In recent days, the sweet potato seeds in Shandong are also almost the same, every Year in May is also when we plant sweet potatoes in Shandong, for sweet potatoes only the temperature can be planted sweet potatoes, sweet potatoes like warm temperatures, too low temperature will reduce the survival rate of sweet potato seedlings, recently a friend in Hubei private message to me, said that not long after their sweet potato insertion, the leaves of sweet potatoes began to appear curly leaves, and some sweet potato leaves have appeared hollow, so I let my friend send a picture over, Later, after comparison, the main reason for the appearance of holes in this sweet potato roll leaf is the sweet potato insect pest - sweet potato roll leaf worm caused. Let's talk about the harm of this sweet potato leaf roll worm, hoping to help more farmers.
<h1 class="pgc-h-arrow-right" > first look at the symptoms of sweet potato leaf invasion</h1>
When we finish cultivating sweet potatoes, generally in the end of May to June will find that the leaves of the sweet potato appeared curly leaves, this time is the sweet potato leaf curl insect began to invade, the beginning of the leaf invasion is not very serious, because this is the first generation of leaf curl insects appeared, sometimes the growers can not find its traces at the beginning of the period, the first generation of pests appear after the first generation of sweet potato leaves began to nibble on the leaves of the sweet potato, the leaves will be nibbled out of the very small wormhole, this time the general growers will not find, However, in the second generation, sweet potato leaf curls first use the spit silk to make the leaves begin to curl, and then nibble on the leaves, and the second generation of pests generally appear after June. At this time, the leaves will be eaten by only the leaf veins, similar to a tulle mesh. When the pest reaches the third generation, the harm is more serious, and when we arrive at the park, we can find that some sweet potato leaves will be eaten and the leaves will turn yellow, and the third generation of pests will appear after July.
When the sweet potato leaf roll worm in the nibbling on the leaves, if the surrounding leaves are finished eating, it will nibble on the young stems of the sweet potato and the young shoots that have just grown, generally when the sweet potato leaf roll insects infested the sweet potato seedlings will generally die after a few days, in addition to the sweet potato leaf rolls that appear in our northern regions, the sweet potato leaf rolls will generally be around 2-3 generations, like the southern region will occur 3-4 generations a year, because the temperature problem of pests will increase the algebra, the southern temperature is high, suitable for the growth of pests, the algebra is more, Therefore, we must grasp the time of occurrence before we can prevent it.
< h1 class= "pgc-h-arrow-right" > why sweet potato roll leafworms almost always appear after sweet potato cultivation</h1>
1, the first is the problem of temperature leads to the emergence of insect pests
From the perspective of the time of insect infestation in recent years, sweet potato leaf roll insects are also related to the temperature of sweet potato needs, such as sweet potatoes like temperature above 20 degrees suitable for growth, but from this temperature point of view, it is the emergence of sweet potato roll leaf worms, leaf roll worms like to survive between 20-30 degrees of temperature, humidity is more frequent when the humidity is more than 80%, once the temperature is increased after the sweet potato roll leaf worm will appear quickly, the temperature is suitable for pupa will quickly feather adults, the same, Like the temperature difference between the southern region and the northern region, the southern insect pest is earlier than the north, sweet potatoes like high temperature and humid environment, especially after entering the summer, the rainy season temperature is high when the sweet potato leaf curl worm occurs more rapidly, especially in the south, the high temperature lasts for a long time, generally in our northern region
2, the emergence of sweet potato leaf curl worms is related to the drought in the field
For the early stage of cutting sweet potato seedlings, the soil in our plot due to the early stage of soil preservation, such soil in the cuttings potato seedlings are easy to appear dry cracking, once the soil appears dry cracking, then the leaf curler has a strong overwintering, after the soil dry cracking temperature rises, the leaf curler will appear, in addition, in the later stage of field management, due to the long-term drought situation, then the leaf curler is more suitable for this environment, so the severity of the insect infestation and the drought in the field are related.
3, sweet potato leaf curl leaf insect harm and the base of the insect source is related
Sweet potato leaf roll leaf worm has a strong reproductive, followed by the base of the insect source is also very large, such as the southern heat will appear several generations, especially like Guangdong and Hunan regions, some places can even appear more than 4 generations a year, and the egg production of sweet potato roll leaf worm is also increased with its algebra, such as the first generation of pest egg laying in 30-40 grains each time, to the second generation of egg production is 50-60 grains, the third generation will reach 80-90 grains, the fourth generation will reach more than 100 grains, And the higher the temperature, the higher the hatching rate of the leaf curlew, and the temperature is the base number that provides the source of the insect. It is concluded that the insect source of sweet potato leaf roll insect is mainly higher in the south than in the north, and if the temperature in the south continues to be high for a long time, the insect source base will increase in the second year.
4, improper management measures in the field lead to the emergence of sweet potato roll leaf worms
When planting sweet potatoes, there is no land preparation, resulting in an increase in underground overwintering pests, in addition to the lack of early bottom fertilizer application, resulting in sweet potato seedlings after planting can not get effective nutrition, there will be slow growth of seedlings stunted, this time is most likely to lead to the emergence of insect pests, late management of weeding is not timely, a lot of sweet potato leaf roll insects will be hidden in the weed pile, especially the southern region of the planted leaf vegetable type of sweet potatoes, due to the long harvest cycle time, there will be a large number of sweet potato disease leaf disease vines in the field, These are also places that can lead to pests inhabiting, in addition, like when insect infestations occur, growers do not find them in time, or the dosage of drugs is small, and some do not use drugs, etc., will cause the emergence of pests.
<h1 class = "pgc-h-arrow-right" > leaf curlews in the field do not panic these points can be prevented</h1>
1, make preparations to cut off the source of insects before planting
For sweet potato leaf roll insects have a strong overwintering, so in the planting of sweet potato seedlings as far as possible in advance of the soil disinfection, if it is summer sweet potato planting, in the harvest after the time of disinfection of the soil to disinfect and kill insects, like the southern region in the winter is difficult to have colder weather need to use insecticidal drugs for soil pest control, to avoid overwintering insect pupae, such as the use of octyl thiophosphate emulsion and soil for deep mixing soil disinfection, the northern region can also be irrigated in the soil in winter, it is best to irrigate once before freezing, Frozen to death overwintering pupae, followed by the use of disease- and pest-resistant varieties when planting sweet potatoes, can reduce the invasion of pests and diseases.
2, after planting, it should be managed in a timely manner
For the planting period when there are conditions can be another soil pest control, because in the early stage of planting due to the overwintering insect pupa does not perceive the appropriate temperature so the feathering rate is very low, this time in the secondary pest control to achieve a better role, followed by planting must be planted according to the temperature, can not be planted too early, can not be too late, planting in the early soil to water to protect the soil, to avoid the later soil drought cracks, while applying the bottom fertilizer must use fermented fertilizer, fertilizer should be sufficient, If the weather is dry after sowing, it is necessary to water in time, especially if the temperature suddenly increases after sowing, it is necessary to go to the park in time to inspect several times.
3, after sweet potato planting, hang insecticidal lamps and odor attractants in the park and use natural enemies
Sweet potato leaf curl insects have a strong phototropism, we can hang high-frequency insecticidal lamps at night or use attractants to lure female leaf curlews to kill, timely killing of female adults is not conducive to pest spawning, or sweet potato parks use honey water and enemy insects to make larvae for luring adult insects to kill in time, secondly, in addition to high-frequency insecticidal lamps, like black light lamps can be used at night for pest control, and then the park can release natural enemies of leaf curls for control, such as long-distance cocoon bees, Bees with belly stalks, flea flies, etc. are natural enemies of leaf curls, and should also pay attention to protection when spraying in the park.
4, timely chemical control measures
For the planting period, we need to understand the occurrence of insect pests, such as planting sweet potatoes in the southern region, basically in less than a month to strengthen the management of the park, sporadic insect pests, especially when the leaves of sweet potatoes do not appear curly leaves, you can carry out artificial killing, while using drugs, it is best to kill before, to prevent the later increase in the source base of insects, if you find that there are cracks in the soil of the park, timely irrigation or use of insecticides to inject into the insecticide, When the insect source base is large, timely spraying is recommended, it is recommended to use kung fu emulsion, cypermethrin emulsion, chloranthrine benzamide suspension, cyanofuran hydrazone suspension agent, insect mite nitrile suspension agent, polycycline suspension agent, avy perchlorous fluoro emulsion and so on.
Don't remind: it should be noted that some growers plant sweet potatoes with leaves and vegetables, then when insect infestation occurs, we can use biological control, such as herbs and positive gas water, we can buy it and open the lid and put the potion in the small bowl of the park, so that the leaf curl worm will fly away after smelling, and if the insect source is large in the later stage, we should pay attention to when spraying, when picking leaves, we should pick leaves after 7 days after spraying, and we cannot pick leaves in advance, which should be noted.