Agricultural measures for controlling Rice pests

In recent years, with the increasing occurrence of rice pests, the dosage of some pesticides with strong toxicity and large residues on rice has gradually increased, which brings hidden dangers to rice safety. In view of this situation, the author has been carrying out agricultural control research in demonstration area since 2004. Through two years of practice, the results show that agricultural measures applied to rice pest control have more unique and excellent effects than chemical control, biological control and physical mechanical control, and play a positive role in improving the control effect of rice pests and ensuring high and stable yield of rice. Several agricultural practices are described below.

1 Reasonable fertilization

Fertilization can improve crop nutrition conditions, increase crop resistance to pests, increase crop volume, reduce the loss of pests to crops, promote crop growth and development, accelerate insect healing, improve soil properties, deteriorate the living conditions of soil pests, and directly kill pests. If sufficient basal fertilizer, early seedling fertilizer and appropriate topdressing were applied to rice, it could promote early growth and rapid development, tiller and heading order of rice, so that early rice could avoid the harm of the second generation of Chilo suppressalis. Silicic acid fertilizer applied to rice can make rice stem firm and reduce the harm of stem borer. In the year when the rice leaf roller occurs seriously, rational fertilization can prevent the rice from growing rapidly in the early stage and delaying maturity in the late stage, which has a good effect on reducing the pest. If nitrogen fertilizer is applied too much and too late in rice field, it will often cause light green leaves and closed rows, thus causing serious damage to stem borers, rice leaf rollers, leafhoppers and planthhoppers.

During the outbreak of rice leaf roller in Mingguang City in 2005, the harm of rice leaf roller was compared between the fields fertilized by soil fertilizer station and the fields fertilized by farmers themselves. It was found that the fields fertilized by soil fertilizer were obviously lower than those fertilized by farmers. The highest leaf bundle rate was 27.6%, the average leaf bundle rate was 12.8%, the highest larvae per hundred clusters was 410, the average number was 185, The highest leaf bundle rate was 41.3%, the average was 23.9%, and the highest larvae per 100 clusters was 660, the average was 290. Therefore, timely and reasonable fertilization, attention to cyanide, phosphorus, potassium coordination, in reducing the damage of rice pests has important significance.

2 Reasonable density

Close planting is an important agricultural measure to achieve high and stable crop yield. Rational close planting can reduce nutrient waste caused by ineffective tillering of rice, make plants grow healthily, head neatly, greatly improve rice resistance to pests, especially reduce stem borer damage. If it is planted too closely, it can cause excessive growth of rice plants, thin stems and poor root system, resulting in high relative humidity and insufficient light in the field microclimate, creating favorable conditions for the occurrence of borers, rice planthoppers and other pests; and over-dense planting and early sealing also bring difficulties to pesticide pest control. If rice lodging occurs, it will be more difficult to control insects with pesticides.

3 Deep ploughing and soil improvement

Tilling the soil can turn the original underground pests to the surface of the soil, turn the above-ground pests to the depth of the soil layer, so that a large number of underground pests die, and the surface pests cannot emerge from the soil; In addition, turning weeds into the soil can cut off the pests 'food, but also eliminate the pests and eggs parasitic on the weeds; Deep ploughing can also cause some pests to be killed by agricultural machinery or their nests and pupal rooms to be destroyed, thus increasing the mortality rate. For example, the larvae of rice weevil and rice root beetle feed on rice roots under the soil throughout their life cycle. Chilo suppressalis and Chilo suppressalis overwinter as larvae in rice piles under soil. For these pests, changes in soil environmental conditions will affect the growth, development and survival of these pests.

4. Selection of improved varieties

The insect resistance of rice varieties is generally non-selective and tolerant. Before sowing seeds, remove mixed weed seeds and insect-bearing seeds in time, select plump, uniform and disease-free excellent seeds for planting, which can ensure that the seedlings are strong, grow neatly and develop rapidly. Studies have shown that rice fields with a selected seed purity of more than 90% have a heading period of only about 9 days and a white panicle rate of 0.4%; rice fields with a purity of about 60% have a heading period of about 32 days and a white panicle rate of about 8%; rice fields with a purity of less than 50% have a heading period of about 33 days and a white panicle rate of about 15%. The reason is that the seed purity is low, so that rice growth uneven, thus extending the damage period of stem borers.

5 Timely irrigation and drainage

Irrigation and drainage can quickly change field environmental conditions and often achieve significant control effects on many rice pests. For example, when the overwintering Chilo suppressalis larvae are about to pupate, timely irrigation can make them cut off oxygen supply and be killed in large numbers. Chilo suppressalis pupated mostly in rice base or leaf sheath with low water level. When larvae matured and pupated, the field water was drained, the pupation position was lowered, and then the field water was soaked for 20cm. The killing effect was good. Drainage and field laying during rice planthopper occurrence period can effectively inhibit rice planthopper occurrence and reduce damage degree by reducing field humidity.

6 Farming systems

Reasonable farming system can artificially control the occurrence and harm of pests, such as reasonable crop rotation, which is beneficial to rice growth and enhances insect resistance, and at the same time has the effect of inhibiting the occurrence of pests with single feeding habits and weak activity ability, even achieving the purpose of direct elimination. For example, rice-wheat rotation in some areas of Mingguang City effectively inhibited the occurrence of rice borers. Compared with fields planted with only one season of rice, the occurrence degree of borers decreased significantly.

7 Weeding

Weeds are places where many rice pests breed and spread. First of all, weeds are the transition bridge of pests. Many pests live on weeds before rice sowing or after harvest, and then migrate to rice to form harm. For example, before rice is planted, the big borer lives on weeds such as grass in the field or by the field. Secondly, weeds are also winter sites for pests. Such as borers, leafhoppers, rice thrips, etc. are part of, or even all of the winter on weeds. In addition, many weeds are nectar suppliers for certain pests. For example, adults of rice bract insects feed on nectar from weeds such as vitex negundo and wild chrysanthemum. Therefore, eliminating weeds and changing plant communities is one of the important measures to prevent and eliminate rice pests.