It's time to raise seedlings for late-autumn zucchini; sow in time so as not to miss the farming season

Late-autumn zucchini is generally sown and raised around August 10, but August is a hot, rainy season with the most rampant pests and diseases, making it the most difficult period of the year for raising seedlings. Zucchini seedlings fear both high temperatures and waterlogging; raising seedlings in this period makes the young plants prone to virus disease, leading to failure of seedling production. To grow robust seedlings free of pests and diseases, a three-protection seedbed must be built, achieving protection against high temperature, strong light and sunscald, protection against waterlogging and damp stagnation, and protection against pests and diseases.

I. Variety selection

In late-autumn zucchini cultivation, the early growth period has high temperatures, and whiteflies, tobacco whiteflies and aphids occur severely, which easily leads to virus disease. In production, varieties with good heat tolerance and strong virus resistance should be selected, such as Zhenyu 35, Zhenyu No. 9, Zhenyu 16, Meiyu and others.

II. Sow at the right time, grow strong seedlings

According to local climate characteristics and cultivation practices, the suitable time for autumn zucchini cultivation is around August 10. Sowing too early means high temperatures and strong light in the early stage, and seedlings are susceptible to virus disease; sowing too late shortens the harvest period and affects economic returns. The suitable seedling age is about 15 days, and seedlings can be transplanted once they have 2 true leaves. If the seedling age is too long, roots are easily damaged at transplanting, which is unfavorable for seedling recovery and easily leads to virus disease.

For late-autumn zucchini cultivation, the method of raising seedlings in substrate plug trays and then transplanting is recommended. Use arched sheds for rain protection, shade nets for shading, and insect-proof nets for pest prevention. Before sowing, spray the seedling substrate with water until it forms a ball when held in the hand and crumbles when released; then fill 50-cell plug trays, sowing 1 pre-germinated seed per cell (the seed should preferably have just sprouted), placing the seed flat in the center of the cell. After sowing, cover with 1-1.5 cm of substrate, spray with clean water, and water the substrate thoroughly. Build a small arched shed over the seedbed and cover it with an insect-proof net to prevent damage by aphids, whiteflies and tobacco whiteflies and to prevent virus disease.

III. Seedbed management

When the seedlings have all emerged, spray once with a fungicide to control damping-off and Rhizoctonia rot. Water lightly once every 2-3 days to keep the seedbed moist, and appropriately spray 1-2 times with a 0.3% potassium dihydrogen phosphate aqueous solution to promote seedling growth and flower bud differentiation. Pay close attention to weather changes and strictly prevent seedling scorching in hot weather and seedling drowning in rainy weather. Add shade nets when shading is needed.

IV. Transplanting

Zucchini has a relatively developed root system and likes fertile soil; choose a loamy plot whose previous crop was not a cucurbit, with good drainage and irrigation conditions and good fertilizer and water retention for transplanting. Apply 5000 kg of farmyard manure, 40-50 kg of superphosphate and 50 kg of three-element compound fertilizer per mu. If root-knot nematode disease has occurred in the plot, use 2-3 kg per mu of 0.5% abamectin granules or Xianzhi granules. Spread the above fertilizers and pesticides evenly on the soil surface, then plow deeply and harrow finely so that the soil and manure are fully mixed. After leveling the plot, form ridges with a ridge spacing of 1.2-1.3 m and a ridge height of 20 cm; after raking the ridge surface flat, cover with black plastic film to prevent weeds.

When the seedlings have 2 true leaves, they can be transplanted; before transplanting, spray the seedlings with pesticides to prevent pests and diseases. The late-autumn crop has a relatively short growth period, so appropriate close planting can increase yield. Plant double rows per ridge with a plant spacing of 0.55-0.6 m, and transplant 1200-1500 plants per mu. Choose a sunny afternoon or a cloudy day to break the film and open holes for transplanting; select pest-free and disease-free seedlings, water the transplanting holes, and then press the plastic film firmly around the seedlings. According to soil moisture, water thoroughly after transplanting to soak the ridge, which can lower soil temperature and help seedling recovery. Note: when watering, strictly prevent standing water from drowning the seedlings and avoid soil crusting at the stem base of the seedlings.