-oascus de- 

 formans, was not as bad as in 1920. He found it destructive in Morgan 

 County and also noted it in Posey County on April 11. It was noted 

 near Lafayette, Vincennes and Bedford in April, and was found rather 

 conspicuous near Peru on May 19. Fruit lesions are shown in figure 7. 



Fi;/. 7. "Bii th-maiU" fruit lesions of the peach leaf-curl fundus. 



Black spot, due to Bucterinm prnni, was by far the most serious 

 disease of peaches in Knox County and was also found in Dekalb County 

 on August 10. It was particularly severe in Knox County during the 

 early part of this season. On April 28, there was abundant leaf infec- 

 tion and much defoliation had already occurred. A few trees showed 

 very conspicuous blig;hting of the young shoots of the current season not 

 unlike the twig blight phase of fiie-blight on pears. Elongated, black- 

 ened cankers had girdled and killed the young twigs. The causal or- 

 ganism was isolated from these blighted twigs and it is likely that this 

 type of attack resulted from bud infection of the previous sea.son. 

 Cankers were not numerous on 1920 wood and usually were located at 

 leaf scars. On June 28, the disease was .still prevalent on the foliage 

 and defoliation was still in progress. Very general fruit infection was 

 evident. The disease was somewhat less severe on the trees in the hol- 

 lows than on the ridges and there was some indication of a partial con- 

 trol from a 1-7-50 Bordeaux spiay that had been applied to a few 

 trees on May 29. On October 21, no recent leaf infection was noted 

 and the disease had removed all but a terminal tuft of the younger leaves 

 on each twig. Very few cankers on 1921 wood could be found. 



