How to prevent and control eggplant Phytophthora fruit rot? The latest practical methods are here
Eggplant Phytophthora fruit rot, also known as rotten eggplant, dropped eggs, water rot, etc., occurs commonly in all vegetable-growing areas. Both open-field eggplant and protected-cultivation eggplant can be affected. In years with heavy rain in early summer or during the plum rain season, or with heavy rain and fog in autumn, the disease is severe. When the disease is severe, it often causes large numbers of fruits to rot, directly affecting yield. Let us take a look together at the prevention and control methods for eggplant Phytophthora fruit rot!
Symptoms
When eggplant seedlings are affected, the base of the stem becomes water-soaked and develops very quickly, often causing damping-off and leading to seedling death. When leaves of mature plants are infected, water-soaked irregular lesions appear, with obvious concentric rings, but the edges are not distinct, brown or purplish brown, and a small amount of white mold grows on the lesions when humid. When the stem is affected, it becomes water-soaked and constricted, sometimes breaks, and bears white mold. After flower organs are infected, they become brown and rot. Fruits are affected most severely, initially showing water-soaked round spots with indistinct margins, slightly sunken, yellow-brown to dark brown. The diseased fruit flesh is dark brown and rotting, and under high humidity the surface of the diseased area grows white cottony mycelium. Diseased fruits easily drop off or shrink and dry into mummified fruits.
Conditions for disease occurrence
The optimum temperature for development is 30°C, and mycelial development is good when the relative air humidity is above 95%. Within the high-temperature range, humidity inside the greenhouse is an important factor in determining whether the disease occurs. In addition, continuous cropping land, high groundwater levels, poor drainage, dense planting, poor ventilation, or rain after the greenhouse canopy is removed, or dripping from the canopy, causing water accumulation and dampness on the ground, all easily induce this disease. It is prone to occur under high temperature and high humidity, sudden clearing after rain, excessive plant density, poor ventilation and light transmission, low-lying terrain, and heavy clay soil.
Open-field prevention and control
1. Plastic film mulching: Use black plastic film to cover the ground or lay it between rows, which can block the splash transmission of pathogen spores in the soil to eggplant fruits. It can also use sunlight for high-temperature sterilization and prevent weed growth.
2. Scientific fertilization and watering: Apply sufficient decomposed organic fertilizer, prevent high temperature and high humidity, increase the application of phosphorus and potassium fertilizers, promote robust plant growth, and improve plant resistance.
3. Careful management: Prune at the proper time, remove lower old leaves, improve field ventilation and light conditions, promptly remove diseased leaves and fruits, and take diseased residues out of the field to prevent reinfection.
Greenhouse prevention and control
1. Disease-resistant varieties: such as Xingcheng Purple Round Eggplant, Guizhou Winter Eggplant, Tongxuan No. 1, Jinan Early Small Long Eggplant, Bamboo Silk Eggplant, Liaoqie No. 3, Fengyan No. 11, Qingxuan No. 4, Laolaihei, etc.
2. Seed disinfection: Disinfect seeds before sowing, for example soaking seeds in warm water at 50°C to 55°C for 7 to 8 minutes before sowing, which can greatly reduce the occurrence of Phytophthora fruit rot.
3. Plug tray seedling raising: 288-cell trays can be used, with one seed per cell. Nutrients are sufficient, the root system is well developed, and roots are not damaged or are less damaged during transplanting, enhancing disease resistance and reducing opportunities for infection.
4. Implement crop rotation: Arrange plots reasonably, and avoid continuous cropping with Solanaceae and Cucurbitaceae crops such as tomatoes and peppers. Generally, a rotation of more than 3 years is carried out.
5. Careful site selection: Choose high, dry plots for planting eggplant, and plow the soil deeply. Use high-ridge cultivation and cover with plastic film to block the spread of pathogens from the soil to the aboveground parts and promote root development.