The protective fungicide mancozeb the forest of leading show fungicides
What is Mancozeb?
The pure product of mancozeb is white powder, and the industrial product is off-white or light yellow powder, with the smell of rotten eggs, hardly soluble in water, insoluble in most organic solvents, but soluble in pyridine, not sensitive to light, heat and humidity Stable, easy to decompose carbon disulfide, easy to decompose and release carbon disulfide when encountering alkaline substances or copper, mercury and other substances, and reduce the effect, low volatility. The so-called protection is to provide Zn elements for plants. In addition to solving the symptoms of zinc deficiency, it can also enhance the ability of plants to resist diseases, so as to relatively play a bactericidal effect.
Main formulations: 70% and 80% mancozeb wettable powder, 80% spray, Dasheng M-45, Xinwansheng wettable powder.
Physical and chemical properties: It is a complex of maneb and zinc, containing 20% manganese and 2.55% zinc. The original drug is gray-yellow powder with a melting point of 192°C to 204°C (decomposition). Solubility: Insoluble in water and most organic solvents, soluble in strong chelating agent solutions. It is usually stable in a dry environment, slowly decomposes in a heated and humid environment, and can cause combustion when it is decomposed by acid and alkali.
Mancozeb drug action
Mancozeb is an excellent protective fungicide, which is a low-toxicity pesticide. Because of its wide bactericidal range, not easy to produce resistance, and its control effect is obviously better than other similar fungicides, it has always been a large-tonnage product in the international market. At present, most domestic compound fungicides are processed and formulated with mancozeb. The trace elements of manganese and zinc have obvious effects on promoting the growth and increasing yield of crops. Spot defoliation, melon and vegetable blight, downy mildew, field crop rust, etc. have remarkable effects, and can effectively control the occurrence of diseases without any other fungicides, and the quality is stable and reliable.
Mancozeb mode of action
The fungicide mancozeb belongs to the dithiocarbamate class of sulfur preparations. Under the action of water and air, the agent sprayed on the surface of the plant is converted into EBIS and EBI successively, and forms on the surface of leaves and fruits. A layer of air-permeable, water-permeable, and light-transmitting dense protective film inhibits the germination and invasion of germ spores, destroys the activities of various enzymes required for the normal physiological metabolism of germs, so as to achieve the purpose of sterilization and disease prevention. .
Features of Mancozeb
1. Broad bactericidal spectrum. From lower fungi to higher fungi, it has effects on most pathogenic bacteria. Registered on more than 70 crops around the world, used to control more than 400 diseases, such as vegetable blight, green pepper, tomato blight, potato late blight, wheat rust and powdery mildew, pear scab, apple leaf spot, Grape downy mildew and other diseases have a good control effect.
2. Not easy to develop resistance. Mancozeb is a protective fungicide product, but there are not many protective fungicides in the existing fungicides. What is even more commendable is that mancozeb can act on multiple sites on the pathogenic bacteria cells, making it difficult for the pathogenic bacteria to develop genetic adaptability, so its risk of drug resistance is low. Although it has been in existence for more than 60 years, it has not been found that plant pathogenic fungi have obvious resistance to it.
3. Good mixability. Mancozeb can be mixed with a variety of fungicides. In practical applications, due to its good mixability, there are 590 mixtures of mancozeb registered in my country within the validity period, far more than the single 286 doses. The mixture is well recognized by growers regardless of the cost of medication or the bactericidal effect. The dosage form is mainly 75% water-dispersible granules and 80% wettable powder. Among the mixture products, the mixture products of mancozeb and dimethomorph, metalaxyl, metalaxyl, oxafefenone, cymoxanil, etc. are more common and widely used, which are mainly registered for Control downy mildew, blight, anthracnose, leaf mold and leaf spot of various crops.
4. Supplement trace elements. As we all know, there are 16 kinds of nutrient elements necessary for the growth of crops, including zinc and manganese, and mancozeb itself contains a large amount of zinc and manganese ions. Even if mancozeb is used to prevent and control diseases, it is equivalent to supplementing the crops with zinc and manganese elements. Among them, zinc element is beneficial to the development of young shoots and leaves, and manganese element can promote the photosynthesis of leaves.
5. It is resistant to rain erosion, and the price is relatively affordable and cost-effective. Mancozeb of good quality, sprayed on the surface of plants, the particles of mancozeb sprayed on the surface of the plant are fine, strong adhesion, under the condition of a little dew or raindrops, secondary distribution, spread on the leaf surface or fruit surface more evenly. Therefore, when controlling fungal diseases of crops in rainy areas or seasons, the pesticide can be sprayed before the rain, and it is generally not necessary to re-spray after the light rain.
Causes of drug spots when mancozeb is used
Mancozeb is a thiocarbamate fungicide, which is a protective agent, but sometimes drug spots appear during use, and sometimes it does not. What is the reason? It turns out that the mancozeb in the complexed state has myrrh spots, and the non-complexed state has drug spots.
1. About the complexation of mancozeb. Mancozeb can play a bactericidal effect because it contains manganese ions and zinc ions, and the content of manganese ions is more than that of zinc ions. Manganese ions are the main force for sterilization, but because they are too active and violent, phytotoxicity will occur if you are not careful. Mancozeb is a particularly good fungicide, so some pesticide manufacturers try to make up for its shortcomings, so the complexed state of mancozeb appears. Because manganese ions are unstable, from a chemical point of view, it adds an intermediate substance to combine with manganese ions to form a stable compound, that is, complexation reaction.
2. Complexation can be said to be a production process. It is divided into full complexation and non-full complexation. The quality of mancozeb complexation depends entirely on the production technology and production equipment of the original drug company. Full complexation is the best, and non-full complexation has 80%, 70% %, 50%, etc. So, how to distinguish between full complexation and non-full complexation? From the visual point of view, it is difficult to distinguish from the packaging or color. How can we tell the difference?
One is the price. The price of mancozeb in the fully complexed state is much higher than that in the uncomplexed state.
The second is to choose products from large companies. Nowadays, the competition among pesticide companies is fierce, and the fully complexed mancozeb is a major selling point. Some manufacturers' pesticide packaging bags are marked as fully complexed, and some unmarked ones need to be consulted with the dealer. Try to choose mancozeb marked with the supply of foreign raw materials (usually marked on the outer packaging), because the current complexation process of mancozeb is still better than foreign technology, and the complexation is relatively thorough. Developed for decades.
3. The difference between fully complexed state and non-fully complexed state. One is security. Mancozeb in a fully complexed state is relatively mild when sprayed on the surface of crops, and will not cause drug spots on the fruit and leaf surfaces of crops, while mancozeb in a non-complexed state contains a certain amount of free manganese ions, which is easy to cause Drug spots are also easy to cause phytotoxicity to crops.
The second is the stability of traits. According to everyone’s spraying habits, it is generally impossible to use mancozeb alone, and it is often mixed with other insecticides and fungicides. The fully complexed mancozeb will not react with other pharmaceutical ingredients, not the fully complexed mancozeb. Manganese zinc has a certain chance to react with other pharmaceutical ingredients to form flocs or precipitates.
The third is the validity period. Mancozeb in fully complexed state is relatively stable, and its duration of action is longer than that of mancozeb in non-fully complexed state. To check the production date when purchasing, select the purchase with the latest production date. In short, the price of full complexation is high, and non-complexation is unsafe. You can choose the corresponding product according to your needs.
Excellent mixing scheme of Mancozeb
1. Dimethomorph + Mancozeb Dimethomorph is a new type of systemic therapeutic low-toxic fungicide, its mechanism of action is to destroy the formation of bacterial cell wall membrane, causing the decomposition of the sporangia wall, so that the pathogenic bacteria die. Compounded with mancozeb, it has the advantages of both, and has excellent control effects on fungal diseases such as downy mildew, late blight, blight (mildew), pythium, and black shank.
2. Carbendazim + mancozeb The main function of carbendazim is to interfere with the formation of the spindle in the mitosis of bacteria, thereby affecting cell division, and has a good control effect on ascomycetes and half-knowledge fungi, and has protective and therapeutic effects , use before the onset can protect the plants from disease, and use after the onset can control the spread of the germs. The compound preparation of carbendazim and mancozeb is mainly used to prevent and control apple tree leaf spot and pear tree scab. It is more effective when used in the early stage of spotted leaf spot disease. The spray should be uniform and can be used continuously for 1 to 3 times. ; and the prevention and treatment of pear scab requires medication at the early stage of the disease, and the formula can also be used to prevent and control apple tree ring spot, litchi tree anthracnose, etc.
3. Metalaxyl + Mancozeb After compounding the systemic fungicide metalaxyl and the protective fungicide mancozeb, it has dual effects of treatment and protection. After spraying, it can be absorbed by plant roots, stems and leaves, and transferred to plant organs with the movement of water in the plant body, with high safety and long lasting effect. This compound formula is mainly used for the prevention and treatment of cucumber downy mildew. The pesticide is applied at the initial stage of cucumber downy mildew. The medicine is applied every 7 days and sprayed continuously for 3 times. The number of uses is 3 times. At the same time, it can be used to control grape downy mildew and tobacco black shank.
4. Falfafen + Mancozeb Falfafen is a new type of high-efficiency, broad-spectrum fungicide with lipophilicity. After spraying on plant leaves, it has the special effect of being easy to adhere and not being washed away by rain. Mancozeb is an excellent protective fungicide, which is a low-toxicity pesticide with a wide range of sterilization and is not easy to produce resistance. The combination of the two can realize the obvious synergistic effect of oxafeconone and mancozeb , good control effect on tomato early blight.
5. Difenoconazole + Mancozeb The compound use of the two has obvious synergistic effect, which combines the advantages of the two broad-spectrum sterilization, overcomes the characteristics of mancozeb that is prone to phytotoxicity, and enhances the curative effect , delays drug resistance, has good protective and therapeutic effects on almost all higher fungal diseases, and is known as the "ten thousand essential oils" in fungicides. The so-called "Wan essential oil" has a wider bactericidal spectrum, and benzo manganese zinc is effective against downy mildew, anthracnose, blight, and late blight caused by fungi such as Deuteromycetes, Flagellate, Basidiomycetes, Ascomycetes, and Zygomycetes. , Early blight, blight, blight, damping-off, powdery mildew, rust and almost all fungal diseases have good preventive and therapeutic effects. Second, it is cost-effective. Benzozinc manganese zinc is compounded by two fungicides that are currently used in the largest amount and are relatively cheap. The price is low and can be used on field crops.
6. Cymoxanil + mancozeb Cymoxanil is a therapeutic fungicide, which is systemic and can be transmitted in crops, and has a destructive effect on contact with pathogenic spores. After the two are compounded, they mainly inhibit the germination of spores And the oxidation of pyruvic acid in the bacteria has dual functions of protection and treatment. This formula is mainly used for the prevention and treatment of cucumber downy mildew. It needs to be applied for the first time immediately after the first batch of cucumber fruits are harvested, and once every 7 days. Spray evenly on the stems and leaves of the plants, the safe interval is 2 days, and use it up to 4 times in the whole season; in addition to cucumber downy mildew, it can also be used to prevent and control tomato late blight.
7. Aluminum triethylphosphonate + mancozeb Aluminum triethylphosphonate is a systemic fungicide with specific effects on diseases caused by oomycetes. After compounding with mancozeb, it can inhibit the spore germination and hyphal growth of pathogenic fungi Both have inhibitory effect, mainly used to control cucumber downy mildew, and can also be used to control apple tree spot defoliation.
How to use Mancozeb
1 spray. To prevent blight, anthracnose, and leaf spot of eggplant and potato, use 80% mancozeb wettable powder 400~600 times liquid, spray at the initial stage of disease, and spray 3~5 times.
To prevent and control spicy (sweet) pepper anthracnose, blight, and leaf spot diseases, use 171-240 grams of 70% mancozeb wettable powder per mu, or 75% mancozeb water-dispersible granules before or at the beginning of the disease 160~224 grams, mixed with 45~60 kg of water and sprayed. Depending on the occurrence of the disease, spray once every 7 days or so, and use the medicine continuously for 2 to 3 times. If you want to prevent pepper damping-off, you should also pay attention to spraying the base of the stem and the surrounding ground.
To prevent tomato early blight and late blight, use 80% mancozeb wettable powder or 80% mancozeb water dispersible granules 150~200 grams per mu, 50% mancozeb wettable powder 246-316 grams, 70% mancozeb wettable powder 175-225 grams, 30% mancozeb suspending agent 240-320 grams, mixed with 45-60 kg of water and sprayed evenly. Depending on the occurrence of the disease, once every 7 days, spray 2-3 times continuously, and stop using the drug 5 days before harvest. The prevention and treatment of early blight can also be combined with painting the stem. Use an old brush or a small cotton ball to dip 100 times the liquid medicine of 80% mancozeb wettable powder, and brush it once on the diseased part.
To prevent and control cucumber downy mildew, anthracnose, and brown spot, start at the early stage of disease or when climbing vines, use 150-250 grams of 80% mancozeb wettable powder or 140 grams of 75% mancozeb water-dispersible granules per mu ~180g, 420g/L mancozeb suspending agent 130~200g, mixed with water 45~60kg spray. It can also be sprayed with 500~600 times liquid of 70% mancozeb wettable powder. Spray once every 7-10 days, continuously spray 2-3 times, stop using the drug 5 days before harvest.
To prevent and control watermelon anthracnose, use 166-250 grams of 80% mancozeb wettable powder or 148.6-240 grams of 70% mancozeb wettable powder, 75% mancozeb wettable powder per mu 220-240 grams of zinc water-dispersible granules, mixed with 45-60 kg of water and sprayed evenly. Spray once every 7-10 days, and spray 3 times in a row.
To prevent and control melon anthracnose, downy mildew, blight, blight, etc., use 150-200 grams of 80% mancozeb wettable powder per mu, and spray with 45-60 kg of water before the onset or when lesions first appear. Spray once every 7 to 10 days, generally spray 3 to 6 times, and stop using the drug 5 days before picking.
Control lettuce, cabbage, cabbage downy mildew, eggplant cotton blight, brown spot, celery blight, spot blight, and cruciferous vegetable anthracnose, use 70% mancozeb wettable powder 500~600 times liquid at the initial stage of disease spray. Spray once every 7-10 days, and spray 3-5 times in a row.
To control bean anthracnose, rust, and red spot, spray with 80% mancozeb wettable powder 400~700 times liquid. Spray once every 7~10 days, and spray 2~3 times continuously.
To control potato late blight, 120-180 grams of 80% mancozeb wettable powder or 137-206 grams of 70% mancozeb wettable powder or 75% mancozeb water-dispersible granules can be used per mu in the early stage of the disease 128~192g, mixed with 45~60kg water, spray evenly.
Use mancozeb to prevent diseases on transplanted vegetables such as cucumbers, watermelons, peppers, and tomatoes. It is best to spray once before transplanting (seedbed stage) to reduce the source of bacteria. After transplanting, start spraying at the early stage before the onset of disease (when the disease spots first appear), use 120-180 grams of 80% mancozeb wettable powder per mu, mix with 45-60 kg of water and spray evenly. Spray once every 5 to 7 days, and spray once every 7 to 10 days for field vegetables. Continuous medication 2 to 3 times.
To prevent and control soybean rust, apply pesticides at the early flowering stage, use 80% mancozeb wettable powder 200~300 times per mu, and spray evenly. Apply once every 7-10 days, 4 times in a row.
To prevent ring spot, anthracnose, scab, red spot, and leaf spot of apples, pears, and peaches, use 80% mancozeb wettable powder 600-800 times liquid to spray at the initial stage of disease.
To control apple moldy heart disease, spray 80% mancozeb wettable powder or 75% mancozeb water dispersible granules 600~800 times once at the end of full flowering.
To control grape black spot and downy mildew, use 80% mancozeb wettable powder 600~800 times liquid to spray in the young fruit stage and the early stage of disease. Spray once every 7-10 days, and spray 4-6 times in a row.
To control banana leaf spot, scab and anthracnose, use 80% mancozeb wettable powder or 75% mancozeb water dispersible granules 600~700 times liquid, 48% mancozeb suspending agent 300~ 400 times liquid etc. spray evenly. Start spraying from the early stage of disease occurrence, once every 10 days or so, and spray 3 to 4 times.
To prevent and control litchi and longan downy mildew, spraying is started from the early stage of the disease, once every 7 days, and sprayed 2-3 times in a row. Spray evenly with 80% mancozeb wettable powder or 75% mancozeb water dispersible granules 600~800 times liquid.
To prevent and control citrus scab, anthracnose, sand skin disease (black spot disease), and anti-pedicle rot, scab, macular disease, etc., use 80% mancozeb wettable powder or 75% mancozeb water dispersion Spray 500~600 times liquid of granules. Spray 2-3 mm of citrus germination, 2/3 of flower withering, and young fruit period. In rainy years and seriously diseased orchards, spraying should be appropriately increased 1-2 times. Spraying at the end of June or early July and mid-August Once, it can completely prevent and control rust ticks, and also prevent fruit diseases such as sand skin disease, anthracnose, scab, and soot disease. Touch tangerines and oranges, and spray again in early and mid-September, which can effectively prevent and control anthracnose.
To control peanut black spot, leaf spot, brown spot, and gray spot, start applying pesticides at the early stage of disease onset. Use 80% mancozeb wettable powder 200 grams per mu, mix 40-50 kg of water and spray evenly. Spray once every 10 days, 2-3 times in a row.
To prevent and control rubber tree anthracnose, sugar beet brown spot, ginseng leaf spot, and maize leaf spot, use 400-600 times dilution of 80% mancozeb wettable powder and spray it at the early stage of the disease. Spray once every 8-10 days, and spray 3-5 times in a row.
To prevent and control tobacco red spot disease, spray with 80% mancozeb wettable powder 600~800 times liquid at the early stage of the disease. To prevent and control tobacco black shank, spray with 43% mancozeb suspension concentrate 400~600 times in the early stage of the disease.
To prevent and control rice blast, when leaf blast occurs, it should be sprayed with 80% mancozeb wettable powder at the early stage of the disease; when ear blast occurs, it should be sprayed with 80% mancozeb wettable powder from the end of the ear to the heading stage.
2 seed dressing. To prevent cabbage damping-off, use 70% mancozeb wettable powder (or dry suspension) to dress the seeds, and the dosage is 0.2% to 0.3% of the weight of the seeds.
To control carrot black spot, black rot, and spotted disease, use 70% mancozeb wettable powder (or dry suspension) to dress the seeds, and the dosage is 0.3% of the weight of the seeds.
To prevent and control cruciferous vegetable black spot, use 70% mancozeb wettable powder (or dry suspension concentrate) for seed dressing, and the dosage is 0.4% of the seed weight.
To prevent blight and damping-off in vegetable seedling stage, use 80% mancozeb wettable powder to dress seeds according to 0.1%~0.5% of seed weight.
3 Soak the seeds. To prevent and control yam wilt, use 70% mancozeb wettable powder 1000 times, soak the tail of yam for 10-20 minutes and then sow.
4 Root irrigation. To control melon blight (at the three-leaf stage of seedlings) and yam blight, use 500 times of 70% mancozeb wettable powder to irrigate the roots.
To prevent and control cucumber wilt, use 80% mancozeb WP 400 times to irrigate the roots.
5 Soil treatment. To prevent cucumber seedling damping-off and pea seedling black root disease, use 1 g of 70% mancozeb wettable powder and 9 g of 25% metalaxyl wettable powder per square meter of seedbed, and then sieve with 4 to 5 kg Mix the dry fine soil to make medicinal soil; after pouring the bottom water of the seedbed, sprinkle 1/3 of the medicinal soil on the seedbed; after sowing, cover the seeds with 2/3 of the medicinal soil.
Precautions for Mancozeb
1. Do not mix with alkaline pesticides and copper preparations. Although mancozeb can be mixed with many pesticides, it cannot be mixed with all pesticides. Because it contains manganese, zinc and other ions, avoid mixing with alkaline pesticides and heavy metal compounds such as copper, and cannot mix with potassium dihydrogen phosphate. Improper mixing will cause chemical reactions, produce gas or flocculent precipitation, affect the efficacy of the medicine and even cause danger.
2. Avoid strong light and high temperature when using. Under high temperature and strong light, the active ingredient of mancozeb will transform too quickly, which may easily lead to phytotoxicity, so it should be used with caution in strong light weather exceeding 35°C.
3. Avoid sensitive crops and crop sensitive periods. During the use of mancozeb, phytotoxicity is likely to occur due to improper application time, application dose, and application frequency, such as damage to crop leaves, formation of drug spots, rough fruit surface, and fruit rust. Therefore, in fruit trees, When using vegetables and other crops in sensitive periods such as young leaves, flowering, and young fruits, the amount and frequency of use should be controlled, especially in the young fruit stages of crops such as melons, apples, cherries, and grapes, to avoid phytotoxicity. produce.
4. Emphasis on prevention, mixed use. Mancozeb is a protective agent, and its main function is to prevent the occurrence of diseases. Therefore, if it wants to exert the best control effect, it should be used in advance, and it should be combined with other agents, especially systemic. Mixed use of antibacterial fungicides, so as to achieve better control effect.
How to rejuvenate the long-standing Daisen fungicides
1 New formula development, innovation and discovery of new indications and new usage. For example, the ternary compound product of tebuconazole + mancozeb + picoxystrobin developed by ADAMA mainly targets the 10,000-ton market of soybean rust in Brazil
2 Development of new dosage forms, such as water-based formulations SC, DF, etc., and dispersible oil suspension (OD) to improve adhesion, etc.
3 Field application demonstration research, scientific and rational drug use, and application of development in delaying drug resistance
4 Development of new high-efficiency dithiocarbamate fungicides.
Scientific and Rational Use of Mancozeb
1. Emphasis on toxicology research
The safety of pesticides to humans and beneficial organisms is the basis for their promotion and application. Since mancozeb is still the main species used as a protective fungicide, and it is harmful to the human body, further research on the environmental behavior of mancozeb is carried out to evaluate the exposure risk of mancozeb, so that researchers can make a conclusion. Risk assessment will be more conducive to the scientific and rational use of mancozeb.
2. Improved processing dosage form
Wettable powder is the main processing formulation of mancozeb. Due to its dust pollution and explosion hazard, it can no longer meet people's requirements for the safe use of pesticides. Granularized and water-based pesticide formulations such as water-dispersible granules and suspension concentrates will become the main development direction of pesticide formulations in the future. In addition, the oil suspension has a strong affinity to plants and is easy to adhere to waxy or smooth leaves, which can enhance the permeability and rain erosion resistance of mancozeb, and has broad development prospects.
3. Pay attention to the problem of drug injury
During the use of mancozeb, phytotoxicity is likely to occur due to improper application time, application dose, and application frequency. In mild cases, it will cause damage to crop leaves, weaken photosynthesis, and affect crop growth. In severe cases, it will form on the fruit surface and leaves. Drug spots (brown spots, macular spots, net spots, etc.) may even cause too large spots, rough fruit surface, and fruit rust, which seriously affects the commercial value of the fruit. Therefore, when mancozeb is used in sensitive periods such as the young leaves, flowering and young fruit stages of fruit trees, vegetables and food crops, the amount and frequency of use should be controlled to avoid phytotoxicity.
4. Monitoring pathogen resistance
At present, there are not many reports on the resistance of pathogenic bacteria to mancozeb. For a long time to come, mancozeb will still be an important fungicide variety for the prevention and control of related diseases. If it is used excessively and unreasonably, it will definitely lead to Rapid development of pathogen resistance. Therefore, further research on monitoring methods and preventive measures for the resistance of pathogenic bacteria to mancozeb will help prolong the service life of mancozeb.
5. Strengthen residue detection
Pesticide residue is a general term for all derivatives such as pesticide parent and its toxicologically significant impurities, metabolic transformation products, and reactants that remain in organisms, agricultural products, and the environment due to the application of pesticides. Among them, ethylenethiourea, as the main metabolite of mancozeb, has carcinogenic, teratogenic, and mutagenic effects on the human population. It is necessary to strengthen the monitoring and treatment of this compound in future applications.
The price of the fungicide mancozeb
Usually, the price of mancozeb, a pesticide and fungicide, will be affected by raw materials, market environment, research and development costs, etc. If you want to know the latest price of the pesticide fungicide mancozeb you need, please contact us to initiate an inquiry.
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