What are the common diseases of peppers in early spring? This article summarizes them for you
Recently, continuous cloudy, snowy and cooling weather has seriously affected the normal growth of chili peppers and sweet peppers. According to what the author learned on March 5 in pepper growing areas such as Jitai Town, Sunjiaji Subdistrict Office and Gucheng Yangjia Village in Shouguang City, chili peppers and sweet peppers currently in the fruiting stage are commonly infected due to the unfavorable weather, mainly with gray mold and sclerotinia disease --- brown water-soaked lesions appear at the top or stem end of young fruits, then become sunken and rot, and a gray mold layer appears on the surface of the lesions; sclerotinia disease spreads from the fruit stalk to the whole fruit, showing water-soaked rot, light grayish brown, and similar symptoms also appear on other parts. Phytophthora blight --- in most cases, infection first occurs at the stem end, showing water-soaked grayish green spots, which then rapidly turn brown and soft-rot, the flesh turns brown and even the seeds turn brown. Due to the continuous cloudy and rainy weather and high air humidity, sparse white mold grows on the surface of the lesions. On other parts such as stems, branch crotches, branches and leaves, water-soaked brown spots are often present. Anthracnose --- especially in colored sweet peppers, the fruit is susceptible to infection when approaching maturity. Initially, water-soaked yellowish brown round spots appear, with a grayish brown center, bearing slightly raised concentric rings and often densely covered with small black dots. When air humidity is high, red sticky matter often appears on the surface of the lesions; when dry, the diseased part shrinks into a film-like state and easily ruptures to expose the seeds. In this issue, this newspaper specially summarizes the common diseases of peppers for the reference of vegetable growers
Gray mold
It can occur at the seedling stage and the adult plant stage. When seedlings are infected, the tips of the cotyledons first die, then the disease spreads to the young stems, which constrict and become thinner and are easily broken and killed at the diseased part. Severely affected seedlings die in patches, and in serious cases the whole greenhouse may be destroyed. When true leaves are infected, semicircular to nearly circular light brown concentric lesions appear, and later gray mold can grow on both leaves and stems, causing the diseased parts to rot. When adult plants are infected, water-soaked large spots first form at the leaf margins, then turn brown and form elliptical or nearly circular pale yellow concentric lesions densely covered with a gray mold layer; in severe cases, the large spots merge into patches and the entire leaf dries up. When fruits are infected, water-soaked brown lesions first appear locally around the fruit stalk of young fruits, and after expansion they become dark brown, sunken and rot, with irregular concentric-ring-shaped gray moldy matter produced on the surface.
When the greenhouse has low temperature (20-30°C), high humidity (air humidity reaching 90%), poor ventilation, excessive planting density, improper management and poor disease resistance of plants, the disease is more severe. The pathogen overwinters in diseased residues and soil and spreads through airflow, irrigation water and farming operations, invading through wounds and senescent or dead tissues.
The control method is to ventilate greenhouses and sheds in time, arrange watering on sunny mornings, appropriately control the amount of watering, and by no means use flood irrigation or excessive watering.
In the early stage of the disease, spray 50% procymidone wettable powder 1500 times solution, 50% vinclozolin wettable powder 1000 times solution, or 40% carbendazim-sulfur suspension concentrate 500 times solution. Under unfavorable environmental conditions such as cloudy and snowy weather, 10% procymidone smoke agent can be used at 250 g per mu each time, or 5% chlorothalonil dust at 1 kg per mu each time, but at this time be sure to ventilate in time on the second day after fumigating the shed to avoid phytotoxicity that would instead affect the normal growth of sweet peppers.
In addition, when dipping sweet pepper flowers, 0.1% of 50% procymidone wettable powder or 50% iprodione wettable powder can be added to the growth regulator to prevent the occurrence of pepper gray mold.
Phytophthora blight
It can occur at the seedling stage and the adult plant stage. When it occurs at the seedling stage, it mainly damages the root crown, causing the root crown tissue to rot, the diseased part to constrict, and the seedlings to lodge, causing wet rot, withering and death. When leaves are infected after planting, the lesions are round or nearly round, dark green and water-soaked, and rapidly expand so that part or most of the leaf becomes soft-rot; after drying, the lesions become light brown and the leaves fall off. When stems are damaged, water-soaked lesions are produced, and after expansion the lesions become longer; later the diseased part turns dark brown, the cortex softens and rots, the branches and leaves above the diseased part rapidly wither, and the plant is easily broken at the diseased part. Fruit infection begins at the stem end, with water-soaked spots first appearing, dark green, then the lesions expand, the peel turns brown and soft-rot, and the fruits mostly fall off or lose water and become mummified fruits remaining on the branches.
This disease is caused by infection with Phytophthora capsici. When the average temperature is above 10°C, peppers in the greenhouse can develop the disease, and the disease develops fastest at 27-30°C. Under conditions of little sunshine, high air humidity and low soil evaporation, infection and disease can occur. Especially during flood irrigation, it is even more likely to cause major outbreaks and epidemics of the disease. The pathogen can overwinter on diseased residues and seeds, and directly infect the stem base of pepper (sweet pepper) plants the following year. Phytophthora blight is a devastating soilborne disease in greenhouse pepper (sweet pepper) cultivation.
The control method is to select disease-free new soil for seedling raising or disinfect the seedbed. Cover the seedbed with Miaojundi medicinal soil. The specific ratio is 6 shovelfuls of soil plus 1 packet of 25 g Miaojundi; after mixing evenly, spread it on the surface of the seedbed as floating soil, or spray the seedbed with 72.2% Previcur at 600 times solution, both of which can prevent the occurrence of damping-off at the seedling stage.
Strengthen farming management, pay attention to ventilation and supplementary lighting, and prevent excessive humidity. Choose sunny mornings for watering, raise temperature and reduce humidity after watering, avoid high temperature and high humidity, and promptly pull out diseased plants and remove them from the greenhouse for centralized disposal.
For chemical control, after planting, spray 80% mancozeb wettable powder 600 times solution for protection, once every 15 days. In the early stage of the disease, spray 40% fosetyl-aluminum wettable powder 200 times solution, or 75% chlorothalonil wettable powder 600 times solution, or 64% oxadixyl-mancozeb wettable powder 400-500 times solution, applying 40 kg of spray solution per mu, once every 7-10 days, for 2-3 consecutive times. In greenhouses, 45% chlorothalonil smoke agent can also be used at 250 g per mu each time, or 5% chlorothalonil dust at 1 kg per mu each time, once about every 9 days, for 2-3 consecutive control applications.
Anthracnose