On April 10, 2014 the Washington State Department of Agriculture (WSDA) was notified by a local newspaper of a suspected pesticide poisoning incident in Douglas County involving pesticides not previously reported in the published literature to be associated with human illness. On that same day, WSDA notified the Washington State Department of Health, which investigated this incident by conducting a site visit, reviewing medical and applicator records, and interviewing affected farmworkers, pesticide applicators, and the farmworkers' employer. In addition, on April 11, WSDA collected swab, foliage, and clothing samples and tested them for residues of pyridaben, novaluron, and triflumizole. In this incident, all 20 farmworkers working in a cherry orchard became ill from off-target drift of a pesticide mixture that was being applied to a neighboring pear orchard. Sixteen sought medical treatment for neurologic, gastrointestinal, ocular, and respiratory symptoms. This event highlights the need for greater efforts to prevent off-target drift exposures and promote awareness about the toxicity of some recently marketed pesticides. Incidents such as this could be prevented if farm managers planning pesticide applications notify their neighbors of their plans. On April 8, 2014, two pesticide applicators were driving tractor-pulled airblast sprayers to apply a mixture of pesticides to prevent psylla infestations in a pear orchard. At about 1:30 pm the tractors approached the end of the orchard, which abuts a cherry orchard. In the cherry orchard, 20 Hispanic farmworkers (19 women and one man) were tying the branches of cherry trees to trellises to improve fruit yields. Median age of the farmworkers was 33 years (range: 25-63 years). The workers were dispersed, and their distance from the edge of the pear orchard ranged from 30 to >350 feet (9 to >107 meters). The farmworkers and applicators disagree regarding when the applicators first observed the farmworkers and when the application ceased. The pesticide mixture included novaluron, pyridaben, and triflumizole, along with mineral oil, boron (a micronutrient), and phosphoric acid (an acidifier, defoaming agent, and fertilizer). The farmworkers had not been notified of the pear orchard pesticide application before starting work in the cherry orchard. All 20 cherry orchard workers reported that they began feeling ill within minutes of exposure to the drifting pesticides. The crew leader called 9-1-1. All of the workers reported two or more symptoms consistent with those caused by the pesticides applied to the pear orchard (1). Emergency medical services personnel decontaminated five workers at the orchard and transported them to an emergency department, where they were treated for their symptoms. A total of 16 workers eventually sought medical care. Six workers had moderate-severity illness, and the remaining 14 workers had low-severity illness. The most commonly reported symptoms were neurologic (100%) (e.g., headache and paresthesias), gastrointestinal (95%)(e.g., nausea), ocular (85%)(e.g., eye pain/irritation), and respiratory (80%)(e.g., upper respiratory irritation and dyspnea). Of the eight workers who were contacted at least 2 weeks after the incident, six (75%) had symptoms that persisted for at least 2 weeks. The two applicators were wearing complete personal protective equipment (including air-purifying respirators and chemical-resistant headgear) and reported no symptoms. Several of the samples collected by WSDA for pesticide residue analysis tested positive, including two clothing samples from farmworkers that tested positive for triflumizole. Both of these workers were working within 50 feet (15 meters) of the pesticide application. Residues of all three pesticides were found on cherry foliage. Residues of novaluron and pyridaben were found on the portable toilet used by the farmworkers (located at the boundary between the two orchards) and on the grass in the cherry orchard. WSDA obtained wind speed and direction data from applicator and meteorologic records. Wind speed, measured hours before the incident by the applicators at the pear orchard using a handheld anemometer and documented in the application record, was low at 0-4 mph (0-6 kph), but the wind direction was variable. When the application began at 7:00 am, the wind direction was away from the cherry orchard, but at the time of the incident the winds were blowing in a circular pattern up to 18 mph (29 kph), and this is thought to have contributed to the incident.