Maryland Pesticide News
Note: The express purpose of this article is to share proposed and upcoming changes to pesticide regulations; the information provided does not supersede existing pesticide labels and regulations.
Forthcoming change: DCPA (Dacthal) herbicide suspended
In September 2023, the U.S. Environmental Protection Agency (EPA) suspended the herbicide dimethyl tetrachloroterephthalate (DCPA) following the registrant’s failure to submit comprehensive data on the effects of DCPA on thyroid development and function. Preliminary data had indicated that DCPA can affect thyroid hormones, particularly in fetuses, at lower doses than previously expected.
The suspension prohibits the sale, distribution, and use of the DCPA technical product (see glossary). Existing products containing DCPA, including those that are being distributed, sold, or already in the hands of pesticide users, are not subject to suspension and can still be used according to the label.
DCPA is used to control weeds in both agricultural (broccoli, Brussels sprouts, cabbage, onions, and other vegetables) and non-agricultural (non-residential turf and ornamentals) settings. According to the 2020 Maryland Pesticide Use Survey, DCPA is applied in the state in small quantities.
Reference: https://www.epa.gov/pesticides/dcpa-dacthal-technical-herbicide-product-suspended-epa
Forthcoming change: New labels for insecticide cyantraniliprole approved
In September 2023, the EPA approved new labels for the diamide insecticide cyantraniliprole that includes new mitigation measures to protect federally listed (threatened or endangered) species. Cyantraniliprole can be foliarly applied on several crops (fruits, vegetables, nuts, etc.) and on turf and ornamental plants. Additionally, it can be applied on the seeds of corn, soybean, canola, rice, etc.
To mitigate effects to non-target species and critical habitats, the revised labels require a) use of spray nozzles that result in medium to coarser droplets, b) maintenance of a 25 feet buffer around a crop when using an airblast sprayer on dormant and non-bearing vegetation or on bearing vegetation that are not at full canopy, c) use of swath displacement to reduce off-target spray drift during aerial applications, d) use of 30 feet vegetative filter strips to mitigate runoff to aquatic habitats, and e) immediate covering and collection of spilled treated seeds during loading.
The new labels also include additional mitigation measures on Bulletins Live Two! to protect 18 listed species and two critical habitats (these are not found in Maryland).
Forthcoming change: New nematicide active ingredient registered
In September 2023, the EPA registered fluazaindolizine, a new nematicide active ingredient for agricultural use. It can be used to control nematodes in vegetables (carrots, squash, tomatoes, eggplant, potatoes, and taro) and fruits (including peaches, and grapes).
Fluazaindolizine is expected to delay the further development of nematicide resistance. Nematodes are estimated to cause at least $10 billion in crop damage annually in the United States.
No human health risk was identified from fluazaindolizine use. However, risks were identified for mammals and honeybees near the use site. These risks will be mitigated with measures such as soil incorporation (mixing the pesticide into the soil) and restrictions that limit spray drift.
To avoid jeopardy to a listed plant species (not found in Maryland), the label will include Bulletins Live Two! language. The U.S. Fish and Wildlife Service could require additional mitigation measures to protect other listed species likely to be adversely affected by fluazaindolizine use.
Reference: https://www.epa.gov/pesticides/epa-registers-new-active-ingredient-fluazaindolizine
Proposed change: Mitigation measures for organophosphate TCVP
In September 2023, the EPA proposed mitigation measures to reduce human and environmental exposure to the organophosphate insecticide tetrachlorvinphos (TCVP). TCVP is used to control fleas, ticks, lice, and flies in or on livestock animals and their facilities, pets, and garbage piles. It is also used as a spot treatment in kennels, residential lawns, and recreational areas.
In 2009, the EPA received a petition to cancel all pet uses of TCVP due to alleged human health risks. In response, the EPA requested and obtained additional data from the registrant. These data identified no human health risks from TCVP pet collar use. However, health risks were identified for pesticide handlers mixing, loading, and applying TCVP to livestock or livestock premises. To mitigate these risks, the EPA is proposing to prohibit certain application methods and require a PF10 or PF50 respirator.
TCVP use is also expected to pose risk to aquatic non-target organisms (primarily from runoff due to manure applications), birds, mammals, and honeybees. Thus, the EPA is proposing to require a) creation of nutrient management plans for livestock use, b) updates to label language to prevent disposal of TCVP down the drain or sewer, c) language on ecological incident reporting and Bulletins Live! Two, etc.
Public comments are being sought until November 20, 2023.
Proposed change: Registration of a novel pesticide technology for potato crops
In September 2023, the EPA proposed to register pesticide products containing the new active ingredient ledprona for three years. Ledprona uses RNAi mechanism (see glossary) to silence an essential gene in Colorado potato beetle (CPB), a major pest of potato crops. This results in CPB mortality. If approved, lepdrona would be the first commercial sprayable dsRNA pesticide (see glossary) in the world.
The EPA identified no human health risks from ledprona exposure through food and drinking water. Applicators must wear personal protective equipment (protective eyewear, particulate filtering respirator, long-sleeved shirt, long pants, socks, and shoes) to mitigate risks from exposure to ledprona spray.
To mitigate risks to non-target animals and plants from spray drift exposure, the EPA is proposing restrictions on application height, boom length, swath displacement, nozzle orientation, and wind speed. Non-target risks from other exposure routes (runoff, consumption of treated plants, etc.) are expected to be negligible.
As ledprona has specific activity against beetle RNA, the EPA undertook an endangered species assessment for the 19 federally listed beetle species. The agency determined that ledprona will have no effect on the listed species.
Public comments are being sought until October 13, 2023.
Glossary:
- Technical product: The pure form of a pesticide active ingredient. It contains minimal impurities and is manufactured by a chemical company prior to being formulated into end-use pesticide products.
- RNAi mechanism: RNA interference (RNAi) is a biological process in which RNA molecules undertake sequence-specific suppression of messenger RNA (mRNA). The mRNA is necessary for the synthesis of proteins.
- dsRNA pesticide: Double-stranded RNA (dsRNA) pesticides employ RNAi mechanism to target and suppress specific mRNA sequences in pest species.
This article appears in October 2023, Volume 14, Issue 8 of the Vegetable and Fruit News