BiologyofAlternariacyamopsidisandBioefficacyofBotanicals againstAlternariaBlight PowderyMildewandBacterialLeaf Blight of Organic Cluster Bean Cyamopsis tetragonaloba L

Abstract

newline cyamopsidis in cluster bean growing areas, morphological, cultural and pathogenic variabilityinisolatesofA.cyamopsidis,effectoftemperatureandHionconcentration on growth and sporulation of A. cyamopsidis, yield loss assessment caused by complex of Alternaria blight, powdery mildew and bacterial leaf blight diseases and effective management of the disease complex through organic practices. newlineSurveys of Alternaria blight disease intensity in cluster bean during Kharif2015 and 2016 at Udaipur, Chittorgarh, Ajmer and Jaipur districts of Rajasthan showed that mean PDI was maximum in Udaipur district (20.62 and 25.39 at flowering stage and 28.33 and 29.32 per cent at pod formation stage), while in Jaipur district (15.91 and 17.30 per cent at flowering stage and 21.63 and 21.26 per cent at pod formation stage), the mean PDI was lowest. newlineThe cultures of A. cyamopsidis and X. axonopodispv. cyamopsidis specieswere isolated, purified and identified under the microscope through morphological characters of the respective pathogen. The isolates of A. cyamopsidis (Ac1 (RCA), Ac2 (UDP 1), Ac3 (UDP 2), Ac4 (CH), Ac5 (AJM) and Ac6 (JPR) collected from six different locations of Udaipur, Chittorgarh, Ajmer and Jaipur districts exhibited considerable variations in symptoms on inoculation on pot-grown plants and also in colony diameter, size, colour of the colony and rate of growth and sporulation onPDA medium. newlineAmong the isolates of A. cyamopsidis, shortest latent period (36.00 hrs) was recorded in Ac1 (RCA), while it was maximum in Ac6 (JPR) isolate (55.00 hrs). Significantly maximum PDI (65.3) was also observed with the isolate Ac1 (RCA) and minimum (38.6) with isolate Ac6 (JPR). newlineIn physiological studies, it was found thatthe most virulent isolate Ac1 (RCA) of A. cyamopsidis could grow on wide range of pH from 4.0 to 8.0. Though, pH 3.0 and 3.5 did not support the growth. It was observed that pH 6.5 is optimum for the growth of test fungus, A. cyamopsidis which yielded significantly highest drymycelial weight (286.90 mg).