The soybean aphid (SA; Aphis glycines Matsumura) was first found in the northern soybean [Glycine max (L.) Merr.] growing regions of the United States in 2000. By 2005, the aphids had spread to 23 soybean growing states reaching as far south as Mississippi and Georgia and also north into Ontario, Canada. The objective of this study was to identify new sources of resistance to the SA. Nearly 200 soybean genotypes (cultivars, breeding lines, and plant introductions [PIs]) were screened for resistance to SA in a greenhouse choice test using SA collected in Wooster, OH. Three PIs (PI 243540, PI 567301B, and PI 567324) were identified as resistant while six PIs were identified as moderately resistant. The findings on the three resistant and three of the six moderately resistant PIs were confirmed through further field and greenhouse tests. PI 243540 displayed strong antibiosis resistance such that SA was unable to survive on this PI in a no‐choice test. The other two resistant PIs possessed mainly antixenosis type resistance. PI 243540 and PI 567301B were also resistant to the SA collection from Illinois. The aphid resistant PIs identified in this study will be useful in efforts to develop aphid‐resistant soybean cultivars.

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Mid-season applications of Quadris with and without Warrior insecticide were evaluated in 2004 and 2005, and Headline, Folicur, Domark, or Headline plus Folicur were evaluated in 2006, 2007, and 2008 in 37 farm scale studies in Ohio. Producer cooperators selected fields, applied treatments at growth stage R3 and harvested fields. Each trial was rated at growth stage R5 or R6 for incidence and severity of brown spot and frogeye leaf spot. Aphids and foliar disease incidence was low in 2004. Soybean aphids were counted at stage R5 in 2005. Brown spot severity was reduced significantly by Headline in seven of the 13 locations. In the absence of soybean aphid, a single application of fungicide(s) increased yield significantly in only six of the 28 locations, of which only three had yield increases greater than 4.2 bu/acre. Populations of soybean aphids were high during 2005 at nine locations, and an insecticide application increased yield significantly at eight locations. These data indicated that foliar diseases and aphids contribute to yield loss in soybeans. However, more studies are required to determine action thresholds for brown spot and frogeye leaf spot. Accepted for publication 14 October 2010. Published 22 January 2010.

Field studies were established in north central Ohio to determine the effect of different application strategies on targeting of foliar pesticides in narrow-row (18 cm) soybeans. Several different application factors were tested, including spray quality, nozzle type, air-assistance, and spray volume. In 2005, the spray mix included a fungicide. In 2006, in addition to the fungicide, an insecticide was included. Plant samples were removed from each test plot, and stems and leaves from the bottom third and middle third of the plant were separated for analysis. Overall, there was significantly less active ingredient found in the lower third of the canopies than the middle third, and significantly less pesticide residue was found on stems than leaves from the same canopy location. Significantly more fungicide residue was found on lower leaves treated by the medium-quality XR8004 flat-fan nozzle in 2005 than the coarse-quality XR8005 flat-fan nozzle. There were no differences in fungicide residue found on middle canopy leaves between the fine, medium, and coarse quality flat-fan nozzles. The twin-fan pattern nozzles (Turbo Duo and TwinJet) produced the lowest amounts of fungicide residue on the lower leaves in 2005. The mechanical canopy opener produced significantly higher fungicide residues on middle canopy leaves than all other treatments. The Jacto air-assist sprayer using JA3 hollow-cone nozzles produced the highest fungicide residues on lower canopy leaves in 2005. There were some statistical differences between the amounts of fungicide and insecticide residue found on plant tissue in 2006 because of the high amount of variability in the sample data. Overall in 2006, the higher volume XR8004 treatment (187 L ha -1 ) and the twin-fan TTJ60-11003 treatment at 145 L ha -1 performed similar to the Jacto sprayer making applications at 145 L ha -1 using either flat-fan or hollow-cone nozzles. In general, higher volume applications produced higher amounts of fungicide and insecticide residue on leaves from the middle of the canopy for conventional flat-fan and air-assist applications. Spray volume had less affect on residues measured on leaves from the lower canopy area. Across two years of different canopies at the same spray volume (145 L ha -1 ), the Jacto sprayer using JA3 hollow-cone nozzles produced more fungicide residue on middle canopy stems and lower canopy leaves than the medium-quality XR8004 flat-fan nozzle.

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