Prevalence of important diseases of pomegranate in Himachal Pradesh and their management

Pomegranate (Punica granatum L) is one of the important fruit crops grown in tropics, subtropics regions of the world showing its versatile adaptability to a wide range of climatic conditions. The mid hill zone (915–1523 m amsl) of Himachal Pradesh provides congenial climate for its cultivation where pomegranate has emerged as the main fruit crop due to its high yield potential, regular bearing habit besides high cost: benefit ratio. Presently, the area under pomegranate cultivation in the state has been estimated to be around 2000 ha. Survey of pomegranate pockets and studies conducted during 2010–2013 have revealed the prevalence of 9 fungal and 1 bacterial diseases in mild to severe form in the orchards threatening the upcoming pomegranate cultivation in Himachal Pradesh. The fruit spot caused by Alternaria alternata has been found to be the first disease to appear in the 1st - 2nd week of June with an incidence ranging from 2.1 to 23.3 per cent followed by Cercospora punicae (Pseudocercospora punicae) causing leaf and fruit spots during 3rd-4th week of June with an incidence ranging from 1.1 to 17.3 per cent. A number of fungal pathogens especially Coniella granati (1.0–10.8%), Phomopsis aucubicola (1.0–14.9%) and in the areas experiencing high annual rainfall (>1200mm) Phytophthora nicotianae have been found associated with fruit rot disease during July -August. Other minor fruit rot disease caused by Botrytis cinerea appears occasionally in mild to moderate form during July-August. During the same period anthracnose caused by Colletotrichum gloeosporioides (traces -7.3%) has also been recorded. A bacterial pathogen Xanthomonas axonopodis pv punicae was found to cause leaf and fruit spots, fruit rotting (1.2 to 7.5%) and stem and twig canker (1.1–9.5%) under heavy infestation. The wilt caused by Ceratocystis fimbriata and Fusarium oxysporum with an incidence ranging from 1.03–15.3 per cent and 1.0–7.3 per cent, respectively, has also been recorded especially in high moisture conditions and in old plantations. For management of the diseases, based on in vitro screening of fungicides against individual pathogen, field testing of schedules and demonstration in farmer's fields, three schedules (I-III) have been formulated. Under field conditions, the schedules however were effective in controlling the prevalent diseases but schedule I was highly effective (93.93PDC) and economical (CBR=1:2.5) followed by schedule II (84.92PDC) with 1:2.33 CBR as compared to farmers practices (CBR=1:1.28). The combination treatment of streptocycline (300ppm) + copper oxychloride (0.25%) was found highly effective (PDC 81.36%) followed by Panchgavya (15%) and were at par in their efficacy in controlling the bacterial blight disease.