Protecting Grain Without Pesticides at the Farm Level in the Tropics
S. Navarro, E. Donahaye, M. Rindner, A. Azrieli and R. Dias*
*Department of Stored Products, Agricultwal Research Organization, The Volcani Center, PO Box 6, Bet Dagaa 50 250, Israel.
Abstract: Three types of sealed structures for modified atmosphere storage of cereal grains stored in the open in tropical and\subtropical climates were investigated. The advantage of sealed storage lies in the generation of an oxygendepleted and carbon dioxide-enriched inter-granular atmosphere of the storage ecosystem to arrest insect development. The three types of strums assessed were: (a) weldmesh-walled silos; (b) frameless flexible envelopes (Volcani Cubes); and (c) a sealed granary (GrainSafe). These structures are based on different logistic principles but have a common structural component, namely, a flexible liner.
A series of experiments carried out in Israel to develop the plastic structures included studies on the permeability of plastic sheeting to oxygen and carbon dioxide, and resistance to insect and rodent penetration. Weldmesh-walled sibs are suitable as medium-sized silos with a capacity of 60-1,000 t. A circular bag of plastic liner contained within a vertical wall consisting of galvanised weldmesh is used The frameless flexible envelopes (Volcani Cubes) are designed for bag storage of small quantities (10,20 and 50 t) of cereal grains. The plastic liner is made of an upper and a lower section which can be zipped together to form a gastight seal. The granary (GrainSafe) was designed to hold 540 kg nominal cipacity of grain, and consists of a gastight cylindrical flexible plastic bag. The bag is inserted into a rigid white polypropylene board curved into a cylinder that forms a sheath surrounding the vertical sides of the flexible bag. Trials conducted with all three types of structures described in this paper in tropical and subtropical climates showed that sealed storage protected grain by maintaining the number of live insects below the threshold of economic damage without the need for pesticides.
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