Corn Rootworm Insecticides Research Articles

IMPACT OF TILLAGE AND PLACEMENT METHODS ON TERBUFOS INSECTICIDE RUNOFF

On a national scale, the damage caused by corn rootworm (Diabrotica virgifera virgifera LeConte), can causeeconomic loss of up to $650 million annually. To limit these losses, corn producers apply terbufos insecticide to approximately11% of all corn acres at a time when there is a high probability of intense precipitation. When combined with low vegetativecover and disturbed soil surfaces, there is a high potential for terbufos transport into surface water bodies. Increased publicconcern for environmental contamination from the use of agricultural chemicals has prompted many crop growers to lookfor crop production practices that minimize the transport of insecticides by surface runoff. A field experiment was conductedat the Haskell Agricultural Laboratory in northeast Nebraska in the spring of 1989 to develop best management practicesfor applying corn rootworm insecticides. The objective of the study was to determine the influence of three tillage practices(DISK, NOTILL, and PLOW) and two insecticide placement methods (BAND and FURROW) on the transport of terbufosinsecticide (Counter.) with runoff water resulting from high intensity simulated precipitation after chemical application.A randomized complete block design of four replications was utilized. Treatments were laid out in a split-plot fashion withtillage as the main plot and insecticide placement as the subplot. Corn was planted up-and-down hill in 0.76 m row spacingson a Nora silt loam (fine-silty, mixed, mesic Udic Haplustoll) with a field slope of 6 %.<br><br>Water runoff was not significantly affected by either tillage practice or insecticide placement method (P < 0.05). Sedimentlosses from NOTILL plots were significantly less than from the DISK and PLOW treatments. Overall, terbufos transport wassignificantly affected by tillage practice with the NOTILL treatment resulting in less terbufos transport than the PLOW orDISK treatments. However, terbufos transport was not affected by placement method. Samples collected 10 and 20 min afterrunoff initiation indicated that sediment-adsorbed terbufos accounted for more than 90% of total terbufos transport. Nosignificant differences in the sediment-adsorbed levels were noted due to tillage treatment or insecticide placement method(P < 0.05). Tillage and insecticide placement methods significantly affected the dissolved terbufos concentration, especiallyfor samples collected 20 min after runoff initiation where the BAND placement was greater than the FURROW placement.Within tillage treatments, the PLOW treatment had greater dissolved terbufos concentration than the NOTILL treatment after 20 min of runoff.

Influence of cropping practices on corn rootworm in Canada as a basis for assessment of the potential impact of Diabrotica virgifera in Germany

Monitoring of populations of adult corn rootworms (Diabrotica virgifera and D. barberi) in Ontario (CA), and surveys of insecticide use against rootworms, showed that populations declined in the last 10 years and that the proportion of the maize area treated with rootworm insecticide has fallen to &lt;7%. This proportion was directly correlated with the percentage of cropping with continuous maize. The area of insecticide‐treated maize could be further reduced by educating livestock producers about the merits of crop rotation and the possibilities of alternative high‐energy crops, such as winter barley. Populations of rootworm adults and area of continuous maize are currently so low in Ontario that there is a good probability of success for an adult monitoring and insurance programme to replace the use of corn rootworm insecticides. In Germany (where D. virgifera is now absent but may potentially be introduced from the outbreak in the lower Danube basin), the four Federal Länder of Niedersachsen, Nordrhein‐Westfalen, Bayern and Baden‐Württemberg maintain a high frequency of continuous maize. If areas with more than 50% of arable land with maize are considered to be at high risk of rootworm infestation, about 348 000 ha of maize fall into this category. This is a third of the maize production area of the above‐mentioned Federal Länder and more than a fifth of the entire maize production area of Germany in 1995. On the basis of long‐term experience of insecticide use in Ontario, there is a potential for treatment of up to 111 000 ha with rootworm insecticide (terbufos) annually in Germany, at an added insecticide cost of 13 million EUR per annum. Without crop rotation or treatment, rootworm infestations could cost German maize producers 25 million EUR in crop losses each year. The experience in Ontario suggests that Germany should follow a strategy of changing crop rotation away from continuous maize, so as to reduce the potential for establishment of D. virgifera, the potential for economic loss and the potential for increased reliance on insecticides.

Agronomics of Corn Production under Different Crop Rotations in New York

The 1996 Federal Agriculture Improvement and Reform Act decouples support payments from production. Consequently, grain producers must devise rotations based on market prices. The objective of this study was to demonstrate to grain producers that soybean [Glycine max (L.) Merr.]-corn (Zea mays L.) or soybean-wheat/red clover (Triticum aestivum L./Trifolium pratense L.)-corn rotations under reduced inputs (banded herbicides plus cultivation, ∼105 Ib N/acre) compared with continuous corn under full inputs (insecticide, broadcast herbicides, ∼140 Ib N/acre) maintains or enhances corn yields. Field-scale demonstrations, with participating farmers performing field operations, were established on four farms in New York in 1993. When averaged across years and sites, the soybean-wheat/clover-corn and soybean-corn rotations compared with continuous corn yielded 10% greater (141, 139, and 127 bu/acre, respectively). Grain yield, however, had site by rotation interactions. The soybean-wheat/clover-corn rotation yielded greater in eight of 12 site-year comparisons, and the soybean-corn rotation yielded greater in seven site-year comparisons with continuous corn. Major production challenges where corn did not respond positively to rotations include adequate stand establishment and weed control in the soybean-wheat/clover-corn rotation and adequate N fertility in the soybean-corn rotation. We successfully demonstrated that soybean-wheat/clover-corn or soybean-corn rotations with reduced inputs compared with continuous corn under full inputs enhanced or maintained corn yield. New York growers, who adopt soybean-wheat/clover-corn or soybean-corn rotations, have the opportunity to reduce corn inputs, thereby improving profitability and reducing potential environmental problems.

Optimization of Soil Insecticide Rates for Managing Corn Rootworm (Coleoptera: Chrysomelidae) Larvae in the North Central United States

Optimization of soil-applied granular insecticides for control of northern and western corn rootworms, Diabrotica barberi Smith & Lawrence and D. virgifera virgifera LeConte, respectively, was investigated in 8 states in the north central United States. Differences in success ratios (Yes:No, whether root ratings were maintained below the economic injury level) of corn rootworm insecticide rates were analyzed at state and regional levels. The following insecticide rate comparisons were carried out: 0.5 versus 1X rate and 0.75 versus 1X for chlorpyrifos, fonofos, phorate, tefluthrin, terbufos; and 0.6 versus 1X and 0.8 versus 1X for chlorethoxyfos. Regional data also were analyzed using 3.0 and 3.5 (based on 1 to 6 root rating scale) economic injury levels under low, medium, and high rootworm feeding damage. Individual state data were analyzed under combined feeding pressures (low to high) at both 3.0 and 3.5 economic injury levels. Under high rootworm pressure and using an economic injury level of 3.0, there were no significant success ratio (lowest versus 1X rate) differences at the regional level, regardless of insecticide. Findings within individual states may be more important than regional analyses when interpreting optimum insecticide rate performances. Significant within-state differences between success ratios of low and 1X rates (chlorethoxyfos in South Dakota, chlorpyrifos in Minnesota, fonofos in Iowa, phorate in Iowa and Wisconsin, and terbufos in Iowa), although infrequent, were observed using the more conservative 3.0 economic injury level. No failures were seen using tefluthrin (0.5 versus 1X that was evaluated in only half of the participating states). With the exception of the 0.5 versus 1X fonofos rate comparison in Iowa, all incidences of significant failure were eliminated at the 3.5 economic injury level (lowest versus 1X comparisons). Thus, less-than-labeled rates of these insecticides applied in an 18-cm band can be used to manage rootworm larvae effectively with as much consistency as full (1X) rates.

Soil Insecticide Efficacy Trials for Managing Corn Rootworms Using Planting Time Applications in South Dakota, 1995

Abstract The 1995 corn rootworm insecticide efficacy trials were conducted at 5 dryland field sites (Aurora, Cavour, Delmont, Garretson, and Lake Andes) in South Dakota. Experimental design for all studies was a RCB with 4 replications. Individual treatment plots consisted of single 15.2 m long rows which were spaced 96.5 cm apart. Untreated control data from tests containing 2 untreated plots was pooled within replicates to obtain a single mean for comparison with insecticide treatments. Granular insecticide formulations were applied with modified Noble metering units mounted on a specially adapted Kinze 4-row corn planter. Metering units were ground-driven, and all units were calibrated on the planter. Banded (B) insecticide treatments were applied in an 18-cm swath over the open seed furrow in front of furrow-closing wheels (T-band), and were incorporated by the wheels and drag chains. In-furrow (F) treatments were placed directly between double-disk furrow openers and into the open seed furrow. Five roots per replicate were dug for each treatment. Roots were washed, examined for corn rootworm larval feeding damage, and rated in accordance with the Iowa 1 to 6 scale. Root injury ratings were analyzed using SAS’s General Linear Models (GLM) procedure with root rating and percent root protection means being compared by Duncan’s Multiple Range Test.

1St Generation European Corn Borer Larvicide Trial, 1995

Abstract The trial was planted 8 May at the Entomology Research Farm in East Lansing, MI. Experimental design was a RCB with 4 replications. Granular insecticides applied at-threshold for ECB control were delivered through electrically driven Noble metering units attached to a toolbar behind the tractor. Liquid materials were applied with a backpack sprayer. Several registered corn rootworm insecticides were included in the test to address the question of whether or not 1 st generation ECB protection can be expected from an insecticide application targeting corn rootworm (CRW) larvae. These were applied as a T-band and incorporated with drag chains. The time of application for the CRW treatments is referred to as “at planting”, except in the case of Furadan 4F targeting CRW which is indicated by “cultivation”. The cultivation treatment was applied on 6 Jun. The Furadan 4F cultivation plots consisted of 3 rows to allow for broadcast application. All other plots were 1 row X 50 ft. Each plot had an untreated buffer row on either side. Ten consecutive plants in each plot were artificially infested with 2 blackhead-stage ECB egg masses. European corn borer threshold treatments were applied 5 d after artificial infestation. The number of artificially infested plants with ECB cavities, the total number of cavities and the cumulative cm of cavity length were recorded as a measure of ECB damage. Data were subjected to ANOVA and means separated using DMRT.

Evaluation of Corn Rootworm Insecticide Treatments and Carry-Over Control of European Corn Borers in South Dakota, 1995

Abstract A secondary benefit of corn rootworm insecticide treatments could be the residual control of European corn borer (ECB) larvae. Our study was repeated at sites near Aurora, Cavour, Delmont, and Garretson, South Dakota to assess the efficacy and secondary ECB control provided by 3 insecticides (Furadan, 60720A, &amp; Regent). Treatment plots consisted of single 15.2 m long rows which were spaced 96.5 cm apart. The study was arranged in a RCBD with 4 replicates at each site. Granular insecticide formulations were applied with modified Noble metering units mounted on a specially adapted Kinze 4-row com planter. Metering units were ground-driven, and all units were calibrated on the planter before applications. Banded (B) insecticide treatments were applied in an 18-cm swath over the open seed furrow in front of furrow-closing wheels (T-band), and were incorporated by the wheels and drag chains. In-furrow (F) treatments were placed directly between double-disk furrow openers and into the open seed furrow. Cultivation-time liquids were applied using a CO2-powered backpack canister sprayer system equipped with a single nozzle (Teejet 8003 flat fan) hand-held boom. The system was calibrated to deliver 20 gpa. To evaluate rootworm damage 5 roots per replicate were dug for each treatment. Roots were washed, examined for corn rootworm larval feeding damage, and rated in accordance with the Iowa 1 to 6 scale. For assessment of ECB control, 10 com stalks were randomly chosen from each plot. Plants were split vertically and examined for corn borer tunneling damage. The number and length of ECB cavities were analyzed along with root injury data using SAS’s General Linear Models (GLM) procedure and means were compared by DMRT.

First Generation European Corn Borer Larvicide Trial, 1994

Abstract The trial was planted on 13 May at the Entomology Farm in East Lansing, Ml. Treatments were arranged in a RCBD with 4 replications. Plots were 1 row × 50 ft long and spaced 30 inches apart for all treatments except the Furadan broadcast treatment, which was 3 rows wide. Corn rootworm insecticides were included in the test to address a question asked by growers concerning whether or not control of ECB larvae is gained from a rootworm insecticide application. Five registered granular rootworm insecticides and 2 experimentals were applied at planting. Furadan 4F was applied for corn rootworm control using the guideline of spraying 10 to 20 d before rootworm egg hatch. Furadan was applied on 3 Jun as a broadcast treatment, and a band directed at the base of the plant at 20 gpa. A blackheadstage ECB egg mass was placed in the whorl of 10 consecutive plants in each plot on 27 Jun. Whorl treatments were applied on 30 Jun at the rate of 22.0 gpa. Granular materials were applied in band over the whorls. Plots were evaluated on 28 July. The number of plants with ECB tunnel damage, cavities per 10 plants, and the cm of tunneling for each treatment were recorded as a measure of the severity of the ECB damage. Means were analyzed with ANOVA and separated using DMRT.

Characteristics of Corn Rootworm Insecticide Granules and the Grit Used by Cornfield Birds: Evaluating Potential Avian Risks

-Granules of five insecticides used for corn rootworm control (Counter 15G, Dyfonate 20G, Furadan 15G, Lorsban 15G and Thimet 20G) were characterized on the basis of size, shape (spherical to oblong), surface texture (angular to well-rounded), composition and color. The five insecticides have similar sized granules (xR = 0.5 or 0.6 mm). Furadan granules are the most spherical and rounded; those of Dyfonate are the most oblong and angular. Furadan granules are purplish red and composed of silica; granules of the other four insecticides have earth-tone colors and are made of clay. Because mistaking granules for natural grit is likely a route of avian exposure to granular insecticides, granule characteristics were compared with those reported for grit found in gizzards of bird species that frequent cornfields when the insecticides are applied. Mean granule sizes of the five corn rootworm insecticides are at the lower extreme of the average grit sizes found in gizzards of the cornfield bird species. Of the five insecticides, the mean surface texture and shape values for Furadan and Dyfonate granules differ most from those of the grit in birds' gizzards. Only Furadan granules are composed of a material that birds normally use for grit, whereas granules of the other four insecticides have hues most similar to the grit consumed by cornfield birds. Knowledge of grit-use patterns and grit characteristics may be useful in modifying granular formulations to reduce avian exposure to insecticides.

Reduced Rates of Soil Insecticides for Corn Rootworm Control, 1987-1991

Abstract The current application rate for most corn rootworm (CRW) soil insecticides is approximately 1.0 lb of actual insecticide per acre. Reduced rates (V2 and % of the labeled rates) of selected CRW insecticides were included in our regular insecticide evaluations to compare their effectiveness with the labeled rates. Experiments were conducted from 1987 through 1991 at several research locations. Soil insecticides were applied at planting time in-furrow or in a 7-inch band ahead of the firming wheels and incorporated into the soil. The experimental designs were randomized complete block with 4 replications. Each treatment was applied to a single 100- ft row; rows were 30 inches apart. Insecticides were metered through Noble units mounted on each of the planter units 0ohn Deere, 7000 series, 4-row Max-Emerge planter). Five roots were evaluated for damage in each plot using the Iowa State 1-6 scale. Stand counts were determined by recording the number of plants per 17.4 linear ft of row.

Comparative Efficacy of Corn Rootworm Insecticide Rates in South Dakota, 1988

Abstract Insecticide trials were conducted in dryland corn using standard recommended and reduced rates of commonly used granular insecticides. Brookings, Nunda, Chamberlain, Pierre, and Fort Thompson sites served as locations for these studies. The experimental design for all studies was a randomized complete block with 4 replications. Individual treatment plots consisted of single rows, 15 meters in length, with 96.5 cm row spacing. Granular formulations of insecticides were applied with modified Noble metering units mounted on a specially-adapted Kinze, 4-row corn planter. The metering units were ground-driven, and all units were calibrated on the planter. Insecticide granules were applied in a 7-inch band in front of the furrow-closing wheels and incorporated by the wheels and drag chains. Furrow applications were directed immediately between the double disk furrow openers. A seeding rate of 22,100/acre at all study locations. Five roots/replication were dug from each treatment. Roots were washed, examined for rootworm feeding damage, and rated in accordance to the Iowa 1 to 6 scale. The 1988 growing season began with spring seedbeds being moderately moist at best. As the season progressed, soil moisture levels became abnormally low at most dryland locations.

Corn Rootworm Larval Control in South Dakota, 1989

Abstract Three granular corn rootworm insecticide studies were conducted to evaluate various application techniques, rates, and formulations. Garretson, Nunda, Rutland, and 2 Lake Andes sites served as locations for these studies. The experimental design for all studies was a randomized complete block with 4 replications. Individual treatment plots consisted of single rows, 15 m in length, with 96.5 cm row spacing. Granular formulations of insecticides were applied with modified Noble metering units mounted on a specially-adapted Kinze, 4-row corn planter. The metering units were ground-driven, and all units were calibrated on the planter. Insecticide granules were applied in a 7-inch band in front of the furrow-closing wheels and incorporated by the wheels and drag chains. Furrow applications were directed immediately between the double disk furrow openers. Wilson brand 1100 was the corn variety utilized, and it was seeded at a rate of 22,100 kernels/acre at all study locations. Five roots/replication were dug from each treatment. Roots were washed, examined for rootworm feeding damage, and rated in accordance to the Iowa 1 to 6 scale. Sufficient levels of soil moisture were present at all locations. Rootworm infestations ranged from moderate to heavy which resulted in untreated plots being severely damaged. Significant treatment separations were observed in all studies among various pesticides.

Comparative Efficacy of Corn Rootworm Insecticide Rates in South Dakota, 1989

Abstract Insecticide trials were conducted in dryland corn using standard recommended and reduced rates of commonly used granular insecticides. Garretson, Nunda, Rutland, and 2 Lake Andes sites served as locations for these studies. The experimental design for all studies was a randomized complete block with 4 replications. Individual treatment plots consisted of single rows, 15 m in length, with 96.5 cm row spacing. Granular formulations of insecticides were applied with modified Noble metering units mounted on a specially-adapted Kinze, 4-row corn planter. The metering units were ground-driven, and all units were calibrated on the planter. Insecticide granules were applied in a 7-inch band in front of the furrow-closing wheels and incorporated by the wheels and drag chains. Furrow applications were directed immediately between the double disk furrow openers. Wilson brand 1100 was the corn variety utilized, and it was seeded at a rate of 22,100 kernels/ acre at all study locations. Five roots/replication were dug from each treatment. Roots were washed, examined for rootworm feeding damage, and rated in accordance to the Iowa 1 to 6 scale. Sufficient levels of soil moisture were present at all locations.

Corn Rootworm Larval Control in South Dakota, 1988

Abstract Five granular corn rootworm insecticide studies were conducted to evaluate various application techniques, rates and formulations. Brookings, Nunda, Chamberlain, Pierre and Fort Thompson sites served as locations for these studies. The experimental design for all studies was a randomized complete block with 4 replications. Individual treatment plots consisted of single rows, 15 meters in length, with 96.5 cm row spacing. Granular formulations of insecticides were applied with modified Noble metering units mounted on a specially-adapted Kinze, 4-row corn planter. The metering units were ground-driven, and all units were calibrated on the planter. Insecticide granules were applied in a 7-inch band in front of the furrow-closing wheels and incorporated by the wheels and drag chains. Furrow applications were directed immediately between the double disk furrow openers. Wilson brand 1100 was the corn variety utilized, and it was seeded at a rate of 22,100 kernels/acre at all study locations. Five roots/replication were dug from each treatment. Roots were washed, examined for rootworm feeding damage, and rated in accordance to the Iowa 1 to 6 scale. The 1988 growing season began with spring seedbeds being moderately moist at best. As the season progressed, soil moisture levels became abnormally low at most dryland study locations.

Evaluation of Corn Rootworm Insecticide Application Dates, 1987

Abstract Two timings of corn rootworm insecticides were evaluated &amp;gt;n a Hagerstown silt loam soil near Rocksprings, Pa. Three common soil insecticides were used in the test. Each insecticide was applied at planting and at cultivation at 1 lb (AI)/acre. In addition, Counter 15G was applied at 2 lbs (AI)/acre. A randomized complete block design with 6 replications of 8 treatments was used. Plots were 40 ft long by 6 rows wide. The at-planting time applications were applied using a Max Emerge John Deere 7000® corn planter on 18 May. At cultivation treatments were applied on 26 Jun using a Noble® granular applicator mounted on bicycle wheels. Both at planting and at cultivation applications were applied in 7-inch bands over the row. The corn was planted on 18 May in 30-inch rows at 27,000 plants/acre. In 1987, rainfall measured 2.75, 2.82, 2.84, and 3.88 inches for May, June, July, and August, respectively. On 17 Jul, 5 corn plants were dug per plot and the roots rated for damage using the Iowa six-category rating system (1, no damage to 6, 3 nodes cut). Corn was harvested on 3 Nov and yield measured from the middle 3 rows of each plot.

Evaluation of Corn Rootworm Insecticide Application Methods, 1986

Abstract Three methods of applying corn rootworm insecticides were tested on a Hagerstown silt loam soil near Rocksprings, PA, during 1986. Two common soil insecticides were used in the test. Both insecticides were applied at planting, at cultivation, and side-dressed with nitrogen. A randomized complete block design with 6 replications of 9 treatments was used. Plots were 40 ft by 6 rows wide. The at-planting time applications were applied using a Max Emerge John Deere 70008 corn planter on 30 Apr. At cultivation treatments were applied on 23 Jun using a Noble8 granular applicator mounted on bicycle wheels. Both at planting and at cultivation applications were applied in 7-inch bands over the row. Liquid nitrogen (160 lb/acre) and liquid formulations of the insecticides were applied on 17 Jun using a tractor mounted liquid nitrogen applicator designed for small plots. The corn was planted no-till on 30 Apr in 30 inch rows at 27,000 plants per acre. In 1986, rainfall was minimal during the months of May and June. On 15 Jul, 5 corn plants were dug per plot and the roots rated for damage using the Iowa six category rating svstem (l = no damage; 6 = 3 nodes cut). Corn was harvested on 13 Nov and yield measured from the middle 3 rows of each plot. Corn yields were corrected to a 15.5% moisture content

Northern Corn Rootworm Control by Granular Insecticide Application at Planting and Cultivation Time12

The experimental insecticide carbofuran provided outstanding control of Diabrotica longicornis (Say) larvae when applied on 3 dates. Each of 5 approved corn rootworm insecticides were applied to separate plots on 9 successive dates to compare the relative merits of cultivation-time treatment (June) as opposed to planting-time treatment (May). Phorate, Dasanit® (O, O -diethyl O-[p-(methyl-sulfinly) phenyl] phosphorothioate), and BUX® 3:1 mixture of m -(1-methylbutyl) phenyl methylcarbamate and m -(1-ethylpropyl) phenyl methylcarbamate) gave equally good protection applied in either May or June. Dyfonate® (O -ethyl S -phenyl ethylphosphonodithioate) performed better when applied at planting time in May, but diazinon gave best results when applied at cultivation time in June. Overall, there was an 82.5% reduction of corn rootworm larvae in corn roots from these treatments.