Weed control is a significant challenge in tomato production, often resulting in considerable yield losses and compromised fruit quality. Common weeds in tomato cultivation, such as nutsedges, annual grasses, and Palmer amaranth, exacerbate this issue. With limited effective weed control options available, there's a critical need for an integrated approach that can alleviate weed pressure while safeguarding crop yield and quality. One promising solution is the utilization of biochar herbicide protection pods (HPPs). In our greenhouse trial, we evaluated the efficacy of HPPs in enhancing tomato tolerance to S-metolachlor and metribuzin herbicides. By incorporating activated carbon within the HPPs to shield crop plants from soil-active herbicides, which they marginally tolerate, we aimed to improve weed management effectiveness. Tomato seeds were encapsulated within four distinct HPPs: DFBC Cornstarch, DFBC Selvol, RHBC Cornstarch, and RHBC Selvol. Control tomato seeds without biochar were also included. Treatments were applied to tomato seedlings at the 2-3 leaf stage with S-metolachlor (1681.28 g/ha) or metribuzin (1120.85 g/ha), with visual injury evaluations conducted at 7, 14, and 21 days after application (DAA). Dry mass measurements were taken at 21 DAA, with an untreated control included for comparison. In the presence of metribuzin, three biochar treatments exhibited injury levels of around 70%, compared to a higher injury rate of 79% in the treatment without biochar. However, there was no significant difference in dry mass. Conversely, no discernible injury differences were noted among treatments with S-metolachlor, yet three biochar treatments demonstrated substantial enhancements in dry biomass. Specifically, treatments with biochar recorded notable increases in dry mass compared to those without biochar, indicating a 28 to 35% boost in biomass. These preliminary findings highlight the potential of biochar HPPs in enhancing crop health, yield, and weed management efficacy in tomato farming.
Poor competitive ability and limited herbicide options make weed management of Brassica crops difficult. Growers often adopt the use of transplants, which is less efficient in terms of time, material, and labor when compared with direct seeding, resulting in higher prices per unit. Seed treatment with protective compounds could decrease crop injury from preemergent (PRE) herbicides making it profitable to direct-seed Brassica plants for production. Research was conducted to evaluate the ability of three candidate safeners [24-epibrassinolide, melatonin, and ascorbic acid (AsA)] to reduce injury caused by four herbicides (S-metolachlor, pyroxasulfone, halosulfuron, and mesotrione) applied PRE on the collard green cultivar Top Bunch and turnip cultivar Purple Top White Globe. Two independent greenhouse trials were conducted at the Clemson University Coastal Research and Education Center in Charleston, SC. Visual injury of the treated plants was evaluated weekly and dry mass was collected 21 days after treatment. Seed treatment did not reduce injury efficiently caused by pyroxasulfone, halosulfuron, and mesotrione; all doses were lethal for both crops. However, collard seeds treated using melatonin and AsA had 66% and 54% less injury caused by S-metolachlor at 514 g⋅ha–1 a.i., respectively. On turnips, melatonin was the only treatment that reduced the S-metolachlor damage on seedlings, with 43% less injury than untreated seedlings. Plant injury and plant weight correlated significantly for both Brassica crops. The reduction in injury caused by S-metolachlor when seeds were treated with melatonin and AsA validated those compounds’ protective ability. Seed treatment with melatonin could be combined with PRE applications of S-metolachlor to overcome the low weed competitive ability of these species early in the season.
Weed management is a common weed management practice in organic weed control, however, this practice is expensive. Other integrated weed management practice could include flaming and cultivation. The study objective is to investigate flaming, cultivation, and hand weeding to develop an integrated weed control program in organic carrot. The study was conducted in an organic certified field at the North Florida Research and Education Center Suwanee County, Live Oak, FL. Treatments were a factorial design with 5 weed management programs and 2 fertilizer types. Weed management treatments were (1) flaming preseeding weekly cultivation, (2) flaming preseeding weekly cultivation 1 handweeding event, (3) flaming preseeding flaming preemergence weekly cultivation (4) flaming preseeding flaming preemergence weekly cultivation 1 handweeding event, (5) flaming preseeding flaming preemergence weekly cultivation 2 handweeding events. Fertilizer treatments were pelleted poultry litter and 50% feather meal 50% poultry litter. Carrot ‘Uppercut’ were seeded on December 3, 2020 and were harvested on May 3, 2021. Eight rows of carrot were planted on a 0.9 m bed top. Fertilizer was applied immediately after seeding. Weeds were counted by species in two 0.5 m2 quadrats prior to each basket weeder cultivation between the rows. Carrots were cultivated 6 times before the carrot were too large and would be injured. Fertilizer type were not different for weed counts at all dates. Cutleaf evening primrose (Oenothera laciniata) was the only weed species in the plots from the beginning of the trial through harvest. The inclusion of flaming preplant and preemergence delayed the emergence of cutleaf evening primrose, however at 6 weeks after planting all the treatments were similar. Mid-season weed species included henbit (Lamium amplexicaule) and common chickweed (Stellaria media), however, these weed species were not present late-season. Purple toadflax (Linaria purpurea) and old world diamond flower (Oldenlandia corymbosa) were the most common weed species late-season. Single handweeding had excellent control early-season, but two handweeding events controlled both the cool and warm season weeds. Early season weed control should include flaming. Between row weed management was best with cultivation. Handweeding is necessary for late season weed control when flaming and cultivation are not available.
After harvest, peppermint is vulnerable to weed interference due to the loss of crop canopy. However, few herbicides are registered for use during this critical time in the production cycle. In response to this, we conducted research trials in 2023 at two commercial peppermint production fields in Indiana (North Judson and Fair Oaks) to determine peppermint response to preemergence and postemergence herbicides. Preemergence herbicide treatments included Zidua (1.84 fl oz/a), Optogen (3 fl oz/a), Spartan (4 fl oz/a), Chateau EZ (4 fl oz/a), Dual Magnum (1 pt/a), Fierce EZ (10 fl oz/a), and Tenacity (3 fl oz/a). Postemergence herbicide treatments included Basagran (2 pt/a), Reviton (2 fl oz/a), Tough (24 fl oz/a), Sharpen (2 fl oz/a), Anthem Flex (4.5 fl oz/a), Aim (1 fl oz/a), and Tough (24 fl oz/a) plus either Optogen (1.5 fl oz/a), Tenacity (1.5 fl oz/a), or Basagran (2 pt/a). Visible crop injury on a scale of 0 (no injury) to 100% (crop death), as well as crop height, was recorded every other week after treatment. Eight weeks after treatment, the greatest injury was observed was from the Group 14 herbicides: Reviton (81-84%), Sharpen (81-88%), and Aim (33-54%). Injury from Group 27 herbicides, Optogen and Tenacity, was more severe at Fair Oaks (63% and 64%, respectively) than at North Judson (28% and 12%, respectively). However, combining a half rate of these herbicides with Tough greatly increased crop injury at both locations (>73%). Injury from Chateau EZ and Fierce EZ differed by location; injury was lower at North Judson (13% and 7%, respectively) than at Fair Oaks (42% and 55%, respectively). Crop injury from Zidua, Dual Magnum, Spartan, Basagran, and Tough plus Basagran were similar to, or less than, Tough applied alone (the registered grower standard). Peppermint height and end-of-season aboveground biomass followed similar trends.
Plastic mulch films and geotextile landscape fabrics are not compatible with specialty crops grown at high densities with narrow in-row spacing. As a result, many growers resort to hand weeding these specialty crops, including leafy greens, carrots, and matted-row strawberries. Our objective was to develop and test value-added weed barrier mulches designed specifically for these crops to grow on and root through. We have conducted 13 trials across 3 crops (lettuce, carrot, and strawberry) and 3 years to evaluate 9 different biobased, compostable weed barrier mulches (BCMs) that include polylactic acid (PLA) resin. The BCMs tested varied in weight basis and material composition including: 1) PLA-only (80, 120, and 180 g/m2), 2) PLA embedded organic fertilizers (soybean meal and composted turkey litter; 150 and 210 g/m2), and 3) PLA paper (105 and 210 g/m2). The BCMs are installed in the field like a typical mulch film roll but are then covered with a 1 to 2.5 cm layer of compost (or other weed-free media) and crop seeds. Data was collected to evaluate effects of BCMs on weed density, soil nitrogen availability, moisture, and temperature, microbial abundance, and crop establishment, yield, and quality. Across all crops and site-years, BCMs reduced weed emergence by 80% to 97% compared to bare soil, and weed suppression was best in PLA paper. The BCMs immobilized some available soil nitrogen and embedded fertilizers in the BCM did not affect this outcome. In carrot, BCMs increased mycorrhizal fungi abundance by up to 59% compared to bare soil. In strawberry, BCMs increased crop canopy area by up to 51%. Yields were usually not different between BCMs and bare soil because weeds were removed weekly after counting. However, poor seedling establishment on BCMs due to heavy rainfall after planting in 2022 reduced carrot yield by 13% and lettuce yield by 20%. To address this issue, lettuce in 2023 was planted in two shallow seed furrows filled with compost on the BCM (instead of broadcast planting across the entire BCM bed top as in previous years). Lettuce establishment in the furrows was two times greater than in bare soil due to improved tilth and reduced erosion, and yield was not different from bare soil. Volumetric soil moisture in BCM compost seed furrows was 27.1% compared to 35.7% in bare soil, highlighting differences in texture and the importance of irrigation in the BCM system during establishment.
Preemergence herbicide application under plastic mulch is an effective strategy for managing weeds in vegetable plasticulture production. However, applying herbicides under plastic mulch in raised beds carries the inherent risk of crop phytotoxicity. This underscores the importance of exploring crop-safe methods for herbicide application in beds covered with plastic mulch. The study aimed to evaluate the efficacy of preemergence herbicide S-metolachlor alone or in combination with super absorbent polymer, soil binding agent, or compost in effectively controlling weeds in plastic mulched tomato beds without impacting the crops. During trials, I and II, preemergence S-metolachlor was applied either as blanket sprays or in combination with super absorbent polymer, soil binding agent, and compost on raised beds before installing plastic mulch. Results from trial II showed that S-metolachlor soil binding agent and S-metolachlor compost mix suppressed weed density by over 85% and 68%, respectively. Similarly, treatments including S-metolachlor alone, S-metolachlor super absorbent polymer, S-metolachlor soil binding agent, and S-metolachlor compost led to a reduction in weed biomass by over 50% compared to the non-treated control. Importantly, these treatments did not significantly impact tomato crop vigor and chlorophyll content during trials I and II, nor did they affect tomato crop biomass and yield. In conclusion, utilizing preemergence S-metolachlor along with different application approaches tested shows promise for controlling tough weeds such as nutsedge in tomato plasticulture beds.
