Downy mildew of cucumber and grape, commonly known as "Paoma Gan" (literally "running horse blight") and "Gan Yezi" (literally "withered leaves"), can infect plants at both seedling and adult stages. It mainly damages leaves and stems, while tendrils and pedicels are rarely affected. Downy mildew has a significant impact on the growth of cucumbers and grapes, and is directly related to their yields. So how to control downy mildew? Today, I will introduce a special fungicide for downy mildew control - Dimethomorph.
Product Advantage
Dimethomorph acts on pathogens mainly in the following three aspects: First, the preventive effect – it can prevent the germination and invasion of pathogen spores; second, the curative effect – it can penetrate into plant tissues and kill fungal hyphae; third, the anti-spore effect – it can inhibit the formation of pathogen spores and reduce the source of infection.
(1) Good efficacy and long duration of effect
Dimethomorph has a unique mechanism of action, which effectively acts on all growth stages of oomycete fungi and has a specific effect on various downy mildews and blights. It not only has preventive and curative effects, but also has the effect of inhibiting spore production. The application interval of dimethomorph is usually about 7-10 days, which is 3-4 days longer than that of other pesticides. Its long duration of effect reduces the number of applications, saving labor hours and costs.
(2) No resistance development
Dimethomorph has no cross-resistance with other fungicides such as metalaxyl and cymoxanil, and has strong miscibility. It can quickly kill pathogens that have developed resistance to other fungicides, ensuring the stable exertion of its efficacy.
(3) Rainfastness
It has excellent water solubility, dispersibility, and strong penetration. It can quickly penetrate leaves and spread locally, with good rainfastness-its efficacy is hardly affected if it rains 1 hour after spraying.
Additionally, it enhances the photosynthesis of plants, makes the color of fruits and vegetables brighter, and comprehensively improves the yield and quality of crops.
(4) Good compatibility for tank mixing / compounding
Dimethomorph can be tank-mixed or compounded with various fungicides, including amisulbrom, azoxystrobin, cymoxanil, mancozeb, propineb, kresoxim-methyl, thiram, chlorothalonil, fosetyl-aluminium, pyraclostrobin, amino-oligosaccharin, prochloraz, metalaxyl, zhongshengmycin, and iprodione.
(5) Good safety
Dimethomorph remains highly safe even when used during the flowering period and fruit expansion stage of crops.
Application
Grapes, lychees, cucumbers, muskmelons, bitter melons, tomatoes, peppers, potatoes, and cruciferous vegetables. Dimethomorph has a good control effect on low fungal diseases such as downy mildew, downy blight, late blight, phytophthora blight, phytophthora rot, pythium rot, and black shank. For vegetables, it can control cucumber downy mildew, muskmelon downy mildew, taro phytophthora blight, pepper phytophthora blight, and cruciferous vegetable downy mildew, etc..
The formulations of Dimethomorph include 25%, 30%, and 50% wettable powders, 25% microemulsions, 10%, 20%, 40%, and 50% suspensions, 40%, 50%, and 80% water-dispersible granules, 50% effervescent tablets, as well as 10% and 15% emulsion in waters.
Dimethomorph appears as a white powder or crystal. It is hydrolytically stable under general conditions, and its stability exceeds 5 years in dark conditions.
Use Method
(1) Control of downy mildew on cucurbits such as cucumbers, muskmelons, and bitter melons
Start applying the pesticide before or at the early stage of the disease. For each mu (a Chinese agricultural unit, approximately 0.067 hectares), use 30-40 grams of 50% water-dispersible granules or 50% wettable powder, 20-25 grams of 80% water-dispersible granules, 40-50 grams of 40% water-dispersible granules, 60-80 grams of 25% wettable powder, or 150-200 milliliters of 10% emulsion in water. Dilute with 45-75 kilograms of water and spray. Apply the pesticide once every 7-10 days, alternate with different types of pesticides, focus on spraying the back of leaves, and apply continuously for 3 times.
(2) Control of pepper phytophthora blight
Start applying the pesticide before or at the early stage of the disease. For each mu (a Chinese agricultural unit, approximately 0.067 hectares), use 30-40 grams of 50% wettable powder and dilute it with 50-75 kilograms of water for spraying. Depending on the development of the disease, apply the pesticide once every 5-7 days and continue for 3 consecutive applications.
(3) Control of tomato late blight
At the early stage of the disease, use 40-60 grams of 50% wettable powder per mu (a Chinese agricultural unit, approximately 0.067 hectares), dilute it with 40-50 kilograms of water, and spray.
(4) Control of tomato phytophthora root rot
At the early stage of the disease, drench with a 2000-fold dilution of 50% wettable powder, or a mixture of a 1000-fold dilution of 50% boscalid water-dispersible granules and a 750-fold dilution of 50% dimethomorph water-dispersible granules.
(5) Control of potato late blight
Start spraying at the early stage of the disease, using a 1000-fold dilution of 50% wettable powder. Spray once every 7-10 days, and alternate with different types of pesticides.
(6) Control of lettuce downy mildew
Start spraying at the early stage of the disease, using a 1000-fold dilution of 50% wettable powder. Spray once every 7-10 days, for about 2 consecutive applications, with a focus on spraying the undersides of leaves.
(7) Control of downy mildew on cruciferous vegetables
For each mu (a Chinese agricultural unit, approximately 0.067 hectares), use 20-25 grams of 80% water-dispersible granules, 30-40 grams of 50% wettable powder or 50% water-dispersible granules, 30-40 grams of 40% water-dispersible granules, 40-60 grams of 25% wettable powder, or 100-150 milliliters of 10% emulsion in water. Dilute with 30-45 kilograms of water and spray.
(8) Control of seedling blight, damping-off, and basal stem blight on fruit and vegetable seedlings
Start drenching (or spraying) the seedbed or the basal part of plant stems with the pesticide solution when the first diseased plants are observed. Apply once every 10 days or so for 2 consecutive applications. Generally, use a 2000-3000-fold dilution of 80% water-dispersible granules, a 1500-2000-fold dilution of 50% wettable powder or 50% water-dispersible granules, a 1000-1500-fold dilution of 40% water-dispersible granules, or a 300-400-fold dilution of 10% emulsion in water.
