Key Management Measures After Planting Spring Eggplants in Polytunnels

1. Temperature control. For spring eggplants grown in large polytunnels, after the seedlings are planted and before they recover from transplanting, the tunnel should be kept closed to retain heat, keeping the temperature inside the tunnel at 28-30°C during the day and 15-20°C at night as much as possible. After the seedlings recover, attention should be paid to ventilation, keeping the tunnel temperature at 23-25°C during the day, generally not exceeding 33°C.

2. Fertilizer and water management. When soil moisture is good, water as little as possible before the door eggplant reaches the size of a walnut, to raise soil temperature and prevent flower and fruit drop. When the door eggplant reaches the size of an egg, apply 10 kg of urea per mu along with watering. After that, appropriately increase the frequency of watering according to soil moisture conditions.

3. Pruning and pinching. After the door eggplant has set, all lateral branches and old leaves below the door eggplant can be removed to concentrate nutrients for fruit development. If two-stem pruning is used, excess lateral buds should be removed promptly. When planting density is high, pinch off the growing tip above the flower leaving 2 leaves when the "four-mother-branch" flower buds appear; when planting density is low, pinch off the growing tip leaving 2 leaves above the "eight-direction" flower buds.

4. Hormone regulation. To prevent flower and fruit drop in eggplants, dip flowers in a 20x10-6 aqueous solution of 2,4-D, or spray flowers with 50x10-6 of fruit-setting hormone.

5. Disease and pest control. The main diseases of eggplant include Phytophthora fruit rot, Verticillium wilt, and Phomopsis rot. Disease control should focus on prevention, through measures such as sunning seeds, soaking seeds in chemicals, disinfecting seedbeds, and practicing crop rotation. Once disease occurs, chemical control can be applied. For eggplant Phytophthora fruit rot, at the early stage of disease, spray 64% Shuangyike wettable powder at 500-800 times dilution or 64% Sandofan wettable powder at 500 times dilution, and drench the roots once every 7-10 days for 2-3 consecutive times. For eggplant Verticillium wilt, drench roots with 50% carbendazim wettable powder at 500 times dilution, applying 0.5 kg of the prepared solution per plant. Drench roots once every 7-10 days for 2-3 consecutive times. For eggplant Phomopsis rot, use 75% chlorothalonil wettable powder at 600 times dilution or 40% metalaxyl-copper wettable powder at 600-700 times dilution, spraying once every 7-10 days for 2-3 consecutive sprays. The main pests of eggplant are aphids and eggplant borers, which can be controlled by spraying 40% omethoate emulsifiable concentrate at 1000 times dilution.

6. Timely harvest. For eggplants grown in large polytunnels in spring, from flowering to harvesting young fruit generally takes 20-25 days under normal management. The initial harvest period for the "door eggplant" is around May 1st. Harvest when there is no white left where the fruit surface meets the five sepals and the fruit surface still has its gloss. The best time to harvest eggplants is in the morning, when the fruit is plump and brightly colored.