Prevalence of phytophthora foot rot in kinnow orchards of Punjab State

Foot rot/gummosis caused by Phytophthora nicotianae var. parasitica (Dastur) Waterhouse has become an important pathogen in the decline of kinnow orchards, Sweet orange and nurseries in the Punjab state. The disease is characterized by rotting of the rootlets, girdling of the trunk, dropping of brightened leaves, canker lesions and gummosis at the base of the trunk, as well as root rot, extending from main roots into feeder roots. Surveys conducted of different agro-climatic zones of Punjab during 2016-19 revealed that Phytophthora foot rot/gummosis occurred in trees of all age groups across the agro-climatic zones with maximum incidence of the disease in sub-mountenous zone (28.6%) followed by 26.2% in the arid-irrigated zone in 15-20 years old trees. Population of Phytophthora nicotianae showed an increasing trend from July onwards and reached maximum in the month of September when hot and humid temperature prevails due to frequent rains during these months which coincides with the favourable conditions for disease development.