Downy mildew and late blight can spread through a field in a few days when the weather turns cool, damp and cloudy. A crop that looks healthy on Monday can show spreading lesions by the weekend. Farmers need a fungicide that protects healthy leaves, acts on early infection and stays on the plant through changing weather. A combination of cymoxanil and mancozeb is designed for this job.
This guide explains what mancozeb fungicide and cymoxanil each do, how contact and systemic action differ, and how BULLET (Cymoxanil 8% + Mancozeb 64% WP) from JU Agri Sciences fits into disease management.
Downy mildew and late blight: why they spread so fast
Both diseases are caused by oomycetes, fungus-like organisms that thrive in moisture. They behave differently from powdery mildews or leaf spots, and not every fungicide works on them.
- Downy mildew: pale yellow patches appear on the upper leaf surface, with a greyish or purplish fuzzy growth on the underside in humid weather. Leaves turn brown and dry out.
- Late blight: water-soaked, dark patches appear on leaves and stems, often with a white growth at the edges in damp conditions. Lesions expand quickly and can damage fruits and tubers.
Cool nights, heavy dew, drizzle, high humidity and dense canopies favour both diseases. Spores travel by wind and water splash, so one infected patch can become a field-wide problem.
Why timing decides the result
Once a large part of the leaf area is infected, no spray restores it. A mancozeb fungicide programme works best when it starts before infection or at the very first symptoms. Weekly scouting, especially after cloudy or rainy spells, helps you act early. The BULLET product page says that applying before infection or after the disease appears gives longer protection, which fits this approach.
Contact fungicide vs systemic fungicide
Understanding these terms helps you choose and use products correctly.
A contact fungicide stays on the surface of the plant. It forms a protective layer that stops fungal spores from germinating. It does not move inside the plant, so it protects only what it covers, and new growth needs fresh protection.
A systemic fungicide is absorbed into the plant tissue and can move within it. It can protect parts the spray did not directly reach and can act on infection that has already started.
Some products are described as “local systemic” or “translaminar.” These move into the leaf and through it but do not travel through the whole plant. Each type has strengths, and a combination can offer both.
For a deeper comparison of a systemic fungicide and a contact fungicide in one product, see our guide to TEBUSUL (Tebuconazole + Sulphur).
What is mancozeb?
Mancozeb is a long-established contact fungicide from the dithiocarbamate group. It works on the surface of the plant and stops spores from germinating. Its main strengths are:
- Broad-spectrum protection against many fungal and oomycete diseases
- Multi-site action, meaning it disrupts several processes in the fungus at once, so resistance is slow to develop
- Protective use, meaning it works best before infection
Because mancozeb is multi-site, it is a valuable partner in resistance management. That is why it is so often combined with other active ingredients.
What is cymoxanil?
Cymoxanil belongs to the cyanoacetamide-oxime group (the BULLET page calls it aliphatic nitrogen). It is locally systemic: it enters the leaf and moves within the treated tissue. It is known for fast uptake and for early curative action on infections that have just begun.
Used alone, cymoxanil gives short-lived protection. Combined with a contact fungicide like mancozeb, the two complement each other: cymoxanil acts inside the leaf on early infection, and mancozeb protects the surface and supports resistance management.
BULLET: Cymoxanil 8% + Mancozeb 64% WP
BULLET is a combination fungicide from JU Agri Sciences containing 8% cymoxanil and 64% mancozeb in a wettable powder (WP) formulation. Because of this form, it is a mancozeb fungicide powder that is mixed with water before spraying.
Key features
- Broad-spectrum control of downy mildew and late blight, as per the product page
- Dual mode of action: contact action from mancozeb and local systemic action from cymoxanil
- Use before infection or after the disease appears, with early curative activity
- Rain resistance: the product page states it remains effective if rain occurs about three hours after application, which helps reduce wash-off, though heavy rain can still reduce protection
- Wettable powder formulation that mixes in water
Pack sizes
BULLET is available in 100 gm, 300 gm, 600 gm and 1200 gm packs.
Dose and crops
The product page does not list the crops, dose per acre, spray interval or number of sprays. Please do not rely on figures from other sources. Follow the BULLET label for the registered crops, dose, water volume and spray schedule, or contact the JU Agri Sciences team.
Why a cymoxanil + mancozeb combination makes sense
- Two actions in one spray. Surface protection plus action inside the leaf.
- Protective and early curative cover. It works before infection and on very early infection.
- Resistance management. Mancozeb’s multi-site action helps protect the more specific active ingredient.
- Convenience. One product replaces separate purchases and tank-mixing steps.
This is why cymoxanil + mancozeb is a common choice against late blight and downy mildew.
How to get the best results
- Spray early. Start when weather favours disease or at the first symptoms.
- Cover thoroughly. Mancozeb protects only what it touches, so wet both sides of the leaves.
- Keep the suspension mixed. A wettable powder can settle. Make a smooth slurry first, then add it to the tank, and keep stirring.
- Choose the right weather. Spray in the early morning or late afternoon. Avoid strong wind.
- Limit repeated use of cymoxanil. Resistance can build when a single-site active is used repeatedly. Rotate with fungicides from different groups.
- Repeat as the label directs. Contact protection is not permanent, and new growth needs cover.
- Combine with field practice. Use clean seed or planting material, avoid overhead irrigation late in the day, allow good spacing and remove infected plant debris.
Safety and responsible use
Wear gloves, a mask and protective clothing while mixing and spraying, and wash thoroughly afterwards. Mancozeb products can irritate skin and eyes. Do not eat, drink or smoke during application. Keep the product in its original pack, away from children, animals and food. Keep spray and washings away from ponds, canals and water sources, and dispose of empty containers safely. Observe the waiting period before harvest stated on the label.
Related guides
- For a systemic and contact fungicide in a sulphur and triazole combination, see our guide to TEBUSUL.
- For rice blast and sheath blight, see our guide to JU-ART.
- For soil-borne diseases, see our guide to ECOLIFE (Trichoderma).
About JU Agri Sciences
JU Agri Sciences offers more than 130 products across fungicides, insecticides, herbicides, biological fertilizers, biological pesticides and bio-stimulants. With more than 5,500 trade partners, 25,000 retailers and over 1,000 trained people supporting farmers in the field, its solutions reach growers across India.
Frequently asked questions
What is cymoxanil + mancozeb fungicide used for? It is used to manage downy mildew and late blight, as per the BULLET product page.
Is mancozeb a systemic or contact fungicide? Mancozeb is a contact fungicide. In BULLET it is combined with cymoxanil, which has local systemic action.
What does 64% WP mean? WP means wettable powder. The 64% refers to the mancozeb content, and the product also contains 8% cymoxanil.
Is BULLET a mancozeb fungicide powder? Yes. It is a wettable powder that you mix with water before spraying.
Can I spray BULLET before the disease appears? Yes. The product page says application before infection or after the disease appears gives protection for a longer time.
Will rain wash it off? The product page says it remains effective if rain falls about three hours after spraying. Heavy rain soon after application can still reduce protection.
What is the dose of BULLET per acre? The product page does not state it. Follow the label or contact our team.
What pack sizes are available? 100 gm, 300 gm, 600 gm and 1200 gm.
Get in touch
For product availability, dose guidance, dealer information or advice on downy mildew and late blight, call 0120 – 4328671 or use the form on our Contact Us page.
