Sweet potatoes are native to South America, introduced to China by the Guangdong "Chen Yi" during the Ming Dynasty, and have been cultivated in China for more than 500 years. Sweet potato is rich in nutrients, has the characteristics of wide adaptability, barrenness tolerance and drought tolerance, and is an important food crop and cash crop in China, which is widely cultivated in most parts of China.
When many people harvest sweet potatoes, they will find that sweet potatoes have a lot of worm eyes, so that sweet potatoes are not only different in taste, but also have a bitter taste when eaten, and the edible value and economic value will be seriously reduced. The direct cause of sweet potato worm eyes is the "underground pest" as a pest, the common underground pests in the sweet potato field are slugs, grubs (soil silkworms), root nematodes, golden needle worms, underground pests will directly eat the tuber of the sweet potato, and the wounds they have eaten are easily infected with germs, so the roots of such sweet potatoes cannot be eaten.
First, apply fully decomposed farm manure
Growing sweet potatoes is indispensable to farm manure, but if the farm manure is not fully decomposed, it is not only easy to cause root burning, but also easy to cause underground pest breeding.
There are two main reasons why uncorried farm manure can easily lead to the breeding of underground pests in the soil:
First, uncorried farm manure contains many worm eggs. Farm manure in the fermentation process will produce high temperature (about 60 ° C), high temperature will kill the vast majority of insect eggs, not fully decomposed farm manure because the eggs are not killed by high temperature, directly applied into the soil is easy to lead to high incidence of diseases and insect pests.
Second, underground pests tend to uncorried manure. Farm manure in the process of decomposition will not only provide organic matter for underground pests, but also to a certain extent to increase the ground temperature, such soil for underground pests to provide a suitable living environment, easy to attract adult insects to lay eggs.
Note: Farm manure in the application of 2 months in advance of the accumulation and fermentation, during the period of turning 1 to 2 times (let it disperse the temperature), fermentation period in the reactor temperature of up to 60 ° C or more, can effectively kill the diseases and insects in the farm manure, fermented farm manure is more easily absorbed by plants.
Second, deep ploughing of the soil in winter
Underground pests are afraid of cold and heat, and when the temperature is low in winter, pests will move deep into the soil for overwintering. Therefore, if there are more underground pests in the soil, then we can destroy the wintering sites of underground pests through "winter tillage".
Overwintering larvae that climb to the surface of the soil will freeze to death or be preyed upon by predators, and will directly cause mechanical damage to the larvae during the process of ploughing. Through winter tillage, the number of underground pests can be effectively reduced in the coming year.
Generally, from the end of November to the beginning of December of each year, the sweet potato reserve field is deeply turned, and the depth is preferably more than 30 cm (the overwintering depth of underground pests is generally concentrated at 10 to 30 cm).
Third, before the potato seedlings are transplanted, combine the preparation of the land and sprinkle "poisonous soil" on the surface
Underground pests are highly concealed in the soil, and can effectively kill underground pests in the soil by killing poisonous soils.
Octyl thiophos is a broad-spectrum organophosphorus insecticide that has a touch killing and gastric toxic effect on underground pests or eggs, and is suitable for the control of underground pests such as caddisflies, grubs, golden needle worms, ground tigers, and heartworms.
How to use: Per acre we can use 5% octyl thiophos granules 2 kg, mix fine soil 30 kg to make poisonous soil, and then evenly sprinkle on the surface, and then plough, can effectively kill the underground pests in the soil.
Fourth, sweet potato tubers expand during the expansion period and sprinkle "poisonous bait" on the surface
If we don't sprinkle poisonous soil when preparing the land, then we can use poisonous bait to trap underground pests during the expansion of sweet potato tubers. In the expansion period of sweet potato tubers, it is often a high incidence of serious underground pest damage, at this time we can prevent underground pests from nibbling on potato blocks.
We can sauté with 5 kg of wheat bran, then add 100 ml of 50% octylthion emulsion, mix evenly and spread it on the surface, and the effect of booby-trapping underground pests is very good.
In addition, the enemy insects also have a touch killing and stomach poisoning effect, we can use 90% of the enemy insect crystals 200 times liquid, evenly mixed on the fried wheat bran, and then sprinkled in the field in the evening, can effectively control underground pests.
Fifth, use sweet and sour liquid for booby traps
For adult worms, which are more sensitive to sweet and sour solutions, we can formulate sweet and sour solutions for booby traps. We can use 6 parts of sugar, 1 part of wine, 3 parts of vinegar, 10 parts of water, mix well and put in an appropriate amount of insects, which can effectively trap scarabs, ground tigers, and grubs.
After the sweet and sour solution is prepared, it is placed in different places in the field, and the insecticidal effect is remarkable.
Sixth, grass and wood ash leaching liquid irrigation roots
Grass and wood ash is alkaline and has the effect of inhibiting pests and diseases. We can irrigate the roots with grass ash leaching liquid during the expansion period of sweet potato roots, which can not only control underground pests, but also promote the expansion of sweet potato roots. This method does not cause pesticide residues and is safer than chemicals for root irrigation.
Note: Sweet potatoes are potassium-loving crops, and potassium fertilizers have the greatest impact on sweet potato yields. The grass and wood ash is a natural potassium fertilizer, containing 6% to 12% potassium, potassium fertilizer can promote the synthesis of carbohydrates and proteins, and can accelerate the expansion of sweet potato roots.
To sum up, in recent years, the harm of underground pests has become more and more rampant, and sweet potatoes affected by underground pests will form insect channels, making sweet potatoes rot, reducing quality, and bringing huge economic losses to the majority of growers. Underground pests are harmful, we should focus on prevention, can be prepared by the land, the application of rotten farm manure, sprinkling poisonous soil, the preparation of poisonous bait, grass and wood ash leaching liquid irrigation and other ways to prevent and control underground pests, so that the sweet potatoes grown have no insect eyes, sell well, high yield.