147 
Bordeaux and nicotine sulphate seemed to result in improved vine vigor 
and yield where no fungous leaf diseases were present. This is hard to 
explain except upon the basis of the partial leaf-hopper control secured 
or the possible stimulation of the plant by the copper. 
Fungous diseases of the foliage were of no importance in the Indiana crop 
this year. Late blight was not reported. Early blight caused by Alternaria 
solani was found in Marion and Blackford counties in June and in Clark 
and St. Joseph counties in October, but was evidently of no economic im- 
portance. 
Fusarium wilt was, however, the cause of serious losses in the late crop 
and was by far the most important fungous disease of Indiana potatoes. 
The percentage of yellowing or dead plants or shoots to be noted late in the 
season was very high in many fields in the northern part of the state. The 
disease seemed to be especially destructive near Valparaiso. The vascular 
discoloration in the base of the main stem and in the stolons was pro- 
nounced. Tubers from diseased plants usually showed vascular discolor- 
ation at the stem end frequently accompanied by a rotted area externally 
visible as a sunken, wrinkled region about the stem end. The effect of wilt 
on the amount of yield is not known, but tubers showing the incipient stem 
end rot do not endure storage. Whether or not this disease as it occurs 
in Indiana, is primarily due to soil or to seed infestation is not known. 
There was undoubtedly a high incidence of infection due to soil infestation 
but in addition there was striking evidence of seed carriage of disease 
in fields planted with seed from different sources as observed by Gregory. 
For example, in a field near Valparaiso, seed from Wisconsin showed less 
than 1% of wilt August 15th., field run Indiana seed, 25% wilt, and Indiana 
seed selected for freedom from Fusarium infection, only 5% wilt. 
There was also in many fields a great abundance of localized root lesions 
in connection with which the relative importance of Rhizoctonia and Fusar- 
ium as causative factors has not yet been determined. Unmistakable Rhiz- 
octonia cankers with the cracked brown tissue were of frequent occurrence 
on the lower stem and with these were associated similar root lesions. Lat- 
eral roots were found entirely cut off by these lesions and in severe cases 
the root system was severely reduced. In Lake County this type of root 
trouble was very bad and apparently resulted in an uneven stand. Cases 
-of a red discoloration of the rootlets suggesting Fusarium attack were also 
frequently found. 
Black leg caused by Bacillus phytophthorus was found by Gregory in a 
small percentage of plants in one field near Indianapolis. 
Among the tuber diseases, in addition to the Fusarium stem end rot 
associated with wilt, common scab, black scurf, and russet scab were of 
importance. Common scab caused by Actinomyces scabies was very severe 
in the heavier soils, but was successfully controlled by seed disinfection. 
In a test field in Dekalb county, 59% of the tubers grown from untreated 
seed were scabby, as compared with 5 to 17% from treated seed. Black scurf 
caused by Rhizoctonia solani is of very general occurrence. <A fairly 
successful control of this disease was also secured by the mercury bichloride 
