sup>l Departmentof Plant Pathology 2Deparlment of Plant Breeding,CCS HAU, Hisar-125004HARYANA,INDIA

Background and objectives
ClusterbeanCyamopsistetragonoloba(L)Taub is indigenous to India and cover nearly 3m ha area yielding 0.80m tons of seed. The endosperm contains about 30 to 32 percent gum (galactomannon) having diversified uses. The biproduct is rich source of protein (>42%).The production is drastically reduced due to attack of Alternaria cucumerina var cyamopsidis. Yield losses up to 81 % due to both alternaria blight (AB) and bacterial leaf blight have been reported (Gupta et al.1996) under artificial epiphytotic conditions. The fungus is seed borne in nature (Sowell, 1965) and attack all plant parts. thereby causing severe economic losses. The main objective of the investigation was to identify source of resistance, date of sowing and effective control measure of AB.

Results and conclusions
Conidiophores arise singly or in small groups. Conidia are solitary, the beak is much larger than body of condia, yellowish brown in colour, 120-200 13-22 size with 8-13 horizontal and several vertical septa, with septate beak. One hundred thirtysix genotypes were screened during 1995,1996 underarlificial inoculation conditions. Genotypes GG 1. HVG 1, HG 79-1-5. RGC 967, GAUG 34, Bundel 1, JGP 1 were found to be highly resistant whereas fourteen genotypes viz. HG 75, HGS 365, CH 39-2, CH 138-1, CHA 4-2. DCB 7-154, HG 281. HG 315, 319, A 310, RGC 9955 1002. 1003 and 1004 showed moderate resistant reaction while rest were found susceptible. CP 42 and FS 277 were highly susceptible. Two moderately resistant and two susceptible cultivars were sown on different dates selected on the basis of rainfall during theyears 1995:1996. Disease intensity (D1) was maximum in susceptible cultivars planted earlier thant henormaidate of sowing i.e. 2nd fortnight of June and minimum underiates own conditions. Moderate to high humidity and moderate temperature played important role in disease development irrespective of date of sowing. Optimum date of sowing in respect of yield was found to be the 2nd fortnight of July. The correlation of DI with temperature, relative humidity and rain fall was positiveandsignificant(r-0.48 to O.71) where as with sunshine hours,itwasnegativeandnonsignificant (i--0.38). The correlation between DI and yield was negative. Soil application of micronutrients did not effect the germination of clusterbean seed in screen house conditions. B and Zn, either individual or in combination gave minimum disease incidence of AB. Soil application as well asfoliarspray of micronutrients gave minimum DI(I4.44%) when all the five nutrients were applied as an integrated treatment followed by treatment in which Zn, Cu, Mn and B were applied in combination. B was most effective in controlling the disease followed by Zn. The soil application of B and Zn was superior over foliar spay. Six fungicides viz. mancozeb, captafol,copperoxychloride, iprodione, captafandchlorothalonil were tested against AB as foliar spray. lprodione (0.2%) was most effective in controlling the disease incidence and yield was also maximum in this treatment in both the cultivars viz. HGS 365 and CP 42. Captafol (0.3%) followed by mancozeb (0.2%)and captaf (0.2%) were next to iprodione in controlling disease incidence. The activity of poiyphenol oxidase, peroxidase and catalase was minimum in disease checks in both cultivars. The activity of these enzymes increased with the increase in disease control and maximum activity of these enzymes was found where the disease control was maximum i.e. iprodione (0.2%) spray.

[1]GuptaPP,SinghJV, SinghVP1996.Symposiumon"Plant Science Research: Present Status and Future Challenges" April 2-3, 1996 CCS HAU Hisar pp. 106. [2] Sowell, PG 1965. The effect of seed treatment on seed borne pathogens of guar.Plant Disease Reporter 49. 695-897.