In vitro Evaluation of Fungicides and Bio-rationals against Pestalotiopsis psidii Causing Guava Fruit Canker

Abstract

Guava (Psidium guajava L.), originating from Tropical America and part of the Myrtaceae family, is a highly adaptable and nutritionally valuable fruit. Known as the "Apple of the Tropics," it ranks as the fourth most important fruit crop globally. India leads in guava production. However, guava production faces serious threats from various diseases, particularly canker caused by Pestalotiopsis psidii. The disease, varying in severity across guava varieties, manifests as brown necrotic spots on fruits that progress to crater-like lesions covered with white mycelium. In vitro evaluation of fungicides and bio-rationals revealed that carbendazim 12% + mancozeb 63% WP and azoxystrobin 11% + tebuconazole 18.3% SC at all the tested concentration i.e. 500, 1000 and 1500 ppm demonstrated complete inhibition of the pathogen, followed by mancozeb 75% WP showed 97.41 per cent inhibition rate at highest concentration i.e. 2000 ppm. Among the bio-rationals, panchgavya completely inhibited mycelial growth at both 5% and 10% concentration, followed closely by buttermilk, which showed growth inhibition of 45.93 and 17.78 per cent at 10% and 5% concentration, respectively.