Melon is a kind of melon vegetable that everyone grows more, and it has the attention of growers for its long time and long fruiting, rich nutrition and health care effect. However, in the planting process, often at the beginning of the fruiting period or the peak period, the plant suddenly wilts, which affects the yield and quality of the loofah. The reason for this phenomenon is that the loofah has root-knot nematode disease, so let's talk about the occurrence and prevention of root-knot nematode disease of the loofah.
1. Understand root-knot nematode disease.
The pathogen of loofah root-knot nematode disease is southern root-knot nematode, which belongs to the genus Nematode and root-knot nematodes. The body of the insect is small and cannot be seen with the naked eye. Male and female adults differ in shape. Female adults are pear-shaped and fixed in the host root, milky white, with a thin epidermis, ringed stripes, and the junction between the head and the body is often bent to one side. The eggs are laid in a glial oocyst secreted at the caudal end. The oocyst remains in the lateral roots and fibrous roots of the decaying crops for a long time, and the oocyst is round and spherical, and there are 100 300 eggs in one oocyst. The survival temperature is 25 30 , and the temperature above 40 or below 5 activity is inhibited. In addition to pumpkins, cucumbers, melons, tomatoes, carrots, etc. are also susceptible to infection.
2. Harmful symptoms.
Loofah root-knot nematode disease mainly affects the roots, and the lateral roots and branch roots are the most susceptible. The lateral roots are covered with nodules that resemble asparagus roots or near-spherical nodules. The affected plants shrank or yellow, the stems and leaves wilted during high temperature and drought, and the growth of the plants was stagnant or dead. The growth of diseased plants is weak, dwarf, yellowing, and it seems to be caused by insufficient water, and does not set fruit or has poor fruit. In the morning and evening, when the temperature is low or if there is sufficient watering, the temporarily wilted plants can return to normal, and as the disease progresses, the wilting will not recover until the plant dies.
3. Prevention and control measures.
1.Agricultural measures: Do not replant, and rotate crops with onions, garlic, leeks or grasses for 2 to 3 years. The straw and fallen leaves left after the harvest before planting should be removed in time, and burned in a centralized manner, or buried 50 cm deep. Shed planting should be 30 cm high ridge, ditch flooding, or summer mulch, closed shed, room 15 20 days, after high temperature and flooding, the control effect of more than 90%. The plots used for open field planting are ploughed in winter and frozen to kill insect eggs. Choose disease-resistant varieties and cultivate strong seedlings without diseases and insects. The shed is smoked with liquid ammonia, 60 100 kg of liquid ammonia per mu, applied into the soil with machinery before sowing or planting, and deeply turned after 6 7 days, and ventilated, and the ammonia is released for 2 3 days before sowing or planting.
2. Drug prevention and treatment
When abamectin is used to control root-knot nematodes, it is generally applied 1 per mu8% avermectin in the amount of 2-4 kg. If you want to irrigate the roots, you can use 18% avermectin is mixed with water 1000 times, and the liquid medicine per plant is 02-0.25 kg, using 5% avermectin to water is generally about 2000 times.
When thiazolphosphine is used, the method of flushing is generally used. You can choose 20% thiazolphosphine water agent, 500g with water to apply about 3-6 acres, or 500g with water to apply about 1200 square meters. The appropriate dosage can be selected according to the growth state of the loofah. When irrigating roots, it can be diluted 6000-9000 times with 20% thiazolphosphine aqueous agent.
Chitin can induce plants to produce chitinase, which can break down chito-oligosaccharides that absorb nematodes and eggs, and chitinase, which inhibits nematodes, resulting in the death of nematodes and eggs. It is generally used in combination with fungicides and insecticides.
Averthiazophosphine is a compound of avermectin and thiazolphosphine, avermectin is a biological root-knot nematode control agent, which has contact killing and stomach toxicity effects. It acts on the nervous system of pests to achieve the purpose of killing nematodes. Thiazophosphine is a contact and systemic nematicide that can hinder the activity of nematodes and prevent the invasion of nematodes into plant roots at low doses.
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