Nauni/Solan: Over the past few years, core rot of apple has emerged as one of the major problem in apple production as it affects almost every orchard of the state that results in loss of 30 to 40 percent of production. Every year core rot results in economic loss to the tune of Rs. 720 million to the state.
Affected fruits initially do not produce any signs and symptoms as the pathogen remains incipient in seed core of the fruit, however, such fruits have a bitter taste when eaten. These fruits are also unsafe for consumption as the fungi responsible for core rot produce lots of mycotoxins that affect consumers’ health.
Rains at the time of pink bud or petal fall result in sufficient moisture and the nectar on the flower attract the visiting insects, which help in pollination. However, they also carry the propagules of fungi responsible for core rot.
Dr. AK Gupta, Professor and Head, Department of Plant Pathology at Dr YS Parmar University of Horticulture and Forestry (UHF), Nauni, Dr. Bhupesh Kumar Gupta and Dr. Shalini Verma explained that core rot of apple affects the seed core of the fruit and this area shows dry or wet rot.
In the core region, the fungi responsible for the rot remain incipient till fruits start ripening and reach maturity. Increased levels of total soluble sugars at the maturity encourage the activity of core rot fungi, which results in the bitterness of pulp in the surrounding areas of the core, Nauni University professors further explained.
Affected immature fruits develop early colour. When such fruits are cut into two halves, the central core of these fruits show fungal growth and during storage soft wet rotting occur in such fruits. Professors stated.
Dr JN Sharma, UHF’s Director of Research, who has done pioneering work in this field, told that Core rot occurs frequently due to the fungi Alternaria Alternata and Trichothecium Roseum.
To control Core rot Dr. Sharma suggested for proper pruning and training of apple trees to allow maximum sunlight and air to reach every part of the tree. Dr. Sharma recommended to spray of Mancozeb (600g) or Zineb (600 g) per 200 litres of water at the pink bud stage.
In addition, orchards having high incidence history of core rot, Dr JN Sharma suggested to spray Difenoconazole (30 ml) or Hexaconazole (100 ml) per 200 litres of water for the management of apple scab and powdery mildew at petal fall stage.