Efficacy of Fungicides Towards Foliar Pathogens of Guava

Efficacy of six fungicides (Metalaxyl+ mancozeb, zineb, ziride, thiophanate methyl, propiconazole and carbendazim) against Pestalotia psidii, Colletotrichum gloeosporioides, Phytophthora nicotianae var parasitica and Botryodiplodia theobromae infecting guava were studied in vitro on potato dextrose agar medium by poisoned food technique. Carbendazim was most effective against all pathogens tested (ED⁵⁰= 2.0) except P. psidii and P. nicotianae var parasitica, which were more sensitive to thiophanate methyl and metalaxyl, respectively. During in vivo evaluation by three protective foliar sprays, thiophanate methyl was recorded as highly prohibitive against P. psidii (1.0% disease index) whereas C. gloeosporioides and B. theobromae were more sensitive to propinoconazole (1.2% and 0.4% disease index, respectively) followed by other fungicides. P. nicotianae var. parasitica was highly sensitive to metalaxyl (1.6% disease index) than others and very less to carbendazim (53.4% DI). The trend of efficacy of different fungicides and their effect on fruit yield was same in different treatments. On the basis of benefit:cost ratio, carbendazim was found to be the best for C. gloeosporioides and B. theobromae while propinoconazole and metalaxyl in case of P. psidii and P. nicotianae var. parasitica.