Many people will ignore sweet potato stem nematode disease, how to identify sweet potato stem nemato

After the onset of the disease, the leaves of the potato seedlings turned yellow, and there were brown brown spots on the surface of the roots, and the stems of the potato seedlings were white at first, and then turned into brown dry rot. The appearance of potato tuber root disease looks the same as that of good sweet potato, but some potato tubers have become brown and white dry potato stem nematodes for migratory endoparasitic nematodes, which can infect sweet potatoes, potatoes, peas, peanuts and other crops, and the disease will cause rot seeds and dead seedlings during the seedling period, and will cause bran core rot during the field period, and cause rotten cellars during storage, and the yield of the general disease plot will be reduced by 20%-50%.

The symptoms after potato nugget damage are divided into bran heart type and bran skin type. Bran heart type, the surface of the diseased potato nuggets looks the same as normal potato pieces, but the weight is very light, the inside of the potato pieces can be seen to become gray-white and brown dry rot sweet potato stem nematode disease, which is also what we often call pityriasis, this disease belongs to a kind of insect pest, but the stem nematode is very small, and the human eye can not see it, but although the nematode is small, the harm is still relatively large, especially the harm of this nematode is not a single sweet potato.

Symptoms] The symptoms of diseased potatoes are divided into bran heart type and split skin type. The bran heart type is caused by the potato seedlings and seed potatoes with disease, the nematode invades the root tuber from the base of the seedling vine, and the disease is caused by the top of the tuber, and gradually develops in the lower part or around, first the root longitudinal section is cotton wool-like white bran tract, sweet potato nematode disease is a parasitic, the pathogen is caused by the infection of slender worm-like stem nematode, the insect body is resistant to low temperature, dry resistance, moisture preference, can overwinter with adults, larvae, eggs in potato chunks or soil, feces, etc., and can survive in the field soil for 3-5 years.

Soaking in warm soup is a traditional method, but it is very effective; For example, use a large pot with water and boil until it reaches 56 degrees. Then soak the seed potatoes in the water, soak them in the inside, the bran heart in this will be light, and it will float to the top of the water after it is light, use the Kham gold medal biological gramamine soaking, a bag with 20 kg of water, inactivate the root-knot nematode source and egg source, and then spray the biological gram to inactivate the root-knot nematode fungus source and egg source in the planting soil (nest soil), which is the most effective method at present.

Mainly look at the stems and leaves of sweet potato, if the stems and leaves appear hollow symptoms, it is likely to be sweet potato stem nematode disease.

The main thing is to look at the shape of the leaves, if the leaves appear to be linear rot, at this time it is necessary to consider whether it is sweet potato stem nematode disease.

You need to see if the sweet potato has a problem with damaged leaves, which is likely to cause hollowing out in severe cases.

Sweet potato stem nematode disease is a devastating disease in sweet potato production, which is harmful and spreads quickly. It can be infected at the seedbed stage, field stage and storage stage, but it mainly infects potato tubers. The skin of the broken sweet potato is brown, blue, cracked, light, and some of the tubers have no abnormal appearance, only the bran skin on the inside.

The disease not only affects the quality of sweet potato, but also seriously affects the yield of sweet potato.

Sweet potato stem nematode disease is caused by parasitic stem nematode infection. Pathogenic nematodes are elongated worm-like with slightly pointed ends and millimeters long, and can overwinter in tubers as adults, larvae, and eggs, as well as in soil and manure. The insect is not tolerant to high temperatures, and 98% of the insect can die after 10 minutes of immersion in warm water at 50 °C.

Insects prefer moisture, tolerate low temperatures, stop their activity at -15, but do not die. This insect is resistant to dryness and can survive for up to a year in extremely dry environments. Therefore, it is difficult to ** this insect.

Selection of disease-resistant varieties: that is, when introducing varieties, excellent varieties suitable for local cultivation should be selected for disease resistance and detoxification. For example, the excellent varieties suitable for planting in central China and resistant to stem nematode disease include Jishu 10, Yushu 13, Sushu 8, Jing 553 and so on.

Cultivating disease-free and strong seedlings: 60 grams of 3% carbofuran granules per square meter of seedbed are sprinkled, and then covered with soil; Soaking seed potatoes in 52-53 warm water for 10 minutes before putting them on the kang can kill nematodes at 7 mm under the skin of seed potatoes. After the second cutting, sprinkle aldicarb (water after application) or pour methyl water amithion solution again. Due to the large number of stem nematodes at the base of the seedlings, high pruning can be used, that is, after picking the seedlings, the roots of the seedlings are cut off by 3-5 cm, and then soaked in 150-200 times of 50% phoxanthion or 50% methyl hydramidothion for 30 minutes.

Sweet potato, which is what we often call sweet potato, sweet potato, sweet potato, has different names in different places. At present, sweet potato is also a crop with a relatively large planting area in China, and it is more popular as a deep-processed product. At present, this season is also the season of harvesting sweet potatoes, and sweet potatoes are also a kind of crop that we usually eat, including the roasted sweet potatoes sold on the street now, which are deeply loved by everyone.

In recent years, China has also developed many varieties of sweet potatoes. For example, purple potatoes, selenium-rich sweet potatoes and other varieties, but as fruits grown in the soil of crops, it is inevitable that they will be attacked by pests and diseases. Today, let's talk about the prevention and control measures of sweet potato stem nematode disease.

In the prevention of sweet potato stem nematode disease, we must first understand the structure of the soil, and some soil quality is easy to breed worm diseases. The second is the control of irrigation time and dosage, and the soil is too humid and easy to breed insect diseases.

To understand the soil quality, light, drainage, weather temperature differences, as well as the quality of soil moisture, the amount of irrigation and so on, you need to master.

The causes of the formation of the disease, the time, the drugs used, the frequency, the efficiency of the drugs, these factors should be understood.

Two or three kilograms are used per mu, and it is best to use it when planting, and it will be solved for about 100 yuan.

Symptoms of sweet potato stem nematode disease: The disease mainly damages tubers, stems and seedlings. The potato seedlings are damaged, short and yellow, the stem base is blue, and there are brown voids in the base of the longitudinal stem, and there is basically no white pulp after cutting.

The potato vine was damaged, and the base of the main vine stem appeared yellow-brown cracks, and the inside was white or light brown dry rot, and in severe cases, it reached the top, causing the main vine to die. The tuber is damaged, the outer skin turns dark purple, often cracked, and the inside becomes white-brown chaff; Sometimes it is only a cracked baff type.

Sweet potato stem nematode disease is also known as hollow heart disease and bran heart disease. Sweet potatoes that are susceptible to disease, the vines are stunted and short, sometimes the epidermis is cracked, forming irregular brown spots, and in severe cases, they are dry and dry, and the whole plant is dead. The inside of the susceptible potato nuggets turns black and dry rot, and the skin of the tuber is black and sloppy, or cracked, and the skin of the tuber is still no different from that of a good melon.

Sweet potato root-knot nematode disease is also caused by nematodes, which can be transmitted by potato tubers, seedlings and soil.

Prevention and control measures. 1) To prevent and control sweet potato stem nematode disease and root-knot nematode disease, it is necessary to carefully quarantine and leave seeds in disease-free areas.

2) Implement 3 to 4 year crop rotation, especially in seriously diseased fields, which must be replaced with corn, wheat, rice and other crops.

3) When raising seedlings, high-yielding varieties with no insect damage and strong disease resistance should be selected, and the seedbed should be sprayed with 1500 times 2% avermectin solution or soaked seed potatoes for 2 3 minutes after planting potato seeds to eliminate the residual nematodes on the seed potatoes. Before and after pulling the potato seedlings, spray them again.

4) When planting seedlings, water the holes with 1500 times 2% avermectin solution + 600 times the day up to 2116 + 500 times 50% carbendazim solution, 100 ml per hole, or add fine soil with kilograms of sweet potato stem spirit liquid per 667 square meters, evenly sprinkle into the seedling holes, and then water and cover the soil.

Prevention and control measures for sweet potato stem nematode disease: (1) Strict quarantine.

It is strictly forbidden to transport seed potatoes or potato seedlings from the diseased area to prevent the introduction of the nematode disease. Dried potatoes transferred from the ward should also be quarantined.

2) Choose disease-resistant varieties.

Such as Nongqing No. 2, American Red, Lushu No. 3, Lushu No. 7, Jishu No. 10, Beijing 553, etc.

3) Strengthen cultivation management.

establishment of disease-free seed potato fields; High-cut seedlings are used to prevent seedlings from carrying nematodes; Severely diseased fields were rotated with rice, tobacco, sorghum, corn, etc. for 4 to 5 years; Timely removal of sick and residual bodies after harvest; Apply well-rotted manure.

4) Pharmaceutical prevention and control.

Soak seed potatoes and potato seedlings with pesticides. Soak seed potatoes with 10% soaking seed water agent or 40% nematoester emulsifiable concentrate 500 times or nematomycete 600 times solution for 1 day, or soak potato seedlings with the above liquid for 20 minutes; Or soak potato seedlings in 1000 times of 50% phoxanthion emulsifiable concentrate for 15 minutes.

Sprinkle granules. When planting potato seedlings, every 667 meters 2 (mu) with 5% stem thread granules 1 kg, or 3% Miller granules 3 4 kg, or 3% phoxanthion granules 2 kg applied to the ridges, and then covered with soil and watered.

The nematodes on sweet potatoes are mainly rotten stem nematodes, which harm potato tubers and potato vines, and can cause low seedbed emergence rate, dwarf seedlings and yellowing. The base of the longitudinal stem has brown voids in it, and there is no or very little emulsion after shearing. The bran core inside the severe seedlings can reach the top of the seedlings.

Damaged in the field stage, the main vine stems show cracked patches, brown chaff inside, and the diseased plants have short vines, yellow leaves, slow growth, and even die.

There are 3 types of potato damage symptoms.

Bran-shaped. The skin of the potato skin is blue to dark purple, and the affected part is slightly depressed or cracked.

Bran heart-shaped. The skin of the tuber is intact, and the internal bran core is brown and white dry rot.

Hybrid. When the onset of the disease is severe in the later stage of growth, the two symptoms of bran and bran heart occur at the same time, and the two symptoms are mixed.

Prevention and control technology. 1. Crop rotation and stubble in planting plots.

2. Detoxified sweet potato seedlings are selected, and high-cut seedlings are used for planting.

3. Try to burn the diseased potato pieces or diseased seedlings as much as possible during harvesting.

4. Soak potato seedlings with pesticides, and soak seedlings with 5 times of 25% chlorpyrifos microcapsules for 5 minutes.

5. Treat the soil with pesticides, 5% aldicarb (used in strict accordance with the instructions) granules per mu with 2-3, and apply them to the hole when transplanting potato seedlings. You can also use 3% methyl isosulfonate granules per mu with 3-4, mix an appropriate amount of soil and apply it into the hole.