THE WILT DISEASE OF PIGEON-PEA. Di 
months. Schikorra [(14) p. 16] similarly found that the parasitism 
of the “St. Johannis’’ disease parasite in water cultures was less 
than in soil. In inoculations below the liquid the explanation may 
simply be that the destructive enzymes by means of which pene- 
tration is effected are diluted as soon as formed and never reach a 
concentration sufficient to injure the roots. This does not explain, 
however, why the vascular system was not penetrated in the cases 
inoculated above the water level, and the problem involved is evi- 
dently of great physiological interest. 
Treatment. 
In the case of an internal root parasite widely distributed in the 
ordinary cultivated soils of the parts of India where pigeon-pea is 
grown, nothing short of extensive sterilisation of the soil will free it 
from the germs of the disease, if frequently cropped with the host 
plant. Such sterilisation is usually not practicable on account of 
the high cost, and is besides very difficult in the wilts hitherto in- 
vestigated. Orton (3) tested the effects of a large number of soil 
fungicides in the allied cotton wilt, and failed to obtain satisfactory 
results with any. Delacroix (5) advocates the use of formaline 
injected into the soil, but the cost of his treatment, which he claims 
was perfectly efficacious against carnation wilt, works out to near- 
ly an anna per square yard, or Rs. 300 per acre. I have tried sul- 
phate of iron and also lime, with results agreemg with those of 
Orton. The sulphate of iron was applied directly to the soil around 
each plant, half a pint of a 2} per cent. solution to each of 323 plants. 
No benefit whatever resulted. The lme was applied at the rate 
of one ton to the acre, the plots being 400 square feet in area. In 
the two limed plots 70 and 45 plants respectively had wilted at the 
end of 5 months, quite as many as in the similar unlimed plots 
near by. Bolley (19) working with the flax wilt Fusarium found 
it was rather more virulent in limed than in ordimary soils. 
No application made to the above-ground parts of the plant 
can possibly do any good, since the fungus lives in the soil and at- 
tacks the plants through the roots. 
