Pea pods with sunken brown lesions and black spots: how to prevent and control brown spot disease

    Pea brown spot disease causes infection and damage every year, affecting the appearance and quality of pea pods and making them difficult to sell. Here is an introduction to the symptoms and control methods of pea brown spot disease.

Pea brown spot disease

    I. Symptoms of pea brown spot disease:  

    Pea brown spot disease mainly damages leaves, stems and pods. When leaves are infected, oblong light brown to dark brown lesions appear, with distinct edges and pinhead-sized black dots on the lesions. When stems are infected, the lesions are brown to dark brown, spindle-shaped or oval; pod lesions are slightly sunken and extend inward, affecting the seeds.  

    II. Control techniques: 

 
    1. Reasonable crop rotation: Since brown spot disease infects not only peas but also other legumes, to prevent the pathogen from remaining in the soil and crop residues and causing infection, heavily diseased fields should be rotated with non-legume crops for 2-3 years.   

 
    2. Select disease-resistant varieties: Choose high-yielding, high-quality, disease-resistant pea varieties according to local conditions. 

 
    3. Establish disease-free seed production plots and collect seeds from disease-free plants: For those using self-saved seeds, a separate seed production plot should be established, with strict control of various diseases and pests, and seeds should be collected from disease-free, vigorous, fully mature pods.  

    4. Strictly disinfect seeds and cultivate sterile strong seedlings: Before sowing, treat pea seeds by dressing with 70% thiophanate-methyl wettable powder or 50% anilazine wettable powder. Alternatively, soak pea seeds in cold water for 4-5 hours, then place them in warm water at 50-55 degrees C for 5 minutes, transfer to cold water to cool, air-dry and then sow.  

    5. Choose high, dry plots and plant at reasonable density: High environmental humidity and high planting density easily lead to the occurrence of brown spot disease, so land with high terrain, good drainage and good soil permeability should be selected for planting peas, and planting density should be strictly controlled, with reasonable close planting according to the variety.  

    6. Spray for control: At the early stage of pea disease onset, apply medication promptly. The agents can be 70% thiophanate-methyl wettable powder at 500 times solution, or 75% chlorothalonil wettable powder at 600 times solution, sprayed for control. At intervals of 7-10 days, apply once, for 2-3 consecutive times.