Eggplant Phytophthora Rot: Symptom Identification and Key Control Points
Eggplant Phytophthora Rot Symptoms and Key Control Points
Eggplant Phytophthora rot causes fruit to rot and drop in whole patches, and is one of the major diseases of eggplant. It occurs commonly in all regions, and eggplant can be affected at any growth stage. Losses are generally 20%-30%, and more than 50% in severe cases. The peak fruiting period is also the peak period of disease occurrence, and in rainy regions and years it often breaks out into a disaster.
I. Symptoms
Phytophthora rot mainly damages the fruit, but can also damage stems, leaves and flowers. At the early stage of the disease, water-soaked round lesions appear on the fruit surface, slightly sunken, yellow-brown or dark brown, and under suitable conditions they spread rapidly, gradually rotting the entire fruit surface. Under high humidity, the diseased parts produce dense white cottony growth, the flesh turns dark brown and rots, and diseased fruits drop easily or shrink to form mummified fruit. It can also damage leaves, stems and flowers; diseased stems form water-soaked, dark green or purplish-brown lesions, and sparse white mold grows when humidity is high. When seedlings are affected, the base of the stem becomes water-soaked and necrotic, causing damping-off.
II. Conditions for Disease Occurrence
Eggplant Phytophthora rot is a fungal disease. It spreads mainly through soil and rainwater. It occurs easily under high temperature and high humidity, sudden clear weather after rain, excessive plant density, poor ventilation and light penetration, low-lying terrain, and heavy clay soil.
III. Integrated Control
For greenhouse and plastic-tunnel eggplant to be sown in August, the following control measures can be taken:
1. Choose resistant (tolerant) varieties: generally round eggplant varieties are more resistant than long eggplant varieties, such as Moheiqie and Jiuyeqie. In addition, thick-skinned varieties are more resistant than thin-skinned varieties, and early-maturing varieties are more resistant than late-maturing varieties.
2. Seed disinfection: disinfect the seeds before sowing, for example soaking the seeds in warm water at 50°C-55°C for 7-8 minutes before sowing, which can greatly reduce the occurrence of Phytophthora rot.
3. Use 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 at transplanting, which enhances disease resistance and reduces the chance of infection.
4. Practice crop rotation: arrange plots reasonably, and avoid continuous cropping with Solanaceae and Cucurbitaceae crops such as tomato and pepper. Generally, a rotation of more than 3 years is practiced.
5. Carefully select the site. Pay attention to choosing plots with high, dry terrain and good drainage, and use deep furrows and high beds for cultivation, which is beneficial for drainage after rain. Avoid as much as possible plots with heavy clay soil that easily accumulate water after rain.
For open-field eggplant currently in the fruit-setting stage, the following control measures can be taken:
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 from the soil to the eggplant fruit. It can also use sunlight for high-temperature sterilization and prevent weed growth.
2. Scientific fertilization and watering: apply sufficient decomposed farmyard manure, increase phosphorus and potassium fertilizer, topdress in a timely manner, irrigate gently with small amounts of water without waterlogging, and immediately irrigate with cool water after heavy rain, so as to resist infection and enhance plant disease resistance.
3. Careful management: prune in a timely manner, remove old leaves from the lower part, improve field ventilation and light penetration, promptly remove diseased leaves and fruits, and carry diseased residues out of the field to prevent re-infection.
4. Chemical control: before transplanting eggplant, spray the seedling bed with 50% captan wettable powder at 500 times dilution. You can also mix 5 kg of 50% carbendazim wettable powder with 100 kg of soil and apply it into the transplanting holes. After the seedlings recover, spray the plant roots with 70% dexon wettable powder at 500 times dilution or 70% zineb wettable powder at 500 times dilution, once every 7-10 days.
As soon as the first diseased plants appear, they should be pulled up and destroyed immediately and pesticide should be sprayed. During the fruiting period, especially before rain, spray for protection, applying 1:1:200 Bordeaux mixture once every 7 days to prevent the disease. After the disease occurs, apply pesticide immediately; optional agents include 75% chlorothalonil at 500-600 times dilution, 50% thiophanate-methyl wettable powder at 800 times dilution, and 40% fosetyl-aluminum wettable powder at 200 times dilution, etc., alternating the agents, generally spraying once every 7-10 days for 3-4 consecutive sprays.
I. Symptoms
Phytophthora rot mainly damages the fruit, but can also damage stems, leaves and flowers. At the early stage of the disease, water-soaked round lesions appear on the fruit surface, slightly sunken, yellow-brown or dark brown, and under suitable conditions they spread rapidly, gradually rotting the entire fruit surface. Under high humidity, the diseased parts produce dense white cottony growth, the flesh turns dark brown and rots, and diseased fruits drop easily or shrink to form mummified fruit. It can also damage leaves, stems and flowers; diseased stems form water-soaked, dark green or purplish-brown lesions, and sparse white mold grows when humidity is high. When seedlings are affected, the base of the stem becomes water-soaked and necrotic, causing damping-off.
II. Conditions for Disease Occurrence
Eggplant Phytophthora rot is a fungal disease. It spreads mainly through soil and rainwater. It occurs easily under high temperature and high humidity, sudden clear weather after rain, excessive plant density, poor ventilation and light penetration, low-lying terrain, and heavy clay soil.
III. Integrated Control
For greenhouse and plastic-tunnel eggplant to be sown in August, the following control measures can be taken:
1. Choose resistant (tolerant) varieties: generally round eggplant varieties are more resistant than long eggplant varieties, such as Moheiqie and Jiuyeqie. In addition, thick-skinned varieties are more resistant than thin-skinned varieties, and early-maturing varieties are more resistant than late-maturing varieties.
2. Seed disinfection: disinfect the seeds before sowing, for example soaking the seeds in warm water at 50°C-55°C for 7-8 minutes before sowing, which can greatly reduce the occurrence of Phytophthora rot.
3. Use 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 at transplanting, which enhances disease resistance and reduces the chance of infection.
4. Practice crop rotation: arrange plots reasonably, and avoid continuous cropping with Solanaceae and Cucurbitaceae crops such as tomato and pepper. Generally, a rotation of more than 3 years is practiced.
5. Carefully select the site. Pay attention to choosing plots with high, dry terrain and good drainage, and use deep furrows and high beds for cultivation, which is beneficial for drainage after rain. Avoid as much as possible plots with heavy clay soil that easily accumulate water after rain.
For open-field eggplant currently in the fruit-setting stage, the following control measures can be taken:
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 from the soil to the eggplant fruit. It can also use sunlight for high-temperature sterilization and prevent weed growth.
2. Scientific fertilization and watering: apply sufficient decomposed farmyard manure, increase phosphorus and potassium fertilizer, topdress in a timely manner, irrigate gently with small amounts of water without waterlogging, and immediately irrigate with cool water after heavy rain, so as to resist infection and enhance plant disease resistance.
3. Careful management: prune in a timely manner, remove old leaves from the lower part, improve field ventilation and light penetration, promptly remove diseased leaves and fruits, and carry diseased residues out of the field to prevent re-infection.
4. Chemical control: before transplanting eggplant, spray the seedling bed with 50% captan wettable powder at 500 times dilution. You can also mix 5 kg of 50% carbendazim wettable powder with 100 kg of soil and apply it into the transplanting holes. After the seedlings recover, spray the plant roots with 70% dexon wettable powder at 500 times dilution or 70% zineb wettable powder at 500 times dilution, once every 7-10 days.
As soon as the first diseased plants appear, they should be pulled up and destroyed immediately and pesticide should be sprayed. During the fruiting period, especially before rain, spray for protection, applying 1:1:200 Bordeaux mixture once every 7 days to prevent the disease. After the disease occurs, apply pesticide immediately; optional agents include 75% chlorothalonil at 500-600 times dilution, 50% thiophanate-methyl wettable powder at 800 times dilution, and 40% fosetyl-aluminum wettable powder at 200 times dilution, etc., alternating the agents, generally spraying once every 7-10 days for 3-4 consecutive sprays.