Miller Magazine Issue: 122 February 2020

71 ARTICLE MILLER / FEBRUARY 2020 trucks that move grain from the field to farm, become the first source of infestation in the supply chain. The solution is simple and obvious: Thorough cleaning of the harvesting equipment at the end of the season and spraying with a contact insecticide. FARM STORAGE Bins, sheds and bunkers protect the grain in the first part of the supply chain. As in all grain storage areas, insect ma- nagement needs 3 basic steps: Prevention, Monitoring and Control. Prevention comes by making the buildings pest proof. This means that insects cannot easily find their way in the asset as there are no openings, there are screens on win- dows and personnel is trained to keep doors closed. Anot- her way to prevent insect development is cleaning. When food is not available insects will not stay. Monitoring for the presence of insects is done with the use of pheromone and UV traps and through regular inspections and grain samp- ling. The use of these traps in sheds and silos full of grain is not possible. The latest trend uses wireless sensors (centaur. ag) positioned in the bins and warehouses to measure tem- perature, moisture, hotspots and CO 2 . These parameters allow an algorithm to identify the presence of insects and predict the development of their population. The system of sensors may even assess the effectiveness of a fumigation. Control of insects is achieved using various methods like A) spraying and fogging on grain and on clean empty bins, B) using diatomaceous earth and C) using fumigants or control- led atmosphere. BULK CARRIERS The weak point in moving grain on ships and barges is fumigation. Very often grain is fumigated in transit for two reasons: a) as part of quaran- tine regulations and b) becau- se voyage duration usually ex- ceeds the needed fumigation time. The basic reason that fu- migations fail on ships is that the gas is not able to reach an equilibrium across the grain mass. A usual fumigant used in ship fumigations is phosphine. Phosphine is able to penet- rate grain at a pace of 5 meters per day. As the fumigant is introduced on the grain surface after loading, it would reach the bottom of a Panamax vessel hold (20m) in 4 days plus 4 days for the actual treatment duration, it shows an 8-day treatment would be sufficient. This is not happening because this duration is not available in all cases, especially on grain moving from the black sea countries to Mediterra- nean ports. The major reason of fumigation failure in ships is the lack of gas recirculation. Convection currents move air inside the grain mass. The air moves to an opposite directi- on in the morning and in the night, depending on tempera- ture differentiation. Convection currents carry the fumigant gas with them creating unstable concentration conditions. In most cases the fumigant never reaches the bottom of the grain hold in levels high enough to kill insect eggs. The solution lies on precision fumigation which is possible by using gas recirculation pumps and tubes and by using wire- less sensors to monitor gas levels every 4 hours in all grain levels, in all holds. PORT SILOS AND ELEVATORS All silos must be cleaned and sprayed when empty. An inspection will also verify the effectiveness of the proce- dure. When silos are full, inspecting for infestation is not Photo 1: Silo analytics