Lawn weeds and chemical control
1. General characteristics of lawn weeds
1.1 The concept of lawn weeds
In a nutshell, lawn weeds are plants that have grown in the wrong place. That is, plants that grow in places that do not want them, or plants that grow in places that should not grow. Matang, Cyperus rotundus, Aquatic peanuts are weeds, Horse muscle tendons and Manila are turfgrass, but when horse ribs grow in cultivated Manila or Manila grows in cultivated horse ribs, it is also considered to be weeds.
1.2 Classification of lawn weeds
1.2.1 Classification of Controlling Herbicides
Weeds are usually divided into three categories: grass weeds, sedge weeds, and broadleaf weeds. Grassy weeds and Cyperaceae weeds are collectively referred to as monocotyledonous weeds. Broad-leaved weeds are also known as dicotyledonous weeds.
Monocotyledonous weeds refer to weeds that contain only one cotyledon in the seed embryo. Dicotyledonous weeds refer to weeds containing two cotyledons in the seed embryo.
The main morphological characteristics of grass weeds are: narrow and long leaves, parallel veins, cylindrical stems, often hollow between nodes, roots are fibrous roots. Such as crabgrass, goosegrass, grass and so on.
The main difference between sedge weeds and grass weeds is that stems are mostly three-spindle, solid, and no-stem, and individual cylindrical and hollow. Such as aconite, light scales, etc.
The main morphological characteristics of broad-leaved weeds are: round, heart-shaped or diamond-shaped leaves, veins usually reticulate, round or square stems. Such as Alternanthera philoxeroides, shamrock, Tianhu wolfberry and so on.
1.2.2 Classification of weeds according to their life history
Weeds are usually divided into two categories, annual weeds and perennial weeds, according to their life history. Annual weeds can be divided into summer weeds and winter ones.
1.2.2.1 Annual Weeds
It refers to the weeds germinating from seeds, growing to flowering, and seeding, and is completed within one year. Such weeds mainly rely on seeds to reproduce and are generally easier to remove.
1) Summer weeds of this type These weeds occur one after another in the late spring and early summer, and flower, seed, and die in autumn. For example, weeds, crabgrass, goosegrass, grasshoppers, alfalfa, etc. all belong to the annual weeds in summer.
2) Annual weeds in winter. These weeds occur in autumn and winter one after another and grow in the spring of the following year. They bloom, seed and die in early summer. Such as early-season quail, Aegiloi mellifera, Cattle communis, and large-necked Vegetables all belong to the annual weeds in winter.
1.2.2.2 Perennial weeds
This type of weed not only produces seed and is mainly propagated through underground rhizomes. Generally, it grows in spring and summer, grows in the summer and autumn, and in winter, it dies in the ground, but the underground part still has vitality. In the second year, it can grow again. Such as aconite, water peanuts, bermudagrass, etc. belong to this type of weeds. Weeds of this type are more difficult to get rid of, and the above-ground parts are uncovered, and new stems and leaves will grow from the underground parts.
1.3 Occurrence types of lawn weeds
Generally, there are two peak periods of weed occurrence on lawn, that is, the peak of weeds occurs in spring from March to April, and the peak of weeds occurs in autumn and winter from September to November. Midsummer (July to August) and severe winter (December to February of the following year) do not occur. The occurrence of lawn weeds can be specifically classified into four types:
1.3.1 Early spring occurrence type
It begins in late February or early March and peaks in late March and late March. For example, weeds such as spring grasshoppers, law grasses, flat storks, and small oysters fall into this category.
1.3.2 spring and summer type
Every year from the middle of March to the end of April and beginning of May, the peak occurs in the middle and late June. Such as weeds, crabgrass, goosegrass, setaria, aconite, water peanuts and other weeds belong to this type.
1.3.3 autumn and winter occurrence type
The onset occurs at the end of August or early September each year, peaking in November and rarely occurring in December and February. Such as early-season cockroaches, cow-breasted clams, mother-in-law, swine clams, etc. belong to this type.
1.3.4 Spring and autumn type
This kind of weeds generally occurs in the cold months of December to February and in July, but the rest of the month can generally occur, so it can also be called four seasons. Such as small clams, leeks, etc.
2. The basis of lawn herbicides
2.1 The characteristics of lawn herbicides
2.1.1 Survival
With some lawn herbicides, weeds and lawns die at the same time. This is called virulence, also known as non-selectivity. Herbicides with this characteristic are called phytotoxic herbicides, also known as non-selective herbicides. Such as commonly used glyphosate, Gramoxone, etc. are all herbicides.
2.1.2 Selectivity
Some lawn herbicides can kill one type of weed, but not another type of weed; or it can be safe for some turf and hurt for others. Herbicides with this characteristic are called selective herbicides. For example, 2.4-D butyl ester can effectively kill broad-leaved weeds in grass lawns without adverse effects on the growth of gramineous lawns, but it is not safe for broadleaf lawns such as horseshoe-gold.
2.1.3 Ingestion
Some lawn herbicides can be absorbed by the roots, stems, and leaves of weeds separately or simultaneously to reach various parts, destroying the internal structure and physiological balance of weeds and causing the death of weeds. This feature is called systemic absorption and has such characteristics. Herbicides are called systemic herbicides. For example, glyphosate can be absorbed by the stems and leaves of green plants and then transported to various parts of the plant, including underground rhizomes, so that glyphosate can not only control the aerial parts of plants, but also kill the underground parts of plants.
2.1.4 Contactability
Some turfgrass herbicides can only kill the part that comes into direct contact with the pesticide when it is sprayed on the plant, and have no effect on the growth of the part that is not exposed to the drug. This characteristic is called contact toxicity. Herbicides with this characteristic are called contact herbicides. For example, Gramoxone can only kill the part of the weed grass that comes into contact with the medicine, and it is ineffective for the underground parts that are not exposed to the medicine, so its control effect on perennial weeds is not complete.
In general, herbicides used in lawns are dominated by selective and systemic herbicides.
2.2 How to use lawn herbicides
2.2.1 Soil Treatment (Closed)
Applying herbicides to the surface of the soil is called soil treatment, also called soil sealing. According to the application time, the soil treatment can be further divided into three kinds: soil treatment before lawn or pre-transplantation, soil treatment before lawn seeding and soil treatment after lawn planting.
(1) Soil treatment before or before transplanting the lawn Before spraying or transplanting the lawn, we spray the herbicide on the surface of the soil and then sow or transplant the lawn.
(2) Pre-emergence soil treatment after lawn sowing The herbicide is sprayed on the surface of the soil from the time when the lawn is sown and before the emergence, and is also referred to as pre-emergence soil treatment. In most cases, this method uses the selectivity of the soil differential to achieve safety and weeding purposes.
(3) Soil treatment after turfgrassing The herbicide is sprayed on the soil surface before the turf growth stage and weed emergence. This is the most commonly used weed control method in turfgrass maintenance.
Soil treatment can be applied by spraying or toxic soil method, and spraying method is most commonly used. When toxic soils are applied, not only must the poisonous soils be evenly mixed, but also they must be spread evenly. It is best to spray water before or after the rain to distribute the chemicals evenly over the soil surface. Soil treatment generally takes place during weed germination or seedling stage.
2.2.2 Stem and leaf treatment
The method of directly spraying the herbicide onto the growing weed stems and leaves is called a stem and leaf treatment method. According to the application time, stem and leaf treatment can be divided into lawn before sowing or pre-transplantation stem and leaf treatment and turf growth during stem and leaf treatment.
(1) Stem and leaf treatment before or before transplanting This is a method of spraying herbicides on weeds that have already been grown before the turf has been sown or transplanted. This method generally requires that the herbicide has a broad spectrum, that the agent is easily absorbed by the stems and leaves, that it is inactive on the soil or does not affect the growth of the turf. Commonly used agents are glyphosate and Gramoxone. The disadvantage of this application method is that only the weeds that have grown up can be eliminated, and weeds that are not emerged are difficult to control.
(2) Stem leaf treatment during turf growth period This is a method of applying an herbicide to control emerged weeds during turf growth. In this method, herbicides not only come into contact with weeds but also hit lawns. Therefore, the herbicides used have a good selectivity and are the most important.
Stem and leaf treatment generally use spray method, which can make the drug easy to adhere and infiltrate weeds, and has better control effect. For turfgrass stems and leaves during the growing season, we should choose the growth stage that is sensitive to weeds and safe to turf.
It should be noted that herbicides for stems and leaves are generally required to be used under fine weather conditions to prevent the rain from flushing away the liquid and reducing the weeding effect. On the contrary, soil treatment herbicides generally require that the soil has a certain humidity, so the light rain after the use of drugs is beneficial to the weeding effect. Of course, heavy rain will also wash away the liquid causing a decrease in weeding.
3. The strategy of chemical weeding in the stadium
The biggest difference between chemical weeding on golf courses and weeding on farmland crops is that once the lawn is set, it will grow in place for a few years, and weeds will occur all year round. Unlike crops, there is only one season of weed damage, so weeding involves To the number of weeding problems.
3.1 Chemical weeding time and frequency
In general, soil treatment herbicides should be used during the buds of lawn weeds to achieve good preventive effects. For perennial weeds or weeds that grow after the expiration date, herbicides can be selected to control the herbicides. In this way, the use of 3 to 4 herbicides in one year, that is, in early spring, spring, summer, autumn and winter, can basically achieve the purpose of controlling the annual weed damage. The focus of control in spring and summer is grass weeds, and the focus of autumn and winter control is broad-leaved weeds.
3.2 The advantages and disadvantages of soil treatment and stem and leaf treatment
Soil treatment refers to the method of applying herbicides to the soil surface during weeding. The advantage of this treatment method is that weeds can be eliminated in the buds, and weeds and lawns are prevented from symbiosis, providing a good growing environment for the lawn. At the same time, it can also control some annual broad-leaved weeds in some annual grass weeds and broadleaf weeds in grass lawns, to a certain extent, ease the control of grass weeds and broadleafs The problem of controlling broadleaf weeds in lawns is low and the cost of control is low. The disadvantage of soil treatment is that it is effective only for annual weeds and is basically ineffective for perennial weeds.
Stem and leaf treatment refers to the treatment of spraying the herbicide directly to the weed stems and leaves. The benefit of this treatment is that the herb is removed, targeted, the conservationist is the most receptive, and has a good control over perennial weeds. Its disadvantages are that some herbicides have poor selectivity, and improper use of the herbicides may cause damage to the turfgrass. After use, the poisoned weeds are yellow and adhere to the lawn surface, affecting the overall appearance of the lawn.
Therefore, the control of weeds in lawns should be based on the principle of soil treatment as the main method, and the principle of stem and leaf treatment as supplementary. The former is the prevention, the active weed control, the latter the treatment, and the passive weed control.
4. How to use lawn herbicide
4.1 symptomatic medication
First of all, it is necessary to clarify the type of turfgrass, because the sensitivity of different turfgrass to herbicides is different. According to the determination, resistance to turfgrass was Manila> Bermuda> Perennial ryegrass> Festuca arundinacea> Poa pratensis> Syringa crenata, so different turfgrass species need to use different herbicide varieties. .
Second, we must find out what weeds are on the lawn, and then weed herbicides to control grass weeds, sedge weeds and broadleaf weeds according to the type of weeds.
Again, to understand the nature of the chosen herbicide, whether it is a soil sealer or a post-emergence stem and leaf treatment agent, a broad-spectrum herbicide or a specific type of herbicide.
4.2 appropriate amount of medication
The standard for using herbicides is to use the least amount of drug to achieve the best weeding effect, that is, efficient, safe, and economical. When we use herbicides, we must accurately weigh and evenly spray them according to the instructions for use. If the dosage is too much, it will not only waste medicine, but also cause turf injury. The result is that, in addition to weeds, it does not protect the lawn. On the contrary, if the dosage is insufficient, the effect of weed control will be poor or incomplete, and the remaining weeds will continue to breed and spread, eventually causing grass shortages, which will also not achieve the purpose of conservation.
4.3 timely medication
The use of herbicides must pay attention to the time of application. This is because any type of herbicide has the best time to control weeds, that is, the appropriate period of control. Therefore, the best control effect can only be obtained if it is used during this period of control. For example, some herbicides that use herbicides as the main killer, the time for their use should not be longer than the leaf stage of weeds at the latest, otherwise the herbicidal effect will be significantly reduced. On the contrary, some postemergence shoots and leaves herbicides, the best time of application should be in the weeds of the 2 to 5 leaf stage, if the medication is too early, part of the weeds have not emerged, the pesticide has no control effect on this part of the weeds If the medication is too late, the tolerance of the weeds to the medicament is increased, and the efficacy is reduced. Therefore, according to the nature of herbicides and the occurrence period of weeds, as well as the growth period of weeds and lawns, the selection of a suitable application period is one of the key conditions for the use of herbicides.
4.4 Understanding the Environment
With good use of lawn herbicides, we must also pay attention to the effects of environmental factors such as light, temperature, rainfall, and soil properties on the efficacy of pesticides. This is an important factor that cannot be ignored. For example, if oxyfenofrus exerts its efficacy, it requires light, and the effect of using under shade is poor. After the soil treatment agent receives light rain, it can increase soil moisture and increase the weeding effect. However, after seedling treatment, the treatment agent will rain, Elixirs are easily washed and the weeding effect is reduced. Therefore, the use of post-emergence stem and leaf treatment agent should choose sunny weather.
4.5 Master the conditions
The use of lawn herbicides is not arbitrary, and they are all subject to strict conditions. Therefore, only when the operator's operation is consistent with the requirements of the herbicide, can we achieve a satisfactory weeding effect and ensure no harm to the turfgrass. For example, L-7 is a superior herbicide for control of aconite roots and leeches in the grass turfgrass. After application, it is arid and the control effect is poor. If the pesticide is sprayed once every 2 to 1 days, the control effect on weeds will be as follows: It will increase significantly. Therefore, mastering the conditions and methods of application of pesticides is also an important part of the use of herbicides.
4.6 Strengthening Management
As the saying goes, “three-point planting and seven-point managementâ€, the degree of tacit understanding of conventional conservation measures such as lawn trimming, fertilization, irrigation, and medication is also closely related to the quality of medication. If herbicides are used for post-emergence shoots and leaves, the lawn must not be mown for two days before and after the application. This is because the mowing of the weeds will be cut off before the application of pesticides. Will reduce, control efficiency will be reduced; and pruning immediately after application, will block the downward transport and conduction of the drug in the weeds, the weeds, especially the perennial grass weeds will greatly reduce the lethality, Can not reach the purpose of "rooting grass". In addition, good management and maintenance measures can promote the healthy growth of the lawn and form a dense layer of grass, which can effectively inhibit the occurrence and growth of weeds, thereby reducing the number of herbicides used and the amount of drugs used to better protect the environment.
5. Different stages of lawn weed control technology
5.1 Lawn sowing
Mainly for the cold-season turf cultivated by live broadcasting. Since lawn seeds are most sensitive to herbicides at this stage, they should be used with caution. Generally selected before the seedlings used in the lawn sowing, a relatively safe herbicide species cyclosulfuron.
5.2 when the lawn is planted
Mainly for the planted lawn, because it has a rooting and survival process, the resistance is worse than that of the flat lawn. This should be noticed. The safer herbicide species is Emasotropin.
5.3 Turf growth period
This is the most difficult problem faced by conservation workers and the most concerned issue. At this point, the traditional method is to manually pull the grass. The results of the study showed that the alternative use of soil treatment and stem and leaf treatment can basically solve the problem of grassland damage.
5.3.1 Soil Treatment (Closed)
Before weeding, we have good control of most annual weeds and broad-leaved weeds. Generally used before emergence of weeds, use 2 to 3 times a year. Optional agents are Shi Tianbu, evil spirits and so on.
5.3.2 Stem and leaf treatment
Control the emergence of weeds, and the time of application is preferably 2-5 leaf stage of weeds. It is required that the used agents must be highly selective.
There are more pesticides that can be used to control broad-leaved weeds in grass lawns, and most of them are safe to lawns. Such as 2,4-D butyl ester, Baicao enemy, make it Long, Bendison and so on. Note that 2,4-D is less safe for bentgrass and modified bermudagrass.
The turfgrass weeds used in control of lawns such as Cyperus rotundus, Rhizoma bungeana, etc. are usually used as a mixture of 2A, 4C and Bendazosone. However, this agent is not effective for perennial weed Aconite and it is not effective for blisters. Baibai Palace not only has a good effect on the aboveground part, but also has a very high inhibition rate for underground rhizomes. The regeneration rate of the aconite roots in the area of ​​application is very low, but Xiubaigong can only be used for warm season lawns.
It is technically difficult to control grass weeds on gramineous lawns, especially the control of perennial weeds such as Bermudagrass, double-headed gar, and other weeds. Generally, oxazolidine may be used, but this agent is not safe for Bermuda, and warm-season turf can also be controlled with Xiebaigong. Pingan 5 can be used for cold season lawns.
5.4 Lawn Dormancy
There is a period of dormancy in the warm season lawn in winter. At this time, the part of the turfgrass is basically dead. If weeds are harmful, we can use the omnivorous herbicide Roundup. It should be noted that because of its internal absorption properties, it can be absorbed by lawns that are not completely dormant during the warm winter months, resulting in the failure to sprout the lawn the following year and causing bald spots. Therefore, attention should be paid when using it.
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