Wheat seed dressing with chemicals can prevent and control multiple diseases and pests

Wheat is the second largest food crop in China after rice. China has a vast territory and complex geographical conditions. Wheat has many types of diseases and pests, a wide range of occurrence, and very serious damage. According to statistics, every year in China, wheat yield is reduced by about 30% due to the occurrence of various diseases and pests. Doing a good job of prevention and control during the autumn sowing period can achieve twice the result with half the effort in controlling multiple wheat diseases and pests. In recent years, with the strong promotion of agricultural departments at all levels, various regions have carried out large-scale chemical seed dressing focused on controlling autumn seedling diseases and pests, enabling effective control of wheat diseases and pests throughout the year.

In order to effectively carry out the autumn sowing chemical seed dressing work for winter wheat in China for 2010-2011, the following prevention and control recommendations are hereby proposed.

I. Main control targets and main areas for wheat autumn sowing chemical seed dressing

1. Wheat stripe rust, with concurrent control of wheat powdery mildew. The main areas are the summering areas of wheat stripe rust and areas where autumn seedling disease occurs.

2. Soil-borne diseases, mainly sheath blight, take-all disease, and root rot. These mainly include areas with relatively high soil moisture in the Yangtze River basin and the lower reaches of the Huang-Huai River basin in China, such as Jiangsu, Henan, Shandong, Anhui, Hebei, and Shaanxi, as well as newly occurring areas of wheat take-all disease.

3. Systemic infection diseases, mainly flag smut, loose smut, and stinking smut. Based on the amount of soil-borne inoculum and the disease incidence of varieties in previous years, there is no fixed area of occurrence.

4. Underground pests, mainly white grubs, mole crickets, and wireworms. They occur in all major wheat planting areas, and whether seed dressing should be carried out should be determined according to the occurrence situation in the previous year. Underground pests generally bite and feed on the root crown of wheat during the autumn seedling stage and after green-up, causing missing seedlings and broken rows.

II. How to carry out chemical seed dressing

Using chemical seed dressing to prevent and control wheat diseases and pests should adopt a zoned management approach. According to the types of local diseases and pests, determine the type of seed dressing chemical, the application method, and the dosage.

1. For prevention and control in the summering and overwintering areas of wheat stripe rust, select triazole fungicides with systemic translocation activity and long duration, such as triadimefon (also known as Bayleton), triadimenol (also known as Baytan), propiconazole, tetraconazole, diniconazole, etc. Each region may select according to the availability of chemicals; for areas where multiple diseases and pests occur simultaneously and cause damage alternately at the seedling stage, it is advisable to select fungicides and insecticides for mixed seed dressing, so as to concurrently control underground pests, blossom midges, aphids, and other seedling-stage pests. The effective concentration of fungicides such as triadimefon is very low, and seed dressing at a ratio of 0.03% (active ingredient) of the dry seed weight can achieve a very good disease control effect. After chemical treatment of wheat seed, delayed emergence (generally 1-2 days later) and plant dwarfing often occur, but there is no adverse effect on emergence rate, later growth, or yield. If the dosage is excessive, it will cause phytotoxicity.

2. Control of underground pests

Before sowing, using chemicals to dress wheat seed and treat soil is the most effective measure for controlling wheat underground pests. Seed dressing treatment: For areas where underground pests generally occur, the method of chemical seed dressing can be used for prevention and control. 50% phoxim can be selected for seed dressing, at 0.2% of seed weight, that is, 100 grams of chemical for 100 jin of seed, mixed with 2-3 kg of water. Alternatively, 48% chlorpyrifos emulsifiable concentrate can be used for seed dressing at 0.3% of seed weight. After dressing, pile and cover for 4-6 hours before sowing, which can effectively control underground pests. Soil treatment: In areas where underground pests occur severely, soil treatment and seed dressing should be combined for prevention and control. For soil treatment, 2-2.5 kg of 3% phoxim granules can be evenly broadcast on the ground per mu, and then turned into the soil. Alternatively, 250 ml of 50% phoxim emulsifiable concentrate per mu can be mixed with 1-2 kg of water and 20-25 kg of fine soil to make toxic soil, evenly broadcast on the ground, and then turned into the soil.

3. Control of diseases such as stinking smut, take-all disease, and powdery mildew

Using chemical seed dressing can not only prevent and control smut diseases of wheat, but also effectively control the occurrence and damage of wheat rust, take-all disease, and powdery mildew before winter, and reduce the amount of overwintering inoculum.

1) In areas where loose smut, stinking smut, root rot, sheath blight, and take-all disease occur, 40% quintozene can be used for dry dressing at 0.5% of wheat seed weight (that is, 40 grams per mu, dressing about 8 kg of wheat), to control wheat stinking smut; alternatively, one bag (10 ml) of 6% tebuconazole (Raxil) suspension concentrate can be selected, added with 0.8-1 jin of water, and used to dress 50-70 jin of seed, or 2.5% fludioxonil (Celest) suspension concentrate can be used for wheat seed dressing at the recommended dosage, while also concurrently controlling autumn seedling rust and powdery mildew; 15% triadimefon wettable powder can be used for seed dressing at 0.2% of seed weight, or 1 jin of 20% triadimefon emulsifiable concentrate mixed with 5 jin of water can be used to dress 500 jin of wheat seed, to control powdery mildew and leaf rust.

2) In areas where wheat take-all disease occurs severely, 12.5% silthiofam (Take-all Clean) suspension concentrate can be selected for seed treatment, which has a very good control effect on wheat take-all disease. Generally, one bag (20 ml) of Take-all Clean is first mixed with 300-500 ml of water, and can dress 20-25 jin of seed. After mixing evenly, cover the seed for 6-12 hours (which helps the chemical work and kills pathogens carried by the seed), then dry in a cool place before sowing.

(3) In areas where wheat yellow dwarf disease and wheat rosette dwarf disease occur, imidacloprid can be used to treat seeds to control virus-transmitting insects and control the occurrence and damage of wheat yellow dwarf disease and rosette dwarf disease, while concurrently controlling underground pests.

4) In areas where multiple diseases and pests occur together, vigorously promote the application of seed coating agents or seed dressing agents compounded with fungicides and insecticides for coating or seed treatment. Each region should select seed coating agents or seed dressing agents with appropriate formulations according to the main local disease and pest types. Their dosage is generally the same as the active ingredient of each single agent in the compound (mixed) agent when used alone.

III. Precautions

1. Determine the type of chemical to use according to the local occurrence of diseases and pests. If local wheat seedling-stage insect pest occurrence is very light and disease occurrence is relatively severe, only fungicide seed dressing is needed, and insecticide need not be used; if diseases and pests occur together, both insecticide seed dressing and fungicide seed dressing should be used; if underground pests occur relatively severely and chemical seed dressing alone may not achieve the expected control effect, seed dressing and soil treatment should be adopted to control wheat insect pests.

2. Accurately master the pesticide dosage. For controlling wheat underground pests, 50% phoxim emulsifiable concentrate can be used; for controlling wheat stinking smut, take-all disease, powdery mildew, sheath blight, and other diseases, 15% triadimefon wettable powder and 6% Raxil suspension concentrate can be used for wheat seed dressing. Practice has proved that when wheat is dressed with chemicals such as triadimefon and phoxim, if the dosage is too large, it will cause obvious phytotoxicity to wheat, leading to delayed emergence and slow growth, and in severe cases even missing seedlings and broken rows, so special attention should be paid.

3. Pay attention to the seed dressing method. When using phoxim and other chemicals for wheat seed dressing, first dilute the pesticide with water, then mix evenly with wheat seed, cover and pile for a period, and then sow. When using quintozene, triadimefon, and Raxil for wheat seed dressing, first spray the seed with clean water until moist, then evenly mix the chemical onto the seed, and then sow immediately or sow after drying in the shade. If both insecticide and fungicide are to be used for seed dressing, insecticide should be applied first, then after piling and covering, fungicide should be applied, and then sow immediately.

4. Dress and sow immediately; do not leave for a long time. After wheat is dressed with insecticide, it is generally piled and covered for 2-3 hours, at most 5-6 hours, and sown immediately after the chemical is absorbed by the wheat seed. Generally, after wheat is dressed with fungicide, it should be sown immediately or sown immediately after drying in the shade.

5. Strictly follow the seed dressing operating procedures to prevent human and livestock poisoning, and it is best to carry out unified seed dressing.