A Summary of the Top Ten Vegetable Seedling Problems in September and Their Control Strategies

September is the suitable period for sowing and raising seedlings of overwintering solanaceous vegetables in greenhouses. Among them, the sowing period for eggplant and chili pepper is from late August to early September, and the sowing period for tomato and sweet pepper is mid-September. Seedling raising has always been a concern for vegetable growers, as it affects later management and harvesting. Below, let us take a look at the causes and solutions for problems such as failure to emerge, root burn, and root rot during seedling raising.

1. Frostbitten seedlings

Cause: Bottom ventilation is used, there is no buffer room at the entrance and exit, no buffer film is hung at the entrance and exit of the plastic greenhouse, the ventilation opening is too large, or the film surface is punctured. Generally, cold wind below 5 degrees C entering will cause frost damage.

Countermeasures: Set up a buffer room or hang buffer film at the entrance and exit, keep the covering film intact, and seal it tightly. If frost damage occurs, immediately spray the seedlings with gibberellin and sugar water or Jiamei Golden Point, and drench the roots with Hongli to promote growth and development and restore growth.

2. No emergence or very few seedlings emerging

Cause: The seeds have lost their germination ability; the ground temperature or air temperature is too low or too high, the seedling bed has poor ventilation and light transmission, the seedbed soil moisture content is too high or too low, too much fertilizer is applied to the seedbed soil, or the covering soil is too thick.

Countermeasures: Conduct germination tests and seed disinfection work; dig into the soil to check. If the seed sprouts have died, reseed immediately; if the seedbed soil is infected with pathogens that affect the seedlings, change the seedbed, accelerate germination, and sow again; if the seed germination rate was very high at sowing and the seeds still show germination potential when checked by digging, then environmental conditions must be improved to remove the obstacle.

3. Uneven emergence with a long interval

Cause: Uneven bed temperature, uneven bed surface, and uneven thickness of covering soil; poor seed germination vigor, different degrees of maturity, part of the seeds affected by moisture during storage, and mixing of new and old seeds; rainwater leaking into the seedling bed, localized damage by underground pests, and uneven mixing of fertilizer in the seedbed soil.

Countermeasures: Create good seedling-raising conditions, level the bed surface as much as possible, make the seedbed soil fine and disinfect and sterilize it; conduct germination tests before sowing to avoid mixing new and old seeds; cover the seedling bed tightly with film and leave few gaps; treat seeds with chemicals before sowing, and mix organic fertilizer and chemical fertilizer evenly in the seedbed soil.

4. “Cap lifting” and “hat-wearing” seedlings

Cause: Too little bottom water before sowing, insufficient moisture on the bed surface, and after germination the mucus between the seed coat and the embryo is absorbed dry by the bed surface soil and loses its lubricating effect, so the seedlings emerge from the ground still carrying the shell; the covering soil is too thin and the pressure is insufficient, so they emerge “wearing hats”; the seeds are not plump, are incomplete or damaged, or have been stored for a long time, resulting in poor germination rate and difficulty breaking through the seed coat, so they emerge with the “cap lifted.”

Countermeasures: Use a watering can to sprinkle some water in the morning or scatter some moist fine soil; use new seeds or seeds with a high germination rate for sowing as much as possible; manually pick open the seed coat.

5. Old small seedlings

Cause: The seedling age is too long, the low-temperature period lasts too long, and the soil is dry.

Countermeasures: The seedling age should be appropriate, and seedling hardening should be moderate. During hardening, the low-temperature period should not be too long. Do not rely on controlling water to harden seedlings, to prevent long-term drought from causing seedling aging. Seedling hardening should adopt the method of controlling temperature but not controlling water.

6. Leggy seedlings

Cause: Sowing density is too high; after emergence, the bed temperature is too high.

Countermeasures: Sow thinly, and immediately lower the temperature to harden the seedlings after full emergence; if the seedlings become leggy, spray the seedlings with 50-100 mg/kg chlormequat.

7. Herbicide-damaged seedlings

Cause: The amount of pesticide used is too large, the concentration is too high, and the seedling bed is too dry.

Countermeasures: Strictly master the pesticide dosage and concentration, and apply evenly. For seedling beds where pesticides are used, water more thoroughly before sowing to keep the soil moist. If pesticide damage is found, spray water promptly to dilute the pesticide concentration, then spray Jiamei Golden Point or Bihu; seedlings can also be divided and transplanted early so that the vegetable seedlings leave the original seedling bed and the pesticide damage is alleviated.

8. Wilting seedlings

Cause: After continuous cloudy days suddenly turned sunny, all covering materials were removed.

Countermeasures: After the weather suddenly turns sunny, do not remove all covering materials and expose the seedlings to the sun; remove them section by section. If wilting seedlings are found shortly after removing the covering, cover them immediately, and remove the covering again only after the seedlings return to normal. Absolutely avoid watering.

9. Root-burned seedlings

Cause: Too much fertilizer in the seedling bed, and the soil solution concentration is too high. Generally, when the soil solution concentration exceeds 0.5%, root burn will occur.

Countermeasures: The amount of fertilizer applied to the seedling bed should be appropriate. Apply decomposed organic fertilizer, and topdressing must have its concentration controlled. When root burn occurs, water appropriately more to reduce the soil solution concentration, and appropriately increase the seedling bed temperature.

10. Root-rot seedlings

Cause: The seedling bed soil moisture is often in a saturated state, the humidity is too high, and air is lacking.

Countermeasures: Control the amount of water used to irrigate the seedling bed; prevent flooding irrigation. Once root rot occurs, ventilate promptly to remove moisture; increase evaporation; scatter dry soil to absorb moisture; and cultivate and loosen the soil frequently to increase permeability.