Soil-applied Insecticides Research Articles

Seedcorn Maggots (Diptera: Anthomyiidae) and Slugs in Conservation Tillage Systems in Ohio

Seedcorn maggot, Delia platura (Meigen), adults and slugs were sampled from three tillage systems (conventional, reduced, and no tillage). There was a trend for more adult seedcorn maggots to emerge from reduced- and conventional-tillage systems than from the no-tillage system. Previous crop history influenced numbers of adults emerging, with more flies collected when the previous crop was soybeans rather than corn. Soil insecticide (phorate) application increased numbers of seedcorn maggots 1 yr and reduced them 1 yr. Based on data from this study, seedcorn maggots are not likely to be a problem in conservation-tilled fields where only soybean or corn residue is present. Slug populations were highest in no-tillage systems where crop residue cover was greatest and lowest when no residue was present. There was a trend for numbers of slugs to be greater when the previous crop was soybeans; this is thought to be related to either the increased amount of dead, weed biomass present or a preference for decomposing soybean tissue in the no-tillage system. Slug problems are expected to increase as conservation tillage becomes more common because of the residue cover and inclusion of soybeans in no-tillage rotational systems.

Soybean Foliage Insects in Conservation Tillage Systems: Effects of Tillage, Previous Cropping History, and Soil Insecticide Application

A 3-yr study was initiated to examine individual and interactive effects of tillage (conventional [moldboard plowing], reduced tillage, and no tillage); previous cropping history (corn, Zea mays L., versus soybeans, Glycine max Merrill); and soil insecticide application (phorate versus none) on insect communities inhabiting soybean foliage. Although, as expected, insect abundance varied seasonally and yearly, there were a number of cropping, tillage, and toxicant effects on herbivore and predator species. Japanese beetle, Popillia japonica Newman, populations were influenced more consistently by previous cropping history, with more beetles following corn, than they were by tillage, although highest beetle density occurred in reduced-tillage systems. Neither tillage treatment, previous cropping history, nor insecticide application significantly affected population density of green cloverworm, Plathypena scabra (F.). Potato leafhopper, Empoasca fabae (Harris), numbers were consistently greater in moldboard-plowed than in either reduced- or no-tillage treatments. Also, soil insecticide application lowered potato leafhopper density during 1 yr of the study. Grasshopper density was lower in moldboard-plowed than in reduced- and no-tillage treatments. Tarnished plant bugs, Lygus lineolaris (Palisot de Beauvois), were influenced by both tillage and previous crop treatments. Numbers of nabids (dealt with collectively), the most abundant predator collected during the study, were reduced with soil insecticide treatment and were positively affected by no-tillage practice and having soybeans as a previous crop. Results demonstrated that three management practices, tillage, previous cropping history, and soil insecticide application, can all have separate and interactive influences on foliage insect communities on soybeans, even when these practices impact most directly on the soil.

Control of Wireworms and Aphids with Soil Applied Insecticides and Nematicides, 1986

Abstract Flue-cured tobacco var. NC2326’ was transplanted at the Border Belt Tobacco Research Station, Whiteville, NC, (BBTRS) on 16 Apr in a Faceville sandy clay soil (pH 5.5). Plots were 16 feet wide (4 rows) and 40 feet (22 plants) long arranged in a randomized complete-block design, having 14 treatments and 3 blocks. On 8 Apr broadcast preplant treatments (BC-PPI) were applied with a COa powered backpack sprayer fitted with two 8004 flat fan nozzles. At 25 psi and ca. 2 mph, this delivered 25 gpa finished spray. The 15 inch band application (15 B) of Standak was applied as above with the exception of the use of a single nozzle and slower speed. Granular materials were applied in a 24 inch band with a Noble� granular applicator. Materials were incorporated to a depth of ca. 6 inches within 1 h of applicaiton with a spring tooth harrow. After all BC-PPI treatments were applied, the remaining plots were harrowed and the entire field ridged within 24 h. Soil moisture was poor. Transplant water treatments (TPW) were applied at 200 gpa with a single row transplanter. Side-dress applications 1 and 2 weeks post-transplant (SD-1 and -2) were applied in 6 inch bands on both sides of the row with a Noble granular applicator and incorporated with a rolling cultivator. Ten plants per plot were gently pulled from the second row 19 days post-treatment (30 Apr) and rated for wireworm damage as follows; 0 = no damage, 1 = scars on stalk surface, 2 = feeding reaching pith but tunnelling < 1 cm, 3 = pith tunnelling < 1 cm, and 4 = dead plant. All plants in the 3rd row per plot were rated on 11 Jun for aphid colonization as follows: 0 = no aphids, 1 = 1 to 10, 2 = 11 to 100, 3 = 101 to 1000 and 4 < 1000 aphids/plant. On 9 May flue-cured tobacco ‘var. NC82’ was transplanted at the Upper Piedmont Research Station, Reidsville, NC, (UPRS) into a Cecil sandy loam (pH 5.9). Plots were 4 rows (45 inches on center) wide randomized complete-block design having 14 treatments and 4 blocks. On 2 May, the BC-PPI and 15 B treatments were applied as previously described. The BC-PPI treatments were applied in a 24 inch band centered over the row. Treatments were by incorporated vi ridging of rows. Soil moisture was adequate. TPW treatments were applied at 320 gpa with a single row transplanter. Wireworm damage was rated 22 days post-treatment (26 Jun) as previously described. Aphids were rated on 1 Jul as above. Counts were analyzed by ANOVA.

Soil Applied Insecticides for Control of Nantucket Pine Tip Moth in Kentucky, 1985

Abstract A stand of (ca 2.5 cm diam) Virginia pine on a commercial plantation was used for evaluation. Fifteen single tree replicates were treated 10 Apr at the drip line with either 70 g of 15% granular carbofuran or 70 g of 15% granular disulfoton or 1-150 g Jobe's 16-4-4 tree spike with 1% carbofuran or 1-150 g Jobe's 15-3-3 tree spike with 1% disulfoton or no treatment. One half of the replicates for each treatment were retreated 4 Jun with equivalent original treatments. Once each month trees were examined and the no of damaged tips per tree was recorded. Data from 2 examination dates, corresponding to peaks of larval activity, were chosen for analysis.

Insect Control on Burley Tobacco with Soil Insecticides, 1986

Abstract Eight soil-applied insecticide treatments were evaluated at the Tobacco Experiment Station, Greeneville. Granular and liquid formulations werre applied and incorporated prior to transplanting on 6 Jun. ‘TN 86’ burley tobacco was transplanted on Huntington soil with 2-5% slope of pH 6.6. Plots were 30 ft × 3 rows with 42 inch spacing between rows; plants were spaced 20 inches apart. Treatments were replicated 4 times in a randomized complete block design. Flea beetle damage was reported as average number of feeding holes/10 leaves; counts were made on the fifth leaf (of width greater than 2 inches) from the top of the plant. Aphid rating ranged from 0 (no evident infestation) to 5 (heavy infestation with necrosis of lower leaf bases). Hornworm counts were the number of hornworms/50 plants.

Evaluation of soil-applied systemic insecticides against cabbage aphid, Brevicoryne brassicae (L.), and resultant survival of the primary parasitoid, Diaeretiella rapae (McIntosh), on cabbage.

Evaluation of soil-applied systemic insecticides against cabbage aphid, Brevicoryne brassicae (L.), and resultant survival of the primary parasitoid, Diaeretiella rapae (McIntosh), on cabbage.

Control of Honeylocust Pod Gall Midge with Soil Applied Insecticides, Ft. Collins, CO, 1985

Abstract Recently transplanted honeylocust trees (‘whips’), 6-8 ft tall and approximately 1 inch diameter were treated with soil applications of liquid insecticides 26 Apr. Treatment timing was made approximately 2 wk prior to the first flush of new growth and the first appearance of the insect. Applications were made by injecting liquid formulations of the insecticides at a depth of 6-8 inches approximately 6 inches from the trunk base. Applications were split on both sides of the trees to increase uptake. Plot size was a single tree, replicated 4 times, and arranged in a randomized complete block design. Tree counts of recent pod galls were made to coincide with the end of first generation (14 May), second generation (2 Jun) and third generation (25 Jun) pod gall production.

Tobacco Flea Beetle and Hornworm Control with Soil Insecticides, 1985

Abstract Seven soil-applied insecticide treatment were evaluated at the Tobacco Experiment Station, Greeneville. Granular and liquid formulations were applied and incorporated prior to transplanting on 20 May. Plots were 30 ft × 4 rows with 40-inch spacing between rows; plants were spaced 18 inches apart. Treatments were replicated 4 times in a randomized complete block design. Flea beetle damage was reported as average number of feeding holes/10 leaves; counts were made on the fifth leaf (of width greater than 2 inches) from the top of the plant. Hornworm damage was counted on 3 Jul and expressed as % plants damaged. Soil type was Hermitage silt loam, 2-5% slope, and pH of 6.0.

Commercial Implementation of a Monitoring Program for Psila rosae (F.) (Diptera: Psilidae) in Southwestern British Columbia

Seasonal catches of adult Psila rosae (F.) on sticky yellow-painted cardboard traps varied significantly among 70 commercial carrot fields monitored in British Columbia from 1980 to 1982. Thresholds of 0.2, 0.4, and 0.5 flies per trap per day for 1980 to 1982, respectively, were used to determine the need for soil-applied insecticides to control P. rosae . Over 3 years, growers applied an average of two sprays per crop per season using the monitoring program, compared with averages of nine or six sprays per crop per season had they followed published government production guides or their previous spray routines, respectively. Damage levels were maintained below economic levels in all but two fields. In 1982, the reduced spray regime provided growers with a mean net saving of $83/ha. This represents a 44% reduction in the cost of P. rosae control compared with growers previous conventional control costs.

Effect of Various Soil and Foliar Applied Insecticides on Leafminers in Bell Peppers, 1984

Abstract Pepper seeds were planted 15 Mar on a Willacy fine sandy loam into double-row beds (10 inch rows, 40 inch ceners) at the Texas A&M Research and Extension Center, Weslaco, TX. Plots were 45 ft long by 2 beds wide and bordered by 1 row of forage sorglium. Sixteen treatments were replicated 5 times in a randomized complete block design. Soil treatments were injected as a side-dress application to each row on 15 May using gravity-fed soil injection equipment at a rate of 10 gal/ acre. Foliar treatments were applied weekly beginning 15 May through a CO2 powered, tractor-mounted spray boom at 5.5 gal/acre (4 mph, 45 psi, 2 TX4 hollow cone nozzles/bed). Monitor and Trithion were applied at 10 lb (AI)/acre during the first 4 sprays and at 1 lb (AI)/acre during the last 4 sprays. Spray dates were 1, 8, 15, 21 and 29 Jun and 6, 13 and 20 Jul. Efiicacy was evaluated using 4 methods. (1) Weekly leaf samples were collected from each plot 72 h post-spray (10 leaves/plot) and held in modified 1 pt ice cream cartons for adult emergence. (2) Weekly counts of larvae and pupae were collected from 3 styrofoam pupal trays/plot. (3) Counts of leaf abscission points (LAP) and remaining leaves (RL) were taken from 10 randomly selected plants/plot. Percent leaf drop (PDL) was calculated by the formula LAP/(LAF + RL) X 100. (4) Fruit was collected from 10 randomly selected plants/plot.

Early Season Control with Soil Applied and Transplant Water Insecticides, 1984

Abstract Tobacco was transplanted 25 May in Maury silt loam soil at Clark Co. KY. Individual plots were 6 rows by 43.56 ft arranged in a randomized complete block design using 4 replications. Plants were spaced 18 inches apart with 42 inches between rows. All plots received 2000 lb/acre of 5-10-15 broadcast and incorporated prior to transplanting. Granular formulations of Furadan and Disyston were applied with a Cyclone seeder 4 days prior to transplanting and incorporated to a depth of 2 inches with a disk harrow. No herbicide was used in the plot. Vydate and Orthene were applied in the transplant water solution at the time of setting.

Birch, Evaluation of Soil-Applied Systemic Insecticides for Control of Fall Webworm Caterpillars and Japanese Beetle Adults, Wayne Co., Oh, 1984

Abstract Trees (6.4-8.9 cm dbh) growing in an experimental birch planting and infested with at least 1 webworm nest were chosen for evaluating soil-applied Standak and Di-Syston for control of fall webworm and Japanese beetles. Soil from the base of each tree to its dripline was cultivated prior to and following application of insecticides. Standak treatments were applied with a sprinkling can at the rate of ca. 545 ml of water/m2 of soil surface. Di-Syston granules were applied in salt shaker fashion to the treatment area, raked-in, and then watered as above. All treatments were applied to 4 single-tree replicates on 31 Jul, 5 days after a 3 cm rainfall, so soil moisture was adequate for movement and uptake of systemic insecticides. During the first and second weeks after application, 4.75 and 3.4 cm of rain fell, respectively, on the experimental area. There was no rain during the third week. Treatment effects were evaluated weekly by observing webs for presence of living fall webworm larvae and for evidence of web expansion. A terminal lateral twig was removed from each treated tree and placed in a 1 liter fonda cup with 5 Japanese beetle adults in the laboratory at weekly intervals for 3 wk after application. Living and dead beetles were counted 48 h after caging.

Birch, Evaluating Soil-Applied Systemic Insecticides for Control of Birch Leafminer, Wayne Co., Oh, 1984

Abstract Efficacy of Standak and Di-Syston was evaluated against birch leafminer on 3- to 4-m-tall birch trees growing in an experimental planting at The Ohio State University, Ohio Agricultural Research and Development Center near Wooster. Standak was applied with a watering can at the rate of 545 ml/m2 of soil surface beneath the entire dripline of 4, single-tree replicates. Di-Syston was applied salt shaker fashion and watered-in at the same rate. Soil beneath all trees was cultivated prior to and immediately following application. Treatments were applied 7 May under cloudy skies at 18°C with a breeze of 8-15 kph. Treatment effectiveness was evaluated 18 June by removing 10 leaves at random from 1 dominant lateral twig per tree and counting the number of mined leaves.

White Grub Control, North Carolina, 1984

Abstract Five soil-applied insecticides were evaluated for efficacy in controlling beetle white grubs in pastureland scheduled for Fraser fir* Christmas tree plantings. Grubs were found feeding on Fraser fir roots, causing tree mortality. The test pasture was thickly covered with a mixture of annual and perennial grasses accompanied by various broadleaf weeds. The pasture had been cut for hay 2 wk prior to insecticide applications. The mineral-organic Porter loamy soil (2-3% organic matter) located in Watauga Co. had a pH of 5.5, and average temperature of 15° C at a depth of 4 inches, and a moisture content of 22% by weight. Test plots measured 10 by 10 ft and contained average of 2.4 grubs per sq ft. Each treatment was replicated 5 times; the plots were organized in a completely random design. Pre-treatment grub counts were acquired on 2 Sep, with insecticides applied the same day. One sq ft of sod per test plot was turned back to expose grubs feeding in the rootzone. The sod was replaced without injuring the grubs. Liquid formulations were mixed with 1 gal of water per test plot and applied with a hand-pressurized portable sprayer. Granular formulations were applied with a 20-inch wide hand-pushed spreader. On 13 Oct, posttreatment grub counts were acquired by turning back a previously undisturbed sq ft of sod. Both surviving and dead grubs were counted. Percent population reduction was calculated from the number of surviving grubs and the number of pre-treatment live grubs.

May Beetle Grub Control, North Carolina, 1983

Abstract Six soil-applied insecticides were evaluated for efficacy in controlling May beetle grubs in pastureland scheduled for Fraser fir (Abies fraseri) Christmas tree plantings. The test pasture was densely covered with a mixture of annual and perennial grasses accompanied by various broadleaf weeds. The pasture is harvested for hay once a year in early Sept and had been cut just prior to insecticide applications. The mineral-organic Porter loamy soil (2-3% organic matter) located in Watauga Co. had a pH of 5.4, an average temperature of 15.2 degrees C at a depth of 4 inch, and a moisture content of 21% by weight. Test plots measured 10 by 10 ft and contained an average of 5.8 late-stage grubs per sq ft. Each treatment was replicated 5 times; the plots were organized in a completely random design. Pre-treatment grub counts were acquired on 16 Sep, with insecticides applied the same day. One sq ft of sod per plot was turned back to expose feeding grubs. The sod was replaced without injuring the grubs. Liquid insecticides were mixed with 2 gal of water per plot and applied with a hand-pressurized portable sprayer. Granular formulations were applied with a 20” wide hand-pushed spreader. On 16 Oct, posttreatment grub counts were acquired by turning back a previously undisturbed sq ft of sod. Both surviving and dead grubs were counted and percent grub mortality calculated. Grubs at the observed high population density were causing extensive root damage and chlorotic conditions to the sod.

Control of Tobacco Flea Beetle and Green Peach Aphid with Soil Insecticides, 1984

Abstract Five soil-applied insecticide treatments were evaluated at the Tobacco Experiment Station, Greeneville, TN. Granular insecticides were applied and incorporated on 17 May; liquid formulations were applied and incorporated prior to transplanting on 24 May. Plots were 30 ft x 4 rows with 40-inch spacing between rows; plants were spaced 18 inches apart. Treatments were replicated 4 times in a completely random design. Flea beetle damage was reported as average number of feeding holes/10 leaves; counts were made on the fifth leaf (of width greater than 2 inches) from the top of the plant. Aphid ratings ranged from 0 (no evident infestation) to 5 (heavy infestation with necrosis of lower leaf bases). Soil type was Hermitage silt loam.

Greenbug Control on Grain Sorghum, 1984

Abstract Four soil-applied insecticides were evaluated for greenbug control on ‘Pioneer 8222’ variety grain sorghum planted 30 Mar on a Raymondville clay loam on 40-inch rows at the TAMU-Hoblitzelle Farm near Mercedes, Texas. Treatments were arranged in a randomized complete block design with 4 replications. Experimental plots were 50 ft by 6 rows. All treatment were applied in-furrow at planting with a Gandy applicator. The additional side-dress application was made 45 days post-plant. All plots were furrow irrigated on 2 Apr, 2 May and 15 Jun. Plant populations were estimated on 17 Apr from plant counts in three 10-ft samples/plot. Greenbug populations were estimated weekly by checking 10 randomly selected plants/plot. Beginning 15 May, sample size was reduced to 5 plants/plot. One application of Lorshan (0.25 lb Al/acre) was applied to control sorghum midge at ca. 50% bloom.

Control of Leaf-Feeding Insects of Flue-Cured Tobacco with Soil Applied Insecticides, 1983

Abstract Tests were established on commercially grown tobacco in Wayne (Test 1) and Hertford (Test 2) Co., N.C. Soil types were Goldsboro (Test 1) and Norfolk (Test 2) sandy loam. Plots were 16-ft wide (four rows) and 75 ft long (0.0267 acre) and were separated laterally by vacant rows and on each end by 12- or 20-ft turn alleys. Treatments were arranged in a randomized complete block design with three replications. Broadcast sprays were applied 29 Apr., Test 1; 5 May, Test 2) using a tractor-mounted boom sprayer delivering 21.8 and 23.4 gal/acre in Tests 1 and 2, respectively, through 8004 flat fan nozzles at 25 lb/in2. Granular broadcast applications were made using two electrically driven tractor-mounted Gandy applicators. All broadcast applications were incorporated by discing twice in opposite directions. Temik narrow band treatments were applied in a 2 to 3-in. band using an applicator shank (3 May, Test 1; 13 May, Test 2). Granules were placed ca. 3 in. below the surface of a partially formed bed and covered with an additional 2 to 3 in. of soil. Transplant water applications were made using the farmers’ tractor-drawn transplanters (Test 1: 9 May, 320 gal/acre; Test 2: 13 May, 208 gal/acre). Sidedress treatments were applied (14 Jun., Test 1; 16 Jun., Test 2) in a 2 to 3-in. band to one side of each row ca. 2 in. below the surface. Insect counts and damage ratings were made on the middle two rows of each plot. Budworms were counted on 20 or 40 plants and the same plants rated for budworm damage: 0, no damage; 1, light damage typical of feeding by 1st to 3rd stage larvae; 2, heavy damage typical of feeding by large larvae; 3, plant topped by feeding. Flea beetles were counted on 10 plants and the number of feeding holes counted on the uppermost leaf over 6 in. long of the same plant. Green peach aphids were counted on the uppermost leaf over 6 in. long of 10 plants. Twenty plants were rated for overall aphid infestation: 0, no aphids seen; 1, 1 to 10 apterous aphids on most infested leaf; 2, 11 to 50 apterous aphids on most infested leaf; 3, 51 to 200 apterous aphids on most infested leaf; 4, 200+ apterous aphids on most infested leaf; 5, plant heavily infested, honeydew and sooty mold obvious. Hornworms (mixed species) were counted on 20 plants. After harvest and curing, tobacco from each plot per harvest was weighed and given a government grade. Grades were converted to a quality index (1 to 99) and a weighted average computed. All variables were subjected to analysis of variance and means separated using the Waller-Duncan K ratio t test (K ratio = 100). For analysis, aphid, budworm, flea beetle and hornworm numbers were transformed to the square root of N + 0.5.

Control of the Green Peach Aphid and Tobacco Hornworm on Flue-Cured Tobacco with Soil-Applied Insecticides, 1982

Abstract A test was conducted on commercially grown tobacco in Wayne Co., N.C. The soil type was Goldsboro sandy loam. Plots were 0.020 acre (16 by 54.4 ft), four rows wide, separated on each side by a vacant row and on the ends by a 20-ft alley. Treatments were arranged in a randomized complete-design with four replications. Broadcast sprays were applied 14 Apr. using a tractor-mougted boom sprayer delivering ca. 25 gal finished spray per acre through 8004 flat fan nozzles at 35 lb/in2. Incorporation was accomplished by discing twice in opposite directions. The broad band treatment was applied in a 14 in. band over the top of a partially formed bed using a tractor-mounted electric granular applicator (30 Apr.). This band was covered by 2 to 3 in. of soil with a hilling disc. Narrow band treatments were applied 30 Apr. in a 2 to 3 in. band ca. 3 in. below the surface of a partially formed bed and covered with an additional 2 to 3 in. of soil. Transplant water treatments were made 4 May using the farmer’s tractor-drawn transplanter delivering 75 gal/acre. Sidedress treatments were applied in a 2 to 3 in. band ca. 2 in. below the surface to one side of each row (25 May). Twenty plants in the middle two rows were rated for aphid infestation as follows: 0, fewer than 10 aphids on any one leaf; 1, 11 to 50 aphids on any one leaf; 2, 50+ aphids on any leaf; 3 plant heavily infested, honeydew and sooty mold obvious. Plants rated 2 or 3 were considered infested. Aphids were counted on the first leaf from the top at least 6 in. long or the second leaf from the top after topping (10 plants). Hornworms were counted on 20 plants in the middle two rows. After curing, each plot per harvest was weighed and graded. Government grades were converted to a quality index and a weighted average computed. All variables were subjected to an analysis of variance and means separated using the Waller-Duncan K ratio t test (K-ratio = 100). Before analysis, aphid and hornworm numbers were transformed to the square root of N +0.5. Infestation ratings were converted to a proportion of the maximum possible and these and % infested plants were subjected to an arc sine transformation.

Wireworm and Flea Beetle Control on Floe-Cured Tobacco with Soil-Applied Insecticides, 1982

Abstract Tests were conducted on commercially grown tobacco in four locations. Plots consisted of 0.020 or 0.025 acre of tobacco in four rows separated laterally by a vacant fifth row and on the ends by a 16 to 20-ft turn alley. Treatments were arranged in a randomized complete block design replicated three times. Broadcast treatments were applied 14 Apr., 19 Apr., 22 Apr. and 3 May in Tests 1 to 4 respectively. Broadcast spray treatments were applied with a tractor-mounted sprayer at 35 lb/in2 through 8004 flat fan nozzles delivering ca. 25 gal finished spray per acre. Granular materials were broadcast using two tractor-mounted, electrically driven granular applicators. Broadcast treatments were incorporated by discing twice in opposite directions. Transplant water treatments were applied using the farmers’ tractor-drawn transplanters (225, 175, 320, 200 gal/acre in Tests 1 to 4, respectively). Transplant dates were 21 Apr., 29 Apr., 4 May, and 5 May (Tests 1 to 4, respectively). Twenty additional plants were set in the middle rows of each plot at transplanting using hand setters. These (or adjacent mechanically set plants in the case of transplant water treatments) were removed 15 to 20 days later and evaluated for wireworm damage on the following scale: 0, no damage; 1, external feeding not reaching pith; 2, feeding reaching pith but less than 0.5 in. vertical tunneling; 3, stem tunneled over 0.5 in. In test 2, ten alternate plants (from a random start) in the middle two rows were checked for flea beetles and rated for flea beetle damage (1, light to 3, heavy). After harvest and curing, tobacco from each plot was weighed and given a standard federal grade. Grades were converted to a quality index and weighted averages calculated. Analyses of variance tests were conducted on all variables and means were separated using the Waller-Duncan K ratio t test (K ratio = 100). For analysis, flea beetle numbers were transformed to the square root of N + 0.5; damage ratings were converted to a proportion of the highest possible rating and subjected to an arc sine transformation.