The hill state is one of India's major apple producing regions, with more than 90 per cent of the produce going to the domestic market. Apples alone constitute 89 per cent of the state's fruit economy.
Horticulture Director M.L. Dhiman told IANS that apple scab has been reported from Ani and Dalash in Kullu district, Janjheli and Thunag in Mandi and Kotkhai, Jubbal, Chirgaon, Rohru and Kharapathar in Shimla.
The government has set up a state-level cell to monitor the situation.
S.P. Bhardwaj, a former joint director at the Y.S. Parmar University of Horticulture and Forestry, told IANS that scab disease is recorded normally in certain pockets of Thunag and Janjheli in Mandi district and Kharapathar and Jubbal area of Shimla district.
"This time it is observed relatively on slightly higher scale in these areas primarily due to poor understanding of disease management practices, particularly in remote areas," he said.
The scab disease, caused by the fungus Venturia inaequalis, makes the fruit impaired, tasteless and undersize. Also it damages the fruit with jet back spots.
Bhardwaj said damage to the apple crop in the state by the scab disease was widespread in 1982.
"At that time no major fungicide sprays were available in the markets. By the time the government arranged the fungicides, the crop in the entire state was almost damaged. Now, too many sprays are available and the disease can be countered at any stage," he said.
According to Bhardwaj, poor crop management is mainly responsible for the spread of the disease.
The major reasons for aggravating the spread of the disease include heavy vegetative growth inside the canopy region, close plantation, less movement of air and low availability of light in the inner canopy, uncontrolled grass and weed growth in the basin area and untimely or virtually no application of recommended fungicides.
Farmers mixing various fungicides, insecticides, acaricides and nutrients combinations not recommended by the university is aggravating pest and disease problems in many areas, he added.
Nitin Jogta, an apple grower in Kotgarh in upper Shimla, said "This season the scab disease is reported in many orchards in the area. High moisture content in the monsoon will help spread of the disease at a higher pace."
He said the government should provide fungicides at subsidized rates to check its impact on the nearby orchards.
Shimla district alone accounts for 80 per cent of the total apple production.
The apple harvesting season is from July to October, depending upon the plant variety.
Over the years, the apple production in the state has been erratic, say experts.
The reason is a prolonged winter spell and lack of adequate rainfall when the apple crop was ripening between May and June.
The fruit production was 4.06 lakh tonnes in 2018-19 (till December 2018) against 5.65 lakh tonnes in 2017-18, said Himachal Pradesh's economic survey for 2018-19.
Apple production during the same period was 3.60 lakh tonnes against 4.47 lakh tonnes in 2017-18.
Besides apples, other fruits like pear, peach, cherry, apricot, kiwi, strawberry, olive, almond and plum are the major commercial crops of the state.
(Vishal Gulati can be reached at email@example.com)