Detailed Explanation of Key Technical Points for Chemical Weed Control in Schisandra Fields
In recent years, the production of Chinese medicinal materials in the Dandong area has developed rapidly, especially the cultivation area of Schisandra has increased year by year, becoming a new highlight of economic growth in our region. However, weeds in Schisandra seedling fields and main fields have always been a major headache for medicinal growers. Traditional manual weeding is labor-intensive and time-consuming, and using herbicides can effectively improve production efficiency, but there have been few trials. We conducted trials on chemical weed control technology in Schisandra fields with relatively large cultivation areas and achieved good results.
1. Survey results of weed species in Schisandra fields show that the weeds causing relatively serious damage in Schisandra fields in the Dandong area include barnyardgrass, monochoria, crabgrass, amaranth, lambsquarters, Persicaria, field horsetail, foxtail, and shortawn foxtail, among which crabgrass and Asiatic dayflower cause particularly serious damage.
2. Using quizalofop for weed control. Quizalofop is a highly selective new post-emergence herbicide for dryland produced in Japan, capable of effectively controlling annual grass weeds such as barnyardgrass, wild oat, crabgrass, goosegrass, shortawn foxtail, foxtail, Chinese sprangletop, and polypogon. Schisandra is transplanted from seedling beds to main fields from late April to early May. After transplanting and seedling recovery, quizalofop can be applied at any time during the vigorous growth period of grass weeds, but it is best to apply it at the 3-5 leaf stage of the weeds. Per mu, 70 mL of 1.5% quizalofop can be mixed with 30-40 kg of water, stirred thoroughly, and then sprayed on weed stems and leaves. When controlling perennial weeds, a single dose can be split into 2 applications, which can improve the weed control effect; the interval between the 2 applications is 20-30 days.
Precautions when applying: (1) Use a low dose when weeds are young, growing luxuriantly, and moisture conditions are good; use a high dose under drought conditions. Higher soil moisture is beneficial to the absorption and translocation of quizalofop by weeds. Do not apply when there is long-term drought without rain and the relative air humidity is below 65%. (2) Generally apply in the morning and evening. There should be no rain within 2 hours after application. Under long-term drought, if rain is expected soon, wait until after the rain when field soil moisture improves before applying. (3) Quizalofop is an aryloxyphenoxypropionate herbicide and should not be mixed with hormone-type, sulfonylurea, or diphenyl ether herbicides such as 2,4-D, MCPA, dicamba, and bentazone.
3. Using Roundup for weed control. Roundup is a systemic, broad-spectrum, non-selective herbicide. It can not only translocate through stems and leaves to the underground parts of weeds, but can also translocate among different tillers of the same plant, and has a strong destructive effect on the underground tissues of perennial deep-rooted weeds. Roundup has a broad weed-killing spectrum and can control weeds from more than 40 families, including monocotyledonous and dicotyledonous, annual and perennial herbaceous and shrub plants. The best effect is achieved when Schisandra is 2-3 years old and weed plant height does not exceed 15 cm. Per mu, 150-200 mL of 48% Roundup aqueous solution can be mixed with water for directed spraying, capable of controlling most annual weeds. To control difficult weeds such as cogongrass, bermudagrass, cattail, and common selfheal, as well as some grass weeds such as sedge, brome, and some difficult broadleaf weeds such as garland chrysanthemum, gorse, field thistle, dock, and Rosaceae weeds, use 400-600 mL per mu. When spraying, spray until the leaf surface is evenly covered with the solution. Roundup can be applied at any growth stage after weed emergence, but the vigorous growth period is best. For perennial weeds, application is best before the transition from vegetative growth to reproductive growth. Application on sunny days is good; application on cloudy days has poor effect.
Precautions when applying: (1) Must choose windless and rainless weather for spraying to prevent the herbicide from drifting to other crops and causing phytotoxicity; the spray nozzle must be equipped with a shield, using low pressure and large droplets for directed inter-row spraying. (2) When applying, do not touch the green buds or green parts of Schisandra to prevent phytotoxicity. If the lower leaves suffer phytotoxicity, remedial measures should be taken immediately, such as spraying foliar fertilizers like Green Pioneer and Wotuan.