This month our product focus is all on MANZATE 75 WG. It’s a multi-site fungicide used to help control potato late blight. The active ingredient - mancozeb - is highly effective at combating multiple strains of the blight fungus, with no known fungicidal resistance. MANZATE is a water dispersible granule - but what exactly does that mean? We talked to UPL scientist Charlie Flood to find out more. What is a water dispersible granule (WG)? A water dispersible granule is simply a liquid in solid form. It contains all the active ingredients of a suspension concentrate (a liquid fertiliser) in a tiny, non-dusty solid formulation that can be added to spray tanks. The term ‘water dispersible’ means the granules quickly disperse when added to water to create a suspension of fine particles. We carefully formulate and measure the mixture of surfactants in the recipe to make sure there’s always a good, even dispersion of the particles to ensure full and complete application coverage. Why are water dispersible granules used instead of a liquid spray? Although most farmers and growers prefer liquid applications, when it comes to certain fungicides - like MANZATE 75 - a suspension concentrate isn’t the best option. The clue is in the name. MANZATE contains 75% of the active ingredient mancozeb. The normal maximum loading of a typical suspension concentrate (liquid) is 40-50%. Any more than that and it becomes too viscous to pour. Why are they chosen for fungicides like MANZATE? We use water dispersible granules for MANZATE 75 because it makes both economic and practical sense. A liquid-based option would be too sticky and too thick. It would lead to lower loading, which would mean a higher application rate, and a higher cost. The 75% active ingredient is essential in combating blight, and is a part of the formulation we don’t want to compromise on. A solid is then the best and most economic option. We could choose between a wettable powder (WP) or a water dispersible granule (WG). Since mancozeb isn’t soluble in water, we can rule out a water soluble granule (SG). WG is our preferred option because it has a much lower dust level than a powder, so it’s much better for reducing operator exposure. How do water dispersible granules impact MANZATE? Because we carefully formulate the mixture and the make-up, there’s no impact to the efficacy of MANZATE 75 WG. The final presentation in the spray tank is much the same (with particles dispersed in water) where it’s a wettable powder (WP) , a suspension concentrate (SC) or a water dispersible granule (WG). There’s no change in efficacy with mancozeb if we add adjuvants, so the high loaded solid makes sense. It means a lower cost compared with an SC, and a lower dust hazard compared with a WP. Which, given MANZATE is used at a high rate per hectare and is fairly low margin, it’s the most financially viable option to have a high loaded solid in the form of water dispersible granules. The key is just to make sure the WG is fully mixed in the tank and all granules are fully dispersed, but there’s no real difference to using a liquid. Find out more about MANZATE here.
