Prevention and control of bean anthracnose caused by long brown leaf spot, stem petiole and petiole

The occurrence of bean anthracnose is common, which is serious in warm, cool and rainy areas and seasons, which will reduce yield, reduce bean quality and marketability, and limit bean production.

Bean anthracnose

1. Symptoms: the shoots of kidney beans could be damaged from ① seedlings to the later stage of harvest. After the seedlings were unearthed, the cotyledons appeared red-brown near-round disease spots and sunken fester. The lower part of the young stem produces reddish brown spots and long prismatic depressions, sometimes the disease spots converge, the base of the stem is cut around, and the seedlings fall and die.

② occurs in the adult stage, with reddish-brown stripes in the veins of the diseased leaves and black reticular veins in the later stage. The stem and petiole were infected with brown sunken tortoise fissures and long black and brown spots in the later stage. The pod is infected with black round sunken spots.

2. The rule of disease: ① can survive on bean seeds for more than 2 years, while overwintering pathogen in soil has a short survival time.

② was transmitted by wind, Rain Water and insects. 22-27 ℃ was beneficial to the disease, and the disease was inhibited when it was higher than 30 ℃ or less than 15 ℃. When the relative humidity is close to 100%, it is suitable for the disease.

Factors such as low temperature, high humidity, low-lying terrain, poor ventilation, over-dense cultivation, heavy soil viscosity and excessive nitrogen fertilizer in ③ will aggravate the disease.

3. Prevention and control methods:

1. Select disease-free bean seeds and seed disinfection: collect seeds from disease-free fields and disease-free pods. The seeds were selected strictly and the diseased seeds were removed. Before sowing, soak in 45 ℃ warm water for 10 minutes, or with formaldehyde 200x solution for half an hour, or 40% formalin 200x solution for half an hour, or 60% Fangmaibao ultra-fine powder for half an hour, fish out, rinse with clean water and dry for sowing; you can also sow seeds with 50% carbendazim or thiram wettable powder according to seed weight 0.3% 0.4%.

two。 Selection of disease-resistant varieties: there were differences in disease resistance among bean varieties. In general, trailing varieties are more resistant than dwarf varieties.

3. Implement crop rotation: bean and non-leguminous vegetables should be rotated for more than 2 years; before using the old shelf material, wash, disinfect and sterilize with 1000 times solution of 50% Dysenamine water agent.

4. Strengthening cultivation management: improving cultivation techniques and covering cultivation with plastic film or rice straw can reduce or prevent the spread of soil germs and reduce air humidity. Ploughing the soil deeply, applying more phosphorus and potassium fertilizer, pulling out diseased seedlings in time, ploughing in time after rain, cultivating soil after energy application, paying attention to drainage and reducing soil water content.

5. Drug prevention and treatment: in the early stage of the onset of ①, start spraying. Use 75% chlorothalonil wettable powder 600 times liquid, or 50% carbendazim wettable powder 500 times liquid, or 50% methyl thiophanate wettable powder 500 times liquid, or 70% mancozeb wettable powder 500 times liquid, 80% anthrax Fumei wettable powder 500 times liquid, or 70% mancozeb wettable powder 500 times liquid, once every 5 days, spray 2 times for 3 times. Spray to be considerate, pay special attention to the back of bean leaves, spray in case of rain, should be timely spray.

② protected area, can use 30% chlorothalonil smoke remover, etc., 250-300 grams per mu, divided into 5-6 places to ignite fumigation control.