Progress 06/01/15 to 05/31/18
Outputs
Target Audience: Farmers, other agricultural professionals, extension and NRCS personnel, soil scientists, agronomists, and other agricultural scientists. Changes/Problems:Because of the cooperators that were willing to work with us, wewere not able to sample the range of field types (i.e., soybean fields embedded in different crop rotations) we originally proposed. We mostly sampled soybeans in corn-soybean rotations, which is the dominant rotation in each state, so our results are expected to be representative of most of the soybean production in the two states. What opportunities for training and professional development has the project provided?A postdoctoral research at Purdue helped design the sampling scheme and implement sampling. Undergraduate students at both Universities assisted with data collection. In both states, county-based extension educators or regional extension staff facilitied the farm visits, and accompanied us on initial visits to each farm. We gave these individuals detailed description of the project, including goals and expected outcomes. Some of these extension staff have incorporated our results in their own extension presentations. How have the results been disseminated to communities of interest?At Penn State, during winter extension meetings in 2016, 2017, and 2018, we featured our results in 33 talks in Pennsylvania, New Jersey, New Hampshire, and Vermont. Over 2000 farmers and other agricultural professionals attended these meetings. In Indiana, this material was presented in 2017 and 2018 as part of extension presentations to soybean producers at NRCS training sessions. Approximately 100 individuals attended the sessions, survey results indicated that 75% of respondents felt that the material presented was "worth their time", and 100% of respondents described the presentation as "very good" (67%) or "good" (33%) overall. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Pennsylvania-based efforts: We completed Pennsylvania surveys in 2015 and 2016. In each year, we sampled 24 soybean fields across three counties (8 fields per county). These fields were planted with soybean seeds that were not coated with insecticides so we could assess insect populations in untreated fields. We visited fields shortly after planting, typically around soybean growth stage V2-V3, then again about 10 days later when plants were V5-V6. With each visit, we quantified insect damage to 100 plants per field, looking for evidence of feeding by bean leaf beetle and wilting caused by white grubs (200 plants per field per season). In the first visit to each field we also established wireworm bait stations, which involved burying flour balls (500 cc unbleached flour/location) 30-cm deep at five locations per field. On the second visit, we dug up these flour balls, which fermented over time (producing carbon dioxide and other chemicals which are attractive to wireworms), and counted wireworm larvae we found. In 2015, from 120 wireworm traps, we found one wireworm, suggesting that the risk from this pest species was mild. From inspecting insect damage to 200 soybean plants per field (4,800 plants per year), no fields exceeded the economic threshold of greater than 25% defoliation, indicating that the bean leaf beetle damage we quantified was non-economic and not worth treating with an insecticide or using an insecticidal seed treatment. We found only two plants wilting from white grub feedings Results from 2016 were nearly identical, but with zero wireworms and zero plants with evidence of white grub feeding. Indiana-based efforts: Indiana surveys were conducted during 2015 and 2017. The results are summarized below: 2015 Sampling Results: Wireworm sampling: wireworms were sampled at 10 locations spread across two eastern IN counties, thought to be at highest risk of infestation. Sampling was conducted using bait stations consisting of flour balls (500 cc unbleached flour/location) buried at 30 cm in fields in early May. Locations were marked and resampled 13 d after placement. A total of 2 wireworms were found in the 10 samples, at two different locations. Results summary: the published thresholds recommend treatment if one wireworm/field is found. In this case, insecticide targeting wireworms (neonicotinoid seed treatments are the only option is soybeans) would be advised on the two fields where wireworms were found. Asiatic garden beetle sampling: Sampled at 10 locations spread across two Indiana counties, with sandy soils and high risk of infestation. Sampling was conducted using a golf course cup cutter to remove 500 cc of soil at five locations in each field. Soil was sifted to separate grubs from soil. A total of 4 AGB larvae were found at three locations. Results summary: See 2017 results, below. Bean leaf beetle sampling: Sampled at 30 locations spread across eight Indiana counties. Fields were visited twice, once prior to pod-fill (R4) and again when pods were drying down (R6). Randomly inspected 25 plants/field and recorded % defoliation, also randomly inspected 10 plants/field and recorded % with pod damage. Sweep-net samples (10 sweeps/location, 5 locations/field = 50 sweeps/field total) were conducted to capture adult beetles. Total no. beetles captured first survey: Avg. 2.94 beetles /field, or 0.058 beetles/sweep Total no. beetles captured second survey: Avg. 9.1 beetles/field, or 0.182 beetles/sweep Avg. percent defoliation soybean leaves/field: < 5 % Avg. percent pod damage/field: 0.46 % Results summary: The pod injury level of 0.46% is negligible and would indicate sampling for beetles is unnecessary. Similarly, the defoliation level of < 5% is well below the late season threshold of ca. 20% defoliation. These results are supported by the very low numbers of beetles/field. 2017 Sampling Results: Wireworm sampling: Six fields were evaluated, 5 treated and 1 untreated. Efforts were made find untreated fields, as were used in 2015, but untreated fields were rare. Soybean growth stage varied from V1 to V4 on the day the traps were installed. Bait stations of flour were placed as outlined above in mid-June. Traps were recovered 7 d later. In addition, 100 plants were randomly chosen and evaluated for root injury and/or wireworm presence at each. From bait stations, a single larva was found, in a treated field. Surveys of cotyledon damage revealed damage to 4 plants at one location, an untreated field. No insects were found during plant excavations, so cause of damage remains unknown. Results summary: the published thresholds recommend treatment if one wireworm/field is found. In this case, insecticide targeting wireworms (neonicotinoid seed treatments are the only option is soybeans) would be advised in the single field where a larva was found. Asiatic garden beetle sampling: Sampled at 10 locations spread across two Indiana counties, with sandy soils and high risk of infestation. Sampling was conducted using a golf course cup cutter to remove 500 cc of soil at five locations in each field. Soil was sifted to separate grubs from soil. One AGB larva was found at a single location. Results summary: No thresholds have been developed for this insect in soybeans. It is not likely to be a pest on soybean roots due to the poor match between AGB feeding and soybean planting and growth - the larvae have pupated before soybeans are growing. However, this work serves to illustrate that anecdotal reports of AGB adults in soybeans are indications of oviposition in those fields. The AGB larvae are economic pests of corn roots (where no effective insecticide options are registered for these pests), and management in soybeans in the year before rotation to corn may be a tactic that warrants investigation. Bean leaf beetle sampling: Sampled at 30 locations spread across eight Indiana counties. Fields were visited twice, once prior to pod-fill and again when pods were drying down. Sweep-net samples (10 sweeps/location, 5 locations/field = 50 sweeps/field total) were conducted to capture adult beetles. Total no. beetles captured first survey: Avg. 2.7 beetles/field, or 0.054 beetles/sweep Total no. beetles captured second survey: Avg. 20.5 beetles/field, or 0.41 beetles/sweep Avg. percent defoliation soybean leaves/field: 1-2 % Avg. percent pod damage/field: 2.9 % Results summary: Thresholds for this pest indicate that fewer than 4 beetles/sweep and between 0-8% pod feeding would indicate a sub-economic threshold and no need for further sampling (https://extension.entm.purdue.edu/fieldcropsipm/insects/bean-leaf-beetle.php). Similarly, the defoliation level of < 1-2% is well below the late season threshold of ca. 20% defoliation. Neonicotinoid concentrations in soybean root tissues:
Publications
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