CHAPTER XXVIII 



DISEASES OF LEGUMINOUS PLANTS 



Ground nuts are grown rather extensively as a field crop in 

 St. Vincent, and to a small extent in some other islands. Pigeon 

 peas are also grown as a field crop in St. Vincent, and are grown 

 everywhere in a scattered way, in small holdings, gardens or on 

 the margins of fields. Cow-peas and Rounceval peas {Vigna spp.) 

 are fairly common as a rotation crop on arable land. Velvet, 

 Bengal and Lyon beans {Stizolohium spp.), Sword and Jack beans 

 {Canavalia spp.) Woolly Pyrol {Phaseolus mungo) and the Tephro- 

 sias are grown to some extent as cover crops and green dressings. 

 Bonavist {DoUchos lahlah) and Lima bean {Phaseolus hmatus) are 

 grown mostly in provision plots and small holdings. 



The diseases of peas and beans have had little attention. 

 In addition to those described below there exist nmnerous 

 leaf-spots and one or more each of rusts, mildews, and wilts 

 which have not been studied. 



Of the general diseases the most serious are the infections 

 following bug punctures (especially those of Nezara viridula, 

 which is partial to these plants) and the rot, affecting all parts 

 near the soil, caused by Sclerotium Rolfsii, both of which are 

 elsewhere described. 



Ground Nut. 



Leaf Rust. 



The rust fungus Uredo AracM.Us Lagh. {Uromyces Arachidis 

 P. Henn.) occurs on ground-nut throughout the Antilles from 

 Cuba and Porto Rico to Trinida'^ and in South America. The 

 pustules are small, yellow-brow i fo dark brown, scattered or 

 thickly crowded, occurring on both sides of the leaf but in greatest 

 abundance on the under side, and present to some extent on the 

 stems. The urediniospores are ovoid-round, minutely echinulate, 

 24-30 microns in diameter, with a yellow epispore. 



The rust is more prevalent in wet than in dry seasons, and 

 worse on heavy or wet than on light land. It has attacked 

 imported varieties more severely than the local ones. 



The incidence of the affection is somewhat erratic. Under 

 favourable conditions it only occurs in quantity towards the 

 end of the season, and mostly on falling leaves, but in other 

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