Efficacy of Kensil Fine, a Diatomaceous Earth, When Applied to Protect Maize Stored under Simulated and Real Farmer Situations in Kenya

Kensil fine, a local diatomaceous earth was evaluated under simulated and real farmer storage conditions. Three serial concentrations of: 0.3%, 0.5% and 0.7% w/w were applied on 8 kg of grain in mini sacks (simulation trial) or 90 kg grain (full bags) under farmer storage conditions. The Australian amorphous silica diatomaceous earth (Dryacide) Dryacide and a cocktail of 1.6% Pirimiphos methyl and 0.3% permethrin (Actellic super), the currently recommended storage chemical dust were included for comparison. All treatments including the control were replicated four times in the simulation trial. Two bags represented each treatment in the farmer situation. Changes in the quantities of dust and foreign matter (fm), grain moisture, pest population (live and dead) and percent grain damage were monitored through sampling. For 24 weeks, there were no statistical differences among treatments or between them and the control at both sites and the trials were extended by three months. After 36 weeks, significant differences were observed between the control and treatments for each of the four parameters. However, no significant differences in the quantity of fm sieved from treatments which reflected the DE doses applied. Grain moisture was slightly influenced by climate while applied treatments effectively suppressed pest establishment resulting into very low grain damage. Higher Kensil doses suppressed infestation, but it was the lowest dose that did not pose health challenge to the farmer and still gave effective grain protection.