176 Proceedings of Indiana Academy of Science 



forded this spring. In March a grower in Marshall County received 

 a consignment of cabbage plants from the Piedmont Plant Co., Albany, 

 Georgia, many of which bore black leg cankers near the ground line. 

 Pycnidia containing spores were present in these cankers. 



Club-root, caused by Plasmodiophora brassicae, has previously been 

 reported from Lake County and was found this year in the muck soils 

 near Goshen. Black leaf spot due to Alternar-ia brassicae was found 

 at Lafayette. Damping-off of seedlings, due to Sclerotinia libertiana, 

 was troublesome in a greenhouse near Lafayette in March and a 

 Sclerotinia collar rot of older plants was sent in from Miami County 

 in July. 



Cantaloupe. — As usual, the most serious disease of cantaloupes was 

 wilt due to Bacillus tracheiphihus. It was noted in Marion and Tippe- 

 canoe counties in July and was reported from Marshall and Franklin 

 counties. The peak of the wilt epiphytotic comes rather early in the 

 season and fewer blank spaces will result in the field if enough seed 

 is planted so that there are several plants in each hill and if the 

 thinning process is postponed until after the disease has run its course. 

 It should be remembered that this disease is spread entirely by the 

 striped cucumber beetle (Diabrotica vittata), lives over winter in this 

 insect, and does not persist in the soil. 



Since most of the good melon soil in Indiana is on the sandy ridges 

 along the rivers and is consequently rather restricted in extent on any 

 one faiTn, there has been a tendency to grow melons in such fields year 

 after year. This practice has resulted in an increased prevalence of 

 diseases which persist in the soil. In general, watermelons can no 

 longer be grown in such fields because of the Fusarium wilt and, 

 since cantaloupes are not subject to such a disease, this crop has super- 

 seded watermelons in many sections. However, failure to rotate the 

 cantaloupe crop very likely is responsible for the increased pievalence 

 of the leaf blight due to Alternaria brassicae nigrescens although the 

 disease also occurs to some extent in fields not previously in melons. 



Another disease favored by the continual culture of cantaloupes 

 year after year not necessarily in the same fields, but in the same locality 

 is the mosaic disease which persists over winter in perennial weeds (11) 

 and is carried to cantaloupes by insects. Mosaic was noted in Knox, 

 Marion and Tippecanoe counties but was not prevalent. In a field at 

 Lafayette, a Fusarium rot of the fruit (fig. 5), much of which resulted 

 from growth crack infection, caused a 15 per cent loss. A Fusarium 

 rot was also reported by U. S. Bureau of Markets inspectors in two cars 

 from Posey County. Anthracnose {Colletotrichum lagenarium) was 

 found on a volunteer plant in September in Morgan County, but was 

 not noted in cantaloupe fields. 



Carrot. — Leaf-spot, caused by Cercospora ajni carotae, was espe- 

 cially prevalent in the Indianapolis market gardens this year, particu- 

 larly where the Skinner system of irrigation was used. It was noted 

 in July and again in September and in many instances was actually 

 killing the leaves. It was also noted near Goshen in September. Micro- 

 scopic examination of specimens collected in July showed abundant 



