How to control sesame stem blight caused by spot blight

After the damage to the sesame stem, the initial yellow-brown water-stained spots, and rapid development, into a circular spot, to the late disease spot, dark brown, and then the stem is hollow and easy to break. After the root was damaged, the main root and branch root gradually turned brown, and a large number of black sclerotia were formed in the cortex of sesame root, which caused the root to die.

Sesame stem blight

The pathogen of spot blight overwinters with sclerotia on seeds, soil and diseased remains. In the second year, the conidia spread in the field by wind, rain and steam, mainly from the base of sesame stem, root and petiole. Sesame is the most susceptible to disease at seedling stage and full flowering stage. Infected sesame plants can produce conidia and then spread infection. High temperature, high humidity and heavy rain are beneficial to the epidemic of point blight, and the damage is aggravated by the application of nitrogen fertilizer, over-dense planting and continuous cropping.

Prevention and control technology:

1. Select disease-resistant sesame varieties and seed treatment. 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 sesame seeds mixed with pentachloronitrobenzene plus thiram (1:1), accounting for 0.5-1% of the weight of sesame seeds, or soaked in 0.5% copper sulfate solution for half an hour, have better control effect.

2. Agricultural prevention and control. Sesame spot blight, the most avoid continuous cropping, sesame and cotton, sweet potato, Gramineae crop rotation for 3-5 years, can control the epidemic of blight. After the sesame harvest, the disease and residue in the field should be cleared in time, burned or buried deeply, so as to reduce the source of overwintering bacteria. Remove the diseased plant in time and take it out of the field for destruction to prevent the spread of germs. Strengthen fertilizer and water management, increase the application of base fertilizer, mainly medium-slow-acting organic fertilizer, and mixed application of phosphorus and potassium fertilizer. No or less nitrogen fertilizer was applied at seedling stage to cultivate healthy seedlings so that it was not easy for germs to invade. The use of high-border cultivation, timely clear ditch drainage, prevent stagnant water in the field, reduce the humidity in the field.

3. Chemical control. Control of sesame diseases, agricultural control, chemical control, spray protection before the occurrence of sesame diseases, 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.