How to Treat Early Blight in Peppers? A Detailed Guide to the Latest Control Methods
Pepper early blight is caused by the fungus Alternaria solani (a deuteromycete in the subphylum Deuteromycotina), which overwinters as mycelium or conidia in diseased plant residues or on seeds, and undergoes repeated infection cycles through airflow and rainwater. The disease breaks out and spreads easily at high temperatures of 26-28°C with relative air humidity above 85%. It is severe in northern regions during hot, rainy summers and in protected cultivation with poor ventilation. Let us take a look at the control methods for pepper early blight below!
Symptoms of Pepper Early Blight
After the pepper stem is infected, brown to dark brown irregular round or oval lesions generally appear at the branching points, with a grayish-black mold-like substance on the surface of the lesions. When the fruit is infected, it mostly occurs near the calyx, initially appearing as oval or irregular brown or black spots that are noticeably sunken; in the later stage, the fruit cracks, the diseased part hardens, and under humid conditions a black mold layer grows on the diseased part. Seedlings can also be affected, generally with dark brown water-soaked lesions appearing at the tips of old leaves or the terminal buds, causing the leaf tips and terminal buds to rot and forming seedlings without growing points; dark green mold layers can be seen on diseased seedlings in the later stage.
Causes of Pepper Early Blight
Pepper early blight is a fungal disease caused by infection with Alternaria solani, a fungus in the genus Alternaria of the subphylum Deuteromycotina. It overwinters as mycelium and conidia with diseased plant residues in the field or on seeds, produces new conidia the following year, and spreads via wind, rainwater, insects, and other means. The pathogen invades through stomata or wounds, and can also penetrate directly through the epidermis. The incubation period is 3-4 days, and the diseased part produces large numbers of conidia for secondary infection. When seedlings are aged and weakened, planted too densely, exposed to excessive humidity, or lacking ventilation and light, the disease is likely to occur. Late transplanting, moist soil, and poor aeration will accelerate the spread of the disease.
Control Methods for Pepper Early Blight
1. Select good varieties: Choose excellent disease-resistant varieties such as Layou No. 4, Layou No. 9, Yuejiao No. 3, Xiangyan No. 9, Yujiao No. 5, etc. Do not grow the same variety year after year; rotate varieties. At the same time, soak the seeds in warm water at 55°C for 15 minutes to achieve disinfection.
2. Proper management: Avoid excessive humidity in the seedbed; after watering the seedbed, ventilate promptly to reduce humidity. For field planting, practice proper crop rotation, plant on high ridges, use rational close planting, pay attention to ditching and drainage, and prune in a timely manner to facilitate field ventilation, reduce humidity, prevent disease onset, and control the spread of the disease. Apply more phosphorus and potassium fertilizers to promote robust growth of the root system and stems and enhance disease resistance.
3. Chemical control: In the early stage of the disease, use 75% chlorothalonil wettable powder at 600 times dilution, or 50% iprodione wettable powder at 1000 times dilution, or 64% oxadixyl mancozeb wettable powder at 600 times dilution, etc., alternating them, once every 7-10 days, spraying continuously 2-3 times.