How to prevent and control root rot in Chinese fir? Key methods explained in one article

Root rot is a common disease in the southern regions of China, and it is extremely harmful to Chinese fir, capable of causing the death of large numbers of seedlings. So what are the prevention and control methods for Chinese fir root rot?

1. Symptoms and onset conditions of Chinese fir root rot

1. Main symptoms

At the early stage of onset, only a few lateral roots and fibrous roots are infected, and the infection gradually spreads to the main root. After the main root is infected, the symptoms of the plant are not obvious in the early stage, but as the degree of root rot intensifies, the absorption function gradually weakens, so that the aboveground part cannot receive an effective supply of water and nutrients, especially around noon when light is strong and evaporation is high. When the condition is mild, the upper leaves of the plant wilt, but can recover at night. When the condition is severe, the wilting cannot recover even at night. At this point, the root bark turns brown and separates from the pith, leading to the death of the whole plant.

2. Onset conditions

Root rot is a fungal disease. The pathogens are Sclerotium rolfsii, a deuteromycete, and Thanatephorus cucumeris, a basidiomycete. The pathogens overwinter in the soil and on diseased residues. The onset period generally begins in May, with the peak onset period from July to August, and the degree of onset is closely related to climatic conditions. In greenhouses in the north, high temperature and high humidity combined with insufficient light very easily trigger this disease. When the substrate is highly clayey, has insufficient fertility, and poor aeration, the growth and development of the root system are hindered, and the disease is also likely to occur.

2. Prevention and control methods for Chinese fir root rot

1. Strengthen the cultivation and management of seedlings

Improve ventilation and light transmission conditions, and try to avoid continuous yearly propagation of a single seedling variety.

2. Disinfection of plant materials

Seeds can be dressed with 0.3% of the seed weight of Tuzet, or soaked for 5h in a 2000-fold dilution of 80% 402 antibacterial emulsifiable concentrate; the base of cuttings can also be dipped for 1h in the same concentration of the solution, and then sowing or cutting can be carried out.

3. Disinfection of seedbed substrate

Apply 1.5g of 50% carbendazim per sq m, or 3g of 75% quintozene, scatter it on the ground surface, and then turn it into the soil. This can achieve the effect of preventing and treating disease, and can also prevent and control damping-off and seedling blight.

4. Chemical control

When the disease occurs, a 1000-fold dilution of 40% root rot ning can be sprayed or poured on diseased plants, a 1500-fold dilution of 80% 402 emulsifiable concentrate can be used to drench the roots, and 1% copper sulfate can be used to drench the roots.

5. Strengthen daily management

(1) Improve tree vigor, improve resistance to pests and diseases, and increase the application of organic fertilizer.

(2) Deeply plow the soil to increase soil permeability.

(3) Use a specific root rot medicine for root drenching treatment.

Warm tip: Chinese fir generally prefers a warm, humid, breezy climate and soil with deep, loose, fertile layers and good drainage. Choose afforestation plots according to the cultivation purpose, matching tree species to site and adapting measures to local conditions. Generally, it is best to choose fertile sloping land at an altitude of 300-800m, with a soil type of mountain red soil or mountain yellow soil.