Performing Department
(N/A)
Non Technical Summary
We aim to develop novel tools for integrated weed management strategies for cotton, targeting the most problematic and/or most common weed species. These tools will supplement cover crops, improve the efficacy of herbicides, and provide another non-chemical tool for weed management that could reduce weed seedbank and curb herbicide-resistant weed evolution. The objectives are to: 1) evaluate the effect of trinexapac-ethyl (TE) on herbicide activity, weed fecundity and germination; 2) extend the residual activity of herbicides using soil adjuvants; 3) define microwave specific energies capable of inactivating weed seeds in soil while maintaining soil health in terms of fertility and beneficial microbes. Microwave application has not been exhaustively explored for weed management before. Preliminary data show some excellent cobinations of TE x Herbicide to manage Palmer amaranth and common lambsquarters. We will test two doses of TE and seven herbicides on four broadleaf species and six herbicides on four grass species. Two soil adjuvants and 12 soil-applied herbicides will be tested in two soil types. Our preliminarytests showed that microwave application can kill weedy rice seeds up to 6 cm soil depth. Microwave application did not affect the soil nutrient profile nor the microbial population. We will test microwave efficacy on ten key weeds, representing a wide range of seed types. This proposal is submitted to the commodity board topic A1811: Develop advanced integrated pest management (IPM) technologies and/or techniques that will complement and preserve current crop protection technologies/products for weeds in cotton, while simultaneously reducing the reliance on conventional pesticides.
Animal Health Component
0%
Research Effort Categories
Basic
(N/A)
Applied
50%
Developmental
50%
Goals / Objectives
The project goal is to develop tools to bolster integrated weed management of cotton, specifically to improve herbicide efficacy while simultaneously reducing weed seed production, germination, and the weed seedbank size. With microwave technology, our overall goal is to understand the efficacy and commercial viability of using microwaves of 915 MHz frequency in cotton fields before planting cotton, which accords deeper soil penetration and to understand variability in efficacy due to soil and weed properties.are:1. Evaluate the effect of TE on herbicide efficacy, weed fecundity, and seed germination capacity of major broadleaf and grass weed species in cotton.Hypothesis: The PGR trinexapac-ethyl can increase the efficacy of some post-emergence herbicides (i.e., glyphosate, flumioxazin, mesotrione, etc.) and reduce fecundity and seed viability of target weeds.2. Test the effect of novel soil adjuvants on the longevity of soil-applied herbicides and evaluate residual activity on fall-planted cover crops.Hypothesis: An appropriate soil adjuvant can extend the effective weed control of some soil-applied herbicides.3. Define microwave specific energies capable of inactivating weed seeds in the soil while maintaining soil health.Hypothesis: Microwave energy can heat the soil to a level that could kill weed seeds in the plow layer (upper 3-10 inches of soil), thereby reducing weed seed germination and weed infestation.
Project Methods
1.Trinexapac-ethyl (TE) andherbicide efficacy onbroadleaf and grass weedsofcotton, weed seed production and germination (Greenhouse).A two-factor factorial experiment will be conducted atSAREC, Fayetteville, AR. Factor A is herbicide (9 levels) and factor B is TE rate (0, 0.3, and 0.6 kg/ha) in 4 replications. Herbicide treatments:glyphosate, glufosinate, mesotrione, topramezone, flumioxazin, prometryn, 2,4-D, dicamba, and no herbicide. The broadleaf species:prickly sida,ivyleaf morningglory,common ragweed,spurred anoda, and Palmer amaranth. For grass weeds, the herbicides will include:glyphosate, glufosinate, topramezone, flumioxazin, prometryn, and clethodim.Grass species:barnyardgrass, goosegrass,Texas panicum, andItalian ryegrass.Data: Weed control 3 wkafter treatment (WAT);number of seeds per plant;and seed germination capacity. Seeds will be collected from survivors oftreatmentsand from nontreated plants. Seeds will be after-ripened. Fifty seeds per treatment, 3 replications, will be placed in Petri dishes lined with filter paper and moistened with 4 mL distilled water. The plates will be sealed and incubated under optimum conditionsand the germinated seeds counted after 14 d. The viability of non-germinated seeds will be checked using tetrazolium test. The germination test will be conducted twice. Total seedsper plant will be weighed and 500 seeds will be weighed to estimate the total number of seeds per plant.2. Trinexapac-ethyl (TE) andherbicide efficacy onbroadleaf and grass weedsofcotton, weed seed production and seed germination (Field Study).Broadleaf weeds: Fieldtests will be conducted at SAREC,Fayetteville in year 1 andyear 2. The test species will include: Palmer amaranth, common lambsquarters, prickly sida, common ragweed, andspurred anoda. The test will be conducted in a field naturally infested with Palmer amaranth and common lambsquarters. The other species will beoverseeded. Seeds will be mixed and spread across the field after land preparation. Cotton resistantto glyphosate, glufosinate, 2,4-Dand HHPD inhibitor herbicides will be planted between mid-April and mid-May. Grass species will be removed by overspraying the field with clethodim.The same herbicides and TE treatments as in the greenhouse studywill be applied, at4 wkafter planting cotton and atlayby. Plots will consist of 4 cotton rows, 36 in apart , 10 ft long. The treatments will be applied at 20 gal/A with recommended adjuvants. Each growth stage will be a separate experiment; the experimental design will be a split-plot randomized complete block with herbicide as the main factor and TE rate as the sub-factor.Grass weed test. Fieldtests will be conducted at SAREC, Fayetteville, AR in year 1 and 2. Weedspecies will include: barnyardgrass, goosegrass, and large crabgrass. The test will be conducted in a field naturally infested with barnyardgrass. Goosegrass and large crabgrass will be overseeded. A herbicide-resistantcotton varietywill be planted between mid-April and mid-May. Broadleaf species will be removed by overspraying the whole field with 2,4-D. The same herbicides and TE treatments as ingreenhouse grass testwill be appliedat: 4 wkafter planting or at layby. Plot size, experimental design, and herbicide application parameters will be the same as inthe broadleaf test.Data: Weed control 3 WAT,number of survivors, andseed production by species; seed germination capacity; and 5) cotton yield. Seed production will be estimated by quantifying seed rain on a 0.5 cm x 0.25 cm area attwo sites per plotusing a drop cloth. Before desiccating cotton, the weed canopy above the drop cloth will be shaken, and the cloth removed to retrieve weed seeds. Twoplants/plot per specieswill be harvested to quantify seeds remaining on the plant. The seeds will be weighed and seed numbers calculated by species. Germination capacity and seed viability will be evaluated as described previously.3.Extending the longevity of soil-active herbicides, for cotton and potential rotational crops, with soil adjuvants.A split-plot experimentwith four replications will be conductedinKibler and Rohwer, ARwherePalmer amaranth andEchinochloaspp. are the predominant species. Morningglory, prickly sida, common ragweed, spurred anoda, barnyardgrass, and large crabgrass will be seeded. This isa non-crop field experiment. The mainplot will be herbicide (13 levels) and the subplot will be soil adjuvant (3 levels) (Table 1). Improved formulations of a soil adjuvant (Anomynous 2023) will be tested: 1) ORO-RZ (2 pt/A), 2) OR369A (2 pt/A), and 3) no soil adjuvant. The treatments will be applied at 20 gal/A. The field will be irrigated at 0.5 A-inch after land preparation and weed seeding. The treatments will be applied 24 hr later. Soil sample will be collected at the time of herbicide application to determine soil moisture. Soil sample will also be submitted to the Soil testing facility of the University of Arkansas for soil texture analysis. The plot size will be 20 ft x 5 ft. Vegetation in the whole field will be desiccatedafter each evaluation time and once monthly thereafter, until Fall. In October, thefield will be no-till planted with a paired strip of cereal rye and Austrian winterpea cover crops perpendicular to theplot orientation to evaluate residual effect of treatments on fall-planted cover crops.Table 1.Herbicides, for cotton and rotational crops, to be tested with soil adjuvants.Common nameRate, medium texture soil (kg ai/ha)Common nameRate, medium texture soil (kg ai/ha)prometryn0.840sulfentrazone0.225metribuzin0.560pendimethalin0.930fluridone0.168chlorimuron0.009mesotrione0.224imazethapyr0.071flumioxazin0.071pyroxasulfone1.430oxyfluorfen0.560acetochlor1.456no herbicideData:density of major weed species 3, 6, 9, and 12 WAT; control of major weed species and overall weed control 3, 6, 9, and 12 WAT; injury on rye and Austrian winter pea 4 wk from planting; and dry shoot biomass of cover crops 8 wkfrom planting. Weeds will be counted in a 0.25-m x 0.25-m quadrat. Shoots of cover crops will be cut at ground level from 0.25-m x 0.25-m quadrat, oven-dried, and weighed.4. Evaluation of microwave energy (MW) for killing weed seeds in soilTen weed specieswill be tested (Table 2). These species represent seeds of different types. MW will tested at different weed seed density and differentsoil depthand soil physicochemical properties. Field soil naturally infested withPalmer amaranth and barnyardgrass will be collected from Kibler and Rohwer. Soil (same weight; 40% moisture, wet basis) will be placed in 6-inch diameter, 8-inch deep pots. Seeds of other species will be placed at different depths and densities. Palmer amaranth and barnyardgrass will be seeded separately into non-infested soil from each location to assess MW efficacy on these species at various depths.After MW treatment, the treated soil will be transferred into rectangular trays, which will be kept in the greenhouse to evaluate weed seed germination. Emerged seedlings will be counted by species at 15 and 30 d after treatment. Seedlings will be removed after counting. The remaining weed seeds will be recovered by washing the soil through a series of sieves of decreasing size and tested for viability.Table 2. Microwave treatments to be conducted at room temperature (23-25 °C)FactorsLevelsSpeciesPalmer amaranth, common lambsquarters, ivyleaf morningglory, prickly sida, common ragweed, spurred anoda, barnyardgrass, goosegrass, Italian ryegrass, and Texas panicumWeed seed density (no. of viable seeds/m2soil up to 12 inch depth)Low (<1000), medium (1000-5000), high (>5000)Soil depth (inches)3, 6, 9, 12Soil properties (temperature, moisture, bulk density, soil type)combinations will be tested to cover the range of the physicochemical propertiesMicrowave power (kW)10, 20, 30Exposure duration (sec)30, 60, 90Replication3; conducted twice