Imperial County, California, has extended an emergency declaration to address rising risk from the sweetpotato whitefly, a pest that has historically caused heavy losses in the region's vegetable and melon crops. The extension, approved by the County Board of Supervisors, allows temporary access to neonicotinoid insecticides following statewide restrictions implemented in January 2024.
The declaration was requested by Agricultural Commissioner Jolene Dessert, who said the exemption permits the use of products that were previously limited under state regulation. The sweetpotato whitefly, also known as the silverleaf whitefly, has caused an estimated US$500 million in losses in California since 1991. County officials warned that early intervention is needed to protect crop production, including the 2024 melon crop valued at more than US$63 million.
Whiteflies feed by extracting plant sap, reducing plant vigor, and facilitating the development of sooty mold that can render harvested fruit unmarketable. Although current trap counts remain low, University of California advisers reported that whitefly numbers can increase rapidly during warm periods. Host crops in the Imperial Valley include melons, squash, broccoli, and cabbage.
Dessert said emergency authority was required because state regulations restrict neonicotinoid applications unless a local emergency is formally declared under 3CCR section 6990(c)(2). Without the exemption, pest control advisers noted that growers would rely on less effective tools, increasing the risk of pesticide resistance and crop losses.
Local pest control adviser Kenny Hughs told the Board, "This exemption would really help out the production of our melon crops and other crops as well. At the end of the day, it leads to us using fewer pesticides and protecting our pollinators, so I would greatly appreciate it."
UC advisers explained that early-season soil applications of imidacloprid or thiamethoxam at planting provide the most effective option for preventing outbreaks. Once infestations escalate, growers can face reduced yields, higher input costs, and unsellable fruit due to mold, blemishes, or stunting. Past outbreaks in the 1990s led to monitoring programs that remain in place today.
The emergency declaration requires that growers obtain written recommendations from licensed pest control advisers and keep records for a minimum of two years. Supervisors approved the extension unanimously. Board Chair John Hawk thanked advisers for their updates and field observations.
Under the resolution, the Agricultural Commissioner and the Director of Emergency Services may take actions permitted by state law to reduce crop loss. The emergency remains active for 60 days unless extended. Dessert noted, "The full scope of potential damage cannot be precisely determined at this time, but can be mitigated in part if immediate action is taken on an emergency basis."
Source: Calexico Chronicle
