Rust disease is one of the main diseases affecting cowpeas, often occurring in the middle and later stages of growth. It commonly causes extensive leaf loss, thereby affecting the quality and yield of cowpeas. So, how can rust disease in cowpeas be prevented and controlled? Let's find out together.
In cowpea cultivation, rust disease is one of the main diseases affecting cowpeas, often occurring in the middle and later stages of growth. It commonly causes extensive leaf loss, thereby affecting the quality and yield of cowpeas. So, how can rust disease in cowpeas be prevented and controlled? Let's find out together.
I. Symptoms: Rust disease mainly affects the leaves, and in severe cases, it can also affect the stems and pods. The initial symptoms include small yellowish-white spots on the leaves, which gradually enlarge and turn brown, forming raised circular or oval yellow-brown lesions. Later, the central part of the lesions becomes dark brown (known as uredinia), often surrounded by a yellow halo, forming "green islands." After the epidermis ruptures, a large amount of rust-brown powder (uredospores) is released. Stems and pods infected with the disease exhibit dark brown protrusions. When the disease is severe, clusters of new and old uredinia form elliptical or irregular rust-brown lesions, which connect with each other, causing the leaves to turn yellow and fall off. As the weather gradually cools in autumn, in the middle and later stages of cowpea growth, the lesions develop into elliptical or irregular black-brown lesions (telia), and black-brown powder is released after the epidermis ruptures.
II. Pathogen and Epidemiological Characteristics: The pathogen prefers warm and humid environments, with the most suitable temperature for disease development being 23 to 27°C and relative humidity above 95%. Cowpeas are susceptible to the disease from flowering to mid-late harvest. The disease is more severe in fields with continuous cropping, low-lying areas, poor drainage, excessively dense planting, excessive plant elongation, and poor ventilation and light transmission. It is more severe in years with high temperatures and rainfall during summer and autumn.
III. Key Prevention and Control Techniques:
-
Crop Rotation: Reasonable layout and rotation with non-legume crops.
-
Clean Fields: Prune in a timely manner, remove diseased residues after harvest, and deeply till the soil.
-
Enhanced Management: Proper planting density, avoid excessive planting density and excessive plant elongation. Apply organic fertilizer, increase the application of phosphorus and potassium fertilizers to promote vigorous plant growth. Cultivate on raised beds, open drainage ditches, and drain promptly after rain. Timely removal of central diseased leaves.
-
Chemical Control: Start spraying to protect against the disease in the early stages, and depending on the development of the disease, spray once every 7 to 10 days, continuously spraying 2 to 3 times. Recommended chemicals include 20% triadimefon wettable powder (1500 times dilution), 25% benomyl emulsifiable concentrate (2500 times dilution), or 12.5% tebuconazole wettable powder (2500 times dilution).
That concludes the introduction on how to prevent and control rust disease in cowpeas. Rust disease in cowpeas is severe, spreads quickly, and can significantly affect yield and quality. Therefore, it is essential to take appropriate prevention and control measures.
