The Cause of Increased Effectiveness of Water-In-Oil Emulsion Over Water Application of Trichoderma Ovalisporum on Theobroma Cacao

Experiments in Costa Rica showed thatTrichoderma Ovalisporum applied in a water-in-oil (corn oil) emulsion gave significantly better control of frosty pod rot disease on cacao (Theobroma cacao) pods when compared to water applications. Experiments were conducted in Ecuador in 2011 and 2012, to determine whether the effectiveness of the T. ovalisporum was supported by the applied spray characteristics (Volume Median Diameter, number of droplets per cm2, droplet volume per cm2, area coverage per cm2, Relative Span Factor and estimated spores per cm2) as opposed to the creation of an environment conducive to spore germination and colonization of the cacao pod. The relative span factor and number of deposits were not different between the two formulations. The Volume Medium Diameter, droplet volume, Droplet volume and area coverage were statistically larger for the water formulation than water-in-oil emulsion formulation but largely proportional to the 50% water content in the water-in-oil emulsion formulation. From the deposit volume, the estimated spore count per mm2 was 1100 for the water formulation and 904 for the water-in-oil emulsion formulation. The spray characteristics of the two formulations did not account for the significantly better control of frosty pod rot by the water-in-oil emulsion. The improved microclimate provided by the water-in-oil emulsion was the primary contributor to the formulation superior performance in the field.

Keywords:Corn oil; Emulsion; Trichoderma; Trichoderma ovalisporum; Backpack mist-blower; Droplet analysis