I. What is the purpose of seed coating and seed treatment for wheat?
1. Reducing losses caused by wheat pests. Wheat pests can be categorized into underground and aboveground types. Underground pests primarily include mole crickets, wireworms, and grubs, while aboveground pests mainly comprise aphids, sap-sucking insects, and wheat spider mites. Severe infestations of underground pests can lead to missing seedlings and broken rows during the seedling stage, resulting in weak, stunted plants that hinder the development of robust seedlings before winter and, consequently, reduce tillering. Similarly, severe outbreaks of aboveground pests can prevent normal growth and grain filling, directly compromising yield. Seed treatments for wheat typically contain insecticides that repel underground pests and help prevent widespread outbreaks of aboveground pests, playing a crucial role in protecting wheat crops.
2. Reducing losses caused by wheat diseases. China has limited arable land and a high multiple-cropping index, leading to a substantial buildup of soil-borne pathogens. Under favorable conditions, these pathogens can readily harm crop growth, with impacts on yield that should not be underestimated.
The major wheat diseases include sheath blight, take‑all, root rot, stem smut, loose smut, and bunt. Some of these diseases attack the base of the stem, impairing nutrient supply and increasing the risk of plant death, while others target the spike, directly hindering grain formation. When these diseases become severe, they can lead to significant yield losses or even total crop failure. Seed treatments for wheat typically contain fungicides, providing preventive protection from the time of sowing by inhibiting pathogen infection and reducing disease incidence, thereby helping to boost yields.
3. Promotes robust plant growth, enhances stress resistance, and increases yield. Achieving high wheat yields depends not only on effectively managing pest and disease outbreaks but also on ensuring an adequate number of spikes per mu and a sufficient grain count per spike. Seed treatment prior to sowing can stimulate growth, accelerate grain filling, strengthen stress tolerance, and help establish an optimal spike density and grain‑per‑spike ratio.
In typical high-yield fields, the number of spikes per mu should be 400,000 to 450,000, with 40 to 50 grains per spike, and a 1,000-grain weight of 40 to 45 grams. Seed treatment before sowing can effectively regulate plant growth, promote robust development, and lay the groundwork for increased yields.
4. Prevention is better than cure; early intervention minimizes damage. Pre-sowing seed treatment primarily serves a preventive purpose. If pests or diseases have already taken hold, resorting to chemical control at that stage will inevitably result in some losses. That’s why the government encourages pre-sowing seed treatment—to initiate pest and disease prevention right from the start of planting and thereby reduce potential damage ahead of time. When properly applied, pre-sowing seed treatment can boost wheat yields by 20% to 40%, or even more.
II. Which seed treatment agent should be used for coating and dressing wheat seeds?
For wheat seed treatment, an imidacloprid‑fludioxonil‑tebuconazole suspension seed coating can be used, at a rate of 130–180 g of active ingredient per 100 kg of wheat seeds, effectively controlling root rot, sheath blight, and aphids during the seedling stage.
In areas where wheat take-all is a recurring problem, you can treat seeds with a benzenesulfonamide‑azoxystrobin suspension seed coating at a rate of 16–18 grams per 100 kilograms of wheat seed. Alternatively, you may use a silthiopham suspension seed‑treatment agent, applying 30–40 grams per 100 kilograms of wheat seed.
To control wheat seedling-stage diseases such as sheath blight, tebuconazole suspension seed coating can also be used.
To control aphids, soil-borne pests, and rust diseases, you may also use a seed treatment consisting of 30 mL of 60% imidacloprid suspension concentrate plus 10 mL of 6% tebuconazole suspension concentrate, diluted with 0.3–0.4 kg of water, to coat 15–20 kg of seeds.
III. Introduction to Five Common Seed Coating Agents
1. Benzovindiflupyr suspension seed coating agent
Benzovindiflupyr is a triazole fungicide that boasts a broad spectrum of activity, strong systemic translocation, high safety, and an affordable price. It effectively controls soilborne diseases in wheat, such as take‑all, root rot, and loose smut, while also providing protection against loose smut, common bunt, and glume blotch. Notably, it exhibits particularly strong efficacy against take‑all and loose smut.
2. Fludioxonil Suspension Seed Coating Agent
Fludioxonil is a pyrrole‑type fungicide that boasts a broad spectrum of activity, high efficacy, excellent stability, a long residual period, and a low propensity to induce resistance. Although it lacks systemic properties, its outstanding stability ensures that, once dissolved, it distributes uniformly around the seedling root zone, effectively controlling soilborne diseases in wheat such as take‑all, root rot, sheath blight, common bunt, and snow mold—particularly exhibiting remarkable efficacy against take‑all.
3. Imidacloprid Suspension Seed Coating
Imidacloprid is a first-generation neonicotinoid insecticide that boasts a broad spectrum of activity, strong systemic translocation, excellent water solubility, prolonged residual efficacy, and cost-effectiveness. It effectively controls pests such as wheat grubs and aphids, with particularly pronounced efficacy against wheat aphids.
4. Thiamethoxam Suspension Seed Coating
Thiamethoxam is a second-generation neonicotinoid insecticide that boasts a broad spectrum of activity, strong systemic translocation, excellent water solubility, good stability, high safety, and a long residual efficacy. Notably, its outstanding systemic movement ensures uniform distribution around the seedling root zone upon dissolution; after seed germination, the active ingredient is rapidly absorbed and transported to the growing point and new leaves. Consequently, it is particularly well suited for seed treatment, effectively controlling both soil-dwelling pests and early‑stage foliar pests. It demonstrates strong control over aphids, grubs, wireworms, leafhoppers, thrips, leafhoppers, ants, flea beetles, weevils, whiteflies, and other harmful insects, with especially pronounced efficacy against wireworms and aphids.
5. Tebuconazole Suspension Seed Coating Agent
Tebuconazole is a triazole fungicide that boasts a broad spectrum of activity, strong systemic translocation, high efficacy, and a long residual period. It effectively controls diseases such as wheat sheath blight, loose smut, take-all, and root rot, with particularly outstanding control of wheat sheath blight and loose smut.
