For my first KPN post, here is a brief refresher on reading agricultural product labels as the season gets into full swing. Before deciding to use a pesticide, the applicator should check three specific points from the label. The pesticide is:
- Labeled for use on the specific crop.
- Expected to manage pest causing the problem.
- Appropriate to be used in the application area.
After confirming these, the pesticide applicator can mix and apply the pesticide as described in the instructions for use, taking care to follow safety and environmental precautions. These topics are discussed in more detail below.
FRAC & IRAC Codes
Let’s suppose we would like to use Ridomil Gold SL, which is labeled for the management of oomycete (fungus-like organisms) diseases in a wide range of crops. The first page of the label is shown in Figure 1, with added notes.
In the green box in Figure 1, FRAC (Fungicide Resistance Action Committee) or IRAC (Insecticide Resistance Action Committee) groups identify pesticides by their mode of action. This refers to the specific biochemical way the pesticide poisons its target. Pesticides with different names, but belonging to the same FRAC or IRAC group, essentially cause the same challenge to the pest. If a pest population has resistance to one product in a FRAC or IRAC group, often the pest population will also have resistance to other products in the same group, since groups are based on the way the products affect the pest(s).
All pesticides define on the label which pest(s) the product may be used to manage (blue box in Figure 1) and which crops the pesticide is safe to be used on. Pest diagnostics become very important here. Many active ingredients (orange box in Figure 1) are only effective for some insects or some diseases.
Keeping with our Ridomil example, we see in the green boxes in Figure 2 that the product is labeled to manage damping-off, blue mold, and black shank; three diseases that are each caused by oomycete pathogens and are specifically listed under tobacco. Damping-off can occur in a number of crops, however, Ridomil may not be safe for use on all of those crops – perhaps it causes phytotoxicity or leaves inappropriate residues, among other safety issues. Therefore, both the pest and the crop must be on the label for acceptable use of the product. Ridomil is not labeled for blackleg (caused by bacteria) or collar rot (caused by a true fungus, Rhizoctonia), and would not be effective in managing these tobacco diseases. This is because bacteria and true fungi have lifecycles that differ from the oomycetes, and mefenoxam, Ridomil’s active ingredient, will not affect them in the same way as the oomycete pathogens.
Additionally, we see that Ridomil is labeled for use as a broadcast soil spray (blue boxes in Figure 2).
In the Product Use Restrictions, it is stated that Ridomil should not be used in the float bed system or for foliar sprays (Figure 3). It is likely that this recommendation, combined with the season-long limit of 1.5 lb of active ingredient applied per acre (orange box in Figure 2), is targeted at reducing the risk of developing resistance to mefenoxam in oomycete populations.
Safety & Health Precautions
Most importantly, the label details health and environmental safety precautions, which may differ from product to product. These include the use of proper personal protective equipment (PPE), ground and surface water application advisories, re-entry and pre-harvest intervals, and first aid information if the applicator accidentally comes in contact with the pesticide (Figure 4). It is very important to always retain the pesticide label with the original pesticide container, not only for first aid purposes but also for proper use of the pesticide. The label also contains information about nozzle selection, pesticide resistance management, and mixing instructions. Each of these items has the potential to change the efficacy of the product on the selected pest.
The Label is the Law
Overall, remember that “the label is the law,” which means that any use of the pesticide that is not consistent with the label may be subject to state or federal penalties. These might include fines, loss of commercial pesticide license, or refusal of the crop by a potential purchaser based on residues that are not allowed. If in doubt, Compliance Assistance is available from the Kentucky Department of Agriculture by calling (270) 945-1110, and more information may be found at http://www.kyagr.com/consumer/agricultural-branch.html. My thought is, it’s better to be safe than sorry! Proper use of pesticides maintains the efficacy of these powerful tools in our shared fight against yield-reducing pests.
Disclaimer: Trade names are used to simplify the information presented in this newsletter. No endorsement by the Cooperative Extension Service is intended, nor is criticism implied of similar products that are not named.
By Emily Pfeufer, Extension Plant Pathologist
Acknowledgement: The author thanks Paul Vincelli, Extension Plant Pathologist, and Ric Bessin, Extension Entomologist, for their thoughtful edits.