Influence of Weather Parameters on the Incidence and Severity of Guava Scab Caused by Pestalotiopsis psidii (Pat.)

Guava (Psidium guajava) is an important tropical fruit crop of India and is known as “apple of the tropics”. It is grown and utilized as an important fruit in tropical countries like India, Indonesia, Pakistan, Bangladesh and South America. Among the biotic and abiotic diseases of guava, guava infected by scab disease [Pestalotiopsis psidii (Pat.) Mordue] is an economically important and reported average yield losses in the range of 12-18%. An experiment was conducted during 2023 at Horticulture garden, Main Agricultural Research Station, University of Agricultural Sciences, Raichur during 2023 to understand the influence of various weather parameters on the guava scab disease development. The results revealed that, irrespective of the varieties, interaction among maximum temperature, minimum temperature, maximum relative humidity, minimum relative humidity, rainy days and rainfall showed significant positive correlation with guava scab disease. And the incidence and severity of guava scab was found to be 23.21, 56.00 (Allahabad Safed), 32.45, 68.50 (Lucknow 49) and 85.00, 74.51 (Arka Kiran) respectively.

Efficacy of Fungicides and Commercially Available Organic Products against Blight of Cotton Caused by Alternaria macrospora

An attempt was made to test available formulation of fungicides and commercially available organic products for their efficacy under laboratory condition, an experiment was carried out at Department of Plant pathology, Raichur, Karnataka, India by using poison food technique. Among the commercially available organic products tested, fatty alcohol and diluents has recorded significantly higher mycelial inhibition of 100 per cent at the concentration of 5 and 10 per cent. In case of contact fungicides propineb 70% WP, metiram 70% WP and mancozeb 75 % WP recorded 100 per cent mycelial inhibition, with respect to systemic fungicides hexaconazole 5% EC, propiconazole 25% EC and difenoconazole 25% WP and among the combi fungicides azoxystrobin 8.3% + mancozeb 66.7% WG were most effective in 100 per cent inhibition of mycelial growth of Alternaria macrospora over the control. The commercially available organic product fatty alcohol and diluents, propineb 70% WP, hexaconazole 5% EC, propiconazole 25% EC and azoxystrobin 8.3% + mancozeb 66.7 % WG were found to be effective against inhibition of mycelial growth of Alternaria macrospora.