Chlorpyrifos is an organophosphate insecticide that was used in many agricultural systems to protect plants, as well as for protection of seeds stored after harvest. Chlorpyrifos was first registered in 1965. It has been used for a large variety of agricultural crops, including soybeans, fruit and nut trees, broccoli, cauliflower, and other row crops, as well as non-food uses. The use of chlorpyrifos for all commodities will expire on February 28, 2022.
There are several brands containing chlorpyrifos; the list below includes some of them:
- Lorsban
- Dursban Pro
- Cobalt
- Govern
- Lorsban Advanced,
- Warhawk
- Storicide
- Yumad
Potential Replacement Insecticides
In general, chlorpyrifos use has declined significantly in the last couple of year as this is a restricted-use insecticide. Currently there are some insecticides that can substitute for chlorpyrifos; they include several pyrethroids:
- z-cypermethrin (Mustang Maxx)
- bifenthrin (Brigade, Fanfare, Capture, Tundra®)
- gamma-cyhalothrin (Declare)
- lambda-cyhalothrin (Karate, Warrior)].
In addition, there are also several newer chemistries that have specific activity against certain insect pests. These include:
- diamides (Prevathon, Exirel) for caterpillars, such as thistle caterpillars and green cloverworms in soybeans
- pyropenes (Sefina Inscalis), sulfoximines (Transform) and butenolides (Sivanto) for control of soybean aphids, although aphids are not a problem in KY
All these new products are more expensive than chlorpyrifos.
Tolerance Testing
We have learned that some companies are now conducting or will conduct tolerance tests on products from different commodities to determine if chlorpyrifos residuals are above the limit. Tests for residual insecticides can be costly, and they can detect very low levels of the products.
Residual tolerances and dates for each commodity are shown on Table 1. For example, for wheat the chlorpyrifos residual will be accepted up to 24 months until March 2024 if applications of chlorpyrifos were conducted before or on February 27, 2022. Records for these types of applications need to be kept to demonstrate the veracity of the applications.
Table 1. Expiration dates for chlorpyrifos residues in various raw agricultural commodities
Additional information can be found in the Questions and Answers Regarding Channels of Trade Policy for Human Food Commodities with Chlorpyrifos Residues: Guidance for Industry document.
By Raul Villanueva, Entomology Extension Specialist
Kentucky Pest News 