Strawberry gray mold causes fruit to rot rapidly - how to prevent and control it?

    Strawberry gray mold is the main disease of greenhouse strawberries. Once infected, strawberries rot quickly and spread rapidly, greatly affecting yield; in severe cases it can reduce yield by more than 40%. 

Strawberry gray mold

    I. Conditions for disease onset 

    The optimum temperature for the development of the strawberry gray mold pathogen is 18—25°C, with air humidity above 80%. Waterlogging in the field, overly dense planting, improper ventilation and air exchange, etc., will all aggravate the occurrence and spread of strawberry gray mold. 

    II. Symptoms of disease onset 

    When flower organs are infected, water-soaked spots the size of a pinprick first appear on the calyx, then expand into larger nearly round or irregular lesions, and gradually extend from the calyx to the ovary and young strawberry fruit, finally causing the young fruit to become wet, soft and rotten. When humidity in the greenhouse is high, grayish-brown mold appears on the diseased parts. Infection of strawberries mainly occurs on green fruit; at first the top stigma of the fruit shows water-soaked lesions, which then turn grayish-brown, while the pathogen infects deep into the strawberry. When the air is humid, diseased fruit becomes wet, soft and decayed; when the weather is dry, diseased fruit becomes dry-rotted, ultimately causing the strawberries to drop. When leaves are damaged, disease generally starts at the leaf base near the petiole, initially appearing as small water-soaked spots, then expanding outward into larger nearly oval, semicircular or irregular grayish-brown lesions, and finally spreading to the petiole, causing the leaves to wither and die. 

    III. Prevention and control methods 

    1. Agricultural control: Reasonable dense planting, ensuring suitable plant and row spacing. The strawberry greenhouse requires good ventilation; pay attention to drainage after rain, and ventilate and let in light at the proper time to reduce humidity in the greenhouse. Frequently remove rotten fruit and diseased, residual old leaves, and bury them deeply or burn them to reduce the pathogen. 

    2. Chemical control: Use 50% iprodione 1000-fold solution, or 50% procymidone 1000-fold solution, or 70% thiophanate-methyl 600-800-fold solution, or 50% duomeiling 800-fold solution, or huinewei 800-fold solution, or dimethachlon 600-800-fold solution; or wanmeiling 600-fold solution, or 40% pyrimethanil suspension concentrate 1200-fold solution, or 65% kemeiwei 1000-fold solution. Add 1000-fold “Tianda-2116” to the above solutions and spray alternately on strawberry plants, or use 5% wanmeiling dust at 1000 grams per mu of greenhouse, or 5% duomeiling dust at 1000 grams per mu of greenhouse, or 6.5% jia mei ling dust at 1000 grams per mu of greenhouse for dusting, or 25% huimeiqing smoke agent at 300-400 grams per mu of greenhouse for smoke fumigation.