What to Do About Rotted Peppers? Targeted Control Is Key

The rainy season has arrived, and under the influence of high temperature and high humidity, pepper vegetables (both greenhouse and open-field types) in the fruiting stage are suffering severe outbreaks of phytophthora blight, along with many other fruit rot and fruit drop problems caused by other pathogens. Regarding this situation, the author consulted relevant vegetable experts in Shouguang City. According to their analysis, rotten fruit in hot (sweet) peppers is a common symptom of multiple diseases, but the pathogens differ, the symptoms vary, and the control methods are also different.

Sunscald fruit rot

In high-temperature weather, the sun-facing part of the fruit is exposed to direct sunlight, causing the skin to fade and harden, producing grayish-white leathery spots. The surface of the affected area becomes thin, and the flesh tissue dies and hardens. In the later stage, it is easily colonized by other saprophytic pathogens, developing black mold and rotting. Water timely, supply water evenly, and improve the field microclimate.

It is recommended that vegetable growers currently leave two leaves when pruning and pinching out the growing tips, which can provide shade and cooling, reducing the occurrence of this disease.

Blossom-end rot fruit rot

The blossom end of the fruit is affected, initially showing dark green water-soaked spots that rapidly expand, the affected area shrinks, and the surface becomes sunken in the later stage. It often turns black or rots due to secondary infection by other pathogens. Spray 1% superphosphate or 0.1% calcium chloride. In addition, if the affected area turns black or rots, it can be controlled together with black mold or soft rot. The main cause is high temperature and drought, insufficient soil moisture supply, and imbalanced calcium supply to hot (sweet) pepper plants, leading to calcium deficiency in the fruit. Excessive nitrogen fertilizer application can also affect the plant's calcium uptake, causing calcium deficiency in the fruit and resulting in blossom-end rot. According to relevant surveys, the disease is prone to occur when soil calcium content is below 0.2%.

Soft rot fruit rot

Initially shows water-soaked dark green spots, then the entire fruit becomes soft and rotted with a foul odor, the internal flesh rots, the skin turns white, and after drying and shrinking the fruit generally hangs on the branch, dropping when subjected to external force. Spray 72% agricultural streptomycin or 50% DT fungicide or 40% streptomycin sulfate soluble powder or Kocide or Kasumin and other agents, once every 7 days, spraying 2 to 3 times consecutively. In addition, cotton bollworm, tobacco budworm, wind and rain are transmission vectors, so promptly use pyrethroid pesticides to kill pests and take rain-proof measures.

Phytophthora blight fruit rot

Most infections start from the stem end, showing water-soaked grayish-green spots, then rapidly turning brown and soft-rotting. In humid weather, sparse white mold grows on the surface, and the affected fruit dries and shrinks without dropping. Other parts such as stem forks, branches and leaves often have water-soaked brown spots. Currently, pepper production at the seedling stage frequently suffers from phytophthora blight, and vegetable growers are advised to strengthen control. Spray a mixture of 64% Sandofan and 55% Ridomil (in 15 kg of water, add 30 g of each), or 58% Ridomil MZ or 69% Anke MZ or 60% Flumorph MZ, etc., once every 7 days, spraying 2 to 3 times consecutively.

Gray mold and sclerotinia rot fruit rot

Gray mold occurs more frequently on the first and second fruits, with brown water-soaked lesions appearing at the top or stem end of young fruits, then becoming sunken and rotted, dark brown, with a gray mold layer on the surface; sclerotinia rot spreads from the fruit stalk to the entire fruit, showing water-soaked rot, light grayish-brown, with similar symptoms on other parts. These two diseases mostly occur during winter periods of low temperature and high humidity, but occasionally occur in open-field hot (sweet) pepper cultivation in summer during prolonged cloudy weather.

For greenhouse cultivation, fumigation with Procymidone smoke agents can be used. For open-field cultivation, spray Procymidone, Dimethachlon, or a mixture of 50% Procymidone and 70% Thiophanate-methyl (in 15 kg of water, add 15 g of each), or a mixture of 40% Dimethachlon and 50% Iprodione (in 15 kg of water, add 15 g of each). During the disease period, spray once every 5 days, spraying 2 to 3 times consecutively.

Anthracnose fruit drop

Fruits are susceptible to infection when turning red. Initially shows water-soaked yellowish-brown round spots, with a grayish-brown center bearing slightly raised concentric rings, often densely covered with small black dots. When humid, the lesion surface often exudes red sticky substance; when dry, the affected area shrinks into a film-like shape and easily ruptures, exposing the seeds. When leaves are infected, initially water-soaked chlorotic spots appear, later becoming small spots with brown edges and light gray centers. Spray chlorothalonil or Xinwansheng, with Xinwansheng being the most effective, once every 7 days, spraying 2 to 3 times consecutively.

Cottony leak fruit rot

Affected fruits rot, and when humidity is high, abundant white mold grows on them. Spray 50% DT fungicide or 14% copper ammonia complex aqueous solution, once every 7 days, spraying 2 to 3 times consecutively.

Black mold fruit rot

This disease generally starts at the top of the fruit, though some start from the fruit surface, with the affected area becoming lighter in color initially. The fruit surface gradually shrinks, accompanied by a greenish-black mold layer. This disease mostly occurs when fruits are near maturity or after ripening. Spray 50% DT fungicide at 500 times dilution or 58% Ridomil MZ at 400 times dilution, once every 7 days, spraying 2 to 3 times consecutively.