Spore Types and Spore Production of Ramularia areola for Screening Cotton Germplasm for Resistance

Abstract

Spore production of Ramularia areola has always been a difficult task. Brazilian isolates of R. areola produce spores of variable size and shape. The typical spores are 3 septate, rarely 4 and 5 septate, together with abundant single celled oblong to round bodies—a phenomenon not re-ported earlier for R. areola. Budding of spores is a continuous process as observed in our isolates. By repeated culturing the pathogen either ceases to produce typical spores or loses its pathogenic character. To solve this problem, a technique was developed to produce large quantity of typical spores under laboratory conditions. Sporulating cultures produced on Petri plates containing V8 juice-agar were kept on the laboratory bench till they became dry and then stored at 5˚C for reiso-lation and/or for production of fresh inoculum. In such dried cultures spores remain viable for a period of over 12 months, and hence isolates of R. areola originated from different geographic re-gions can be maintained in sporulating form. Results of the present investigation would aid cotton breeders and pathologists in screening germplasm resistant to Ramularia and in other genetical studies under glasshouse conditions.