Latest Field Management Plan for Winter Wheat at the Green-Up Stage

The green-up stage of wheat is a critical period for producing spring tillers and forming new spring roots. If managed improperly, it can easily lead to a contradiction between aboveground growth and underground growth, as well as a contradiction between effective tillers and ineffective tillers, affecting the robust growth of wheat seedlings. In order to cultivate strong seedlings, the focus should be on preserving soil moisture and increasing temperature, supplemented by fertilization. Main objectives: promote winter tillers, increase spring tillers, promote roots, control excessive growth, ensure a sufficient number of effective spikes, achieve the goal of large spikes with many grains, and lay a foundation for abundant and high yields.

Management by Seedling Condition

The main objective at the green-up stage is to combine promotion and control to cultivate strong stems and large spikes. ① For strong seedlings with a total stem number above 700,000 per 667 sq m before winter, control should be the main approach, combining promotion and control. The key is to loosen the soil and improve aeration, increase temperature and preserve soil moisture, control aboveground growth and promote underground growth, increase effective tillers, and reduce ineffective tillers. ② For medium seedlings with a total stem number of 500,000 to 700,000 per 667 sq m before winter, insufficient total stem number before winter and insufficient spike number are the main reasons affecting yield. The key measures are to preserve winter tillers and increase spring tillers, focus on spike number, apply green-up fertilizer in a timely manner, irrigate with green-up water, and strive for as many spikes as possible. ③ For fields sown relatively late, with poor soil fertility, insufficient base fertilizer, or wheat seedlings already damaged by freezing, and weak seedlings with a total stem number below 500,000 per 667 sq m, irrigate in a timely manner, appropriately apply more green-up fertilizer, strive for early spring tillering, and promote rapid recovery of wheat seedlings.

Field Management Measures

1. Spring harrowing

Spring harrowing can loosen the soil and preserve moisture, raise soil temperature, promote roots and strengthen tillers, and eliminate weeds. In our region, it is mostly carried out in early April. Spring harrowing must ensure quality, otherwise it cannot play its due role. To ensure the quality of spring harrowing, it is generally advisable to harrow when the soil surface just begins to turn white after the beginning of spring. Harrowing too early when the soil is wet will not break up the soil, while harrowing too late when the soil is dry will create clods. The suitable tool for harrowing is an iron T-shaped harrow, with a harrowing depth of 3 to 4 cm. Behind the iron harrow, a willow-woven drag harrow can be attached to improve soil breaking and seedling clearing effects and improve harrowing quality.

2. Irrigation

Irrigation can be carried out when the 5 cm soil temperature stably passes above 5°C and the wheat field has completely thawed. Generally, the first irrigation is applied in mid-to-late April; combined with irrigation, apply 10 to 15 kg of urea per 667 sq m, and irrigate the second time at an interval of 8 to 12 days. Before the second or third irrigation, apply additional urea according to the seedling stage. The total topdressing amount is 20 to 30 kg per 667 sq m.

3. Weed control

Wheat fields mainly have dicotyledonous weeds. When using chemical weed control, the following three points must be mastered:

① Choose herbicides according to local conditions. Many years of practice have proven that, in addition to wheat-specific herbicides such as Puma and Puma Super (mainly controlling monocotyledonous weeds such as foxtail, barnyardgrass, wild oat, etc.), the main herbicides suitable for wheat fields are 2,4-D butyl ester and MCPA, which mainly control dicotyledonous weeds such as field bindweed, lamb's quarters, shepherd's purse, etc. Each has its advantages: MCPA has lower temperature requirements and no drift, and when sprayed it is less likely to damage surrounding dicotyledonous crops such as safflower, melons, and certain trees. However, the dosage is relatively large, and compared with 2,4-D butyl ester, the weed-killing effect is not ideal. 2,4-D butyl ester has higher temperature requirements, generally showing significant effects above 15°C, but it has drift and can easily damage surrounding dicotyledonous crops with the wind, while its weed-killing effect is good. It can be selected according to actual conditions.

② Grasp the timing of spraying. The best time for chemical weed control in winter wheat fields is before the wheat seedlings joint, and the best period for controlling weeds is the 2- to 4-leaf stage, because at this time overwintering weeds and early spring weeds are not large, and late spring weeds are still tender and small, so the herbicide solution can normally exert its efficacy with obvious results. If spraying after jointing, because the weeds are large, the weed-killing effect is poor, and it is also easy to cause phytotoxicity to crops.

③ Dosage. For controlling dicotyledonous weeds: use 200 to 300 g of MCPA per 667 sq m, diluted in 30 kg of water for spraying; or use 60 to 100 g of 2,4-D butyl ester, diluted in 30 kg of water for foliar spraying.

Use 40 to 50 mL of Puma per 667 sq m, or 60 to 70 mL of Puma Super, diluted in 30 kg of water for foliar spraying, to control monocotyledonous weeds.

When broadleaf weeds and grass weeds grow mixed in wheat fields, Puma can be tank-mixed with 2,4-D butyl ester or MCPA to achieve the purpose of controlling both monocotyledonous and dicotyledonous weeds in one application, increasing the Puma dosage to 70 to 80 mL per 667 sq m.

The spraying dosage depends on the temperature and the amount of weeds, but it must not be excessive, otherwise phytotoxicity will occur. Regardless of which dosage is used, spraying should be uniform according to terrain and wind direction. Generally, spraying is done in the evening, when the physiological water absorption of plants is strongest, the efficacy is significant, and the weed-killing effect is good.