How to prevent and control root rot? Mastering these methods is key
Root rot is caused by the rotting of the root system, which gradually weakens its ability to absorb water and nutrients, ultimately leading to the death of the entire plant. It mainly manifests as yellowing and wilting of the leaves of the whole plant. It generally occurs from late March to early April, and enters its peak period in May. It can be caused by infection from various pathogens such as Pythium, Fusarium, and Phytophthora. Let us take a look below at how to prevent and control root rot!
Symptoms of root rot
Root rot mainly damages seedlings, but it can also occur during the mature plant stage. In the early stage of the disease, only individual lateral roots and fibrous roots are infected, and it gradually spreads to the main root. After the main root is infected, the plant shows no symptoms in the early stage. Later, as the degree of root rot intensifies, the ability to absorb water and nutrients gradually weakens. Because the aboveground parts cannot get enough nutrients, the new leaves first turn yellow. Around noon, when light is strong and evaporation is high, the upper leaves of the plant wilt, but they can recover at night. When the condition is severe, the wilting cannot recover even at night. The leaves of the whole plant turn yellow and wither. At this point, the root bark turns brown and separates from the pith, and finally the whole plant dies.
Pathogenic mechanism of root rot
Root rot often has symptoms similar to root suffocation and is a fungal disease. The pathogen overwinters in the soil and on diseased plant residues. It generally occurs from late March to early April, and enters its peak period in May. Its occurrence is closely related to climatic conditions. Low temperature, high humidity, and insufficient light in the seedbed are the main environmental conditions that trigger this disease. Seedling beds with heavy clay soil that easily becomes compacted and has poor aeration, thereby hindering root growth and development, are also prone to the disease. In addition, after roots are damaged by underground pests and nematodes, there are many wounds, which facilitates pathogen invasion. Under these conditions, not only are herbaceous flowers propagated by sowing and cuttings susceptible, but woody flowers such as rose, cotton rose, and Chinese hibiscus propagated by cuttings, division, and layering are also susceptible.
Organic control of root rot
1. Agricultural control: Strengthen seedbed management. After sowing in the seedbed, the soil covering should not be too thick. When watering the seedbed, it depends on soil moisture and weather, and the amount of water should not be too much. Do not water around noon in summer. Cultivate more to provide soil aeration.
2. Physical control: Soak seeds in warm water at 55°C for 10 minutes.
3. Chemical control: For seedbed prevention, use wettable powder at 2-4 grams per sq m for root irrigation. It can also be used before onset or in the early stage of onset at 1500-3000 times dilution for root irrigation, with 200 milliliters of solution per plant. When the disease is severe, remove diseased plants and at the same time use Gugen for root irrigation.
How to prevent and control root rot?
1. Select superior varieties: Choose and prepare the seedling plot well. Select high-quality varieties, treat seeds with seed soaking plus seed coating agent, and sow at the appropriate time.
2. Disinfection treatment: Before sowing, seeds can be mixed with 0.3% of seed weight of Tuijunte or 0.1% of seed weight of triadimefon, or soaked for 5 hours in a 2000-times solution of 80% 402 antibacterial emulsifiable concentrate. The base of cuttings can also be soaked for 1 hour in the same concentration of solution before cutting.
3. Soil disinfection: For the seedbed, use metalaxyl-hymexazol or carbendazim for soil disinfection, which can also control damping-off and seedling blight.
4. Cultivate strong seedlings: Plow and prepare the land finely, cultivate strong seedlings carefully, try not to damage the roots during transplanting, arrange carefully, ensure there is no water accumulation or root suffocation, and apply sufficient base fertilizer.
5. Water appropriately: After planting, water timely and appropriately according to temperature changes to prevent aboveground water evaporation and plant water transpiration, and isolate viral infection.
6. Spray phosphate fertilizer: Spray phosphate fertilizer at the flower bud stage, young fruit stage, and fruit expansion stage respectively to enhance the plant's nutrient matching function, thicken the fruit stalk, promote healthy plant growth, and strengthen disease resistance.
7. Chemical control: Copper preparations or metalaxyl-hymexazol can be used for prevention and control. When the disease occurs, metalaxyl-hymexazol or copper preparations can be used for root irrigation, and at the same time timely control underground pests and nematode damage.