What are the control methods for vegetable nematode disease?
Which methods can control vegetable nematode disease
(Agricultural Wealth Network) In recent years, nematode disease in vegetable fields, especially in protected cultivation vegetables, has become increasingly serious. It occurs on almost all vegetables, such as cucumber, bitter melon, tomato, carrot, eggplant, potato, sweet potato, common bean, and even spinach. Because nematode disease is highly concealed and difficult to control, it causes serious losses to farmers through reduced yield and income. How should nematode disease be diagnosed? What are some good control methods? For this reason, a reporter interviewed Professor Xiao Yueyan from the College of Agronomy and Biotechnology at China Agricultural University.
Xiao Yueyan pointed out that nematode disease in vegetable fields has indeed gradually worsened. The main reasons are: first, long-term continuous planting of one or two kinds of vegetables allows the number of pathogenic nematodes to continuously accumulate; second, nematodes mostly damage the roots, while the aboveground part mainly shows slow growth and yellow, thin plants, which is often mistaken for a fertilizer and water problem, so no attention is paid to checking for and controlling nematode disease; third, even if nematodes are found, the insecticides commonly used have little effect on them. In addition, vegetable fields in greenhouses in the north provide conditions for nematodes to overwinter safely, which is also an important factor in their continuous rise.
How can nematode disease be distinguished from the symptoms of fertilizer deficiency? Xiao Yueyan said that from the aboveground part, nematode disease and malnutrition are indeed difficult to distinguish, as both make plants yellow, thin, and short, and the fruit cannot mature. During diagnosis, the roots must be dug out and observed. During surveys, it was found that most nematodes occurring in vegetable fields in the north are root-knot nematodes. As the name implies, they cause tumors to grow on the roots of diseased plants, small ones like millet grains and large ones like mung beans, round, spindle-shaped, or irregularly swollen, and later they also rot, grow maggots, or develop other pathogens. But the first organism to infect the plant may still be the nematode.
Xiao Yueyan said that nematode disease is indeed not easy to control. Nematodes can tolerate many insecticides, and many pesticides that were previously effective are banned because they are highly toxic to humans and livestock or seriously pollute the environment, such as carbofuran, aldicarb, isofenphos-methyl, and fenamiphos (ethoprophos, Miral). Some pesticides that can be used in orchards, peanut fields, and wheat fields, such as ethoprophos and cadusafos, also cannot be used in vegetable fields. Therefore, we should especially strengthen agricultural and physical control, and also develop biological control. Specific methods include: implementing quarantine and field sanitation, that is, not allowing nematodes to enter farmland through seeds, seedlings, or soil and manure, and diseased plant residues should be taken out and buried deeply in a centralized manner; high-temperature greenhouse sealing, which uses high temperatures above 55°C to kill nematodes. The specific method is to spread chopped rice straw or sorghum stalks after plowing, splash on quicklime water, plow about 30 cm, then water thoroughly and cover with plastic film, and the greenhouse must also be sealed tightly. After sealing in this way for more than 15 days, the nematodes can be killed. In the north, winter plowing before winter and not covering the greenhouse in winter can also use low temperatures to kill nematodes. Use paddy-upland rotation or rotation with crops such as Welsh onion, Chinese chives, chili pepper, and garlic; select disease-resistant varieties.
Xiao Yueyan pointed out that some pesticides can also be used for control. For example, before sowing, treat the soil with abamectin, thiazophosphine (10% Fuqiduo), Junxianke, and other agents, or in the early stage of the disease use these agents diluted with water to irrigate the roots. He also reminded farmers to always pay attention to the safety of humans and livestock.
Xiao Yueyan pointed out that nematode disease in vegetable fields has indeed gradually worsened. The main reasons are: first, long-term continuous planting of one or two kinds of vegetables allows the number of pathogenic nematodes to continuously accumulate; second, nematodes mostly damage the roots, while the aboveground part mainly shows slow growth and yellow, thin plants, which is often mistaken for a fertilizer and water problem, so no attention is paid to checking for and controlling nematode disease; third, even if nematodes are found, the insecticides commonly used have little effect on them. In addition, vegetable fields in greenhouses in the north provide conditions for nematodes to overwinter safely, which is also an important factor in their continuous rise.
How can nematode disease be distinguished from the symptoms of fertilizer deficiency? Xiao Yueyan said that from the aboveground part, nematode disease and malnutrition are indeed difficult to distinguish, as both make plants yellow, thin, and short, and the fruit cannot mature. During diagnosis, the roots must be dug out and observed. During surveys, it was found that most nematodes occurring in vegetable fields in the north are root-knot nematodes. As the name implies, they cause tumors to grow on the roots of diseased plants, small ones like millet grains and large ones like mung beans, round, spindle-shaped, or irregularly swollen, and later they also rot, grow maggots, or develop other pathogens. But the first organism to infect the plant may still be the nematode.
Xiao Yueyan said that nematode disease is indeed not easy to control. Nematodes can tolerate many insecticides, and many pesticides that were previously effective are banned because they are highly toxic to humans and livestock or seriously pollute the environment, such as carbofuran, aldicarb, isofenphos-methyl, and fenamiphos (ethoprophos, Miral). Some pesticides that can be used in orchards, peanut fields, and wheat fields, such as ethoprophos and cadusafos, also cannot be used in vegetable fields. Therefore, we should especially strengthen agricultural and physical control, and also develop biological control. Specific methods include: implementing quarantine and field sanitation, that is, not allowing nematodes to enter farmland through seeds, seedlings, or soil and manure, and diseased plant residues should be taken out and buried deeply in a centralized manner; high-temperature greenhouse sealing, which uses high temperatures above 55°C to kill nematodes. The specific method is to spread chopped rice straw or sorghum stalks after plowing, splash on quicklime water, plow about 30 cm, then water thoroughly and cover with plastic film, and the greenhouse must also be sealed tightly. After sealing in this way for more than 15 days, the nematodes can be killed. In the north, winter plowing before winter and not covering the greenhouse in winter can also use low temperatures to kill nematodes. Use paddy-upland rotation or rotation with crops such as Welsh onion, Chinese chives, chili pepper, and garlic; select disease-resistant varieties.
Xiao Yueyan pointed out that some pesticides can also be used for control. For example, before sowing, treat the soil with abamectin, thiazophosphine (10% Fuqiduo), Junxianke, and other agents, or in the early stage of the disease use these agents diluted with water to irrigate the roots. He also reminded farmers to always pay attention to the safety of humans and livestock.