What herbicide to use before and after emergence in sesame fields? Plus key cultivation techniques

Sesame, also known as zhi ma and hu ma, is the seed of the flax plant. Weeds in sesame fields will also affect the growth of sesame, so timely removal of weeds is the right way. So what herbicide to use in sesame fields?

What herbicide to use in sesame fields?

1. Post-sowing pre-emergence weeding, that is, after sowing and before the seedlings emerge, choose a soil treatment agent, dilute it with water and spray it on the soil surface. After application, it can effectively control annual grass weeds such as barnyardgrass, foxtail, crabgrass, Chinese sprangletop, lovegrass, goosegrass and wild bamboo, and it also has a certain controlling effect on broadleaf weeds such as purslane, shepherd's purse, knotweed and lambsquarters. Applying the herbicide once during the entire sesame growth period can fundamentally solve the weed problem.

The specific method of use is: within 3 days after sowing sesame, use 200-250 ml of 48% Lasso emulsifiable concentrate per mu, or 100 ml of 72% Dual emulsifiable concentrate, or 60 ml of 90% Harness emulsifiable concentrate, dilute with 40-50 kg of water and spray evenly. Take care to keep the soil moist, and within 50 days after application, do not carry out intertillage and loosening of the soil, so as not to destroy the herbicide layer and affect the weeding effect.

2. Post-emergence weeding, that is, choose a foliage treatment agent, and when most grass weeds are at the 3-4 leaf stage, dilute the agent and spray it directly on the weed stems and leaves. Generally, use 20-30 ml of 10.8% high-efficiency haloxyfop-R-methyl emulsifiable concentrate per mu, dilute with 50 kg of water and spray. Also take care to keep the field moist, and within 20 days after application, do not carry out intertillage and loosening of the soil.

Sesame cultivation techniques

I. Land preparation and bed making

Whether it is summer sesame or autumn sesame, it is sown in a season with high temperatures and large evaporation, so fine land preparation and maintaining soil moisture are the key to full seedlings. When soil moisture is high, after plowing, harrow the land finely in both directions, and after sowing, harrow the land to cover the seed. When soil moisture is low, sow immediately after harrowing, harrow to cover the seed, and press the soil to preserve moisture. Sesame is afraid of waterlogging, and its growth period is in a period with more rain, so when growing sesame alone, beds should be made——about 2-3 m wide, with bed ditches, waist ditches and surrounding ditches opened level, so as to facilitate timely irrigation and drainage.

II. Timely sowing

1. Sowing period: the suitable sowing period for summer sesame is late May to early June. The suitable sowing period for autumn sesame is early to mid-July, and under conditions of better heat it can be delayed to late July.

2. Seed rate per mu: 400 g for broadcast sowing, 350 g for drilling, and 250 g for dibbling. In fields with high soil fertility, few pests and diseases, and high water content, sowing can be appropriately reduced.

3. Sowing methods: there are three sowing methods for sesame: dibbling, broadcast sowing and drilling. Broadcast sowing is the traditional sowing method in the Jianghuai region and is suitable for sowing to catch soil moisture. When broadcast sowing, the seeds are evenly scattered and the soil cover is shallow, so seedlings emerge quickly, but it is not conducive to field management. Drilling can control row and plant spacing, implement reasonable close planting, and facilitate field management such as thinning and intertillage, and is suitable for mechanized operations. For dibbling, 5-7 seeds per hole. Regardless of the sowing method, shallow sowing and even sowing, with a depth of 2-3 cm, are appropriate.

III. Field management

1. Chemical weeding: 3 days after sowing, use 60 ml of 60% Harness emulsifiable concentrate per mu, dilute with 50 kg of water and spray evenly on the bed surface, which can reduce weed growth.

2. Timely thinning: after more than ten days, when 2-3 cotyledons have grown, thin the seedlings, and thin again after 5-6 days, so that the plant spacing is between 22-24 cm, with 8000-10000 plants per mu. Suitable plant spacing is beneficial to branching.

3. Removing the terminal bud: after the full fruiting stage, when the leaf nodes at the top of the main stem cluster and growth nearly stops, choose a sunny morning to remove the terminal bud. The topping method is very simple, that is, pinch off the top growth point within 1 cm, but topping is limited only to the top growth point, not a long section at the top; pinching too much will reduce the number of capsules per plant and lead to reduced yield.

4. Irrigation and drainage: sesame is most sensitive to soil moisture, fearing both waterlogging and prolonged drought, so attention must be paid to irrigation and drainage.

IV. Reasonable fertilization

1. Early application of seedling fertilizer: because sesame seeds are relatively small, and because too much nitrogen fertilizer is often applied as a base fertilizer, it is easy for the seedlings to grow excessively and form leggy seedlings. Therefore, sesame should be combined with early thinning and early final thinning, and a seedling fertilizer mainly of quick-acting fertilizer should be applied early according to the seedling condition. Applying seedling fertilizer well is an important measure for early development and healthy growth of sesame. For seedling-stage fertilizer, diluted decomposed human excrement and urine or urea is preferable. Generally, after final thinning, apply 2-3 kg of urea per mu as a topdressing; when drought is severe, first relieve the drought and then topdress, or dilute with thin human excrement and urine and pour it on. For those with weaker seedling vigor, the method of “opening a special meal” should also be adopted to apply a seedling-promoting fertilizer as a topdressing. When topdressing seedling fertilizer to sesame, also according to the characteristic that sesame roots are relatively shallow, apply it as shallowly as possible or mainly around the roots.

2. Skillful application of bud fertilizer: the sesame budding stage is exactly when flower bud differentiation begins, and at this time the plant's vegetative growth and reproductive growth are both vigorous at the same time. Therefore, applying bud fertilizer well plays a decisive role in high sesame yield. Bud-stage fertilizer is generally mainly nitrogen fertilizer, supplemented by phosphorus and potassium fertilizer. Per hectare, 75-150 kg of urea can be applied respectively, plus 150-225 kg of phosphate fertilizer and 75-150 kg of potassium fertilizer. When fertilizing, for drilled sesame, open a furrow about 10 cm from the sesame plants and apply it in a band or by dibbling, applying it into a 10 cm deep soil layer to facilitate root absorption, and cover with soil after application. For broadcast-sown sesame, decomposed cake fertilizer or granular urea can be mixed fully into finely crushed soil and broadcast, and immediately after fertilization carry out intertillage and loosening of the soil to cover the fertilizer. In dry weather, after application, water should be sprayed to fully bring out the fertilizer effect. A pouring method can also be used, that is, use 4-6 kg of urea per mu mixed with 200 kg of water and pour it on the base of the sesame plants. In addition, in boron-deficient areas and boron-deficient soils, boron fertilizer should also be increased as appropriate.

3. Heavy application of flower fertilizer: sesame grows most rapidly when it enters the flowering stage, and the nutrients absorbed during this period account for 70%-80% of the entire growth period. In order to meet the needs of plant growth and development, spraying potassium dihydrogen phosphate 1-2 times can delay leaf senescence, make sesame grow vigorously, accumulate more photosynthetic products, increase the number of flowers and capsules, keep steady growth in the later stage without premature senescence, and make the grains plump. At the same time, in the flower and pod stage, lateral roots have begun to form in large numbers, the absorption capacity of the root system is enhanced, the growth rate of the plant accelerates, and the demand for nutrients also increases significantly. Therefore, a flower and pod fertilizer should be applied heavily once; for branching varieties it is generally applied when branches appear, and for single-stem varieties it is applied from budding to the beginning of flowering. For foliar fertilization, generally 0.4% potassium dihydrogen phosphate is used; generally use 5-8 kg of urea per mu mixed with 200 kg of water and pour it on the base of the sesame plants, and composted cake fertilizer, human excrement fertilizer, etc. can also be applied. In addition, from the beginning of flowering to the full flowering stage, foliar topdressing can be carried out by choosing a sunny afternoon and spraying a 0.3% potassium dihydrogen phosphate solution on the front and back of the leaves, with an interval of 5-6 days each time, spraying 2-3 times in succession.

V. Disease control

1. Fusarium wilt and phytophthora blight

When fusarium wilt and phytophthora blight occur at the sesame seedling stage, use 0.5 kg of 50% yekuling wettable powder per mu, mix with 20 kg of moist fine soil, apply in a band at the bottom of the furrow (soil disinfection) and then sow. Alternatively, when sesame seedling disease is first seen, use 25 g of 25% copper-ammonia complex fungicide ruikumai per mu mixed with about 40 kg of water, or spray with 800-1000 times copper sulfate solution or 800 times 80% DuPont Xinwansheng solution, once every 7 days, spraying 2-3 times in succession.

2. Bacterial wilt

Sesame bacterial wilt may occur throughout the entire growth period. Use 50 g of 20% yeqingshuang wettable powder per mu, or 50 g of 50% carbendazim wettable powder mixed with about 50 kg of water and spray. If the disease occurs obviously in spots and patches, changing to pouring the medicinal liquid on the roots gives an even better effect.

3. Stem spot blight

Sesame stem spot blight is more serious in the later stage of its growth. Use 50 g of 50% carbendazim wettable powder per mu, or 60 g of 70% thiophanate-methyl wettable powder mixed with about 50 kg of water and spray.

4. Sesame shoot borer

The sesame shoot borer occurs from the early flowering stage to before harvest, but it causes more and heavier damage during the full pod stage. You can grasp the peak larval period and use 800-1000 times 90% trichlorfon solution per mu, spraying about 50 kg of medicinal liquid per mu.

5. Hawk moth

The sesame hawk moth occurs more in the middle and late stages. You can seize the peak larval period and use 800-1000 times 90% trichlorfon solution per mu, or 1500 times 80% dichlorvos emulsion, spraying 50 kg of medicinal liquid per mu.

6. Viral disease

Sesame mosaic virus disease shows mosaic and wrinkling in diseased plants, with twisted and dwarfed stems, generally without setting seed, or with small capsules and shrunken, shriveled seeds, and the mosaic turns yellow after expanding. Virus-resistant varieties can be selected, such as Hubei's Baguchai, Suxuan No. 5, Ezhima No. 1, Henan's Zhengzhi No. 1, Xiangyin 55, Liutiaoqing, etc., and at the same time pay attention to controlling sesame aphids.

VI. Timely harvest

Harvest in August-September when the fruit turns yellow-black. Cut the whole plant, tie it into small bundles with the top pointing upward, dry it in the sun, thresh out the seeds, remove impurities, and then dry again.