What causes zucchini fruit abortion

Zucchini fruit abortion is the most common problem in zucchini cultivation. 3 to 4 days after the female flower opens, the tip of the young fruit loses its green color and turns yellow, becomes thin and soft, the tip shrivels, the fruit does not enlarge, and it eventually rots or drops off. Zucchini fruit abortion is generally caused by unsuitable environmental conditions and imbalanced nutrient supply, mainly in the following aspects.

1. Poor pollination. Zucchini is a cross-pollinated crop, and its requirements for environmental conditions during flowering are very strict. When the female flower opens, if the temperature is below 15°C or the humidity is too high, pollination will be poor and fruit abortion will result.

2. Too many fruits set. ① Too many female flowers differentiate, as with winter-spring greenhouse zucchini and spring plastic-tunnel zucchini, whose seedling stage occurs under low-temperature, short-day conditions that favor female flower differentiation and formation, so many young fruits set. ② Some varieties have very strong fruit-setting ability themselves, setting many young fruits, even several fruits per node. Because too many young fruits set, they compete with one another for nutrients, causing fruit abortion.

3. Unsuitable temperature. The optimum temperature for zucchini growth and development is 18-25°C. If the temperature is too high, especially when the night temperature stays above 15°C for a long time, respiration increases, nutrient consumption grows, nutrient accumulation in the fruit weakens, and fruit abortion results. If the temperature is too low, both photosynthesis and root absorption capacity decrease, leading to insufficient nutrients and fruit abortion.

4. Planting density too high. If the planting density is too high, root systems compete with one another for nutrients in the soil and leaves compete for space and light, so both the root absorption rate and the photosynthesis rate drop greatly, leading to nutrient deficiency and fruit abortion.

5. Harm from harmful gases. In greenhouse zucchini cultivation, if organic fertilizer or quick-acting nitrogen fertilizer is applied improperly, or sulfur powder is mistakenly used for fumigation disinfection, harmful gases such as NH3, NO2 and SO2 are often produced. When these harmful gases accumulate to a certain level, zucchini shows symptoms of damage and fruit abortion occurs.

6. Excessive vegetative growth. If the greenhouse temperature is relatively high, especially the night temperature, with insufficient light, excessive water and fertilizer, and too much nitrogen fertilizer, zucchini is very prone to excessive vegetative growth, which makes vegetative growth too vigorous and inhibits reproductive growth, resulting in fruit abortion.

7. Damage from gray mold. Zucchini gray mold invades spent flowers, grows a gray-brown mold layer, and then infects young fruits, which quickly soften and shrivel, causing fruit abortion.

8. Not harvesting in time. If zucchini is not harvested in time after ripening, the marketable fruit grows too large, which affects plant growth and the absorption of nutrients by newly set young fruits, and the newly set young fruits are prone to abortion.