Browsing by Author "VanGessel, Mark J."
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Item Cereal rye seeding rate does not affect magnitude of weed suppression when planting green within Mid-Atlantic United States(Weed Technology, 2022-12-12) Ficks, Teala S.; VanGessel, Mark J.; Wallace, John M.In the Mid-Atlantic United States, there is increasing interest in delaying cereal rye termination until after soybean planting (i.e., planting green). Improved understanding of cereal rye seeding rate effects is needed to balance weed and agronomic management goals. We investigated the effects of cereal rye seeding rates on weed control and crop performance when planting green in complementary experiments in two Mid-Atlantic regions. The Pennsylvania experiment was replicated at three site-years and the Delaware experiment at two site-years. In both experiments, population-level weed responses were evaluated across four cereal rye seeding rates: 0, 51, 101, and 135 kg ha−1. The Delaware experiment also implemented a nitrogen treatment factor (0 and 34 kg N ha−1; spring applied). Both experiments showed that integrating cereal rye in the fall significantly improved winter- and summer-annual weed suppression compared with the fallow control, but no differences in total cereal rye biomass production or weed suppression were found among alternative cereal rye seeding rates (51 to 135 kg ha−1). Soybean yield did not differ among treatments in any of the studies. These results show there is no reason to increase cereal rye seeding rates for weed suppression services or to decrease seeding rates for agronomic reasons (i.e., soybean population and yield) when employing planting-green tactics in no-till soybean production within the Mid-Atlantic region of the United States.Item Influence of growth stage and dicamba rate on eggplant, cucumber, and snap bean tolerance and yield response(Weed Technology, 2022-11-10) Wasacz, Maggie H.; Sosnoskie, Lynn M.; VanGessel, Mark J.; Besançon, Thierry E.Following the introduction of dicamba-resistant (DR) soybean in 2017, concerns have increased with regard to dicamba off-target movement (OTM) onto sensitive crops, including vegetables. Field trials were conducted in New Jersey, New York, and Delaware to evaluate cucumber (‘Python’), eggplant (‘Santana’), and snap bean (‘Caprice’ and ‘Huntington’) injury and yield response to simulated dicamba drift rates. Crops were exposed to dicamba applied at 0, 0.056, 0.11, 0.56, 1.12, 2.24 g ae ha–1, representing 0, 1/10,000, 1/5,000, 1/1,000, 1/500, and 1/250 of the maximum soybean recommended label rate (560 g ae ha–1), respectively. Dicamba was applied either at the early vegetative (V2) or early reproductive (R1) stages. Minimal to no injury, vine growth reduction, or yield loss was noted for cucumber. Dicamba was more injurious to eggplant with up to 22% to 35% injury 2 wk after treatment (WAT) at rate ≥1.12 g ae ha–1; however, only the highest dicamba rate caused 27% reduction of the commercial yield compared to the nontreated control. Eggplant also showed greater sensitivity when dicamba exposure occurred at the R1 than at theV2 stage. Snap bean was the most sensitive crop investigated in this study. Injury 2 WAT was greater for ‘Caprice’ with dicamba ≥0.56 g ae ha–1 applied at V2 compared to R1 stage, whereas a similar difference occurred as low as 0.056 g ae ha–1 for ‘Huntington’. Compared to the nontreated control, reduction in plant height and biomass accumulation occurred for both cultivars at dicamba rate ≥0.56 g ae ha–1. Dicamba applied at 1.12 g ae ha–1 or greater resulted in 30% yield loss for ‘Caprice’, whereas ‘Huntington’ yield dropped 52% to 93% with dicamba ≥0.56 g ae ha–1. ‘Caprice’ bean yield was not influenced by dicamba timing of application. Conversely, ‘Huntington’ bean yield decreased by 8% following application at R1 compared to V2 stage.Item Post-harvest drone flights to measure weed growth and yield associations(Agricultural & Environmental Letters, 2022-06-14) Miller, Jarrod O.; Shober, Amy L.; VanGessel, Mark J.Drone flights are often only performed during the growing season, with no data collected once harvest has been completed, although they could be used to measure winter annual weed growth. Using a drone mounted with a multispectral sensor, we flew small plot corn (Zea mays L.) fertility, cover crop, and population studies at black layer and 0–14 d after harvest (DAH). Yields had positive correlations to normalized difference vegetation index (NDVI) at black layer but often had negative correlations to corn yields 0–14 DAH. After harvest, NDVI could be associated with weed growth, and negative correlations to yield could point to reduced corn canopy allowing light to reach late-season weeds. In fertility studies, excess nitrogen appears to increase weed biomass after harvest, which can be easily identified through drone imagery. Flights should be performed after corn harvest as weed growth may provide additional insight into management decisions. Core Ideas: - Corn yields can be correlated to post-harvest weed biomass by using NDVI. - Drone flights efficiently mapped weeds and made correlations to yield and management. - Fall weed control can be prioritized using drone mapping. Abbreviations: DAH days after harvest LAI leaf area index NDVI normalized difference vegetation indexItem Varietal Tolerance of Cucurbitaceous Crops with S-metolachlor Applied Postemergence(HortTechnology, 2024-06-01) Vollmer, Kurt M.; Lynn M. Sosnoskie; VanGessel, Mark J.; Besançon, Thierry E.Cucurbit crops comprise ∼25% of the vegetable acreage in the mid-Atlantic and Northeastern United States. However, options for postemergence weed control in these crops are limited. Overlapping herbicides is a technique that involves sequential applications of soil-applied residual herbicides to lengthen herbicidal activity before the first herbicide dissipates. Residual herbicides such as S-metolachlor will not control emerged weeds, but weed control efficacy may be extended if these herbicides are applied after crop emergence, but before weed emergence occurs. Currently S-metolachlor is not labeled for broadcast applications over cucurbit crops. Greenhouse studies were conducted to evaluate pumpkin, cucumber, and summer squash variety response to varying S-metolachlor rates. S-metolachlor was applied at 1.42 and 2.85 lb/acre at the two-leaf stage of pumpkin and 0.71, 1.42, 2.85, and 5.7 lb/acre at the two-leaf stage of cucumber and summer squash. Cucumber showed a greater response to S-metolachlor with up to 67% injury observed at 5.70 lb/acre. S-metolachlor applications to pumpkin and summer squash resulted in less than 6% injury, regardless of application rate or crop variety. S-metolachlor applied at 2.85 lb/acre reduced pumpkin and cucumber dry weight 6% and 19%, respectively, but did not reduce squash dry weight. S-metolachlor reduced cucumber dry weight 78% for all varieties. Pumpkin varieties ‘Munchkin’ and ‘Baby Bear’ exhibited a 23% difference in dry weight, but no other differences were observed among other varieties because of S-metolachlor applications. Summer squash varieties ‘Respect’ and ‘Golden Glory’ exhibited a 31% difference in dry weight, but no other differences were observed among other varieties. Results show that pumpkin and summer squash demonstrated good crop safety when S-metolachlor was applied as a broadcast treatment after crop emergence. However, caution should be urged when applying this herbicide to cucumber.