According to experts at the YS Parmar University of Horticulture and Forestry, apple yields were severely affected earlier due to scab epidemic, now for the last five years is under constant threat from the outbreak of premature defoliation of apple and red spider mites. Improper nutrition of crop was also a major problem and coupled with erratic environmental factors, insects, pests and disease infestation, had led to poor per unit production as compared with the developed countries.

According to experts the premature defoliation observed in an endemic form in some apple growing areas, particularly in Chamba belt, resulted in reduced photosynthetic activity. This eventually affected apple production. Little doubt that the per hectare apple production in Himachal Pradesh is about 4 tonnes.There are reports that soil-nutrient supplies toplants have been poor due to erratic distribution of rainfall during the year thus affecting yields in the hill state where apples are grown on sloppy topography.

The problem has been reported to be associated with a fungus known as "marssonina coronaria" which appears on the leaves after heavy rains, poor drainage of the soil, prolonged drought, poor canopy management and inadequate nutrition. Premature leaf fall, a disease of uncertain etiology has been threatening the existence of apple orchards.

According to experts out of a total area of 190,000 hectares under fruit cultivation, apple accounts for 40 per cent of the total area.

Experts point out that an invasion by European red mite took place first in Mandi and Kulu Districts then it spread to Chamba and Shimla. The mites are minute red coloured creatures 0.4 mm in diameter and are barely visible to naked eye.

Over 62 per cent of total apple orchards have been reported to be infested with the mite and this attack of mites increases with the useof untimely pesticides, improper coverage of plant surfaces and poor monitoring of pest population. The insecticide fungicide mixtures are usually sprayed on crop resulting in large scale killing of beneficial mites.