Key Technical Points for Safe Pesticide Use in High-Oil Soybean Production
Although soybean can fix free nitrogen from the atmosphere through root nodules, this accounts for only 30%-50% of its requirement, and the rest must still be supplied by the soil. Therefore, applying nitrogen fertilizer to soybean can strengthen stems and increase branching, expand leaf area, enhance photosynthesis, and improve stress resistance. In plots with poor soil fertility, topdressing should be carried out at the seedling stage...
In the process of high-oil soybean production, the safe use of pesticides is very important. Improper pesticide use can cause poisoning of humans and livestock, environmental pollution, and affect soybean yield and quality, with a particularly large impact on soybean oil content. Safe pesticide use includes two aspects: first, the selection of pesticide varieties, and second, the application technology. For high-oil soybean production, pesticide varieties should be selected that have obtained a pesticide registration certificate or temporary registration certificate from the Institute for the Control of Agrochemicals, Ministry of Agriculture, have been organized by plant protection departments for testing and demonstration, have mature application technology, and at the same time have good safety for soybean. The following is an introduction to the techniques for controlling diseases, insect pests, and weeds in high-oil soybean production:1. Disease and insect pest control technology
a. Soybean root diseases and insect pests. Soybean root diseases and insect pests mainly include root rot, cyst nematode, and bean root maggot, followed by thrips and flea beetles. Soybean root rot is caused by mixed infection by multiple pathogens such as Fusarium, Pythium, Rhizoctonia solani, and Penicillium purpurogenum. The pathogens infect starting from soybean seed germination and can still cause disease until the middle and late growth stages of soybean. Fusarium (Fusarium oxysporum f. sp. fragariae, Fusarium graminearum, Fusarium solani, Fusarium avenaceum, etc.) is conducive to growth and development under soil conditions of pH 5.5-6.5, while Pythium, Rhizoctonia solani, etc. are conducive to growth and development under soil conditions of pH 6.5-7.0. The requirements for seed coating agents are the ability to protect the main root, protect seedlings, delay pathogen infection, and reduce damage; the sterilization spectrum should be broad, and the residual effect period should be relatively long, preferably with a residual effect period of 2 months. Celest (fludioxonil) suspension seed coating agent is effective against Fusarium and Rhizoctonia solani, with a residual effect period of more than 2 months; Apron (metalaxyl) suspension seed coating agent is effective against Pythium, with a residual effect period of about 25 d; Vitavax (carboxin+thiram) suspension seed coating agent is effective against Fusarium, Rhizoctonia solani, and Pythium, with a residual effect period of more than 1 month; ninanmycin aqueous solution is effective against Fusarium and Pythium, with a residual effect period of about 25 d; MB-97 microbial inoculant (MB-97, Streptomyces microflavus variant) is effective against Fusarium and Penicillium purpurogenum; Yiwang (Bacillus cereus) has good preventive and inhibitory effects on soybean root rot pathogens, with a residual effect period of more than 45 d; 35% duokefu (thiram+carbendazim+carbofuran) seed coating agent is effective against Fusarium, Rhizoctonia solani, and Pythium, with a residual effect period of about 25 d. In low-lying land and continuous cropping land, soybean root rot is severe. Seed coating agents should be mixed or used in combination with biological agents to obtain good control effects. For every 100 kg of soybean seed, use 2.5% Celest 150 mL + 20% Apron 40 mL, or use 2% ninanmycin 1000-1500 mL or 35% duokefu 1000-1500 mL + Yiwang 100-150 mL for mixed seed dressing; for each hectare, use 45-75 kg of MB-97 microbial inoculant mixed with soybean seed fertilizer or biological fertilizer. 35% duokefu is effective against soybean root maggot, flea beetle, and thrips, and has only a 10-15 d repellent effect on soybean cyst nematode. It should be used in plots where soybean cyst nematode occurrence is below moderate-light level; in plots with occurrence above moderate level, only crop rotation is available and there are no other effective control measures.
b. Soybean sclerotinia stem rot. At the 2-3 compound leaf stage of soybean, spray a mixture of 25% Sportak (prochloraz) 1050 mL or 40% junhejing 250-1000 g or 50% Ronilan (vinclozolin) 1500 g or 50% Sumilex (procymidone) 1500 g or 80% carbendazim 750 g or 40% carbendazim 1500 mL + Yiwang 120-250 mL or 0.13% Kangkai 30-40 g + rice vinegar 1.5 L per hectare.
c. Soybean frogeye leaf spot. From late July to early August (early pod stage of soybean), spray a mixture of 80% carbendazim 750 g or 40% carbendazim 1500 mL or 70% thiophanate-methyl 900-1000 g or 50% thiophanate-methyl 1200-1500 mL + potassium dihydrogen phosphate 2500-3000 g + rice vinegar 1.5 L + Yiwang 150-250 mL per hectare.
d. Soybean aphid. Per hectare, use 50% pirimicarb 150-225 g or 2.5% Kung Fu (cyhalothrin), 2.5% Decis (deltamethrin), 10% cypermethrin, 5% Sumi-alpha (esfenvalerate) 225 mL or 7% Admire (imidacloprid) 15-20 g + rice vinegar 1.5 L for mixed spraying.
e. Soybean pod borer. Per hectare, use 2.5% Decis 375-450 mL or 2.5% Kung Fu 300 mL or 50% Sumi-alpha 450 mL or 10% cypermethrin 375-450 mL or 20% Meothrin (fenpropathrin) 450 mL + rice vinegar 1.5 L + Yiwang 150-250 mL + potassium dihydrogen phosphate 2500-3000 g for mixed spraying.
f. Soybean thrips. Per hectare, use 5% Regent (fipronil) 300-450 mL.
g. Meadow moth. Per hectare, use 2.5% Kung Fu or 2.5% Decis 225-300 mL or 5% Sumi-alpha 300 mL.
For disease and insect pest control, the spray volume per hectare is 100-150 L for manual application, 100 L for tractor application, and 15-30 L for aerial application. When applying pesticides, add 0.5%-1.0% vegetable oil-type spray adjuvant to the spray liquid, such as Synertrol, Yaoxiaobao, etc., which can reduce the pesticide dosage by 30%-50%.
2. Weed control technology
Herbicides that can be selected include Dual Gold, Dual (metolachlor), propisochlor (Lefengbao, Pulebao, Xianlebao), Harness (90% acetochlor), clomazone (Command, Guangmiejing, Tiandeji, Doucaoling), Sumisoya (flumioxazin), Broadstrike (flumetsulam), Pursuit, Stomp, fluazifop-P-butyl (Jingwenshade), high-efficiency gallant (quizalofop-P-ethyl), quizalofop-p-ethyl (Jinghecaoling, Gimao, Fengshan Gaicaoling), Pent (quizalofop-P-tefuryl), Whip (fenoxaprop-P-ethyl), Dadouhuan, Baodouning, Hunacao, fomesafen, Basagran (bentazone), Gengtianyi, Douyigeng, Zacaofen, Kekuole, Kexiuling, Jindou (not recommended for use in low-lying, cold and cool areas), Sencor (metribuzin, restricted to use on upland fields, soils with organic matter content greater than 2%, and pH less than 7). The dosage of 72% 2,4-D butyl ester per hectare is limited to below 750 mL; it is effective against emerged perennial and annual broadleaf weeds and is safe for soybean. The prominent problem in soybean fields is the control of difficult-to-control weeds, such as Commelina communis, cocklebur, Cirsium setosum, Cirsium arvense, Sonchus brachyotus, reed, black nightshade, wild millet, etc. The following control measures should be adopted.
a. Combine mechanical weed control with chemical weed control. Deep plowing and deep turning have a 70%-80% control effect on perennial weeds. By cutting the underground rhizomes of perennial weeds, they are easier to control with herbicides. In plots where perennial weeds are severely damaging, relying solely on chemical weed control is unlikely to achieve good weed control results.
b. Select herbicides well. For pre-emergence herbicides in soybean fields, per hectare use 70% Dadouhuan 3.0-3.5 L; 48% Command (Guangmiejing, Tiandeji, Doucaoling) 1.0-1.5 L + 96% Dual Gold 0.8-1.0 L or 72% Dual 1.5-2.0 L or 72% propisochlor 1.5-2.0 L or 50% Lefengbao 2.2-2.9 L or 90% Harness (90% acetochlor) 1.5-1.9 L + 80% Broadstrike 30 g or 50% Sumisoya 70-90 g or 72% 2,4-D butyl ester 750 mL for mixed spraying. From the true leaf stage to the 1 compound leaf stage after soybean emergence is the best period for controlling difficult-to-control weeds. Per hectare use 18% Gengtianyi 3.0-3.3 L; 48% Command (Guangmiejing, Tiandeji, Doucaoling) 1.0 L + 25% fomesafen 1.0 L or 48% Basagran (bentazone) 1.5 L + 45% fluazifop-P-butyl 600 mL or 10.8% high-efficiency gallant 375 mL or 5% quizalofop-p-ethyl 600 mL for mixed spraying. For pre-emergence herbicide application, the spray volume per hectare is 180-200 L for tractor application and 300 L for manual application; for post-emergence herbicide application, the spray volume per hectare is below 100 L for tractor application and 100-150 L for manual application, and 1.0% vegetable oil-type spray adjuvant must be added to the spray liquid, such as Yaoxiaobao, Synertrol, Quad7, Hasten, etc.
c. Select nozzles well. For pre-emergence herbicide application, select Teejet 11003/11004 fan nozzles for tractor and manual application, equipped with 50-mesh filters. For post-emergence herbicide application, select Teejet 80015 fan nozzles for tractor application and Teejet 11001/110015/80015 fan nozzles for manual application, equipped with 100-mesh filters.
d. Select appropriate pressure and vehicle speed. For pre-emergence and post-emergence contact herbicides, the spray pressure is 196.1-294.2 kPa; for post-emergence systemic herbicides, the spray pressure is 294.2-490.3 kPa. When applying herbicides, the tractor travel speed is 6-8 km/h.
e. Pay attention to application time. The application time should be before 8 a.m. and after 5 p.m., preferably at night. At the same time, the temperature during application is required to be below 28°C, the relative air humidity above 65%, and the wind speed below 4 m/s.