Control of soft rot of desert rose

Desert rose soft rot is a major disease of desert rose. Desert rose has bright flowers, luxuriant flowers and short and strong plants, especially the rhizome is simple and vigorous, so it is an excellent succulent plant in the tropics. It has been introduced into China for more than 10 years and has grown well, but the occurrence and damage of soft rot often lead to the death of the whole plant. 1. Symptoms: soft rot is a major disease of desert roses. Desert roses soften in the form of water stains near the surface, initially white or yellowish, then dark brown, break and rot and stink in wet conditions, and the internal tissue is black. Sticky and soft when touched. 2. Etiology: desert rose soft rot is mainly caused by high temperature and stuffy heat in summer, poor ventilation or stagnant water in the basin. ① summer high temperature and stuffy heat and poor ventilation or rain are the key factors causing the disease. During the growth of ②, the tubers and roots were asphyxiated and the absorptive capacity of roots decreased. The planting of ③ in pot or seedling transplanting is too deep or there is too much soil on the rhizome, which is beneficial to the disease. The humidity at the base of the stem is high, which is beneficial to the reproduction and invasion of bacteria and promote the occurrence of diseases. 3. Control methods: sandy loam with good drainage and medium fertility was selected in ① cultivation, 3 parts of coarse sand, 1 part of rotten leaf soil and a small amount of plant ash could be used, and garden soil should not be used as seedling soil. In order to prevent the occurrence of soft rot in advance, ② should start from planting seedlings, first of all, disinfect the potted soil where flowers are planted, and the soil should be used. 0.5%-1% formalin solution was sterilized and transmitted to each other. The depth is generally slightly exposed above the neck of the seedling, about 1 beat 3 above the neck of the seedling stem, and 1 big 2 above the old tuber. ③ watering: usually watering can not be too much, lest the basin soil is too wet, especially in the early stage of the basin should pay attention to less watering, hot weather to micro-tide is better, from early September can be properly watered. Drug prevention and treatment of ④: 1000 times of agricultural streptomycin or 150 times of Bordeaux should be sprayed every 1 month or so.