With apple foliar diseases reported from some areas of Himachal Pradesh, Y S Parmar University of Horticulture and Forestry (UHF) Nauni, Solan-Himachal Pradesh has issued an advisory to apple farmers for effective management.

An official spokesperson of the varsity informed that three teams of the scientists from, UHF, Nauni, KVK Shimla, and KVK Kandaghat conducted field visits to various apple orchards in Shimla district namely Chopal (Deha, Chambi, Khagna -Roo,Mandal, Deiya, Bhanal, Kiyar), Rohru (Sheikhal, Dhara, Kamoli, Samoli, Karalash, Kharla, Kadiyon) and Kotkhai (Bhadaich, Matlu, Bagi, Sheglta, Ratnari, Panog, Badeiyon, Jashla, Deyorighat) and Jubbal (Nandpur, Ruyildhar, Kathasu, Batargalu).

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The primary objective was to assess the prevalence of Alternaria leaf spot or blight and other leaf spot diseases, and to conduct awareness camps for farmers, and provide guidance on effective management strategies, he added.

“Visual assessments of plant health, leaf symptom identification, and disease severity estimation were carried out. Additionally, awareness camps were organized in Kotkhai, Jubbal and Deha to disseminate information on disease management practices,” he said.

“Alternaria and other fungal species were identified as the primary causal agent of these leaf spot or blight disease based on observed symptoms and microscopic observations,” he said.

The disease exhibited a widespread distribution, recording variable levels of average disease severity in different orchards of the district namely in Kotkhai, Jubbal, Rohru, Chirgaon, Theog, Chopal, however, the farmers following proper need based sprays of pesticides as per spray schedule depicted minimum disease severity, he revealed.

The university has also deputed four new teams to visit other apple growing belts of the state and assess the severity of the disease or pests.

Several factors were identified as contributing to the severity of leaf spot disease that include adverse climatic conditions, a combination of less rain (November, 2023 to July 2024) and intermittent rainfall in June 2024 created an environment conducive to disease development.

Furthermore, pest infestations with high mite populations contributed to overall tree stress, exacerbating leaf spot disease development and imbalances in crop management due to non-judicious use of chemical sprays, including the mixing of nutrients, insecticides, and fungicides, led to phytotoxicity and weakened plant health, increasing susceptibility to disease.

Underlying conditions such as root rot, collar rot, and canker weaken tree vigour, making them more susceptible to leaf spot infections also contributed to the disease.

The university has recommended spray of fungicides as the recommended spray schedule given by the Directorate of Horticulture and the University in the apple orchards where these diseases are prevailing.

Additionally, farmers should continuously monitor the status of these leaf spots or blights and need based application of fungicides should be done as per the recommendations in the spray schedule, advocated UHF.