Causes of herbicide damage of Schisandra chinensis

Chemical herbicides are widely used because of their advantages of low investment, quick effect and labor saving. The types of herbicides are increasing year by year, and the amount of herbicides used is increasing continuously. Although the agricultural department has done a lot of publicity and training on the use of herbicides for farmers, according to the recent investigation of the Beijing Drug Office and Yichun Plant Protection Station, due to the influence of the drift of herbicide droplets, the problem of drug damage to Schisandra chinensis planted nearby is particularly prominent.

According to a survey conducted by Bei Pharmaceutical Office and Taoshan Forestry Bureau in Tiili City, Heilongjiang Province, the drug-damaged area of 2730 mu of Schisandra chinensis in Tieli City reached more than 95% by June 16, and the economic loss is estimated to be about 5 million yuan. Of the 2265 mu of Schisandra chinensis under the full light of Taoshan Forestry Bureau, the area affected by drug damage reached 833.3 mu, accounting for 36% of the total area; 1031.5 mu of Schisandra chinensis was cultivated under the forest, with an area of 581.25 mu, accounting for 59% of the total area, with a direct economic loss of 3.25 million yuan. Herbicide damage has brought serious economic losses and social impact to Schisandra chinensis growers, which has become a major obstacle to the development of characteristic agriculture in Yichun to some extent.

The cultivation garden of Schisandra chinensis is mostly critical to soybean and corn fields. Acetochlor + 2.4 Mel D butyl, Daihuanhuan and Guangmianling are common herbicides in soybean and corn fields, and their usage occupies the first place. It was found that the main causes of drug damage of Schisandra chinensis were 2.4 murine D-butyl, Guangmiling and other farmland herbicides.

1 main characteristics of herbicides

1.1 2.4 murine D butyl ester

At present, soybean pre-seedling soil treatment, corn pre-seedling soil treatment and post-seedling stem and leaf treatment are widely used herbicides, which are also chemical herbicides that cause great damage to Schisandra chinensis. 2.4 Mel D butyl ester is a phenoxy acetic acid hormone type selective herbicide, which has strong internal absorption and conductivity and affects many physiological metabolic processes of plants by interfering with endogenous hormones. After spraying on the stem and leaf surface of weeds, the solution passed through the stratum corneum and plasma membrane, and finally transmitted to all parts of the plant. Inhibit nucleic acid metabolism and protein synthesis at the top of the plant, stop the growth of the growing point, prevent the young leaves from stretching, inhibit the normal progress of photosynthesis, and transmit to the lower part of the plant, increase the synthesis of nucleic acid and protein in the stem tissue, promote abnormal cell division, root tip expansion, loss of absorptive capacity, resulting in stem distortion, deformity, sieve tube blockage, phloem destruction, organic transport blocked. Thus destroy the normal living ability of plants, and eventually lead to plant death.

2.4 the drift of butyl ester solution is the main cause of drug damage to the surrounding sensitive crops. 2.4 the drift of Mel D butyl ester is two drifts, one is spraying drift, and when spraying on the ground, it can drift 1000cm to 2000m. The agent has good expandability, strong permeability, easy to enter the plant and is not easy to be scoured by Rain Water, resulting in drug damage to nearby contaminated sensitive crops such as watermelon, Schisandra chinensis, trees and other dicotyledonous plants. The other time is volatilization drift, which has strong volatility. In the case of high temperature and drought weather above 15 ℃, that is, when the temperature is too high and the sunshine is strong, it can enhance the chemical activity of 2.4 Mel D butyl ester, so that its active components evaporate from the soil surface and drift with the wind. The medicament droplets can drift far in the air and increase with the increase of temperature, so that the dicotyledonous medicinal plants have a weak ability to resist 2.4 ml D butyl ester. The degradation rate of 2.4 murine D butyl ester was slow, resulting in drug damage.

1.2 Trimethoprim

Organic nitrogen-containing heterocyclic herbicides (English general name Dimethazone), Chinese name isoxazolone, isoxazone, chemical name: 2-(2-chlorobenzyl)-4-dimethylisoxazoline-3-one. As a selective herbicide, single agent can be used for weeding before and after sprouting in soybean fields. early application after soybean seedlings is safe for soybean and has a good contact effect on weeds. The main ingredient of the mixture, such as Soybean Huan, is 2.4 murine D butyl ester + trimethoprim + isopropachlor can only be used for pre-bud weeding in soybean fields. Guangmianling absorbs through roots and buds, transports upward, spreads to leaves through xylem, and inhibits the synthesis of chlorophyll and carotene in sensitive plants. Although these sensitive plants can sprout and unearthed, they become white seedlings because there is no pigment and die in a short time. Soybeans are selective. after being absorbed by crops, the active components of trimethoprim are transformed into non-toxic degradation products by special metabolism. Guangmianling has a high solubility in water, but it has moderate adhesion with soil, which affects its fluidity in soil and does not flow below 30cm on the surface of soil. It is one of the residual herbicides in soil. It is mainly degraded by microorganisms in soil. Its half-life in soil is about 30,135 days, and its biological activity can last for more than 6 months. Guangmianling is volatile, fog droplets or vapor drift can cause the leaves of sensitive plant Schisandra chinensis to turn white, poplar and pine trees in the forest belt are safe, and willow trees are sensitive, but they can return to normal growth after 20 days and 30 days.

2 the cause of occurrence

2.1 the distribution of crops is unreasonable. The land management is scattered, which leads to the disorderly planting of many kinds of crops, and it is often caused by drug damage to many crops caused by one household.

2.2 the application time is concentrated and the area is large. Soybeans and corn are generally sprayed with herbicides in the middle and last ten days of May, during this period, the temperature is low and the rainfall is frequent, the high temperature is encountered after the medicine, and the application area accounts for more than 90% of the sown area, which results in the high suspension concentration of herbicides in the air in a short period of time. Drift with the wind or rain on plants is the main cause of drug damage to sensitive crops such as Schisandra chinensis.

2.3 improper application method. Most farmers use motorized fogging machines to spray herbicides to control weeds in soybean and corn fields, which aggravates the drift of the liquid.

3 Prevention

3.1 do a good job in regional planting planning

District (bureau) forest farms (institutes) should have a unified planning and rational layout when planting crops. Schisandra chinensis should be planted together, and it is best to stay away from soybeans, corn and other crops. Within 2000m of Schisandra chinensis, it is strictly forbidden to use a herbicide with drift damage for chemical weeding, and it should also be used at a safe distance when there is no wind and low temperature. Avoid the harm of herbicide drift.

3.2 the method of application should be correct

Soybean, corn fields to use herbicides to choose no wind or breeze weather, with knapsack manual sprayer high capacity uniform spraying, application should try to lower the sprinkler, or do directional spraying or sprinkler plus protective cover, generally per mu (667 square meters, the same below) water 40~50kg.

4 remedial measures

4.1 timely detoxification

Pay attention to the trend of the use of herbicides in neighboring fields, the use of drift herbicides is too large, detoxification measures should be taken as soon as possible, the method is to wash the plants with water at the first time to reduce the drugs stuck to the plants.

4.2 Chemical regulation

Once it is found that Schisandra chinensis has mild drug damage, plant growth regulators should be sprayed in time for reverse regulation. Plant growth regulators have a good stimulating effect on the growth and development of crops. at the same time, trace fertilizers such as zinc, iron, molybdenum and foliar fertilizers can be used to promote crop growth and effectively reduce drug damage. The most commonly used plant growth regulators are gibberellin, Tianfengsu and brassin. if crops are damaged at seedling stage, 30~50mg/kg gibberellin solution can be sprayed on the leaves, which can obviously promote plant growth. Specific methods: spraying gibberellin 10~40mg/kg or Tianfengsu 1mg/kg for 2 times and watering in time can effectively accelerate the growth of damaged crops.

4.3 Fine management

After herbicide damage occurs, timely removal of chlorotic and abnormal branches and leaves can reduce the penetration and transmission of herbicides in the plant, and timely ploughing and loosening soil and proper application of phosphorus and potassium fertilizer can promote root development and enhance the resistance of plants. It is best to supplement foliar fertilizer, which can alleviate drug damage and restore growth. principles for selecting foliar fertilizer: high content of a large number of elements, moderate trace elements, concentration does not produce drug damage, and rain-resistant foliar fertilizer, such as lobular enemy, Lvlingbao and plant activating element, etc.; it can also apply an appropriate amount of quick-acting nitrogen fertilizer to crop seedlings to promote the growth and development of plants as soon as possible.