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Few published studies exist documenting banana pepper tolerance to clomazone. Therefore, field trials were conducted in 2022 at two Indiana locations [Meigs Horticulture Research Farm and the Pinney Purdue Agricultural Center (PPAC)] to evaluate crop safety in plasticulture-grown banana pepper. The experimental design was a split-plot in which the main plot factor was the clomazone rate (0, 840 and 1,680 g ai ha-1), and the subplot factor was cultivar (‘Pageant’ and ‘Sweet Sunset’). Clomazone was applied over-the-top of black polyethylene mulch-covered raised beds and their respective bare ground row middles one day prior to transplanting 12 pepper plants per subplot. Data collected included crop injury on a scale from 0% (no injury) to 100% (crop death) at 2, 4, and 6 wk after treatment (WAT), and plant stand. Two harvests were performed in which mature fruits were counted and weighed. Injury presented as interveinal bleaching only at PPAC 2 and 4 WAT. At this location 1,680 g ha-1 clomazone resulted in greater injury to ‘Sweet Sunset’ at 2 and 4 WAT (53 and 15%, respectively) than to ‘Pageant’ (19 and 3%, respectively), however, plant stand and yield were not affected by either clomazone rate. These results suggest that the clomazone rate range currently used for bell pepper (280 to 1,120 g ai ha-1) can be applied prior to transplanting plasticulture-grown banana pepper with minimal crop injury and without reducing yield.
A dose-response trial was conducted in two experimental runs at the Purdue University Horticulture Greenhouses, West Lafayette, IN, in 2021/2022 to determine the effect of mesotrione rate on simulated dormant ‘Redefined Murray Mitcham’ peppermint. Peppermint was established in 20-cm-diam polyethylene pots, it was then harvested, and pots were placed in a cooler (4 C) for 1 mo. Potted peppermint plants were removed from cold storage and treated with one of five mesotrione rates: 0 (nontreated control), 53, 105, 210, or 420 g ai ha–1. As mesotrione rate increased from 53 to 420 g ai ha–1, predicted peppermint injury increased from 35% to 80% at 2 wk after treatment (WAT), 36% to 95% at 4 WAT, 9% to 82% at 6 WAT, and 8% to 90% at 8 WAT; and peppermint height decreased from 74% to 42% of the nontreated control (7 cm) 2 WAT, 74% to 17% of the nontreated control (20 cm) 4 WAT, 81% to 15% of the nontreated control (28 cm) 6 WAT, and 88% to 19% of the nontreated control (37 cm) 8 WAT. Mesotrione rates from 53 to 420 g ai ha–1 reduced peppermint dry weight from 40% to 99%, respectively. Results from this experiment showed that mesotrione applied even at half of the recommended field use rate for corn (53 g ai ha–1) was not safe for peppermint due to a reduction in aboveground biomass.
Dose-response trials to determine the tolerance of summer squash and watermelon to fomesafen applied (over the top of black polyethylene mulch and respective row middles) pre-transplanting were performed between 2020 and 2021 at three Indiana locations: the Meigs Horticulture Research Farm (MEIGS), the Pinney Purdue Agricultural Center (PPAC), and the Southwest Purdue Agricultural Center (SWPAC). Summer squash trials were performed at the MEIGS and PPAC locations, and watermelon trials were performed at the MEIGS and SWPAC locations. The experiments for both summer squash and watermelon had a split-plot arrangement in which the main plot was herbicide rate, and the subplot was cultivar. Summer squash injury included necrotic leaf margin, chlorosis, brown and white spots, and stunting. Fomesafen rates from 262 to 1,048 g ai ha−1 in 2020 at both locations, and from 280 to 1,120 g ai ha−1 in 2021 at MEIGS did not affect summer squash yield. However, in 2021 at PPAC, fomesafen applied at rates from 280 to 1,120 g ha−1 delayed summer squash harvest and decreased marketable yield from 95% to 61% compared with the nontreated control. Watermelon injury included bronzing and stunting. Fomesafen rates from 210 to 840 g ai ha−1 did not affect marketable watermelon yield or fruit number. Crop safety was attributed to rain, which washed off most of the herbicide from the polyethylene mulch before plants were transplanted or little to no rain after transplant. Injury was observed only when there was no rain before transplant followed by excessive rain shortly after transplant. Overall, the 1× rate used for each trial was safe for use 1 d before transplanting summer squash and 6 to 7 d before transplanting watermelon.
Trials were conducted in two experimental runs at the Purdue University Horticulture Greenhouses, West Lafayette, IN, to determine ‘Redefined Murray Mitcham’ peppermint tolerance to tiafenacil. Established peppermint in 20-cm-diameter polyethylene pots was subjected to a simulated harvest by removing aboveground biomass at the substrate surface; then, tiafenacil was applied at 0, 25, 50, 100, and 200 g ai ha−1. Visible crop injury, height, and aboveground dry biomass data were subjected to regression analysis to generate predictive models. At 2 wk after treatment (WAT), peppermint injury increased from 63% to 86% and from 25% to 76% in Experimental Run 1 and 2, respectively, as tiafenacil rate increased from 25 to 200 g ha−1. At 4 WAT, injury increased from 0% to 63% and from 4% to 37% in Experimental Run 1 and 2, respectively, as tiafenacil rate increased from 25 to 200 g ha−1. By 7 WAT (both experimental runs), injury increased from 0% to 17% as tiafenacil rate increased from 25 to 200 g ha−1. At 4 WAT, height decreased from 23.0 to 8.6 cm and from 17.6 to 10.3 cm in Experimental Run 1 and 2, respectively, as tiafenacil rate increased from 0 to 200 g ha−1. At 7 WAT, height decreased from 28.1 to 21.4 cm as tiafenacil rate increased from 0 to 200 g ha−1. Aboveground dry weight of the nontreated check was 20.3 g pot−1 and decreased from 19.3 to 7.0 g pot−1 as tiafenacil rate increased from 25 to 200 g ha−1. Despite acute necrosis, injury from tiafenacil at lower rates was not persistent. The proposed 1X rate of tiafenacil for peppermint, 25 g ha−1, resulted in ≤4% injury 4 and 7 WAT and in only a 3% reduction in plant height and a 4.7% reduction in aboveground dry weight compared to the nontreated check.
There is zero tolerance for dicamba and dicamba metabolite residue in tomato (Solanum lycopersicum L.) fruit following exposure to dicamba. Field trials were conducted in 2020 and 2021 to determine the persistence of dicamba and metabolite (5-hydroxy dicamba and 3,6-dichlorosalicylic acid [DCSA]) residue in processing tomato shoots and fruits. Dicamba was applied 49 d after transplanting at 0, 0.53, 5.3, and 53 g ae ha−1. Tomato plants were harvested 5, 10, 20, 40, and 61 d after treatment (DAT). No 5-hydroxy dicamba was recovered from any sample. In 2020, the DCSA metabolite was detected from tomato shoot tissue when dicamba was applied at the 53 g ha−1 rate at 0 (14 µg kg−1), 5 (3 µg kg−1), and 20 DAT (5 µg kg−1) and from tomato fruit tissue at 53 g ha−1 at 20 (2 µg kg−1) and 61 DAT (2 µg kg−1). In 2021, DCSA was not detected from tomato shoot or fruit tissues at any harvest date. By 5 DAT, dicamba was only detected from tomato shoot tissues treated with 53 g ha−1. At 0 DAT, dicamba residue was detectable only from tomato fruit on plants treated with 53 g ha−1. Tomato fruit dicamba residue from plants treated with 5.3 g ha−1 had a predicted peak of 19 µg kg−1 at 11.3 DAT. Tomato fruit dicamba residue from plants treated with 53 g ha−1 decreased from 164 to 8 µg kg−1 from 5 to 61 DAT. Furthermore, this study confirms that dicamba is detectable from tomato fruits at 61 DAT following exposure to 5.3 or 53 g ha−1 dicamba. Growers who suspect dicamba exposure should include tomato fruit tissue with their collected sample or sample tomato fruits separately.
Three dose-response trials were performed in 2020 and 2021 to determine the tolerance of two Jack O’Lantern pumpkin cultivars to fomesafen applied preemergence at two Indiana locations: the Southwest Purdue Agricultural Center (SWPAC) and the Pinney Purdue Agricultural Center (PPAC). The experiment was a split-plot arrangement in which the main plot was the fomesafen rate of application (0, 280, 560, 840, and 1,220 g ai ha–1), and the subplot was the pumpkin cultivar (‘Bayhorse Gold’ and ‘Carbonado Gold’). As the fomesafen rate increased from 280 to 1,120 g ha–1, the predicted pumpkin emergence decreased from 85% to 25% of the nontreated control at SWPAC-2020, but only from 99% to 74% at both locations in 2021. The severe impact on emergence at SWPAC-2020 was attributed to rainfall. Visible injury included bleaching and chlorosis due to the herbicide splashing from the soil surface onto the leaves and included stunting, but injury was transient. As the fomesafen rate increased from 280 to 1,120 g ha–1, the predicted marketable orange pumpkin yield decreased from 95% to 24% of the nontreated control at SWPAC-2020 and 98% to 74% at PPAC-2021. Similarly, the predicted marketable orange pumpkin fruit number decreased from 94% to 21% at SWPAC-2020 and 98% to 74% at PPAC-2021. Fomesafen rate did not affect marketable orange pumpkin yield and fruit number at SWPAC-2021 and marketable orange pumpkin fruit weight at any location-year. Overall, the fomesafen rate of 280 g ha–1 was safe for use preemergence in the pumpkin cultivars ‘Bayhorse Gold’ and ‘Carbonado Gold’ within one day after planting, but there is a risk of increased crop injury with increasing rainfall.
Morningglories (Ipomoea spp.) are among the most troublesome weeds in cucurbits in the United States; however, little is known about Ipomoea spp. interference with horticultural crops. Two additive design field studies were conducted in 2020 at two locations in Indiana to investigate the interference of ivyleaf morningglory (Ipomoea hederacea Jacq.), entireleaf morningglory (Ipomoea hederacea Jacq. var. integriuscula A. Gray.), and pitted morningglory (Ipomoea lacunosa L.) with triploid watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai]. Immediately after watermelon was transplanted, Ipomoea spp. seedlings were transplanted into the watermelon planting holes at densities of 0 (weed-free control), 3, 6, 12, 18, and 24 plants 27 m−2. Fruit was harvested once a week for 4 wk, and each fruit was classified as marketable (≥4 kg) or non-marketable (<4 kg). At 1 wk after the final harvest, aboveground biomass samples were collected from 1 m2 per plot and oven-dried to obtain watermelon and Ipomoea spp. dry weight. Seed capsules and the number of seeds in 15 capsules were counted from the biomass sample to estimate seed production. Ipomoea spp. densities increasing from 3 to 24 plants 27 m−2 increased marketable watermelon yield loss from 58% to 99%, reduced marketable watermelon fruit number 49% to 98%, reduced individual watermelon fruit weight 17% to 45%, and reduced watermelon aboveground biomass 83% to 94%. Ipomoea spp. seed production ranged from 549 to 7,746 seeds m−2, greatly increasing the weed seedbank. Ipomoea spp. hindered harvest due to their vines wrapping around watermelon fruits. The most likely reason for watermelon yield loss was interference with light and consequently less dry matter being partitioned into fruit development due to less photosynthesis. Yield loss was attributed to fewer fruits and the weight of each fruit.
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