Identification and prevention of crop damage symptoms caused by herbicides

With the rapid development of modern agriculture, chemical weeding is playing a more and more important role in production. Followed by the use of herbicides in the serious problem of crop damage, because any crop can not completely resist the damage of herbicides, can only tolerate a certain dose of herbicides, beyond its selective range, the crops will suffer. The severity of drug damage ranges from the death of all crops to the slight inhibition of growth that does not affect yield. Therefore, correctly identifying the symptoms of drug damage in crops is helpful to prevent the occurrence of drug damage and relieve it.

First, the causes of herbicide damage.

Herbicides do harm to crops in many ways, but most of them are caused by improper use of technology. For example, when 2Di 4-butyl, 2-methyl-4-chlorine and paracetamol are used for weeding in wheat and corn fields, the nearby sensitive crops are often hurt due to the drift of fog droplets (especially wind spray, high-pressure spray, etc.). Hedazhuang and fluralin damage sensitive crops such as beans, melons and tobacco through volatile gases; improper mixing of herbicides and pesticides; poor condition of spraying equipment and uneven spray Misuse, overuse or improper use period; herbicide degradation products cause drug damage; abnormal climatic conditions and incomplete cleaning of equipment after herbicide spraying can cause damage to some sensitive crops.

Second, the diagnosis of drug damage. The drug damage symptoms of the same herbicides were basically similar.

The main results are as follows: 1. The symptoms of drug damage caused by amides (alachlor, Metolachlor, Acetochlor, Acetochlor, etc.) are: young buds and young leaves can not be fully unfolded, maize leaf sheath can not clasp normally; soybean leaf midvein becomes shorter, leaves wrinkle, rough, produce heart-shaped leaves, heart leaves turn yellow, leaf edge growth is inhibited, and cup-shaped leaves appear; peanut leaves become smaller and appear necrotic spots.

2. Dinitroanilines (trifluralin, pendimethalin, etc.). The symptoms of drug damage are: short and thick roots, no secondary roots or sparse and short secondary roots, root tip swelling into Toona sinensis head, inhibition of bud growth, Hypocotyl swelling.

3. Phenoxy carboxylic acids (2 mine4-drop, 2-methyl-4-chloro) and benzoic acids (paracetamol). The typical drug damages caused are: morphological deformities, such as short, curved or twisted stems, tumors and adventitious roots in the aboveground and underground parts, nearly parallel veins in dicotyledons, leaflets healing in compound leaves, and the leaf body heals into a tube along the leaf edge. The number of sepals, petals and stamens increased or decreased, and the shape was abnormal. Gramineae plants form onion-shaped leaves, inflorescences are difficult to pull out, and there are double spikelets, spikelets opposite, rebirth, whorl and so on.

4. Sulfonylureas (azosulfuron, broad leaf powder, metsulfuron, etc.). The symptoms of drug damage are as follows: the true leaves can not be extracted, the growth point is necrotic or deformed, resulting in growth stagnation, leaf loss of green, necrosis or dark green and anthocyanin color, shortening of internodes, root aging, short lateral roots and main roots, and a small number of lateral roots. from the appearance of injury symptoms to death is relatively slow.

5. Triazobenzenes (atrazine, prometryne, xicaojing, etc.) and ureas (chlorotoluron, diuron, etc.). As a result, the leaf margin and leaf tip of the crop become green and dry, and then the mesophyll becomes green and dry, the growth stagnates, and the whole plant dies.

6. Bentazon caused brown spots in crop leaves, and glyphosate caused slow withering, green loss and necrosis of crop leaves.

Pay attention to distinguish the symptoms that are easy to be confused with herbicides

The symptoms of drug damage caused by abnormal environmental conditions in ⑴ production, such as freezing, high temperature, drought and hot air, are similar to those of herbicides.

The symptoms of leaf injury caused by ⑵ topdressing were similar to those of contact herbicides.

The symptoms caused by nutrition deficiency, pollution and excessive fertilization of ⑶, especially nutrient deficiency, SO2, O3 and Cl2, are easy to be confused with mesophyll chlorosis caused by herbicides.

The soil-borne disease of ⑷ is similar to the herbicide damage of some pre-seedling soil treatments.

The malformed leaves caused by ⑸ virus disease and pathogen infection were similar to those caused by phenoxy carboxylic acids, soil treatment amides and vulcanized carbamate herbicides. After the occurrence of drug damage, timely and multi-directional observation should be made to prevent misdiagnosis.

IV. Prevention and rescue of drug damage

1. Preventive measures. The correct selection and use of herbicides is the key to prevention. ⑴ should adjust the dosage and correctly grasp the period of use. ⑵ adjust the spraying equipment, spray evenly, and clean the sprayer thoroughly after spraying. After the application of long residual herbicides in ⑶, the following crops should be arranged reasonably. Adding a small amount of methoxyphenolone or BNA-80 to ⑷ can prevent defluorination reaction and avoid dwarfing of rice.

2. Rescue measures. Herbicide damage should be treated differently, some drug damage does not affect yield, and will disappear naturally with crop growth, such as wild swallow withered medicine, wheat leaves turn yellow for a short time and recover naturally with growth; some drug damage causes yield reduction, rescue measures should be taken in time.

For the drug damage caused by the inhibition of photosynthesis after application, ⑴ should apply quick-acting fertilizer outside the root in time.

⑵ alachlor, ethanolamine and other amides caused drug damage, can be sprayed with gibberellin

⑶ application of organic fertilizer, activated carbon and ploughing can eliminate or reduce the residual activity of herbicides in soil.