Total Spray Volume Research Articles

Agricultural spray drone deposition, Part 1: methods for high-throughput spray pattern analysis

Abstract Effective pesticide application is dependent on precise and sufficient delivery of active ingredients to targeted pests. Water-sensitive papers (WSPs) have been used to estimate the stain coverage, droplet density, droplet size, total spray volume, and other spray-quality metrics by analyzing deposit stains using image analysis software. However, because WSPs are expensive, they are typically distributed along unidimensional transects at intervals of 0.5 m or more, which comprises 0.5% or less of the total treated area. This might limit the ability to accurately represent the deposition of agricultural sprayers with irregular patterns, such as agricultural drone sprayers in the early developmental stage. This study introduces a novel approach utilizing white Kraft paper and a blue colorant proxy for assessing spray deposition. A custom Python-based image analysis tool, SprayDAT (Spray Droplet Analysis Tool), was developed and compared with traditional image analysis software, DepositScan. Both models showed increased accuracy in detecting larger objects, with SprayDAT generally performing better for smaller droplets. DepositScan underestimated the total deposited spray volume by up to 2.7 times less compared with the colorant extraction assessed via spectrophotometry and the predicted output based on flow rate, coverage, and speed. Accuracy of software-estimated spray volume declined with increasing total stain coverage, likely due to overlapping stain objects. Droplet density exhibited a Gaussian trend, with peak density at approximately 22% stain cover, offering evidence for overlapped stains for both DepositScan and SprayDAT as stain cover increased. Both models showed exponential growth in volumetric median diameter (VMD) with increasing stain cover. SprayDAT is freely accessible through an online repository. It features a user-friendly interface for batch processing large sets of scanned images and offers versatility for customization to meet individual needs, such as adjusting spread factor, updating the standard curve for spray volume estimation, or modifying the stain detection threshold.

Spray Tip Configurations with Pulse-Width Modulation for Glufosinate-Ammonium Deposits in Palmer Amaranth (Amaranthus palmeri)

Abstract. A commercial sprayer operated at a field speed of 24 km h-1 simultaneously applied glufosinate-ammonium through seven spray tip treatments spaced along a 30.5 m boom for measured foliar deposits of herbicide in 35 cm tall Palmer amaranth weeds and spray deposits on foliar-mounted water-sensitive paper (WSP). The experiment followed one that found increased herbicide deposits for dual tips with an adjacent, fore-aft mount, downward-pointed pre-orifice tip (Extremely Coarse) operated with blended pulse-width modulation (bPWM) and a pre-orifice tip (Fine) operated constant (non-bPWM) under moderate ambient wind velocities from 3.1 to 4.1 m s-1. Additional dual-tip treatments were added to the dual-tip configuration for the current experiment to expand droplet Coarseness and to add dual tips operated constant to isolate bPWM effects. Tested treatments in common with the previous experiment included the original dual-tip bPWM and non-bPWM combination, Y-adapter fore-aft-mounted pre-orifice tips with diverging spray patterns both operated bPWM, and an air-induction extended-range tip operated constant. Palmer amaranth weeds, total spray volume rate of 93.5 L ha-1, sprayer speed of 24 km h-1, and test methods were similar between studies, except for negligible wind in the current experiment. Conditions were clear and sunny during spraying without indicators of a stable atmosphere. Overall mean glufosinate-ammonium deposits recovered from leaves were greatest for dual-tips operated constant at reduced droplet size (Very Coarse and Fine) due to reduced required tip size operated without bPWM, and for increased droplet size for Y-adapter-mounted pre-orifice tips (Extremely Coarse and Coarse) operated with bPWM, resulting in overall mean glufosinate-ammonium leaf deposits of 15.9 and 15.0 µg a.i. cm-2, respectively. The combination of dual tips at reduced droplet size or the Y-adapter fore-aft spray pattern divergence of bPWM tips coupled with high sprayer speed enhanced droplet interception by Palmer amaranth plants under negligible wind conditions, since the collected deposits, even without summed integration over foliage height, significantly exceeded the applied rate of 8.2 µg a.i. cm-2. An air-induction extended-range tip non-bPWM (Very Coarse) provided the next highest mean in overall glufosinate-ammonium deposit. One increased-droplet size dual-tip, pre-orifice tip bPWM and non-bPWM (Ultra Coarse and Coarse) resulted in a mean deposit that was not significantly different from the air-induction extended-range tip operated non-bPWM. Other dual-tip combinations with bPWM and non-bPWM, including the original dual-tip configuration in the previous study, resulted in significantly reduced mean herbicide deposits. Considering all tested tips, advantages of bPWM depended on spray tip droplet size classifications and Y-mounted fore-aft divergence of spray patterns. Overall mean WSP spot deposits were greatest for reduced droplet size (Very Coarse and Fine) dual pre-orifice tips operated non-bPWM, corresponding with the highest numerical overall mean of glufosinate-ammonium deposit. This correspondence of highest spot deposits and highest mean glufosinate-ammonium deposit also occurred in the previous study. Increased Palmer amaranth control correlated with increased glufosinate-ammonium deposit and decreased volume median diameter (Dv0.5) determined with WSP electronic scans, with the air-induction extended-range tip operated constant and the Y-adapter pre-orifice tip operated as bPWM providing the highest weed control. Overall mean WSP spot deposits ranged from 42.3 to 81.1 spots cm-2, compared to 14.0 to 47.0 spots cm-2 previously reported for similar spray conditions, with spot deposits attributed to negligible wind versus wind, respectively. Thus, the spray environment, particularly wind, exhibited effects on nozzle tip comparisons for foliar deposition and may offer some rationale for the conflicting published data beyond the examined treatments. Keywords: Application technology, Blended pulse-width modulation, Herbicide, Herbicide resistance, Nozzle, Spray deposition, Water-sensitive paper, Weed.

Season-long Management ofDrosophila suzukiiin Rabbiteye Blueberry, 2014

The objective of these trials was to determine efficacy of season-long insecticide programs against SWD in rabbiteye blueberries. Trials were conducted at the University of Georgia Blueberry Research and Demonstration Farm in Alma, GA. We evaluated nine treatment programs each consisted of weekly applications of different insecticides (Table 1). Treatments were organized in an RCB design with three blocks of nine treatments and an untreated check. The plots were approximately 0.09–0.12 acres and included three to five rows of blueberry bushes. Insecticides were applied weekly from June 2014 to July 2014 at the manufacturer-recommended maximum field rate with a standard airblast sprayer. Water was used at the rate of 50 gpa for the foliar spray applications. Induce (nonionic surfactant) was added at the rate of 1 pt/100 gal of total spray volume …

SOIL APPLICATIONS OF IMIDACLOPRID AND CYANTRANILIPROLE FOR CONTROL OF SWEET POTATO WHITEFLY ON STAKED TOMATOES, 2013

Bemisia tabaci biotype B also known as Bemisia argentifolii is key pest of tomato in Florida due primarily is role as vector of tomato yellow leaf curl virus (TYLCV). TYLCV greatly reduces tomato yields, especially when symptoms appear early in the crop cycle. Seedlings of a susceptible variety ‘Florida 47’ obtained from a commercial greenhouse were transplanted at the Southwest Florida Research and Education Center in Immokalee Florida on 8 Mar. Plants were spaced 18-inches apart on 2 sets of 3 beds 420 ft in length and covered with black polyethylene film mulch after incorporating approximately 25% of the expected macronutrient requirements as 10-2-10 NPK. The remainder was injected during the course of the crop as liquid 7-2-7 through drip tapes (2 per bed) with 4 inch emitter spacing. A RCB design was used with 6 treatments and 3 replications. Each plot had 30 plants per row across three rows for a total of 90 plants. Soil drenches of Admire Pro and Verimark were made 12 Mar by delivering a 120 ml suspension per plant using an EZ-Dose® sprayer operating at a pressure of 45 psi. (Table 1). Admire Pro and Verimark were also injected for some treatments on 4 Apr by sectioning off the drip tape in each treated plot with a ball valves and pressurizing the tape using a 12 volt pump operating at 0.23 gpm to inject 3 gal of water, followed by 4 gal of suspension and finally a 5 gal water flush (Table 1). Foliar sprays (Table 1) were applied with a single row high clearance sprayer operating at 180 psi and 2.3 mph. The sprayer was fitted with two vertical booms equipped with yellow Albuz® hollow cone nozzles, each delivering 10 gpa for a total spray volume of 40 gpa. Actigard (0.33 – 0.50 oz/ac) Koicide (1.5 lbs/acre) and Manzate Pro Stick (1.5 lbs) were sprayed as needed for bacterial infections. Acramite at 1.0 lb/acre was applied on 12 Apr for spidermites and Xentari DF at 1.5 lbs was applied 24 Apr and 8 May for southern armyworm control.

Spray drift as influenced by meteorological and technical factors

The objective of this study was to investigate spray drift from a conventional field sprayer as influenced by meteorological and technical factors, and to provide spray operators with data on which to base sound judgements when applying pesticides. The study was conducted in grazing fields and cereal crops. Interpreting the results from 15 field trials under varying meteorological conditions using different boom heights and driving speeds indicates that, during normal spraying conditions, the most decisive factors influencing the total spray drift (TSD) will be boom height and wind speed, followed by air temperature, driving speed and vapour pressure deficit. One important finding was that TSD (within the encompassed range of meteorological conditions and a boom height of 0.4 m) could be expressed as a simple function of the fraction of droplets ≤ 100 µm. In cereal crops: TSD = 0.36 + 0.11× [fr. (d ≤ 100 µm)] and in grazing fields, TSD = 1.02 + 0.10× [fr. (d ≤ 100 µm)]. In most cases a fraction of the airborne drift passed over the 6 m sampling mast located 5 m downwind of the spray swath. Under specified conditions, the present results indicate a simple relation between the total spray drift and volume fractions of droplets ≤ 100 µm. Given the nozzle type, it was concluded that the most decisive factors determining TSD are wind speed and boom height. Evaluating the relative importance of the meteorological and technical factors contributes to increasing knowledge in this field of research.

Influence of Spray Volume on Spray Deposition and Coverage within Nursery Trees

Abstract Information on better utilizing airblast sprayers to achieve high pesticide spray application efficiency in nursery tree production is needed. Foliar spray deposition and coverage at different heights inside crabapple tree canopies were investigated for a conventional airblast sprayer operating at four different application rates ranging from 230 to 900 liters/ha [24 to 94 gallons per acre (GPA)]. Deposition on the ground at various distances from the sprayer was also measured at the 700 liters/ha (73 GPA) application rate. Foliar deposition and coverage on targets below 2.6 m (8.5 ft) inside tree canopies increased as the application rate increased, but the increase in the coverage was much lower than the deposition. For trees taller than 2.6 m (8.5 ft), the sprayer could not deliver uniform spray deposition and coverage across the tree height. The portion of trees below 2.1 m (6.9 ft) was well covered by the spray deposits with 230 liters/ha (24 GPA) application rate while higher application rates resulted in over spray application. Less than 30% of total spray volume was deposited on target trees while over 34% of the total spray volume was lost on the ground. The tree-row volume method should include foliage density and tree-row gaps to avoid excessive estimation of spray application rates for nursery tree crops.

Comparative Performance of Air-induction and Conventional Nozzles on an Axial Fan Sprayer in Medium Density Apple Orchards

A series of experiments was undertaken to compare the performance of an axial fan air blast sprayer equipped with air induction (AI) or conventional (C) nozzles in medium density apple (Malus ×domestica) orchards. Performance was compared by assessing 1) spray coverage within the canopy at four levels of across-row wind speeds, 2) ground deposits from airborne drift under still conditions, and 3) biological efficacy of a postbloom thinning spray and a seasonal “high-risk” fungicide program where thiophanate methyl was not included. Spray coverage was reduced by up to 50% with increasing across-row wind speeds, the most dramatic reductions occurring between 0 and 4 mph and at heights greater than 8 ft in the canopy. AI nozzles resulted in a 2-fold increase in spray coverage in the canopy of trees in the row immediately adjacent to the sprayer compared with C nozzles regardless of across-row wind speed. AI nozzles resulted in significantly less airborne drift compared with C nozzles under still conditions in an open field and within a mature ‘Cripps Pink’/ ‘M.7’ orchard planted in rows 20 ft apart. Sprayer efficiency, measured as the proportion of total spray volume that was intercepted by the tree canopy, was higher for an airblast sprayer fitted with AI nozzles (38%) than for C nozzles (26%). The efficacy of a postbloom thinning spray (100 ppm benzyladenine plus carbaryl at 1 lb/100 gal) applied to ‘Morgan Spur Red Delicious’/‘M.111’ trees planted at a between-row spacing of 15 ft was slightly greater when applied with AI nozzles compared with C nozzles. However, application of a “high-risk” fungicide program with AI nozzles resulted in a higher incidence of fruit with flyspeck (Zygophiala jamaicensis) at harvest compared with C nozzles. These inconsistencies were related to the combined effects of nozzle type, orchard row spacing, and canopy density on spray deposition on trees in the second row from the sprayer or to possible effects of nozzle type on droplet density on the target. AI nozzles should provide equivalent or possibly improved coverage and biological efficacy compared with C nozzles in well-managed orchards planted at distances of 18 ft or less between rows. However, when orchard rows are spaced greater than 18 ft apart, AI nozzles will result in reduced spray coverage and chemical efficacy compared with C nozzles because of a reduction in spray carry-over to adjacent rows as a result of reduced airborne drift.

CANOPY STRUCTURE AND DEPOSITION EFFICIENCY OF VINEYARD SPRAYERS

A field study was performed to analyse how deposition efficiency from an axial-fan sprayer was affected by the canopy structure of vines trained to the High Cordon, Low Cordon and Casarsa systems, at beginning of flowering and beginning of berry touch growth stages. An empirical calibration method, providing a dose rate adjustment roughly proportional to canopy height, was used. The canopy structure was assessed using the Point Quadrat method, and determining the leaf area index (LAI) and the leaf layer index (LLI). Spray deposits were measured by colorimetry, using a water soluble dye (Tartrazine) as a tracer. Correlation between deposits and canopy parameters were analysed and discussed. Foliar deposits per unit leaf area were relatively constant, suggesting that empirical calibration can reduce deposit variability associated with different training systems and growth stages. Total foliar deposition ranged from 33.6% and 82.3% of total spray volume, and increased proportionally with the LLI up to LLI<4. Deposits on bunches significantly decreased with the LLI in the grape zone. The results suggest that sprayer efficiency is improved by a regular, symmetrical canopy, with few leaf layers in the grape zone as in Low Cordon. However, a LLI<3 over the whole canopy and >40% gaps in the foliage both reduced total deposition, and may increase the risk for larger drift losses.

Two‐Phase Flow Characterization by Automated Digital Image Analysis. Part 2: Application of PDIA for Sizing Sprays

AbstractA series of experiments were conducted in order to assess the robustness and accuracy of a recently developed digital image analysis technique (PDIA). This paper investigates the application of the PDIA technique to the sizing of relatively small fuel droplets of diameters in the range 5 to 30 μm produced by a pressure‐swirl atomizer. The measurement performance of the PDIA system has been assessed in terms of individual object diameters and also number and volume probability density functions of diameter in comparison to phase Doppler anemometry (PDA) data obtained under identical conditions. PDIA measurements revealed good agreement with spray data obtained by PDA at a measurement location 36 diameters downstream from the nozzle orifice with differences in the arithmetic mean diameter, D10 and volume mean diameter, D30 of approximately 5 and 3% respectively. The PDIA technique was shown to detect the presence of very large, predominantly non‐spherical droplets whose diameters were in excess of 100 μm. These droplets, although few in number constitute a significant proportion of the total spray volume and would have otherwise been either erroneously measured or have passed through the probe volume undetected using PDA due to non‐sphericity. Smaller objects may also be measured correctly by both methods although sensitivity to signal‐to‐noise ratio, for both methods can generate spurious and contradictory errors.

EVALUATION OF INSECTICIDES FOR CONTROL OF CHINCH BUG AND MEXICAN CORN ROOTWORM, 2002

Two experiments were planted 20 and 22 Feb, respectively, in Wharton and Goliad counties. Plots were 2 rows (38-inch centers) x 30 ft with four replications arranged in a RCB design. Seed was planted at 48 kernels/row with a John Deere 7100 model MaxEmerge planter modified with research cone planters. In the Goliad County experiment, the clay soil (23% sand, 28% silt, and 49% clay) contained 1.5% organic mater and had a 7.6 pH. In the Wharton County experiment, the Norwood silty clay loam soil (8% sand, 64% silt, and 28% clay) contained 1.3% organic matter and also had a 7.6 pH. Corn had been planted on the land at each location for at least the five previous years. Soil moisture conditions at-planting at both locations were good with soil temperatures at the 4-inch depth ranging from 62-64° F. On the day of planting, the herbicide Bicep II Magnum at 2.1 qt/acre was broadcast with a CO2 backpback sprayer in a total spray volume of 11.4 gpa, at 30 psi and a speed of 2.5 mph. Granular materials were banded over the open seed furrow (6inch bander). Treatments were assessed by (1) counting the number of plants on 13.75 ft row on both rows of plots on 22 Mar [Wharton County site], and 24 Mar [Goliad County site], (2) assigning a damage rating [1 = no damage up to 5 = stunting, uneven growth and yellowing] to each plot on 22 Mar [Wharton] and 24 Mar [Goliad], (3) counting the number of Chinch bug (CB) by digging around 10 plants/plot on 5 and 15 Apr [Wharton] and 24 Mar and 10 Apr [Goliad], and (4) digging 5 plants/plot for MCR damage ratings on 9 and 10 May, at the Wharton and Goliad County locations, respectively. Data were analyzed by ANOVA and means were separated according to LSD (P = 0.05) using Agriculture Research Manager, revision 6.1.6 (4th edition) dated August 31, 2000 from Gylling Data Management, Inc.

Petroleum Oils as Navel Orange Fruit Thinning Agents

The potential of petroleum sprays to thin navel orange (Citrus sinensis) crops in the San Joaquin Valley of California was examined in 1996, 1997 and 1998. Petroleum oils had not been used within the experimental site as adjuvants in other sprays or as pesticides in the previous year or during the experiment. `Bonanza' navel oranges trees were treated annually or in alternate years with a light narrow-range petroleum oil [distillation midpoint of 415 °F (213 °C)], a medium narrow-range oil [distillation midpoint of 440 °F (227 °C)] and/or heavier oil [distillation midpoint 470 °F (247 °C)] in a range of applications from 5 to 15% by volume in a total spray volume of 200 gal/acre (1870 L·ha-1). Trees treated with oil in 1996, 1997 and 1998 had 38% and 27% fewer fruit per tree in 1997 and 1998, respectively compared to trees not treated with oil indicating that crop thinning had occurred. In 1998, yield was lower in the trees that had been treated with oil annually for three consecutive years. Consecutive, annual applications of petroleum oil applied 1 to 3 weeks after petal fall produced a shift from smaller fruit sizes to larger fruit sizes beginning the second year.

Control of Quackgrass (Elytrigia repens) and Field Mint (Mentha arvensis) with Glyphosate Applied Preharvest

Field experiments showed that quackgrass could be controlled by glyphosate applied preharvest to barley. In separate experiments, field mint was controlled by glyphosate applied pre- and postharvest to barley and wheat. Suppression of quackgrass regrowth one year following treatment was 90% or greater when glyphosate was applied at 0.9 kg ai/ha alone or at 0.45 kg ai/ha in combination with both tallow amine ethoxylate at 0.5% of total spray volume and ammonium sulfate at 3 kg/ha. Field mint shoot counts were reduced 84% the year following treatment when glyphosate was applied at 0.25 kg ai/ha and 95% when applied at 1.0 kg ai/ha. Suppression of field mint shoot regrowth the following year was 84% when glyphosate was applied postharvest and 93% when applied preharvest. Addition of tallow amine ethoxylate did not improve field mint control. Glyphosate applied preharvest to barley and wheat at less than 30% grain moisture content had no effect on grain yield.

Relationship between the Spray Droplet Density of Two Protectant Fungicides and the Germination of Mycosphaerella fijiensis Ascospores on Banana Leaf Surfaces

The effect of fungicide spray droplet density (droplet cm-2), droplet size, and proximity of the spray droplet deposit to fungal spores was investigated with Mycosphaerella fijiensis ascospores on the banana (Musa AAA) leaf surface for two contact fungicides: chlorothalonil and mancozeb. When droplet size was maintained at a volume median diameter (VMD) of 250 μm while total spray volume per hectare changed, M. fijiensis ascospore germination on the leaf surface fell below 1% for both fungicides at a droplet deposit density of 30 droplet cm-2. At a droplet deposit density of 50 droplet cm-2, no ascospores germinated in either fungicide treatment. When both droplet size and droplet cm-2 varied while spray volume was fixed at 20 litre ha-1, ascospore germination reached 0% at 10 droplet cm-2 (VMD=602 μm) for both fungicides. At lower droplet densities (2–5 droplet cm-2 VMD=989 μm and 804 μm respectively), ascospore germination on the mancozeb-treated leaves was significantly lower than on the chlorothalonil-treated leaves. The zone of inhibition surrounding a fungicide droplet deposit (VMD=250 μm) on the leaf surface was estimated to extend 1·02 mm beyond the visible edge of the spray droplet deposit for chlorothalonil and 1·29 mm for mancozeb. The efficacy of fungicide spray droplet deposit densities which are lower than currently recommended for low-volume, aerial applications of protectant fungicides was confirmed in an analysis of leaf samples recovered after commercial applications in a banana plantation. Calibrating agricultural spray aircraft to deliver fungicide spray droplets with a mean droplet deposit density of 30 droplet cm-2 and a VMD between 300 and 400 μm will probably reduce spray drift, increase deposition efficiency on crop foliage, and enhance disease control compared to aircraft calibrated to spray finer droplets. © 1997 SCI.

Relationship between the Spray Droplet Density of Two Protectant Fungicides and the Germination ofMycosphaerella fijiensisAscospores on Banana Leaf Surfaces

The effect of fungicide spray droplet density (droplet cm-2), droplet size, and proximity of the spray droplet deposit to fungal spores was investigated with Mycosphaerella fijiensis ascospores on the banana (Musa AAA) leaf surface for two contact fungicides: chlorothalonil and mancozeb. When droplet size was maintained at a volume median diameter (VMD) of 250 μm while total spray volume per hectare changed, M. fijiensis ascospore germination on the leaf surface fell below 1% for both fungicides at a droplet deposit density of 30 droplet cm-2. At a droplet deposit density of 50 droplet cm-2, no ascospores germinated in either fungicide treatment. When both droplet size and droplet cm-2 varied while spray volume was fixed at 20 litre ha-1, ascospore germination reached 0% at 10 droplet cm-2 (VMD=602 μm) for both fungicides. At lower droplet densities (2–5 droplet cm-2 VMD=989 μm and 804 μm respectively), ascospore germination on the mancozeb-treated leaves was significantly lower than on the chlorothalonil-treated leaves. The zone of inhibition surrounding a fungicide droplet deposit (VMD=250 μm) on the leaf surface was estimated to extend 1·02 mm beyond the visible edge of the spray droplet deposit for chlorothalonil and 1·29 mm for mancozeb. The efficacy of fungicide spray droplet deposit densities which are lower than currently recommended for low-volume, aerial applications of protectant fungicides was confirmed in an analysis of leaf samples recovered after commercial applications in a banana plantation. Calibrating agricultural spray aircraft to deliver fungicide spray droplets with a mean droplet deposit density of 30 droplet cm-2 and a VMD between 300 and 400 μm will probably reduce spray drift, increase deposition efficiency on crop foliage, and enhance disease control compared to aircraft calibrated to spray finer droplets. © 1997 SCI.

Control of Tarnished Plant Bug, 1995

Abstract Cotton (‘DES 119’) was planted on 5 May in plots 8 rows (40 inch centers) by 65 ft on the Delta Branch Experiment Station, Stoneville, MS. Treatments were arranged in a RCBD with 4 replicates. Treatments were applied on 20 and 27 Jun by a high-clearance spray machine equipped with a compressed-air apray system. Total spray volume was 6 gpa at 5 mph and 35 psi using two TX10 nozzles/row. Visual samples were taken by examining 25 terminals per plot and recording numbers of adults and nymphs. Damage was also assessed similarly. Tarnished plant bug adults and nymphs were sampled with a drop cloth (1.0 by 0.97 m) from 1 m of a row at 4 random locations in each plot on each sample date. In each plot, 4 random sweep net samples were taken; 10 sweeps across a single row constituted a sample. Numbers of adults and nymphs captured in the samples were determined in the field. Pretreatment counts were made on 19 Jun and counts were taken 3 DAT for each application.

Evaluation of Microbial and Conventional Insecticides for Control of Larval European Corn Borer on Whorl Stage Corn, Clay Center, Ne, 1995

Abstract Bacillus thuringiensis formulations and conventional insecticides were evaluated for efficacy against larval ECB in whorl stage field corn. All plots were planted without soil insecticide on 16 May. The experimental design was a RCB with 4 replicates. Each plot consisted of a single row, 40 ft long with a 30-inch row spacing. Plots were artificially infested with black-head stage ECB egg masses. The egg masses were deposited on wax paper discs, precounted in the laboratory and placed in the whorl of the infested plants on 30 Jun and 9 Jul. Crop growth stage was 37 and 57 inches extended leaf height, respectively. The same 5 plants in each treatment replicate were infested with 10 egg masses per infestation date. All granular insecticides were applied on 13 Jul. Environmental conditions were: air temperature, 81°F; wind direction and speed, west (250°) at 7 mph; relative humidity, 53%; and crop growth stage, 63 inches extended leaf height. A 10-inch Almaco smooth belt cone rear mounted on a Hahn Hi-Boy was used to apply preweighed amounts of the granular insecticides over the top of the plant whorls (G). Liquid insecticides were applied on 15 Jul. Environmental conditions were: air temperature, 74°F; wind direction and speed, east (80°) at 5 mph; relative humidity, 76%; and crop growth stage, 67 inches extended leaf height. A CO2 pressurized backpack sprayer at 30 psi was used to apply a band application over the top of the whorl (total spray volume = 1050 ml/plot) of premeasured amounts of the liquid insecticides (L). All infested plants were evaluated for ECB larval feeding damage on 14-15 Aug. The stalks of the infested plants were split lengthwise and the accumulated length and number of cavities in the 5 plants per treatment replicate were used to evaluate ECB larval damage. The percent infestation at evaluation was determined by the plants with a minimum of 1 cavity per treatment replicate. Data were analyzed by ANOVA for RCB with mean separation using DMRT.

Control of Tarnished Plant Bug, 1994

Abstract Cotton (‘DES 119’) was planted on 6 May in plots 8 rows (40 inch centers) by 65 ft on the Delta Branch Experiment Station, Stoneville, Miss. Treatments were arranged in a RCBD with 4 replicates. Treatments were applied on 21 Jun by a high-clearance spray machine equipped with a compressed-air apray system. Total spray volume was 6 gpa at 5 mph and 35 psi using two TX10 nozzles/row. Tarnished plant bug adults and nymphs were sampled with a drop cloth (1.0 by 0.97 m) from 1 m of a row at 4 random locations in each plot on each sample date. In each plot, 4 random sweep net samples were taken, and 10 sweeps across a single row constituted a sample. Numbers of adults and nymphs captured in the samples were determined in the field. Efficacy was determined 3 DAT.

Cotton Aphid Control, 1995

Abstract Treatments were tested for relative efficacy against cotton aphid in nonirrigated cotton planted 5 May at Stoneville, MS. Plots of 8 rows (40 inch centers) by 65 ft, separated by 15 ft alleys, were arranged in a RCBD with 4 replicates. All treatments were applied by a high-clearance spray machine equipped with a compressed air spray system. Total spray volume was 6 gal/acre at 5 mph and 35 psi using 2 TX10 nozzles/row. Plots within a replicate were sprayed consecutively with the boom rinsed twice and blown clear between plots. A pretreatment survey on 19 Jun indicated a moderate aphid infestation. Treatments were applied on 20 and 27 Jun. Efficacy was determined by counting aphids per square inch on leaves in the top and middle portions of 80 randomly chosen plants/treatment at 3 and 6 or 7 DAT.

Cotton Aphid Control, 1994

Abstract Treatments were tested for relative efficacy against cotton aphid in nonirrigated cotton planted 6 May at Stoneville, MS. Plots of 8 rows (40 inch centers) by 65 ft, separated by 15 ft alleys, were arranged in a RCBD with 4 replicates. All treatments were applied by a high-clearance spray machine equipped with a compressed air spray system. Total spray volume was 6 gpa at 5 mph and 35 psi using 2, TX10 nozzles/row. Plots within a replicate were sprayed consecutively with the boom rinsed twice and blown clear between plots. Treatments were applied on 5 Jul. Efficacy was determined by counting aphids per square inch on leaves in the top and middle portions of 40 randomly chosen plants/ treatment at 3 and 6 DAT.

Ovicidal Activity Trial, 1995

Abstract Treatments were applied to cotton grown in small plots at Stoneville, Miss. Plot size was 30 ft X 4 rows arranged in a RCBD with 4 replicates/treatment. Treatments were applied on 12 Jul (Test 1) and 18 Aug (Test 2) by a high-clearance spray machine equipped with a compressed-air spray system. Total spray volume was 6 gpa at 5 mph and 35 psi using two TX10 nozzles/row. TB eggs were obtained from cultures maintained in the laboratory. Test 1 eggs were obtained from a susceptible STV-LAB strain and Test 2 eggs were from a resistant G2-95 strain. The STV-LAB strain had been in culture without insecticide selection pressure since collection from cotton in 1984; the G2-95 strain was collected from cotton 13-16 Jun, 1995, and had been shown to have multiple resistance by standard bioassays. All eggs used were laid the previous night on tulle cloth material. Eggs were not washed or subjected to chemical treatments before use and were easily removed by crumpling the material. Eggs treated in the field were placed on the upper surface of the last 3-4 expanded leaves in the terminal of 4 plants in each replication by brushing a weak solution of xanthan gum and water on the leaves and sprinkling eggs on the surface. Plots were sprayed 30 min after application of the eggs. Eggs were sprinkled on the leaves in an effort to get at least 10 eggs/leaf. Eggs remained in the field for 2 h after treatment and were then taken to the laboratory to determine mortality. The number of viable eggs was counted on each leaf in the laboratory 24 h after being sprayed. The number of eggs averaged 15.0 ± 5.5 (S.D.). Leaves were held in Petri dishes on water-moistened filter paper at 82° F. The number of unhatched eggs was determined at 48 and 72 h after eggs were applied. Eggs were considered dead when black and shriveled. Cumulative egg mortality (EM) 72 h after treatment is reported. Hatched larval mortality (LM) was observed at 48 and 72 h after treatment and is reported as cumulative larval mortality at 72 h after treatment. Larval mortality was used to calculate total mortality (TM) at 72 h.