Herbicide Use Status and Weed Management Strategies
Current status of herbicide use in Southeast Asia
In Southeast Asia, the introduction of herbicides was mainly through agricultural production, although phenoxycarboxylic acid herbicides such as 24.5-T were mainly used to control woody perennials, and were mixed with 2.4-D as "Agent Orange" during the Vietnam War. Afterwards, the registration of 245-T was cancelled, and the product was voluntarily taken off the shelves by the manufacturer in 1985. The herbicide 2.4-D was first tested in the Philippines in 1948 for the eradication of weeds in lawns and pastures, and subsequently for weed control in rice. In the late 1950s, Thailand considered 2.4-D to be the only rice herbicide of value. In the 1960s, 24-D was used in limited rice areas in Malaysia. However, in 1972 Indonesian rice farmers started using MC-4 for the control of broadleaf weeds and sedges, but switched to 2.4-D in 1978 due to supply shortages in the country. The 2.4-D herbicide remains one of the most effective herbicides ever developed.
Cambodia
In Cambodia, the earliest documented reports of pesticide use appeared in the 1990s, when only 0.7% of farmers used herbicides, while 38.0% and 28.0% of farmers used insecticides and rodenticides, respectively. However, in In 2016, the most commonly used pesticides were herbicides and insecticides. The increase in herbicide use is mainly driven by the dwindling rural labor force and the expansion of arable land. Farmers of cassava, maize and rice are the main users of herbicides. About 30 herbicide active ingredients are allowed to be used in Cambodian agriculture.
Malaysia
Malaysia is the country that uses the most herbicides among Southeast Asian countries, and herbicides account for about 80% of the country's pesticide use. According to FA02022 data, Malaysia used about 34,084 tons and 56,430 tons of herbicide active ingredients in 2006 and 2016, respectively, which is equivalent to an average annual growth rate of 6.56% in 10 years. Because rice, oil palm, rubber and other crops have a single production system, they are highly dependent on herbicides. Paraquat, glyphosate, glufosinate, fluazifop, metsulfuron-methyl, and triclosan
Active ingredients such as pyroxyacetic acid are commonly used in oil palm and rubber plantations, while 2.4-D, tribenuron-methyl, pyrazosulfuron-methyl, propanil, quinclorac and cyhalofop-ethyl are widely used in rice.
Myanmar
Myanmar is the second largest country in Southeast Asia, with 60% of the population directly or indirectly dependent on agricultural activities for their livelihoods. Myanmar is similar to Thailand in terms of crop cultivation, planting patterns and weather conditions. However, the use of pesticides is relatively low. Pesticides are rarely used in Myanmar's traditional agriculture, but in the past 20 years, pesticide imports from China have seen a relatively large increase. From 2004 to 2014, the import volume of pesticides ranged from 1,000 tons to 6,000 tons, and after 2015, the import volume stabilized at more than 10,000 tons. The amount of herbicides and
The proportion has increased rapidly, while the amount of pesticides has gradually decreased. The use of herbicides in Myanmar has increased from 38 tons in 2000 to 9,740 tons in 2019, an average annual increase of 41.24%. As of 2019, there are about 20 active ingredients available to farmers, of which the most sold are glyphosate, 2.4-D, pretilachlor, fomesafen and quinclorac, with a total import volume of about 900 tons per year.
The Philippines
Similar to Indonesia, herbicides are widely used for weed control, although usually as a supplement to mechanical and hand weeding. Herbicide use in the country dates back to 1948, when 2.4-D was used to control broadleaf weeds. The use of 2.4-D marked the beginning of selective chemical weed control, paving the way for the gradual use of herbicides in the late 1950s. In the 1960s and 1970s, the amide herbicides (butachlor and propanil) and the thiocarbamate group grass
were introduced and quickly accepted by rice farmers because these herbicides are effective in controlling weeds before emergence. Oxadiazone, promethachlor, bendazone, and pendimethalin were also introduced in rice and other crops for weed control in the 1970s and 1980s; triazine herbicides (atrazine, In the 1960s and 1970s, the urea herbicides (diuron and diuron), the uracils (bromadil and triquat) and the bipyridyl herbicides (paraquat) Introduced for weed control in plantation and field crops such as pineapples, sugar cane, and bananas, and is still commonly used today; Long) was introduced in the 1990s for post-emergence control of rice broad-leaved weeds; from the 1990s to the beginning of the 21st century, penoxsulam, saflufenacil, mefentrazone, clomazone and Bispyribac is registered for weed management in rice.
As of 2021, a total of 55 herbicide active ingredients have been registered in the Philippines for the production of single or mixed doses (Philippine Fertilizer and Pesticide Authority, 2022). Of these, glyphosate accounted for 48% of the total active ingredients used and was used primarily in maize and plantation crops, although glyphosate was also used in non-crop areas and as a pre-sowing treatment for no-tillage annual crops. In rice production, butachlor, propanil, promethachlor, 2.4-D, bispyribac and cyhalofop are commonly used to control broadleaf weeds and gramineous weeds.
On average, the country imports 10,000 tons of herbicides per year.
Vietnam
In Vietnam, herbicides are widely used for weed control, but usually as an aid or supplement to mechanical and manual weeding. In the 1970s, herbicides began to be used for weed control with the use of 2.4-D, propanil and pentachlorophenol in rice fields. In the 1980s, only a few herbicides were additionally introduced, most of them for spring crops. However, herbicide use began to increase in the 1990s. In 1991, the country's herbicide usage was about 900 tons. In 2019, Vietnam's Ministry of Agriculture and Rural Development published a list of 503 active ingredients allowed to be used in the country's agriculture, 85 of which are herbicides, mainly used in rice. The most commonly used active ingredients in rice are clopyr, quinclorac, bisfluben, butachlor, pyrazosulfuron-methyl, oxadiazone, pretilachlor, propanil, 2.4-D, ethoxysulfuron, cyanogen Fluoxate, bensulfuron-methyl and acetochlor etc. Glyphosate is the most commonly used herbicide in plantations. It is used 2-3 times a season for land consolidation and weed control between crops, accounting for 36% of the total herbicide use in the country.
Current status of herbicide use in Southeast Asia
Cotton and rice are the main crops for herbicide use, accounting for 50% and 18% of the world's total herbicide consumption, respectively. However, glyphosate and 2.4-D are widely used herbicides in tea and coffee plantations in South Asia. In India, glyphosate accounts for 37% of the total active ingredients of herbicides used, of which nearly 24% is used in cereals, cotton, sugar cane, some fruits and vegetables. The application area of glyphosate in India is close to 12 million hectares, with an average application rate of 0.68 kg/ha. Because, glyphosate is an effective and economical solution to weed problems.
More than 55% of the arable land in South Asia is grown with rice, for which chemical weed control offers an economical solution. To effectively control weeds and delay the development of weed resistance, herbicides with different mechanisms of action are often recommended. Until the 1980s, the rate of development and commercialization of newer herbicides with different mechanisms of action was one every 2.5 to 3 years. There will be no herbicides with new mechanisms of action in the future. New herbicide products with existing mechanisms of action can only be used in situations where cross-resistance has not occurred so far in weeds. The growing number of cases of evolution of resistance to existing herbicides suggests that most herbicides may not be available in the future. New herbicide-resistant crops are also resistant to older herbicides such as 2.4-D New herbicide-resistant crops are also resistant to older herbicides such as 2.4-D, so the choice of new herbicides is very limited.
Glyphosate is one of the most important and widely used active ingredients, accounting for 73% of the active ingredients of herbicides used in seven countries including Australia, China, India, Indonesia, Philippines, Thailand and Vietnam, accounting for 38% of the total weeded area. In addition, expenditures for the use of glyphosate alternatives could increase the annual cost of weed control by US$ 22-30/ha in seven countries. About 82 million kg of glyphosate active ingredient is used annually in Asia for agricultural use (50% of global use).
16%~18%). Glyphosate is one of the most important and widely used active ingredients, accounting for 13%-73% of the total use of herbicide active ingredients in Asia and 7%-38% of the total herbicide sprayed area. India and China, two agricultural powerhouses, use 20.1 million kg and 14.2 million kg of glyphosate active ingredient, respectively, in various herbicide formulations. However, weed resistance to glyphosate is steadily developing, resulting in reduced efficacy and higher weed management costs, with more than 48 glyphosate-resistant weed species worldwide. Therefore, with the development of new transgenic technology, the threat of glyphosate's poor efficacy has attracted people's attention.
With the technological shift from subsistence to intensive and commercial cultivation, and from traditional ecology to conservation ecology. Weed populations are clearly shifting towards uncontrollable weeds. For example, before the Green Revolution in India, safflower was one of the main weeds in wheat. With the development of irrigation facilities and the introduction of semi-dwarf Norin wheat varieties, konjac and long glume have become difficult weeds to control. Changes in the way crops are grown as resource-conserving techniques become more widespread have also led to a shift from perennial grasses to broadleaf weeds. Climate change may lead to a potential shift of weeds with less phenotypic plasticity due to warmer Earth temperatures and higher CO2 concentrations, as well as some other weeds displacing native weeds and expanding in new areas. The movement of these weeds in intensive systems has forced the continued use of highly effective and recently introduced low-dose herbicides. With few existing herbicides to choose from, over-reliance on a few herbicides becomes a concern.
The dramatic increase in the use of herbicides, especially glyphosate under intensive cropping conditions in South Asia, has become a matter of concern. Resistance to glyphosate has been reported by several weed species in nearly 35 major crop fields from more than 35 countries, including South Asia. The persistence of glyphosate in the environment may exceed several years, therefore, large swaths of the world's farmland are vulnerable to high environmental pollution and ecological hazards.
Current status of weed resistance development
When a weed biotype survives previously controlled herbicide doses, it is called a herbicide resistant weed biotype. If 15% or more of weeds in the entire weed population are resistant, alternative weed management methods are recommended. Over time, the proportion of these resistant weed biotypes increases with continued selection, resulting in genetically resistant weed populations. Resistance to 2.4-D was reported in Canada in 1957 on wild carrots, the first herbicide for which resistance was reported. In 1968, Senecio resistance to atrazine and simazine was reported in the United States; over time, developing countries also reported resistance to almost all major classes of herbicides. However, most cases of resistance have been with triazine herbicides. Resistance of rice weeds to 2.4-D was reported in Malaysia as early as 1989; later, resistance to propanil, quizalofop-p, oxacarb-p The resistance of Ling and benzsulfame. Growing problem of weed resistance in developing countries, distribution of resistant weeds targeting herbicides with different mechanisms of action. Resistance in weeds is the result of their adaptive evolution to the intense selective pressure imposed by the continued application of herbicides.
Herbicide resistance involves two types of mechanisms
1. Target resistance caused by structural changes or increased activity of herbicide target proteins
2. Off-target resistance caused by reduced uptake or transfer of herbicides by weeds or enhanced metabolism. Metabolism-based herbicide resistance to different chemical groups and different modes of action due to enhanced activity of endogenous plant enzymes such as cytochrome P450 monooxygenases, glycosyltransferases, and glutathione-S-transferases Herbicide resistance leads to cross-resistance.
In Southeast Asia, there were 37 unique cases involving 17 weed species and 30 herbicide active ingredients, with Malaysia topping the list with 20 cases; followed by Thailand, Indonesia and the Philippines with 7, 5 and 3 cases respectively. The Philippines was the first country to record weed resistance, in 1983 involving the resistance of cuneiform flowers to 2.4-D. After 22 years, the country has reported a second case involving barnyardgrass resistance to butachlor and propanil, both in rice. In contrast, herbicide resistance cases in Malaysia vary by active ingredient, weed species, and crop, and among active ingredients, paraquat resistance has been reported in eight cases; in addition, multiple and cross-resistance issues also exist in Malaysia.
Weed Resistance Management Measures
1. Sustainable weed management
Unsustainable weed management can lead to various problems such as economic losses, changes in weed flora, development of herbicide resistance, and adverse impacts on the environment. Integrated weed management approaches combine direct and indirect control methods and are based on critical periods of crop-weed competition, providing a sustainable approach to weed problems while reducing the cost of cultivation and minimizing environmental impact harm. An increasing number of farmers are adopting more inclusive weed management strategies that minimize reliance on herbicides and weeds are highly responsive to management measures. Therefore, taking different approaches and exploiting the synergistic effects of each control strategy will help achieve long-term and sustainable weed management. Different strategies to manage weeds include use of clean and high quality seeds (free of weed seed contaminants and vegetative propagules), proper tillage practices, seedbed rearing techniques, field sanitation, physical and mechanical weeding, mulching, ten soil days Sunshine, intercropping, crop rotation, alternating dry and wet fields, use of biological control agents (fungal herbicides, insects and weeds with allelopathic effects), etc.
The use of weed-competitive and allelopathic rice varieties and increased weed-competitiveness through seed priming is another strategy for sustainable rice weed management. In direct-seeding and aerobic rice ecosystems, where weeds are a major hazard because limited water availability inhibits weed growth, the use of weed-competing rice varieties can be an alternative solution when suitable herbicides are not available, and Achieve higher food production. The successful development of weed-competitive rice varieties will provide Southeast Asian countries with an effective new strategy for weed control, no longer through single herbicide application to manage weeds, thereby reducing herbicide use and production costs, and preventing Development of herbicide resistance.
sustainable herbicide management
The use of herbicides is considered to be the most cost-effective and practical means of controlling weeds. However, the sustainability of herbicide use is being threatened by the development of herbicide resistance in weed populations. Through herbicide rotation, mixed or sequential use, alternate use of herbicides with different modes of action can solve and alleviate herbicide resistance, especially due to the substitution of herbicide targets. However, sequential application of herbicides can occasionally lead to multiple resistance problems, where a single population accumulates resistance-target mutations to several herbicides belonging to different modes of action. This is an emerging challenge that needs to be addressed by providing more herbicide options, smarter herbicide combinations and sequential application. In herbicide formulations or tank mixing two or more active ingredients of herbicides with different modes of action that are compatible with each other will significantly reduce the probability of weed populations developing resistance to a specific herbicide. Combining herbicide control strategies with other non-herbicide control strategies can also help mitigate and slow the evolution of resistance in weed populations.
A greater threat to the sustainability of herbicide use is herbicide resistance based on metabolic mechanisms that confer resistance to existing, new and soon-to-be-discovered herbicides and further limit farmers' options Herbicide selection for sexual weed control. In other words, metabolic herbicide resistance challenges well-known strategies for controlling and mitigating herbicide resistance by rotating herbicides with different modes of action, or using different herbicides in mixtures, or sequentially. In this case, even
Mixed or alternate or sequential application of various herbicides with different modes of action cannot effectively control the population of weeds with enhanced herbicide-metabolizing enzyme activity. To solve this problem, an effective strategy is to inhibit the activity of herbicide-metabolizing enzymes by using chemical synergists. Identifying and using more potent chemical synergists as supplements to existing herbicide active ingredients could be one of the strategies to combat metabolism-based herbicide resistance, leading to more sustainable herbicide use.
The price of herbicides
Usually, the price of herbicides will be affected by raw materials, market environment, research and development costs, etc. If you want to know the price of herbicide, please contact us to initiate an inquiry.
Tel: 13563082345 Email: sales@agripesticide.com
Supplier of Herbicide
Agripestcide is a professional pesticide chemical manufacturer provides high quality and effective Herbicide with high quality and good service. If you are looking for Herbicide in bulk, feel free to contact us to get the latest price.