Choosing Organic Pesticides over Synthetic Pesticides May Not Effectively Mitigate Environmental Risk in Soybeans

Background: Selection of pesticides with small ecological footprints is a key factor in developing sustainable agricultural systems. Policy guiding the selection of pesticides often emphasizes natural products and organic-certified pesticides to increase sustainability, because of the prevailing public opinion that natural products are uniformly safer, and thus more environmentally friendly, than synthetic chemicals. Methodology/Principal Findings: We report the results of a study examining the environmental impact of several new synthetic and certified organic insecticides under consideration as reduced-risk insecticides for soybean aphid (Aphis glycines) control, using established and novel methodologies to directly quantify pesticide impact in terms of biocontrol services. We found that in addition to reduced efficacy against aphids compared to novel synthetic insecticides, organic approved insecticides had a similar or even greater negative impact on several natural enemy species in lab studies, were more detrimental to biological control organisms in field experiments, and had higher Environmental Impact Quotients at field use rates. Conclusions/Significance: These data bring into caution the widely held assumption that organic pesticides are more environmentally benign than synthetic ones. All pesticides must be evaluated using an empirically-based risk assessment

Effect of Prothioconazole Application Timing on <i>Fusarium</i> Mycotoxin Content in Maize Grain

In 2010 and 2011, studies to determine the optimal timing of prothioconazole application (200 g a.i./ha) for reducing <i>Fusarium</i> mycotoxin accumulation in grain were conducted in controlled replicated experiments under small-plot mist-irrigated experiments and in field-scale experiments using two hybrids susceptible to <i>F. gramineaerum</i> infection. A significant decrease in total deoxynivalenol (DON) [DON + 15-acetyl-DON + DON 3-glucoside + 3-acetyl-DON] and zearalenone concentrations was observed when fungicide was sprayed at VT (tasseling) and R1 (silking; <i>P</i> < 0.01) followed by applications at V18 (18th leaf) and R2 (blister; <i>P</i> < 0.05) stages, corresponding to silk completely emerged and fully elongated and to silk emergence and browning, respectively. No reduction in <i>Fusarium graminearum</i> toxins was found after silk senescence (R3 or milk) stage. Moniliformin, fumonisins, beauvericin, enniatins, HT-2 and T-2 toxins were also found in small quantities, and no reduction was observed after treatment (<i>P</i> > 0.05). Mean reduction (±s.d.) of 59 ± 20% and 57 ± 38% of total DON and zearalenone was observed at full silk elongation, respectively

Occurrence of Penicillium verrucosum, ochratoxin A, ochratoxin B and citrinin in on-farm stored winter wheat from the Canadian Great Lakes Region

The occurrence of P. verrucosum and ochratoxin A (OTA) were surveyed for 3 and 4 years, respectively. A total of 250 samples was collected from an average of 30 farms during the 2011, 2012, 2013 and 2014 winter seasons. Most storage bins surveyed were typically 11 m high round bins made of corrugated, galvanized steel, with flat-bottoms and conical roofs. Samples of clumped grain contained the most P. verrucosum (p<0.05, n = 10) followed by samples taken from the first load (n = 24, mean = 147±87 CFU/g) and last load (n = 17, mean = 101±77 CFU/g). Five grain samples (2.2%) tested positive for OTA, citrinin and OTB at concentrations of 14.7±7.9, 4.9±1.9 and 1.2±0.7 ng/g, with only three samples exceeding 5 ng/g. Grain samples positive for OTA were related to moisture resulting from either condensation or migrating moist warm air in the bin or areas where precipitation including snow entered the bin. Bins containing grain and clumps contaminated with OTA were studied in detail. A number of statistically-significant risk factors for OTA contamination were identified. These included 1) grain clumps accumulated around or directly under manhole openings, 2) debris and residue of old grain or grain clumps collected from the bin walls or left on storage floor and augers and 3) grain clumps accumulated around side doors. Even when grain enters storage below the 14.5% threshold of moisture, condensation and moisture migration occurs in hotspots in modern corrugated steel storage bins. Hot spots of OTA contamination were most often in areas affected by moisture migration due to inadequate aeration and exposure to moisture from precipitation or condensation. Further, we found that the nature of the condensation affects the nature and distribution of small and isolated areas with high incidence of toxin contamination and/or P. verrucosum prevalence in the grain bins examined

Neonicotinoid insecticide residues in subsurface drainage and open ditch water around maize fields in southwestern Ontario.

Neonicotinoids are widely used class of insecticides. Most are seed treatments and during planting active ingredient may be abraded and lost in fugitive dust. Much of this active ingredient contaminates surface waters, exposing aquatic organism to potential ill effects. This study examines concentrations of neonicotinoids appearing in tile drains and open ditches around commercial maize fields around planting time where neonicotinoid seed treatments had been used. This sample set represents surface water leaving the point of origin, for which data are sparse. Clothianidin was found more often than thiamethoxam and at higher concentrations; at a median concentration of 0.35 ng/mL in tile drain water and almost twice that (0.68 ng/mL) in ditches into which the tiles are draining after applications of 19 g/ha on seed. This concentration reveals a 40 to 50 fold dilution for neonicotinoid residues between the points where they leave the field in which they were applied and when they are found in nearby streams in a similar ecosystem. Our data support that for a no-observed-effect concentration of 0.3 ng/mL for thiamethoxam there would be between a 1.6 and 100-fold margin of safety to mayflies in most streams if fugitive dust on pneumatic planters were properly mitigated

HPLC-ESI-MS/MS optimized instrument parameters and recovery (%), repeatability (SD%), LOD and LOQ of OTA, OTB and citrinin spiked in winter wheat flour.

<p>HPLC-ESI-MS/MS optimized instrument parameters and recovery (%), repeatability (SD%), LOD and LOQ of OTA, OTB and citrinin spiked in winter wheat flour.</p

<i>P</i>. <i>verrucosum</i> colony counts (CFU/g), mycotoxin occurrence (ng/g) and aeration practices associated with OTA positive grain samples found during the 2011–2014 on-farm storage survey of Ontario winter wheat.

<p><i>P</i>. <i>verrucosum</i> colony counts (CFU/g), mycotoxin occurrence (ng/g) and aeration practices associated with OTA positive grain samples found during the 2011–2014 on-farm storage survey of Ontario winter wheat.</p

Occurrence of <i>Penicillium verrucosum</i>, ochratoxin A, ochratoxin B and citrinin in on-farm stored winter wheat from the Canadian Great Lakes Region

<div><p>The occurrence of <i>P</i>. <i>verrucosum</i> and ochratoxin A (OTA) were surveyed for 3 and 4 years, respectively. A total of 250 samples was collected from an average of 30 farms during the 2011, 2012, 2013 and 2014 winter seasons. Most storage bins surveyed were typically 11 m high round bins made of corrugated, galvanized steel, with flat-bottoms and conical roofs. Samples of clumped grain contained the most <i>P</i>. <i>verrucosum</i> (<i>p</i><0.05, n = 10) followed by samples taken from the first load (n = 24, mean = 147±87 CFU/g) and last load (n = 17, mean = 101±77 CFU/g). Five grain samples (2.2%) tested positive for OTA, citrinin and OTB at concentrations of 14.7±7.9, 4.9±1.9 and 1.2±0.7 ng/g, with only three samples exceeding 5 ng/g. Grain samples positive for OTA were related to moisture resulting from either condensation or migrating moist warm air in the bin or areas where precipitation including snow entered the bin. Bins containing grain and clumps contaminated with OTA were studied in detail. A number of statistically-significant risk factors for OTA contamination were identified. These included 1) grain clumps accumulated around or directly under manhole openings, 2) debris and residue of old grain or grain clumps collected from the bin walls or left on storage floor and augers and 3) grain clumps accumulated around side doors. Even when grain enters storage below the 14.5% threshold of moisture, condensation and moisture migration occurs in hotspots in modern corrugated steel storage bins. Hot spots of OTA contamination were most often in areas affected by moisture migration due to inadequate aeration and exposure to moisture from precipitation or condensation. Further, we found that the nature of the condensation affects the nature and distribution of small and isolated areas with high incidence of toxin contamination and/or <i>P</i>. <i>verrucosum</i> prevalence in the grain bins examined.</p></div

Winter wheat production and fluctuation of on-farm grain stocks held in Ontario, Canada from July 1997 to December 2012.

<p>Data acquired from Statistics Canada from 1997–2012. Source: Annual Field Crop Reporting Series, Stock of principal field crops.</p

Analysis of variance for reduced model of the distribution of <i>P</i>. <i>verrucosum</i> inoculum found in grain and grain clumps (CFU/g) collected in winter 2011–2013 from on-farm storage bins located in Ontario, Canada.

<p>Analysis of variance for reduced model of the distribution of <i>P</i>. <i>verrucosum</i> inoculum found in grain and grain clumps (CFU/g) collected in winter 2011–2013 from on-farm storage bins located in Ontario, Canada.</p