The S.L.A.M. post-harvest Integrated Pest Management (IPM) strategy is a systems approach to maximize grain quality. Its success depends on production and harvest practices, grain handling equipment, drying systems and storage management. There are four simple steps sanitation, loading, aeration, and monitoring. The objective of S.L.A.M. is to maintain post-harvest quality by protecting stored grains from insects, weather, rodents, self-heating, molds, mycotoxins, and pesticide residues.

Sanitation
Be sure that the storage structure as well as any grain handling equipment (conveyors, wagons, trucks, elevators) are free of leftover grain. The cleanup is most effective if completed in early spring, immediately after bins are emptied. Unnecessary grain residue present during early summer only allows insect infestations to increase during warming temperatures. Repairs such as sealing cracks and/or holes can be completed simultaneously. Old grain being moved to different storage should be screened and, if infested, treated by fumigating.

Clean outside around the bin, beneath perforated floors and inside ducts in addition to cleaning the bin. Sweep or vacuum grain dust and old grain from floors, walls and ceilings where hiding places exist for stored grain insects. If you can tell what has previously been in the bin, it is not clean. In bins where the perforated floor cannot be easily removed, chloropicrin fumigant can be applied to control insects in the sub-floor area. It has NOT been approved for direct application to grain for many years. Chloropicrin is a highly toxic chemical and as such, all label instructions and safety measures must be carefully adhered to. Debris and grain spills outside the bin also encourage rodents and insects which can then move in through openings.

Roof leaks commonly lead to columns of spoiled grain. Check for these leaks by looking for light coming into the bin. Moisture coming into the bin through the seal between the bin and concrete will cause spoilage around the perimeter of the bin at the base. Check the seal since sealants do deteriorate. Water will run away from the seal at the base of the bin wall if the concrete is sloped away from the bin. Also check the seals around the doors and hatches.

Specific practices that help approach the ideal grain mass include limiting kernel damage through slow drying methods, limiting the number of times grain must be handled, operating augers and elevators at capacity and slowest possible speeds, and storing grain in aerated structures. Use a spreader to fill the bin and core the fines from the center of the grain. Be sure to level peaked grain soon after harvest.

If insecticide protectants are going to be applied to the grain, treat the grain stream just before it reaches final storage. Grain that is treated and then transferred long distances through numerous grain handling systems (such as pneumatic systems, belt augers, conveyors, spouts, legs, etc.) before storage will have less insecticide residue when the grain is finally dropped into the bin. It is very important to note that in situations where grain drying is necessary, an insecticide protectant should be applied after the grain has gone through the drier. Commercial grain driers generate enough heat to rapidly degrade insecticides applied to grain prior to the drying process.

Immediately after the bin is filled and the grain leveled, apply a surface treatment ("top dressing") of an approved grain protectant. The surface treatment will help control insects that enter the grain through roof openings. Surface treatments alone generally will not keep the grain insect-free, but they can reduce insect populations during the storage period. Surface treatments are effective if the following limitations are understood. Surface treatment will not control an established insect infestation already in stored grain. The surface treatment should not be disturbed, since it provides the protective barrier against insect infestations.

Aeration
In the fall, aerate to cool the stored grain and create a better storage environment in any bin larger than 2,000 to 3,000 bushel capacity. We should be able to cool grain to temperatures below 50 F by gradually cooling the grain through the fall. Insect activity is reduced at this temperature. Local winter temperatures allow us to achieve a target temperature for stored grain of 25 F for the winter. At this temperature, insect activity ceases and some mortality will occur for a number of our stored insect pests. 

The grain mass should be cooled and dried uniformly. Move cooling front completely through and out of the grain mass and maintain low grain temperatures as long as possible during storage. It is not necessary to rewarm dry grain with fans during the spring and summer.  

Monitoring
Check stored grain regularly for temperature, moisture, insects and molds. Inspect grain at 7 to 14 day intervals after grain is placed in storage structures. Grain with temperatures exceeding 50°F should be checked every 7 days. Check for insects by screening them from the grain, examining kernels for damage, looking for webbing, detecting off-odors, or monitoring grain temperatures. Insect infestations can raise grain temperatures to as high as 110°F. During the summer and fall, insect infestations are usually near the surface of the grain. During cold weather stored grain insects will congregate at the center and lower portions of the grain mass and may escape detection until extensive heating has developed. Check binned grain every 3 - 4 weeks during cold months after the condition of the grain has been stabilized for long term storage.

Stored Grain Management Resources  

Post-Harvest Handling of Crops
Program Leader: Bill Wilcke
University of Minnesota,
Biosystems and Agricultural Engineering

http://www.bae.umn.edu/extens/postharvest/  

Post Harvest Grain Quality &
Stored Product Protection Program
Purdue University

http://pasture.ecn.purdue.edu/~grainlab/  

Grain Drying, Handling, & Storage
Project Leader: Dr. Kenneth J. Hellevang, P.E.
North Dakota State University Extension Service

http://www.ag.ndsu.nodak.edu/abeng/postharvest.htm

Phillip Glogoza
Regional Extension Educator  -  Crops