The annual amount of antiscient used in China can be said to be very large, which also explains the huge loss caused by root nematodes to a certain extent. According to statistics, the world's annual losses caused by nematodes reach the level of 100 billion US dollars, although China currently has no very clear data statistics, but the impact is absolutely huge.
Nematodes are an obligate parasite, common in China are the following classifications, the following to do some more comprehensive introduction. A bit boring, but important! Many friends simply cannot identify the type of disease through the symptoms, let alone prescribe the right medicine, often spending money to make efforts to be unflattering, or even counterproductive.
Diseases caused by root-knot nematodes:
The main attack is the root system of the crop including rhizomes, bulbs, etc., there are no special symptoms in the early aerial parts after being infected by nematodes, with the reproduction and development of nematodes, the root system gradually stops growing, resulting in short plants in the aboveground parts, dry yellow leaves, and even cause death! The underground root system forms irregular root knots, which gradually disappear. The specific symptoms are as follows:
Nematodes reproduce rapidly and their transmission routes are very diverse, so it is very difficult to control nematodes. It can be transmitted mainly through the following channels: irrigation water, rainwater, agricultural tools, and insect-bearing soil contaminated on shoes, insect-bearing seedlings, etc. More attention should be paid to all aspects of agricultural affairs.
Diseases caused by cystic nematodes:
Cystic nematodes are mainly harmful to cereal crops such as soybeans, wheat, barley, sorghum, etc., and can cause up to 30% of the yield reduction. The main judging feature is still in the roots, the infected roots will produce clump-like roots, and the sporangia appear white and brown at different growth stages. Infected crops are short, flowers and fruits are scarce, and nitrogen-fixing nodules of legumes are also affected. The following figure shows soybeans infested with cystic nematodes:
Diseases caused by root rot nematodes:
Root rot nematodes occur on a variety of plants, in addition to the common corn, citrus, bananas and tea trees will be infected by it. Infected plants exhibit dwarfing, fading greenery, as symptoms of deficient or drought. The surface of the plant's underground organs is covered with many black scars. At first it shows small water-stained spots, then quickly turns brown, and finally it almost turns black. Spots appear on new roots that are eaten, and the spots mainly expand along the root axis, but also develop along the sides, combine with each other until they surround the entire root, until the root dies, rots, the root becomes shorter, and it is easy to form a compound infection with fungi. As shown in the following figure:
Diseases caused by stem nematodes:
Crops infected with stem nematodes generally exhibit dwarfing, have distinctly correct maculas on the stems, short and twisted leaves, and many leaves have many open wounds. Stem nematodes are distributed all over the world and are one of the most destructive plant parasitic nematodes. Plants like sweet potatoes, oats, hyacinths, strawberries and other plants are infected by it.
Diseases caused by semi-puncture nematodes:
Semi-puncture nematodes are more prominent in citrus trees, and after the newly planted orchards are infested with citrus nematodes, the tree growth is weak and the yield is low. The severity of symptoms develops slowly with the development of nematodes populations, manifested by poor root growth, smaller, greenery leaves, and weak tree growth. In addition to citrus, lychees, fir trees, and grapes are also susceptible to their infestation. After being severely infected, the vegetative root is thicker than the healthy root, and the appearance of the root appears very dirty due to the soil particles attached to the colloidal oocyst on the surface of the root. Due to the destruction of the root surface, as well as the infestation of secondary pathogens at the feeding point of the cortex, the nutritional roots are decayed, the cortex is peeled off and the roots die.
Diseases caused by pine wood nematodes:
Some friends may have seen this on pine trees; The leaves of the pine tree and even the whole tree will suddenly turn gray-green, and the resin will constantly flow from the wound. Then the conifers turn yellow-green, and then all the conifers turn brown. For 4 to 6 weeks from the onset of symptoms, all the conifers of the branches are brown and wilted. Sometimes the needles remain on the tree and do not visibly wither. After a long period of time, the whole tree went to death. This is a typical symptom of pine wood nematodes, as shown in the following figure:
Diseases caused by nephrotic nematodes:
The nematode is easy to infect a variety of vegetables, fruit trees, including cotton, pineapple and other hundreds of plants will be parasitic by it. The aboveground part of the affected plant is characterized by faded leaf color, purple stems, short plants, heavy stems and leaves scorched, and dead seedlings. When there are higher levels of nematodes populations, the leaf margins of older plants appear purple, the fruit becomes smaller, the ripening period is delayed, and the yield is reduced. The roots of the diseased plant are small, yellowish brown, with many necrotic spots, and very few vegetative roots. As shown in the following figure:
Diseases caused by leaf nematodes:
Leaf nematodes mainly harm Crops such as rice, flowers, and strawberries in China. Infected buds and growth sites tend to no longer grow and become brown or grow into shrub-like plants with small, twisted leaves. As the seasons go by, the leaves appear yellow spots from the bottom up, then turn black-brown and then heal into large spots. Initially, the plaque is often limited by the large leaf veins, but gradually, the spots or large plaques fill the entire leaf. The leaves become atrophied, crunchy, and finally fall off the ground. Flowers no longer grow after they are infected. Severely diseased plants will die.
The above several nematodes are the most influential nematodes in China, and the annual losses caused to vegetables and soybeans are tens of billions of yuan, and it is necessary to fully recognize the harm of nematodes and carry out various prevention and control work scientifically and effectively. Pay attention to Henan Compson Agriculture and learn more about the scientific control measures of root nematodes!
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