Methods for Using Several Herbicides in Forestry Nurseries

Use of Several Herbicides in Forestry Nurseries

1 Mechanism of Herbicide Action

After being absorbed by plant roots and buds, herbicides act on specific target sites, interfering with the plant's physiological and biochemical metabolic reactions, causing plant growth to be inhibited or the plant to die. The effects of herbicides on plants are divided into primary action and secondary action. Primary action refers to the earliest effect of the herbicide on the plant's physiological and biochemical reactions, that is, the direct effect on the target enzyme or protein in the early stage of herbicide treatment. The chain reactions caused by the primary action further affect other physiological and biochemical metabolisms of the plant, which is called the secondary action.

2 Several Common Herbicides in Forestry Nurseries

2.1 Glyphosate

2.1.1 Scope of application. In nurseries, glyphosate is mainly used on fallow land, roadsides and beside ditches; it can be used where there are no stems or leaves below 50cm on tree trunks.

2.1.2 Method of use. Applying the chemical when weeds are flowering is optimal; apply when annual weeds are 15cm tall, and when perennial weeds are 30cm tall. For inter-row weed control in crops, when the plants are taller than the weeds and there is a height difference, the application effect is safest. Usually, when the soil temperature is suitable and field humidity is high, the weed control effect is best. This herbicide is suitable for use after rain, on sunny afternoons, and on overcast and rainy days. It is not suitable for use in drought, without rain, or under scorching sun. Single application dose: 70-80mL each time, mixed with 15kg of water each time. It works better when combined with Goal (oxyfluorfen); the mixing ratio: for each sprayer, use glyphosate 40mL each time; Goal 15mL.

2.2 Goal

2.2.1 Scope of application. Goal has high activity, a broad weed-killing spectrum, and is safe for humans, livestock and the environment. After years of trials, it has been confirmed that Goal is suitable for weed control in the seedling cultivation of coniferous species such as Chinese pine, Mongolian Scots pine, spruce, Chinese arborvitae and larch, and it is also very effective for weed control in sea buckthorn seedling cultivation, with significant economic benefits. Target weeds include crabgrass, barnyardgrass, foxtail, goosegrass, bluegrass, purslane, knotweed and lambsquarters, fleabane, dandelion, thistle, plantain, sowthistle, dayflower, horsetail, cocklebur, and various species of Artemisia.

2.2.2 Method of use. For sowing and emergence, the first application is before emergence, with early May being optimal, at a dosage of 45-50mL/667m2. For the second application, it should be at least about 50 days from the first application; the specific timing should be determined according to how early or late emergence occurs and the amount of emergence. The chemical dosage is 40-45mL/667m2.

For transplanted seedlings and seedlings kept in the bed, the first application is in mid-April, at a dosage of 80mL/667m2. The second application is 30 days after the first application, at a dosage of 30mL/667m2 each time; combined with Gallant (haloxyfop), at a dosage of 1,500mL/667m2 each time, the effect is better.

Spraying method: usually, the dosages described above are suitable for three sprayers. Divide the above liquid into three portions, mix each with 15kg of water, and after stirring evenly, spray uniformly; the weed control effect is relatively good.

2.3 Napropamide

2.3.1 Scope of application. Napropamide is a post-emergence herbicide that can be used for weed control in nurseries of poplar, willow, larch, Mongolian Scots pine, Korean pine, spruce, fir, sea buckthorn and others. Its target weeds include barnyardgrass, crabgrass, shortawn foxtail, foxtail, bermudagrass, quackgrass, goosegrass, wild oat and other weeds.

2.3.2 Method of use. This herbicide belongs to the foliage treatment type. Therefore, during application, the weeds must have at least 3-5 leaves; use on soil is prohibited, as the effect is not obvious. Dosage: a 20% concentration is suitable at 8-10mL/667m2.

The spraying method is the same as for Goal. When applying, spray on the leaves of the weeds, not on the soil. To ensure the effectiveness of the chemical, choose a sunny day with wind below force 2 and a temperature above 20°C for application.

3 Measures and Suggestions for Enhancing the Effectiveness of Herbicide Use

3.1 Select suitable herbicides according to actual needs

Generally speaking, each herbicide has a specific weed-killing spectrum, with strong selectivity and total-kill properties. Therefore, during practical application, which herbicide to choose should be determined according to the crop species and the weed varieties. At the same time, the local farming system should also be taken into account. In addition, pay attention to the mixed use and alternating use of several herbicides. After a herbicide is used continuously in one place for several years, it can enhance the resistance of weeds, leading to the ineffectiveness of that herbicide. Therefore, the mixed and combined use of herbicides can achieve the goal of long-term weed removal.

3.2 Select the optimal timing for application according to the properties of the chemical

The specific choice of when to apply should comprehensively consider the properties of the herbicide, the growth period of the weeds, the growth period of the crop, and so on. There are many types of herbicides to choose from, including foliage treatment type, soil treatment type, contact-kill type, total-kill type and so on. Some are suitable for pre-emergence, and some are suitable for the foliage stage. Taking the soil treatment type as an example, it can be sprayed directly on the soil surface to kill newly sprouting weeds. For example: Dual (metolachlor), acetochlor and so on are suitable for use before weeds emerge. Once the weeds have emerged, using them often gives unsatisfactory results and may even harm the trees. Therefore, it is essential to choose the appropriate time for application.