What are the control methods for soft rot in desert rose?
Desert rose soft rot is a major disease affecting desert rose. The desert rose has gorgeous flowers, blooms profusely, and is a short, sturdy plant; especially the root and stem portions have an ancient, vigorous posture, making it an excellent succulent plant for tropical regions. It has been introduced into our country for more than 10 years and grows well, but the occurrence and damage of its soft rot often causes the entire plant...
Desert rose soft rot is a major disease affecting desert rose. The desert rose has gorgeous flowers, blooms profusely, and is a short, sturdy plant; especially the root and stem portions have an ancient, vigorous posture, making it an excellent succulent plant for tropical regions. It has been introduced into our country for more than 10 years and grows well, but the occurrence and damage of its soft rot often causes the entire plant to die.
1. Symptoms: Soft rot is a major disease of desert rose. Near the soil surface, the desert rose develops water-soaked softening, initially white or pale yellow, finally turning dark brown. Under moist conditions it will split and rot and has a foul odor, the internal tissue is black, and it is sticky and soft to the touch.
2. Causes: Desert rose soft rot is mainly caused by high summer temperatures and muggy conditions, poor ventilation, or water accumulating in the pot.
① Hot, muggy summer weather with poor ventilation or exposure to rain is the key factor causing this disease.
② Excessive watering during the growing period suffocates the tuber and roots, and the roots' absorption capacity declines.
③ When potting or transplanting seedlings, planting too deep or mounding too much soil around the root and stem area favors the disease. High humidity at the stem base favors pathogen reproduction and invasion, promoting the occurrence of the disease.
3. Control methods:
① When cultivating, choose sandy loam with good drainage and medium fertility. You can use 3 parts coarse sand, 1 part leaf mold, plus a small amount of plant ash; do not use garden soil as seedling-raising soil.
② In order to prevent soft rot early, start from the planting seedlings. First, disinfect the soil in the flower pot. The soil must be disinfected with 0.5%-1% formalin solution, each square [unit] mutually infecting. The depth should generally be such that the neck of young seedlings is slightly exposed above the surface; for mature plants, about 1/3 of the stem neck is exposed above the surface, and for old tubers, about 1/2 is exposed above the surface.
③ Watering: Do not water too much at ordinary times, so as to avoid the potting soil becoming too wet. Especially in the early potting stage, be careful to water less. In hot weather, slightly moist is best. From early September, watering can be appropriately increased.
④ Chemical control: About every 1 month, spray with agricultural streptomycin 1000 times solution or 150-200 times Bordeaux mixture.