Plastic film in the late period of premature aging
The main manifestations of premature aging of mulching watermelon are: weak growth, slow growth, thin upper leaves, light green leaves, thin leaves, lower leaves become yellow or brown, the weight and quality of melon decreased, a large area of ​​reduced production. Therefore, the plastic film in the later stage should pay attention to the following five measures to prevent premature aging.
First, prevent de-fertilization
The basic basal fertilizer of watermelon is applied more than enough, but due to cultivation earlier, and cover the mulch, high temperature fertilizer breaks down quickly, is absorbed by the plant more, the loss is also larger, so the performance of defertilization after sitting melon, resulting in premature aging of watermelon, Therefore, timely supplements should be added later. When the watermelon grows to the size of the egg, 40 kg of urea and 7 kg of potassium dihydrogen phosphate should be recovered per mu, and water should be given to the fertilizer. According to the growth of the plant, the fertilizer may be topdressed once or sprayed with foliar fertilizer for 2 to 3 times (a mixture of urea and potassium dihydrogen phosphate may be used, or sprayed with Po, and flour may be used).
Second, ensure sensation
Watermelon watermelon period has the greatest requirement for soil water content. During this period, the outside air temperature is high. In addition, the watermelon root system is shallow when the film is covered and the soil is easy to lose water. The water content is too low, causing premature aging. To prevent loss, cover the roots of the plants with grass. After sitting on the melon, the virtual soil under the membrane around the plant is pressed down by hand to form a small basin. When it rains, it can make the rain seep into the root of the watermelon along the pellicle hole at the base of the plant. In addition, it can spray high-efficiency drought-repellent agent, water-retaining agent and so on.
Third, remove the first melon
Precocious watermelons usually produce the first female flower in the main vine 7-8, and the lateral vines produce female flowers in the 6-8 section. In the future, regardless of the main vines and lateral vines, 1 female flower is produced every 5 to 6 times. After the appearance of the first female flower, it is the time that the melon bud begins to prosper. If the first melon is retained, it will consume a lot of nutrients and affect the growth and development of the melon mushroom. It is easy to form a “small calluse†and cause premature aging. As a result, the first melon should be removed.
Fourth, avoid sunburn
During the late growth period of mulching watermelon, it will produce high-temperature burning vines causing premature aging. Therefore, the melon leaves at the base of fruits and melon vines should not be over-cleaned. Mesh can be covered with shade nets or leaves and dry weeds to provide proper coverage and support. There are few branches of early maturing varieties, and they do not have to fight.
V. Prevention of pests and diseases
During the late growth period of watermelon, it is a season of high temperature and rainy weather, and various pests and diseases are prone to occur. When the occurrence of pests, leaf damage, photosynthesis blocked, it will produce premature aging. For watermelon anthracnose, spray 50% carbendazim WP 500 times or 50% anthraquinone WP WP 300 to 400 times. For watermelon wilt disease, 50% carbendazim or 70% thiophanate-methyl chloride 1.3 kg can be used to create a 1:50-fold medicinal soil, which is applied to the soil before planting. In the early stage of disease, 70% of the enemy can be used to irrigate the roots with 800 to 1000 times each, 250 ml per plant, or mix 10 grams of the enemy's original powder with 200 grams of flour, add water to make a paste, apply it to the plant base, or use an antibiotic. Kunming or double effect irrigation roots. For watermelon virus disease, 20% imidacloprid 2500 times spray can be used to kill the virus-infected aphids and slugs. At the beginning of the disease, spraying a mixture of 500 times the virus and 800 times the enemy of the yellow leaf, 5 to 7 days, and even spray 2 or 3 times.
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