Herbicide Drift Research Articles

Tree Nut Crop Response to Simulated Florpyrauxifen-benzyl and Triclopyr Herbicide Drift

California is the nation’s primary producer of almonds, pistachios, and walnuts, and an important producer of rice. Because of California’s diverse cropping systems, off-target herbicide drift can be a considerable problem, particularly from aerial applications that are commonly used in flooded rice production systems. Triclopyr is an auxin-mimic type herbicide that has been commonly used in rice for many years for control of broadleaf weeds and the industry is familiar with symptoms of off-target triclopyr drift. Florpyrauxifen-benzyl is a newly registered auxin-mimic herbicide in California rice with activity on key weeds and is being rapidly adopted. Although symptoms typically are similar among auxinic herbicides, it is important to understand subtle differences and risks among these herbicides as stewardship for newly registered products. This research was conducted in 2020 and 2021 to determine the relative sensitivity of almond, pistachio, and walnut trees to simulated drift rates of florpyrauxifen-benzyl and triclopyr as well as characterize and compare symptoms caused by these two herbicides. The fractional herbicide rates tested were 1/200X, 1/100X, 1/33X, and 1/10X of the florpyrauxifen-benzyl use rate of 29.4 g·ha−1 a.i. and 1/200X, 1/100X, and 1/33X of the triclopyr use rate of 420.3 g·ha−1 a.e. Florpyrauxifen-benzyl and triclopyr herbicides were applied directly to one side of the canopy of 1- to 2-year-old almond, pistachio, and walnut trees. The general symptoms of florpyrauxifen-benzyl and triclopyr were chlorosis, chlorotic spots, leaf curling, leaf narrowing, leaf distortion, leaf malformation, leaf crinkling, shoot curling, stem coloring, stunting, terminal bud death, and twisting. The florpyrauxifen-benzyl and triclopyr injury symptoms were compared at the same fractional rates and found to be similar to each other. The herbicide injury was observed on the entire pistachio canopy, particularly on developing leaves and terminal buds. In contrast, injury symptoms on almond and walnut were more apparent on the side of the canopy to which the herbicides were applied. Symptom severity peaked at 14 days after treatment with the 1/10X florpyrauxifen-benzyl rate, when the visible injury was 16%, 48%, and 78% on almond, walnut, and pistachio, respectively. Although almond and walnut symptoms from the 1/10X florpyrauxifen-benzyl rate remained visible longer than all other treatments, all trees gradually recovered throughout the growing season. In contrast, pistachio trees did not recover fully and had injury symptoms that persisted for the remainder of the treatment year and at leaf-out the following spring. When drift occurs, it is typically at rates below 1/100X up to 1/33X of herbicide use rates. This research suggested that proper herbicide drift management practices and application precautions are likely to minimize the risk of significant injury from florpyrauxifen-benzyl drift to almond and walnut because of low injury symptoms at the typical drift rates. However, extra precautions may be needed if there are nearby pistachio orchards.

Simulated herbicide drift alters native plant flowering phenology.

Data for herbicide effects on plant flowering are needed to determine potential impacts on plant reproduction. Thus, flowering phenology was determined for up to 12 weeks after herbicide treatment for native Willamette Valley plants growing in small plots on two Oregon State University experimental farms. Six perennial species were evaluated: Camassia leichtlinii (CALE), Elymus glaucus (ELGL), Eriophyllum lanatum (ERLA), Festuca idahoensis subsp. roemeri (FEID), Iris tenax (IRTE), and Prunella vulgaris var. lanceolata (PRVU). Effects of glyphosate and dicamba, alone and in combination, were determined using simulated drift rates of 0.1 or 0.2 x field application rates (FAR) of 1119 g ha-1 active ingredient (a.i.) (830 g ha-1 acid glyphosate) for glyphosate and 560 g ha-1 a.i. for dicamba. Flowering phenology was evaluated as stage of development on a scale from no buds (converted to 0), buds (1), pre-flowering (2), flowering (3), post-flowering (4), to mature seeds (5) before herbicide treatment and for 12 weeks after treatment. Flowering response to herbicides varied by species and farm; but, in general, dicamba and glyphosate resulted in earlier flowering stages (delayed or not full flowering) for the dicot ERLA, and to a lesser extent, PRVU; and glyphosate resulted in earlier flowering stages for the monocot IRTE. Based on these data, the concentration of herbicide affecting flowering stage was 0.1 x FAR. Once flowering stage was inhibited by dicamba and glyphosate, plants generally did not recover to full flowering. This study provided evidence that common herbicides can affect flowering phenology of native plants with implications for seed production.

Herbicide residue detection in cotton as influenced by time, drift rate, and sampling method

Abstract Herbicide drift to sensitive crops can result in significant injury, yield loss, and even crop destruction. When pesticide drift is reported to the Georgia Department of Agriculture (GDA), tissue samples are collected and analyzed for residues. Seven field studies were conducted in 2020 and 2021 in cooperation with the GDA to evaluate the effect of (1) time interval between simulated drift event and sampling, (2) low-dose herbicide rates, and (3) the sample collection methods on detecting herbicide residues in cotton (Gossypium hirsutum L.) foliage. Simulated drift rates of 2,4-D, dicamba, and imazapyr were applied to non-tolerant cotton in the 8- to 9-leaf stage with plant samples collected at 7 or 21 d after treatment (DAT). During collection, plant sampling consisted of removing entire plants or removing new growth occurring after the 7-leaf stage. Visual cotton injury from 2,4-D reached 43% to 75% at 0.001 and 0.004 kg ae ha−1, respectively; for dicamba, it was 9% to 41% at 0.003 or 0.014 kg ae ha−1, respectively; and for imazapyr, it was 1% to 74% with 0.004 and 0.03 kg ae ha−1 rates, respectively. Yield loss was observed with both rates of 2,4-D (11% to 51%) and with the high rate of imazapyr (52%); dicamba did not influence yield. Herbicide residues were detected in 88%, 88%, and 69% of samples collected from plants treated with 2,4-D, dicamba, and imazapyr, respectively, at 7 DAT compared with 25%, 16%, and 22% when samples were collected at 21 DAT, highlighting the importance of sampling quickly after a drift event. Although the interval between drift event and sampling, drift rate, and sampling method can all influence residue detection for 2,4-D, dicamba, and imazapyr, the factor with the greatest influence is the amount of time between drift and sample collection.

Simulated Herbicide Drift Effects on Seed Germination, Seedling Emergence, and Seedling Growth of Native Plants of the Northern Great Plains.

Small concentrations of herbicide, such as those found in drift, can affect nontarget plants at different life-history stages including seed germination and seedling emergence as well as seedling growth. Fragmented landscapes, such as those in the northern Great Plains, lead to increased proximity of ecological restoration sites to agricultural lands using herbicides. Germination, emergence, and growth are crucial life-history stages leading to ecological restoration success, but these stages are sensitive to impacts from external factors such as herbicide exposure. A lab germination experiment and a greenhouse emergence experiment were performed to examine the effect of herbicides (2,4-dichlorophenoxyacetic acid [2,4-D], atrazine, and trifluralin) on species used in ecological restorations in the northern Great Plains. Seed germination, seedling emergence, and seedling growth of many study species decreased with exposure to herbicides at different concentrations representative of herbicide drift. At concentrations as low as 0.1% recommended application rate 2,4-D elicited broad effects on final seed germination percentage and germination rate. Atrazine affected seedling emergence and growth for a number of study species at concentrations as low as 10% recommended application rate. Trifluralin affected germination, emergence, and growth of the fewest number of study species. The information gained from these experiments can be used to inform restoration practitioners of best practices and recommended species to use when implementing ecological restoration adjacent to agricultural lands. Environ Toxicol Chem 2024;43:2387-2397. © 2024 The Author(s). Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Adsorption of spray droplets reduced adsorption of dicamba spray droplets on leaves as droplet size increases

Abstract Off-target movement of growth regulator herbicides can cause severe injury to susceptible plants. Apart from not spraying on windy days or at excessive boom heights, making herbicide applications using nozzles that produce large droplets is the preferred method for reducing herbicide drift. Although large droplets maintain a higher velocity and are more likely to reach the leaf surface in windy conditions, their ability to remain on the leaf surface is poorly understood. Upon impact with the leaf surface, droplets may shatter, bounce, roll-off, or be retained on a leaf surface. We examined how different nozzles, pressures, and adjuvants impact spray droplet adsorption on the leaf surface of common lambsquarters and soybean. Plants were grown in a greenhouse and sprayed in a spray chamber. Three nozzles (XR, AIXR, and TTI) were evaluated at 138, 259, and 379 kPa. Dicamba (0.14 kg ae ha⁻¹) was applied alone and with methylated seed oil (MSO), a non-ionic surfactant, silicone-based adjuvant, crop oil concentrate, or a drift reduction adjuvant. A 1, 3, 6, 8-pyrene tetra sulfonic acid tetra sodium salt was added as a tracer. Dicamba spray droplet adsorption when using the XR nozzle, which produced the smallest spray droplets, was 1.75 times greater than when applied with the TTI nozzle with the largest spray droplets. Applying dicamba with MSO increased adsorption on leaf surfaces nearly four times the amount achieved without an adjuvant. The lowest application pressure (138 kPa) increased dicamba spray volume adsorbed more than 10% compared to the higher pressures 259 and 379 kPa. By understanding the impacts of these application parameters on dicamba spray droplet adsorption, applicators can select application parameters, equipment, and adjuvants that will maximize the amount of dicamba spray volume retained on the target leaf surface while minimizing dicamba spray drift.

Simulated drift of 2,4-D and dicamba in pecan (<i>Carya illinoinensis</i> K. Koch) and olive trees (<i>Olea europaea</i> L.)

The cultivation of pecan (Carya illinoinensis K. Koch) and olive trees (Olea europaea L.) near pasture and grain cultivation areas in southern Brazil has caused herbicide drift problems. Therefore, the objective of this study was to evaluate the phytotoxic effects of herbicides 2,4-D and dicamba on the growth of pecan and olive tree seedlings. A total of 8 underdoses were used, as follows: 0, 1.56, 3.125, 6.25, 12.0, 25.0, 50.0, and 100% of the recommended doses of herbicides 2,4-D (670 g a.e ha−1) and dicamba (720 g a.e ha−1) for burndown. The applications were carried out in 80 cm-high seedlings with the aid of a CO2 pressurized sprayer with a spray solution volume of 150 L. ha−1. The analyzed variables were phytotoxicity at 7, 14, 21, 30 and 60 days after spray (DAA) and plant height and stem diameter at 30 and 60 DAA. The drift of hormonal herbicides caused damage to the growth of pecan and olive trees, decreasing their stem diameter and height, with the herbicide dicamba showing the greatest damage. In addition, doses above 12.5% of both herbicides resulted in phytotoxicity levels greater than 60%, and doses of 50 and 100% were responsible for leaf senescence.

Response of conventional sunflower cultivars to drift rates of synthetic auxin herbicides.

The agrochemical industry has launched several new synthetic auxin herbicides in rice to combat increasing numbers of herbicide resistant weeds to other modes of action. Excessive or inappropriate use of these herbicides has resulted in unintended consequences near the sites of application, such as herbicide drift. This study was conducted to determine the impact of drift of quinclorac and florpyrauxifen-benzyl+penoxsulam (FBP) on the yield and yield components of two sunflower cultivars. In a growth chamber experiment, quinclorac and FBP were applied to 2-4 true leaf stages at rates ranging from 2.93 to 93.75 and from 0.51 to 16.25 g ai ha-1, respectively. Nonlinear regression analyses indicated that the cultivar Bosfora was more sensitive to quinclorac and FBP than the cultivar Tunca. In field experiments, these sunflower cultivars were treated with drift rates of quinclorac (<375 g ai ha-1) and FBP (<65 g ai ha-1) when they were at the 8-10 true leaf stage. Quinclorac and FBP drift rates resulted in up to 52-61% and 85-100% injury and 82-88% and 100% yield loss, respectively. Crop injury and yield data clearly showed that cultivar Bosfora was more sensitive to FBP and quinclorac rates than cultivar Tunca, and both cultivars were more sensitive to FBP than quinclorac. In our work, we also found that plant height reduction caused by quinclorac at early growth stages may be a valuable indicator to evaluate crop injury and yield loss.

Experimental Study of Quizalofop-p-Ethyl Herbicide Drift Damage to Corn and the Safety Amount of Drift Deposition

Experimental Study of Quizalofop-p-Ethyl Herbicide Drift Damage to Corn and the Safety Amount of Drift Deposition

Can herbicides of different mode of action cause injury symptoms in non-herbicide-tolerant young soybean due to simulated drift?

Accidental herbicide drift onto neighboring crops, such as soybeans, can seriously harm non-target plants, affecting their growth and productivity. This study examined the impact of simulated drift from ten different herbicides (2,4-D, dicamba, glyphosate, saflufenacil, oxyfluorfen, hexazinone, diuron, diquat, nicosulfuron, and isoxaflutole) on young soybean plants. These herbicides were applied at three simulated drift levels (1/4, 1/16, and 1/32) equivalent to recommended commercial doses, and the resulting symptoms were carefully evaluated. Simulated drift caused distinctive symptoms, including chlorosis, twisting, necrosis, and growth abnormalities, varying depending on each herbicide’s mode of action. Dicamba proved more toxic than 2,4-D, and symptom severity increased with drift proportion, with all herbicides causing over 30% injury at the 1/16 proportion. Notably, 2,4-D, dicamba, glyphosate, hexazinone, and diquat exceeded the half-maximal inhibitory concentration (IC50) value, significantly reducing total biomass. Dicamba consistently caused 50% injury at all proportions, while hexazinone, at the highest dose proportion, led to plant mortality. Dicamba also had biomass accumulation beyond the growth reduction (GR50), whereas hexazinone exhibited less than 10% accumulation due to its capacity to induce plant mortality. This study emphasizes the importance of understanding herbicide drift effects on non-target crops for more effective and safe weed management strategies.

Simulated Drift of Dicamba and Glyphosate on Coffee Crop.

Weed management in areas adjacent to coffee plantations makes herbicide drift a constant concern, especially with the use of nonselective products such as dicamba. The objective of this study was to evaluate the phytotoxic effects of the herbicide dicamba alone and mixed with glyphosate as a result of simulated drift in a coffee-producing area. The study was conducted in duplicate at two different coffee cherry development stages. The study was performed with a randomized block design and a 2 × 5 + 1 factorial scheme with four replications using two herbicide spray solutions (dicamba and dicamba + glyphosate) and five low doses (0.25; 1; 5; 10; and 20%). Additionally, a control treatment without herbicide application was also employed. In this study, we evaluated the phytotoxic damage and biometric and productive parameters. Visual damages were observed with the use of dicamba and dicamba + glyphosate doses reduced by 0.25% to 5% in the first days after application. The main symptoms were new leaf epinasty, changes in the internodal distance, and plagiotropic branch curvature. Low doses led to reduced plant height and branch length. The treatments did not reduce productivity and performance but altered the physical classifications of grains.

Intoxication of newly implanted coffee plants by simulated drift of the dicamba herbicide

After the release of soybean cultivars resistant to the herbicide dicamba, this product should be used more frequently in weed management programs, which may increase the risk of drift to neighboring crops, since the molecules are volatile and might cause damage in non-target plants. This work was developed to evaluate the effects of sub-doses of the herbicide dicamba on young coffee plants, simulating a drift situation. The experiment was carried out in a greenhouse, with a randomized block design of eight treatments and five replications. Each plot consisted of a 4 L pot, filled with sieved clayey soil and tanned manure (3:1 v/v), with a seedling of Catuaí IAC 144 coffee. The treatments used were: 0 (control), 0.0001, 0.001, 0.01, 0.1, 1.0, 10.0, and 100.0 g ha−1 of dicamba. Plant's percentual phytotoxicity was evaluated up to 49 days after application (DAA), SPAD index (14, 28, and 42 DAA), and dry matter biomass, at 49 DAA. In all evaluations, no differences were observed regarding phytotoxicity for dicamba sub-doses of up to 0.01 g ha−1. The highest doses of dicamba caused visual injuries of up to 31%. At 49 DAA, there were no differences regarding dry matter biomass. Leaf symptoms caused by the herbicide were observed, such as curling, wrinkling, and epinasty. No plant death was observed. Compared to other crops, coffee might be considered more tolerant to sub-doses of dicamba, with adequate recovery capacity for reduced doses of this herbicide.

Effect of Low Rate of Dicamba on Tomato (Solanum lycopersicum) at Different Growth Stages

Tomatoes are highly sensitive to herbicides, and concerns have been raised regarding off-target movement of dicamba and 2,4-D with the advent of new technologies in crops like soybean and cotton. Greenhouse studies were conducted over two years to assess the effect of low rates of dicamba on tomatoes at different growth stages and investigate fruit contamination. Treatments included untreated controls and dicamba applied at 1/16X, 1/32X, 1/64X, and 1/128X rates with non-ionic surfactant (NIS). Tomato plants at three growth stages (vegetative, flowering, and fruiting) were evaluated for dicamba sensitivity. Vegetative stage plants showed the highest sensitivity, while no significant differences in injury were observed between flowering and fruiting stages. Only the untreated controls produced fruit at the vegetative stage. Plants at flowering and fruiting stages successfully produced fruits. Harvested tomato fruits from each dicamba rate and the untreated control were planted, and progeny (F1) seedlings were evaluated for dicamba symptomology. No visual dicamba symptoms were observed in the tomato progeny, indicating the absence of dicamba contamination. High-performance liquid chromatography analysis confirmed no detectable levels of dicamba in the fruit samples. These findings indicate that low rates of dicamba, even at simulated drift levels, do not significantly affect tomatoes or result in fruit contamination. The results contribute to understanding the risks associated with herbicide drift and its impact on sensitive crops like tomatoes.

The consequences of synthetic auxin herbicide on plant-herbivore interactions.

Although herbicide drift is a common side effect of herbicide application in agroecosystems, its effects on the ecology and evolution of natural communities are rarely studied. A recent shift to dicamba, a synthetic auxin herbicide known for 'drifting' to nontarget areas, necessitates the examination of drift effects on the plant-insect interactions that drive eco-evo dynamics in weed communities. We review current knowledge of direct effects of synthetic auxin herbicides on plant-insect interactions, focusing on plant herbivory, and discuss potential indirect effects, which are cascading effects on organisms that interact with herbicide-exposed plants. We end by developing a framework for the study of plant-insect interactions given drift, highlighting potential changes to plant developmental timing, resource quantity, quality, and cues.

Efficacy and non‐target effects of herbicides in foothills grassland restoration are short‐lived

AbstractQuestionsSelective herbicides are frequently used in ecological restoration to control invasive non‐native forbs and recover plant communities. However, the long‐term efficacy of this practice, its non‐target effects on native plants, and its role in facilitating secondary invasions are not well understood. Similarly, little is known about the extent to which herbicide drift may affect native plant communities.LocationFoothills grasslands of Montana, USA.MethodsWe conducted a 6‐year experiment to investigate changes in the abundance of a target invasive plant, knapweed (Centaurea stoebe subsp. micranthos) and plant community structure in response to the herbicides Tordon® (picloram) and Milestone® (aminopyralid), applied at a recommended rate and a diluted rate that simulated drift.ResultsKnapweed cover and the richness of native and non‐native forb species declined in the first 3 years in response to treatment at recommended rates, but not drift rates. Secondary invasion by non‐native monocots was significant but weak. The cover of native forbs and the cover and richness of native monocots did not differ among treatments but changed significantly with the year. Surprisingly, 6 years after treatments, there were no differences among treatments in the cover of the target invasive plant or community structure.ConclusionsOur results demonstrate that the efficacy and non‐target effects of herbicides in grassland restoration can be short‐lived and idiosyncratic because of year effects. Restoration of knapweed invasions might require other active interventions, such as seeding or repeated spraying. Our study supports previous calls for long‐term monitoring of herbicides application in ecological restoration.

Modeling Soybean Planting Decisions with Network Diffusion: Does Herbicide Drift Affect Farmer Profitability and Seed Selection?

AbstractU.S. soybean farmers are currently grappling with dicamba herbicide drift. Using a network diffusion framework that accommodates key features of soybean farmer networks, we estimate the damages incurred from dicamba drift across different regions. Under our baseline assumptions, we estimate an average yield loss of 3% and predict sizable levels of forced switching to dicamba-resistant seed in response to drift. The relative importance of drift on damage and seed choice holds across a range of economic and network assumptions. In the absence of policy, this damage may cause regional adoption rates of dicamba-resistant soybean seed to increase.

Herbicide drift vs. crop resilience - the influence of micro-rates

A greenhouse study was conducted to test the effects of low herbicide dose exposure on different crops measuring visible damages, plant height, leaf area, and dry matter. Seven crops were tested: lettuce (Lactuca sativa L.) cv. Novosadska majska maslena, oil pumpkin (Cucurbita maxima Duch) cv. Olivija, oilseed rape (Brassica napus L.) cv. NS Ras, pepper (Capsicum annuum L.) cv. Kurtovska kapija, soybean (Glycine max (L.) Merr) cv. ZP Laura, sunflower (Helianthus annuus L.) cv. NS Kruna, and tomato (Solanum lycopersicum L.) cv. Dunavski Rubin. Herbicide dicamba in the range of 0.14 to 1 155.6 g a.i. (active ingredient)/ha inhibited biomass, height, leaf area, and visual injury of all crops, while glyphosate doses from 0.48 to 3 840 g a.i./ha also reduced the growth of all tested species. A rate of 116 g a.i./ha mesotrione was needed to reach 80% visual injury in oilseed rape, while the same effects on lettuce only required 1.8 g a.i./ha of mesotrione. Tomato and oil pumpkin were also sensitive to low mesotrione doses, where only 1.3 g and 0.5 g a.i./ha of mesotrione was needed for 80% of biomass reduction, respectively. Lettuce was the most sensitive crop of all tested species; biomass was reduced by 80% by dicamba, glyphosate, mesotrione, and nicosulfuron at the low rates of 33 g a.i./ha, 19 g a.i./ha, 1.25 g a.i./ha, and 2.7 g a.i./ha, respectively. Among all herbicides, visible injuries were detected in dicamba at the lowest rates. Soybean was the most tolerant of glyphosate, mesotrione, and nicosulfuron. Based on the available literature and obtained results, herbicide off-target movement must be mitigated to maximise herbicide efficacy and decrease the negative influence on susceptible plants and the environment.

Practical Knowledge of Injuries Caused by Simulated Herbicide Drift in Young Tomato Plants

Tomatoes are often grown in proximity to other crops such as grain, which can increase their susceptibility to herbicide drift and subsequent crop. Therefore, the objective of this study was to evaluate the effect of simulated herbicide drift on tomato plants. Treatments were established in a 10 × 3 + 1 factorial scheme using a completely randomized design with four replications. The first factor consisted of ten herbicides, while the second was composed by three subdoses (1/4, 1/16, and 1/32) along with an additional treatment without herbicide application. The herbicides 2,4-D, dicamba, glyphosate, saflufenacil, oxyfluorfen, and isoxaflutole caused injury levels greater than 20% or reductions in plant biomass greater than 30% at the lowest subdose. Increasing the subdose resulted in a corresponding increase in injury level and a reduction in biomass. Tomato exposed to hexazinone, diuron, nicosulfuron, and diquat at a subdose of 1/64 exhibited low injury levels and biomass reductions. However, at other subdoses, these herbicides caused significant plant damage. Among the herbicides tested, the auxinic herbicides, particularly dicamba, presented a higher risk for the tomato crop. The documentation and description of the visual symptoms caused by each herbicide applied to tomatoes will aid producers to identify drift problems in the field.

Physiological and growth responses of cacao to glyphosate exposure

Herbicide drift phytotoxicity is a problem in plantation crops due to application failures and unfavorable spray conditions. With the increased use of glyphosate in cacao plantations in Ghana, there are concerns about the effect on cacao growth and productivity from doses that potentially could be expected from drift. The aim of this study was to evaluate the physiological and growth response of young cacao plants exposed to glyphosate. Two field experiments were conducted in randomized blocks, with four replications. Glyphosate was applied at rates 0 to 720 g a.e. ha−1. Crop injury, shikimate accumulation, chlorophyll content, quantum efficiency of PSІІ (Fv/Fm), height, and stem diameter were evaluated. Increased glyphosate rates increased crop injury and shikimate accumulation and decreased chlorophyll content, quantum efficiency of PSІІ (Fv/Fm), and plant growth. Glyphosate rates 360 g a.e. ha−1 or higher resulted in >60% foliar injury and more than 10-fold increase in shikimate accumulation. Glyphosate reduced chlorophyll content to <10 and Fv/Fm to <0.35 at the highest rates. Glyphosate rates ≥180 g a.e. ha−1 reduced height and stem diameter of plants and caused reductions in stand count. Thus, cacao showed sensitivity to glyphosate, and severe injury impaired plant growth.

Фотосинтетична активност и продуктивност на царевица (Zea mays L.), изложена на симулиран дрифт oт хербицида имазамокс и лечебно приложение на протеинови хидролизати

The use of herbicides is а traditional method for weed control in crop-producing systems. Along with the high effective weed control, herbicides might cause phytotoxicity for crop plants, due to insufficient herbicide selectivity, combining herbicide treatment with unsuitable meteorological conditions, long-term persistence of herbicide in the soil or off-target transfer of the herbicide – drift. Imazamox is a selective herbicide of imidazolinone group, used to control annual and perennial weeds in imidazolinone-resistant (IMI-R) crops. Protein hydrolysates (PHs) are a group of plant biostimulants containing small peptides and free amino acids, reported to ameliorate plant abiotic stress tolerance, including herbicide phytotoxicity. This report evaluates the damaging effect of simulated imazamox drift on growth, photosynthetic performance and productivity of maize plants as well as the efficiency of foliar application by protein hydrolysates as therapy means. The received results demonstrated that the simulated imazamox herbicide drift has a strong inhibiting effect on maize plants. This is well illustrated by the retarded growth of maize plants, their disrupted photosynthetic activity and productivity losses. The foliar supply of PHs to imazamox damaged maize plants ameliorates their photosynthetic performance, growth and crop productivity.

Opportunities to Mitigate Particle Drift from Ground-Based Preemergent Herbicide Applications

Highlights Drift data collected from herbicide applications for corn, soybean, and cotton, including three commercial producers. Drift volumes and drift distances were estimated and correlated to wind speed, boom length, spray height, tractor speed, and droplet size (DV50). Boom length and spray height appear to be the dominant parameters affecting drift volume and drift distance, respectively. The results show a three- to fourfold reduction in drift using a hooded sprayer or spraying in calm weather. Abstract. Although several best practices are available, there are still opportunities to mitigate off-target pesticide drift, protect nearby sensitive crops, and address health concerns for humans/animals. The purpose of the study is to identify opportunities to mitigate drift from ground-based preemergent herbicide applications. Seven herbicide applications were tested for corn, soybean and cotton, including three regional commercial producers. Drift data were collected using water sensitive cards. ImageJ was used to analyze the droplet spectrum. Drift volumes and drift distances were estimated for each experiment. Data collected on wind speed, boom length, spray height, tractor speed, droplet size (DV50), and chemical application rate were used as explanatory variables of drift volume and drift distance. Individual and multiple linear regressions (MLRs) were carried out between drift volume, drift distance, and the explanatory variables. Our results show a three- to fourfold reduction in drift using a hooded sprayer or spraying in calm weather. Boom length and spray height appear to be the dominant parameters affecting drift volume and drift distance, respectively. The MLR results suggest that we can estimate drift (a) volume reasonably using a combination of boom length, DV50, and tractor speed and (b) distance reliably using a combination of spray height, boom length, and DV50. Keywords: Drift distance, Droplet spectrum, Fence board, Herbicide drift, Hooded sprayer, Preemergent herbicide, Water sensitive card.