DISEASES OF LEGUMINOUS PLANTS 339 



circumstances an infestation can bring about the partial defolia- 

 tion and premature ripening of the haulms, with the production 

 of a large proportion of shrivelled kernels. W. Robson has 

 carried out in Montserrat a series of annual tests of the effect of 

 spraying with Bordeaux mixture. The treatment results in 

 the control of the fungus, the leaves on the spra^'^ed plots remain- 

 ing at the end of the season green and healthy, with only a few 

 scattered pustules, when those on unsprayed plots have on occas- 

 sion been heavily infested and failing. The effect on the crop is 

 variable. In some j^ears an obvious and considerable increase 

 has resulted, in others very little. This is probably to be ex- 

 plained by the absence of any serious injury from the fungus 

 when the infestation is developed late. 



The indications are that the first spraying should be given 

 at 6-8 weeks from planting, and that one or two more applica- 

 tions should be made at intervals of a fortnight. 



Leaf-Spot. 



A leaf-spot disease produced by the attacks of the fungus 

 Cercospora personata Ellis {Septoglceum Arachidis Rac.) appears 

 to be met with in all parts of the world where this crop is grown, 

 being capable of transmission by spores adhering to the seed. 

 In St. Vincent, where ground-nuts are grown extensively as a 

 field crop, it is not in general regarded seriously, but local attacks 

 are sometimes heavy enough to cause appreciable damage. 

 This is more or less the position in other islands where the crop 

 occurs. The disease is more prevalent in wet weather and 

 more severe in its effects on imported varieties. In India it is 

 regarded as one of the major diseases of cultivated crops, and is 

 responsible at times for very great destruction. Its effect is 

 described as not unlike that of potato blight, the plants being 

 almost entirely defoliated. 



The older leaves are first attacked, and brown to black 

 nearly circular spots, usually 2-4 mm. in diameter, are produced. 

 Yellowing and shedding of the leaf may follow. 



The conidiophores are brown, tufted, short, and irregular in 

 outline. The conidia are light brown, mostly more or less 

 club-shaped, several (usually 3-4) celled, 30-50 X 5-6 microns. 



Trials of spraying with Bordeaux mixture have not been 

 successful either in the West Indies or India. Very satisfactory 

 control has been achieved in India by the introduction of exotic 

 varieties with better powers of endurance, which seems to have 

 reduced the disease to a position similar to that which it occupies 

 on the varieties established in these islands. 



Root Disease. 

 The " root disease " described by F. W. South is due to the 



