Vol. 11, Issue 12 (2022)

Author(s):
Dr. SM Vastrad and Arun Satareddi

Abstract:
The new molecule Azoxystrobin 11% + Tebuconazole 18.3% W/W SC (Custodia) was assessed for its bioefficacy against downy and powdery mildew separately and in large scale investigation against both from 2017-18 and 2018-2019 at Regional Agricultural Research Station, Bijapur, Karnataka, India and grape grower’s gardens of Northern Karnataka. The results revealed that, the new fungicide molecule Azoxystrobin 11% + Tebuconazole 18.3% W/W SC (Custodia) @ 1.5 ml/l was equally effective in per se performance as compared to recommended popular check fungicides Metalaxyl MZ-6+64 WP @ 2.5 g/l and Triadimefon 25% WP @ 1 g/l in reducing the severity of both downy mildew and powdery mildew of grape. The results of 2017-18 and 2018-2019 against downy mildew revealed mean severity of 13.1 Percent Disease Index (PDI) with Custodia @ 1.5 ml/l was superior to severity of Metalaxyl MZ-72-WP @ 2.5 g/l (PDI 24.8) and significantly superior over untreated check (PDI 52.9). The pooled results of 2017-18 & 2018-18 against powdery mildew indicated seventy of 11.90 PDI with Custodia @ 1.5 ml/l was on par with Triadimefon @ 1 g/liter (PDI 9.99) and significantly lower than untreated check (PDI 79.73). In the large scale field trails in Farmer’s fields during 2019 targeting both the mildews revealed downy mildew severity of 10.13 PDI and powdery mildew seventy of 11.48 PDI with Custodia @ 1.5 ml/l and found on par with severities noticed with Metalaxyl 6% MZ-64 WP @ 2.5 g/liter + Triadimefon @ 1 g/liter. The untreated checks recorded higher mildews severities (PDI 70.38 of downy mildew & 84.47 of powdery mildew). Application of Custodia @ 1.5 ml/l for mildews management also significantly influenced grape yields in both micro plot and large scale experimentation and found on par with present recommendation of Metalaxyl 6% + MZ 64% WP @ 2.5 g/l and Triadimefon @ 1 g/l. The economics of mildews management showed higher net income in Custodia @ 1.5 ml/l (Rs. 4,05,000) with C:B ratio of 1:2.76 as compared to positive checks Metalaxyl (Rs. 3,19,000) and Triadimefon (Rs. 3,97,275) with C:B ratio of 1:2.27 and 1:2.73 respectively. There were no phytotoxic effects such as leaf epinasty, hyponasty and wilting etc even at higher concentrations of Custodia @ 6 ml/l. The present investigations revealed that Custodia @ 1.5 ml/l as an effective fungicide for the management of both downy mildew and powdery mildew of grape. In the events of higher disease pressure, the new product can effectively be employed in the management of mildews in grape ecosystem and in future to tackle the development of resistance by pathogen to conventional molecules.