RESUMO
Pesticides are critical for protecting agricultural crops, but the off-site transport of these materials via spray drift and runoff poses risks to surface waters and aquatic life. California's Central Coast region is a major agricultural hub in the United States characterized by year-round production and intensive use of pesticides and other chemical inputs. As a result, the quality of many waterbodies in the region has been degraded. A recent regulatory program enacted by the Central Coast Regional Water Quality Control Board set new pesticide limits for waterways and imposed enhanced enforcement mechanisms to help ensure that water quality targets are met by specific dates. This regulatory program, however, does not mandate specific changes to pest management programs. In this study, we evaluate the economic, environmental, and pest management impacts of adopting two alternative pest management programs with reduced risks to surface water: 1) replacing currently used insecticide active ingredients (AIs) that pose the greatest risk to surface water with lower-risk alternatives and 2) converting conventional arthropod pest management programs to organic ones. We utilize pesticide use and toxicity data from California's Department of Pesticide Regulation to develop our baseline and two alternative scenarios. We focus on three crop groups (cole crops, lettuce and strawberry) due to their economic importance to the Central Coast and use of high-risk AIs. For Scenario 1, we estimate that implementing the alternative program in the years 2017-2019 would have reduced annual net returns on average by $90.26 - $190.54/ha, depending on the crop. Increased material costs accounted for the greatest share of this effect (71.9%-95.6%). In contrast, Scenario 2 would have reduced annual net returns on average by $5,628.12 - $18,708.28/ha during the study period, with yield loss accounting for the greatest share (92.8-97.9%). Both alternative programs would have reduced the associated toxic units by at least 98.1% compared to the baseline scenario. Our analysis provides important guidance for policymakers and agricultural producers looking to achieve environmental protection goals while minimizing economic impacts.
Assuntos
Agricultura , Controle de Pragas , Praguicidas , California , Agricultura/economia , Controle de Pragas/economia , Produtos Agrícolas , Qualidade da ÁguaRESUMO
The Orthotospovirus impatiens necrotic spot virus (INSV) is a thrips-transmitted pathogen of lettuce that has rapidly emerged as a serious threat to production in the Salinas Valley of Monterey County, California. As a first step toward understanding the severity of the virus, we utilized Spatial Analysis by Distance IndicEs (SADIE) to characterize the distribution and progression of INSV outbreaks and thrips infestations in two commercial lettuce fields. In both fields, INSV incidence rapidly increased from 15.86% ± 1.77 to 80.24% ± 2.60 over the course of 7 weeks and aggregated at specific edges in both fields as early as 3 weeks after planting (Ia = 1.63, Pa = 0.0100, and Ia = 1.53, Pa = 0.0300). In one of the fields, thrips populations aggregated in areas that also experienced the most INSV (Ia = 1.2435, Pa = 0.0400, week 3; Ia = 1.4815, Pa < 0.0001, week 6; Ia = 1.5608, Pa < 0.0001, week 9), while in the second field, thrips were distributed randomly despite the aggregated effects that were observed for INSV incidence. Economic analysis estimated that the virus accounted for over $475,000 in losses for the two fields, while stakeholder surveys documented over 750 fields that experienced INSV infection during the 2021 season in Monterey County alone. These studies enhance our knowledge on the epidemiology of thrips and INSV under current lettuce production practices in the Salinas Valley, while elucidating the economic consequences and broader challenges that are associated with managing thrips-transmitted viruses.
Assuntos
Tisanópteros , Tospovirus , Animais , California , Lactuca , Doenças das PlantasRESUMO
Thresholds for Helicoverpa zea (Boddie) in cotton Gossypium hirsutum L. have been understudied since the widespread adoption of Bt cotton in the United States. Our study was possible due to the widespread presence of H. zea populations with Cry-toxin resistance. We initiated progressive spray timing experiments using three Bt cotton brands (Deltapine, Stoneville, and Phytogen) widely planted across the U.S. Cotton Belt expressing pyramided toxins in the Cry1A, Cry2, and Vip3Aa19 families. We timed foliar insecticide treatments based on week of bloom to manipulate H. zea populations in tandem with crop development during 2017 and 2018. We hypothesized that non-Bt cotton, cotton expressing Cry toxins alone, and cotton expressing Cry and Vip3Aa19 toxins would respond differently to H. zea feeding. We calculated economic injury levels to support the development of economic thresholds from significant responses. Pressure from H. zea was high during both years. Squares and bolls damaged by H. zea had the strongest negative yield associations, followed by larval number on squares. There were fewer yield associations with larval number on bolls and with number of H. zea eggs on the plant. Larval population levels were very low on varieties expressing Vip3Aa19. Yield response varied across experiments and varieties, suggesting that it is difficult to pinpoint precise economic injury levels. Nonetheless, our results generally suggest that current economic thresholds for H. zea in cotton are too high. Economic injury levels from comparisons between non-Bt varieties and those expressing only Cry toxins could inform future thresholds once H. zea evolves resistance to Vip3Aa19.