Below are a few comments from Dr. Mike Toews, UGA Extension Specialist on Grain Storage
For the first time in many years, we have several new products on the market as noted below.
Products for Empty Bins
Centynal EC. This is a good product for treating empty bins and elevator boots. Note that the active ingredient in Centynal EC, Defense SC and Suspend SC are identical so these are not good rotation partners.
Defense SC (labeled for empty bin use only). This is a good product for treating empty bins and elevator boots, but is not labeled for application directly to grain. Note that the active ingredient in Centynal EC, Defense SC and Suspend SC are identical so these are not good rotation partners.
Suspend SC. This is a good product for treating empty bins and elevator boots. Note that the active ingredient in Centynal EC, Defense SC and Suspend SC are identical so these are not good rotation partners.
Tempo SC (labeled for empty bin use only). Tempo is a good product for treating empty bins and elevator boots, but is not labeled for application directly to grain.
Products for Application to Grain
Actellic 5E (labeled for corn only). This product has been the standard for many years, but it is expensive. A full rate will provide protection from weevils for 9-12 months. Reducing the rate will decrease the longevity of the protection. Our data suggest that Actellic is susceptible to heat degradation in the drier when grain temperatures exceed 120 F.
Centynal EC (labeled for corn and wheat). Centynal EC is a new formulation that will
provide 3 to 6 months of protection from weevils at the 0.5 ppm rate or 6 to 12 months of protection at the 1.0 ppm rate. This material is heat stable in the drier (tested up to 150 F).
Diacon (labeled for corn and wheat). Diacon is an insect growth regulator that is effective for killing nearly all immature grain moths and beetles, except weevils. The 4 oz per 1000 bu rate is sufficient for tank mixing.
Diacon IGR PLUS (labeled for corn and wheat). This product is a premix of Centynal EC and Diacon.
See comments above for rates and activity.
Malathion (labeled for wheat and corn). Although widely used in the past, this product is no longer recommended due to well documented resistance in many stored grain insect populations.
Sensat (labeled for corn and wheat). This product is new to the market, but has been in our evaluation program for several years. Test results show excellent weevil control for up to 12 months. No dryer stability data at this time.
Storcide II (labeled for wheat only). Storcide II is an industry standard for stored wheat, but is not labeled for use on corn. Protection will degrade with heat and time.
Suspend SC (labeled for corn and wheat). This product is an older formulation that must be completely suspended before measuring and requires frequent agitation. It provides 3 to 6 months of protection from weevils.
Three-way tankmix (only tested on corn). UGA tests from 2014-2016 showed that a threeway tank mix of Centynal (8.5 oz) plus Diacon IGR (4 oz) plus PBO-8 Synergist (13.5 oz) will provide 6-9 months of protection from weevils. This is a moderately priced option for growers in markets where other products are unavailable or cost is a limiting factor.
Regardless of the product used, be mindful that grain protectants are not a silver bullet. Shelled corn should be dried to a maximum of 15% moisture content before dropping it in the bin. Chemical applications should only be made to clean grain that will be stored for more than 3 months. Apply protectants at the bottom of the auger in a course spray to maximize coverage as the kernels are moving up to the top of the bin. Long-term grain storage requires appropriate moisture content, proper housekeeping, use of a spreader when filling bins, and managed aeration.
Additional information is available in the 2017 Georgia Pest Management Handbook or in a recent Extension Publication
https://www.aces.edu/pubs/docs/I/IPM-0330/IPM-0330.pdf
that Dr. Kathy Flanders at Auburn University and I authored.