How to prevent and control cucumber tip wilting in high-temperature seasons
When cucumbers are cultivated in greenhouses or plastic tunnels in summer, as the temperature rises, if ventilation is not carried out in time or is poor, the temperature inside the greenhouse can reach 40-50°C, and sometimes can exceed 50°C in the afternoon, causing serious harm to cucumber growth and development, resulting in a great impact on cucumber yield and quality. Recently, with the arrival of summer, temperatures have continued to rise, especially in weather that turns suddenly sunny after overcast skies, and cucumber production in various regions has shown "tip" wilting to varying degrees, affecting plant growth.
I. Symptoms
??? The cucumber plant tip shows thin stems, short internodes, small, thin and soft leaves, a shrunken tip that does not unfold, and small flowers.
II. Causes
??? In summer, when facility vegetables are subjected to prolonged poor ventilation or improper cooling measures, especially from noon to before 3 p.m. on sunny days, the temperature inside the greenhouse can easily exceed 40°C and cause high-temperature stress, such as increased respiration, greater consumption than accumulation of substances, reduced enzyme activity in the plant body, plant physiological disorders, and stunted growth. When the air temperature inside the greenhouse reaches 48°C, it can, within a short time, cause the small leaves near the cucumber growing point to wilt and the leaf margins to turn black, which is what we call "tip" wilting. If the high temperature lasts for a longer time, the leaves of the whole plant will wilt as if scalded by hot water.
III. Prevention and control methods
1. Ventilation and cooling
??? To prevent and control high-temperature stress in summer facility vegetables, the key is to manage greenhouse ventilation well. Be sure to open all the upper and lower vents of the plastic tunnel or greenhouse so that cool air from outside enters and forms convection with the hot air inside, thereby accelerating the outflow of hot air. It should be noted that a wind-blocking film can be set below the vents to prevent cold air from blowing directly onto the fruit surface of the vegetables, which can cause fruit cracking, splitting, and so on.
2. Improve the tolerance of vegetables in the greenhouse to high temperature and strong light
By spraying foliar fertilizers such as chitosan, amino acids, and alginic acid on the leaves, plant growth can be promoted to be robust and their resistance to high temperature can be improved.
3. Use shade nets or spray cooling agents to lower the temperature
??? When summer temperatures are relatively high, promptly set up shade nets to reduce the light transmittance of the greenhouse film and weaken the light inside the greenhouse. A cooling agent can also be sprayed on the greenhouse film to achieve a cooling effect.
??? 4. Watering to cool down
Watering is the most effective cooling method. Watering should be done in the evening or early morning; watering at noon under high temperature is prohibited, because watering at noon under high temperature not only fails to achieve a cooling effect, but instead has a harmful effect. Where conditions permit, drip irrigation or soaking irrigation is best.