How to Prevent Root Rot in Chrysanthemums
Chrysanthemums, as one of China's traditional famous flowers, often cause headaches for flower enthusiasts due to root rot issues. Especially during the high-temperature season of summer, wilt diseases are prone to occur, leading to root rot, which not only affects the quality of flowering but can also cause plant death in severe cases. Mastering scientific prevention and control methods is the key to ensuring the healthy growth of chrysanthemums.
Guide to Identifying Chrysanthemum Root Rot Diseases
Be alert when the plant shows yellowing leaves and browning stems. Initially, the leaves lose their green color and droop, and the base of the stem develops light brown spots. As the condition progresses, the vascular system gradually turns brown and necrotic. The outer skin of the roots shows black rot, and some plants may exhibit longitudinal cracking of the stem. Under a microscope, the typical characteristics of the Fusarium oxysporum fungus can be seen: small conidia are pseudocephaloid in aggregation, and chlamydospores are spherical in distribution.
Analysis of the Incidence Pattern of Chrysanthemum Root Rot
Influence of Environmental Factors
When the temperature continues between 27°C-32°C and the humidity is >70%, the activity of the pathogen significantly increases. Continuous rainy weather leads to an increase in soil temperature, and when the matrix moisture content exceeds 30%, root respiration is obstructed, and the plant's resistance to disease decreases.
Cultivation Management Inducements
Heavy, compacted soil, excessive application of nitrogen fertilizer, and clogged drainage holes in containers can all exacerbate the occurrence of diseases. Experimental data shows that the incidence rate in alkaline soil with a pH > 7.5 is 3.2 times higher than in neutral soil.
Practical Scheme for Preventing and Treating Chrysanthemum Root Rot
Optimization of Cultivation System
It is recommended to use a mixed matrix of perlite: decomposed leaf soil: vermiculite = 3:5:2, ensuring a porosity >40%. Water every 3-5 days in spring and autumn, and use the saucer watering method during high-temperature periods in summer. Apply a balanced fertilizer containing calcium and magnesium (NPK 20-20-20) every half month.
Biological and Chemical Control
Water the matrix with hot water at 50°C for 30 minutes before planting. In the early stages of the disease, apply a combination of carbendazim (500 times solution) and Bacillus subtilis (10^8 CFU/g) to the roots, 200ml per plant, combined with foliar application of seaweed extract to enhance resistance.
By establishing a protection system focused on prevention and comprehensive management, the incidence of chrysanthemum root rot can be significantly reduced. It is recommended to conduct root health checks monthly, replace old substrates in a timely manner, and maintain good ventilation in the environment. Only by preventing early, detecting early, and treating early can chrysanthemums maintain vigorous vitality.