Occurrence characteristics and control measures of sesame blight

Sesame blight is a destructive disease. Mainly damage the base of sesame stem, stem, capsule, leaf. After the damage to the base of the stem, it first showed dark green water stains, and then showed reddish brown, depression and longitudinal split of the cortex. After the damage to the stem and capsule, the diseased part showed a dark green water stain, constricted and sunken, and produced cotton floc-like white mold. After the damage to the leaves, there are yellowish-brown disease spots, the disease spots have no obvious wheel pattern. The pathogen overwintered in the remnant of the diseased plant with hyphae or oospores. In the following year, the pathogen infected the base of the stem, produced sporangia, spread by wind, rain and running water, and expanded and re-infected. The disease began in the budding stage of sesame in July and reached the peak in August. It's rainy and damp.

Prevention and control technology:

1. Disease-resistant varieties and seed treatment were selected. Varieties with good quality, high yield, waterlogging tolerance and strong disease resistance were selected, such as Yuzhi 8, Yizhi 1 and so on. Soak the seeds in 55 ℃ warm water for 10 minutes or 60 ℃ warm water for 5 minutes before sowing, then sow the seeds after drying. Or seed dressing with pentachloronitrobenzene plus thiram (1:1), which accounts for 0.5-1% of the seed weight, or soaking the seed with 0.5% copper sulfate solution for half an hour has a better control effect.

2. Agricultural prevention and control. Sesame soil-borne diseases and insect pests are serious, and continuous cropping is most avoided. the rotation of sesame with cotton, sweet potato and gramineous crops for 3-5 years can better control the epidemic of the disease. After the sesame is harvested, the diseased remains in the field should be removed in time and burned or buried deeply in order to reduce the source of overwintering bacteria. Remove the diseased plants in time and take them out of the field for destruction to prevent the spread of germs. Strengthen the management of fertilizer and water, increase the application of base fertilizer, the base fertilizer is mainly medium and late-acting organic fertilizer, and mixed application of phosphorus and potassium fertilizer, no or less nitrogen fertilizer at seedling stage to cultivate healthy seedlings and make it difficult for bacteria to invade. High border cultivation is adopted to clear ditches and drain in time to prevent stagnant water in the field and reduce the humidity in the field.

3. Chemical control. The prevention and control of sesame diseases should be based on agricultural control, and chemical control should be controlled by spraying protection before the occurrence of the disease or the use of drugs at the initial stage of the disease. The control agents include 37% chlorhexidine wettable powder 800x solution, 40% carbendazim suspension 700x liquid, 50% methyl topiramate wettable powder 800x 1000 fold solution, 80% copper sulfate wettable powder 800x liquid, and so on.