Susceptibility of Different Provenances of Pinus roxburgii to Cercospora Needle Blight at Amarkantak (M.P.)

The studies on needle blight disease caused by Cercospora pini-densiflorae in different provenances of P.roxburghii exhibited that there was no mortality in plants of Supkar (MP) origin and Rohri (HP) origin,whereas other provenance were highly susceptible to this infection. The heavily infected plants also exhibited a greater number of stomata and conidia in the needles. The size and septation of spores obtained from infected needles of different provenances also vary. The germination of conidia was very less or negligible in distilled water. The addition of glucose increased the higher percentage of germination. Bavistin and Dithane M-45 at 0.2 per cent concentration conSiderably checked the germination of different provenances under study. Fytolan at 0.2 per cent failed to check the germination but the germination was minimised to a considerable extent. On basis of the susceptibility of different provenances of p.roxburgii for C.pini-densiflorae it is recommended that the plants of Supkhar (MP) origin have developed a high tolerance to needle blight fungus as compared to other provenances. The plants of this origin may be used for plantation in Madhya Pradesh.