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The test was conducted in a grower’s solid-set, sprink Ier-irrigated field. The soil type was Ritzville silt loam (Calciorthidic HaploxerolIs), and the organic matter content was less than 0.5%. On Apr 2, 5 soil samples were taken at each of 10 sites to a depth of at least 18 inches with a posthole digger; 28 wireworms were found for an estimated density of 2.24 wireworms/ft2 . The test area consisted of 4 adjacent blocks of 4 different application methods: i preplant broadcast (BCST), at-plant sidedress (APSD), at-plant seed furrow (FURR), and post-emergence sidedress (PESD). Each plot’ measured 40 ft long and 4 rows wide (34 inch row spacing), and each treatment was replicated 4 times. On May 1, BCST applications were made: granular formulations with a hand-operated Cyclone grass seeder, and liquid formulations diluted in water to a volume of 1 qt with a hand-held, 2-row sprayer with a boom consisting of 4 TeeJet (No. AL80015) nozzles and applied at a rate of 24 gal/acre at a pressure of 30 psi. The plots were rototilled to a depth of 4-6 inches within 1 hr after application.

The test was conducted at the Oregon State University Columbia Basin Experiment Station in a solid-set sprinkler-irrigated field. The soil type was Ephrata sandy loam (Xerollic Camborthids), and the organic matter content was less than 1%. The test area consisted of 4 adjacent blocks of 4 different application methods: preplant broadcast, at-plant sidedress, seed-piece furrow, and postemergence sidedress. Each plot measured 12.2 m and 4 rows wide (86.4 cm row spacing). On Apr 30, broadcast applications were made: granules were broadcast with a hand-operated Cyclone grass seeder, and liquid formulations were applied with a hand-held 2-row sprayer with a boom consisting of 4 TeeJet (No. AL80015) nozzles. Liquid formulations were diluted in water to a volume of 0.95 litre and applied at a rate of 224.5 litre/ha at a pressure of 2.1 kg/cm2 . The plots were rototilled to a depth of 10.2-15.2 cm within 1 hr after application. On May 2-3, potato seed pieces were planted with a 2-row planter and the at-plant sidedress and seed-piece furrow applications were made. On June 1, postemergence sidedress materials were applied 2 rows at a time with tractor-mounted Gandy and liquid applicators in a manner similar to that used with the at-plant sidedress materials. On Oct 2-4, tuber samples were harvested from the 2 center rows of each replicate (from ca. 4.6 m/row). All tubers were washed and examined for wireworm feeding, and the percentages, by weight, of tubers injured and damaged were determined. “Injured” was defined as any penetration of a tuber by a wireworm and “damage” as any injury as severe as described in Sec. 51.1560 and 51.1564 of the U.S. Standards for Grades of Potatoes. All percentages were transformed to arcsine Percentage and analyzed by analysis of variance (a modified split-plot design in which replications were within application blocks) and Duncan’s multiple range test. Materials that were not applied with all 4 application methods were not included in the analysis.

The soil type was Ritzville Series, silt loam, with less than 0.5% organic matter. On March 3 and 11, soil samples were taken with a posthole digger to estimate the wireworm population. Thirteen wireworms were found in 132 samples, a calculated density of 0.9 wireworms/ft2, based on a 95% confidence limit. Preplant broadcast and at-plant band treatments were separate experiments. Each treatment was replicated 4 times in a randomized complete block design. Individual plots were 6 rows wide (34 in apart) and 50 ft long. On April 29, the preplant broadcast treatments were applied and incorporated into the soil. Granules were broadcast with a hand-operated grass seeder, and EC formulations were applied with a hand-held 2-row sprayer consisting of 4 Teejet nozzles. The EC formulations were diluted in water to a volume of 1 qt and applied at a rate of ca. 12.8 gal/acre at a pressure of 30 psi. The plots were rototilled to a depth of 6 inches within 2 hr after application. Potatoes were planted on May 22 and on May 23, the at-plant band treatments were applied 4 inches to each side and level with the seed pieces. Granules were applied with tractor-mounted Gandy applicators in 1-inch bands, 2 rows at a time. The EC formulations were diluted in water to a volume of 1 qt and applied at a pressure of 30 psi to 2 rows at a time by using a tractor-mounted applicator. All plots were sprinkler irrigated. Tuber samples were harvested on October 6 to 8 from the 2 center rows of each plot (15 ft/row). All samples were washed and examined, and the percentages, by weight, of injured and culled tubers due to wireworms were determined. “Injured” was defined as any injury severe enough to meet the description of “damage” in Sec. 51.1554 of the U. S. Standard for Potatoes. The percentages were transformed toX + 0.5 and analyzed by analysis of variance (split-plot design) and Duncan's new multiple range test.

The test was conducted in a grower’s solid-set, sprinkler-irrigated field. The soil type was Ritzville silt loam (Calciorthidic Haploxerolls), and the organic matter content was less than 0.5%. The test area consisted of 4 adjacent blocks of 4 different application methods: prep I ant broadcast, at-plant sidedress, seed-piece furrow, and postemergence sidedress. Each plot measured 12.2 m long and 4 rows wide (86.4-cm row spacing). On Apr 20, broadcast applications were made: granules were broadcast with a hand-operated Cyclone grass seeder and liquid formulations with a hand-held, 2-row sprayer with a boom consisting of 4 TeeJet (No. AL80015) nozzles. Liquid formulations were diluted in water to a volume of 0.95 litre and applied at a rate of 224.5 litres/ha at a pressure of 2.1 kg/cm2. The plots were rototilled to a depth of 10.2-15.2 cm within 1 hr after application. On Apr 24-26, potato seed pieces were planted with a 2-row planter and the at-plant sidedress and seed-piece furrow applications were made. On May 30, postemergence sidedress materials were applied 2 rows at a time with tractor-mounted Gandy and liquid applicators in a manner similar to that used with the at-plant sidedress materials. On Sep 24-26, tuber samples were harvested from the 2 center rows of each replicate (from ca. 4.6 m/row). All tubers were washed and examined for wireworm feeding, and the percentages, by weight, of tubers injured and damaged were determined. “Injured” was defined as any penetration of a tuber by a wireworm and “damage” as any injury as severe as described in Sec. 51.1560 and 51.1564 of the U.S. Standards for Grades of Potatoes. All percentages were transformed to arcsine percentage and analyzed by analysis of variance (a modified split plot design in which replications were within application blocks) and Duncan’s multiple range test. Materials that were not applied with all 4 application methods were not included in the analysis.

The test was conductad in a grower's solid-set, sprinkler-irrigated field. The soil type was Ritzville silt loam (Calciothidic Haploxerolls), and the organic matter content was less than 0.5%. On Mar 20, five soil samples were taken at each of 20 sites in the field (75 acres) to a depth of at least 18 inches with a posthole digger to estimate the wireworm population. Six wireworms were found in 100 samples, a mean density of 0.24 wireworms/ft2. The soil temperatures at 6, 12 and 18 inches were 8, 7 and 6°C, respectively. The test area consisted of 4 adjacent blocks for four different application methods: preplant broadcast, at-plant sidedress, seed piece furrow, and postemergence sidedress. The same granular formulations were applied in each block. Plots within the blocks measured 32-ft long and 4-rows (11.3 ft) wide (34-inch row spacing). Each treatment was replicated 3 times in a randomized complete block design within each block. Broadcast applications were made Apr 12 with a hand-operated Cyclone grass seeder. Plots were rototilled to a depth of 4-6 inches within 1 hour after application; and potato seed pieces, 'Russet Burbank', were planted on Apr 13 with a two-row planter. The at-plant sidedress applications were made with Gandy applicators mounted on the planter and the chemicals were shanked 3-4 inches to each side and level with the seed piece in 1-inch bands; then the materials applied in the seed furrow were deposited through the planter shoe in 1-inch bands immediately after the seed pieces dropped. The postemergence sidedress applications were made May 19 with tractor-mounted Gandy applicators in a manner similar to the at-plant sidedress applications. On Sep 26-27, tuber samples were harvested from the two center rows of each replicate (ca 15 ft/row). All tubers were washed and examined and the percentages, by weight, of tubers injured and culled tubers because of wireworms were determined. “Injured#x201D; was defined as any penetration of a tuber by a wireworm, and “culled#x201D; was defined as any injury severe enough to meet the description of “damage#x201D; in Sec. 51.1560 and 51.1564 of the U.S. Standards for Grades of Potatoes. The percentages were transformed to arcsine percentage and analyzed by analysis of variance (split-plot design) and Duncan's multiple range test.

The test was conducted in a grower’s center-pivot, sprinkler-irrigated field. The soil type was Ritzville (Calciorthidie Haploxerolls) silt loam; it contained less than 0.5% organic matter. Soil samples (150) taken in a similar adjacent field with a 51/2-in. diam posthole digger to a depth of at least 18 in. gave 12 Great Basin wireworms and 40 false wireworms. Each plot measured 50-ft long and 6-rows wide (34-in. apart), and each treatment was replicated 4 times in a randomized complete block design. The materials, all granular formulations, were broadcast Apr 1 with a hand-operated grass seeder and disced to a depth of 4-6 in. within 1 h after application. The seed pieces were planted Apr 2 by the grower. On Aug 29, tubers were obtained from rows 2 and 5 of each plot (15 ft/row). All were washed and examined, and the percentages, by weight, of injured and culled tubers were determined. “Injured” was defined as any penetration of a tuber by wireworms or false wireworms and “culled” was defined as any injury severe enough to meet the description of “damage” in Sec. 51.1554 of the U. S. Standard for potatoes. The percentages were transformed to arcsine and analyzed by analysis of variance and Duncan’s multiple range test. All of the treatments produced significantly fewer injured and culled tubers than the check.

The test was conducted in a grower’s center-pivot, sprinkler-irrigated field. The soil type was Ritzville (Calciorthidic Haploxerolls) silt loam; it contained less than 0.5% organic matter. On Mar 31 and Apr 7, soil samples were taken with a 5 1/2-in. diam posthole digger to a depth of at least 18 in. in the vicinity of the test site (ca. 10 acres) to estimate the wireworm population; 5 wireworms were found in 90 samples. Soil temperature at depths of 9, 12, and 18 in. was ca. 10°C. Two adjacent blocks were used; one was treated by preplant broadcast and one by sidedress applications at planting. Both blocks were divided into 2 subblocks, each of which contained several insecticide treatments and an untreated check. Each plot measured 50-ft long and 60rows wide (34-in. apart), and each treatment was replicated 4 times in a randomized complete block design within each subblock. On Apr 27 and 28, broadcast treatments were applied; granules were applied with a hand-operated grass seeder, and EC formulations were diluted in water to a volume of 1 qt and applied with a hand-held, 2-row sprayer with a boom consisting of 4 Teejet (No. 8001) nozzles at a rate of ca. 12.8 gal/acre at a pressure of 30 psi. The plots were rototilled to a depth of 4-6 in. within 2 hr after appli-cation. On Apr 30, potato seed pieces were planted by the grower and on May 3 and 4, sidedress treatments were applied 2 rows at a time, 3-4 in. to each side of and level with the seed piece. Granules were applied with tractor-mounted Gandy applicators in 1-In. bands, and EC formulations were diluted to a volume of 1 pt and applied at a pressure of 30 psi with Teejet 35 (No. 4916) nozzles with a tractor-mounted applicator. On Oct 5 and 6, tubers were harvested from rows 2 and 5 of each plot (15 ft/row). All were washed and examined, then the percentages, by weight, of injured and culled tubers were determined. “Injured” was defined as any penetration of c tuber by a wireworm, and “culled” was defined as any injury severe enough to meet the description of “damage” in Sec. 51.1554 of the U.S. standard for Potatoes. The percentages were transformed to arcsine percentage and analyzed by analysis of variance (split-plot design) and Duncan’s multiple range test. The methods of application were considered main-plot treatments, and the compounds or formulations were subplot treatments. Subplot treatments that were not used in both main plot treatments were not included in the analysis.

The soil was Ritzville silt loam (Calciorthidlc Haploxerolls) with an organic matter content of less than 0.5/6. The larvae were field-collected and of medium size. The bioassays were conducted as follows: Insecticides were mixed with air-dry soil in a Twin shell blender for 10 min, distilled water was added (6.8 parts:100 parts soil by weight) and mixed for another 10 mln, and the treated soil was placed in 0.5 pt glass fruit jars. Dosage rates simulated broadcast treatments, and the incorporation of materials 6 inches deep in soil. One boiled wheat grain was pushed down ca 1 inch into the soil of each jar. One wireworm was then placed on the soil of each jar; only those that burrowed into the soil within 2 min were used in the test. The jars were covered with plastic lids and were held In a laboratory maintained at ca 20-25°C. Each treatment consisted of 10 jars (replicates), and Dyfonate was included in each test as a standard. Once a week, each jar was checked to determine mortality, the soil and larva were returned to the jar, new boiled wheat grain was added, and moisture, if required, was added to the soil as required. Percent mortality for any given week was based on the weekly cumulative total of dead larvae and moribund larvae that died the following week.

The test was conducted in a solid-set, sprinkler-irrigated field at the Oregon State University Columbia Basin Agricultural Research and Extension Center to evaluate rates, formulations, and application methods of various chemicals in reducing wireworm damage to potatoes. The soil type was Ephra.ta sandy loam (Xerollic Camborthids) with an organic matter content of less than 1%. On 19 Mar, 50 soil samples were taken with a posthole digger to a depth of at least 18 inches; 4 wireworms were found for an estimated density of 0.32 wireworms/ft2. The test was conducted in a randomized split-plot design with 4 replications. The main treatments (application methods) were: preplant broadcast (BCST), at-plant sidedress (APSD), at-plant seed furrow (FURR), and postemergence sidedress (PESD). Each plot measured 38 ft long and 4 rows wide (34 inch row spacing). On 29 Apr, BCST applications were made: granules with a hand-operated Cyclone grass seeder, and liquid formulations diluted in water to a volume of 1 qt applied with a hand-held, CO2boom sprayer consisting of 4 TeeJet AL80015 nozzles at a pressure of 30 psi (25 gal/acre). The plots were rototilled to a depth of 4-6 inches within 1 h after application. On 29-30 Apr, all the plots were planted with a 2-row planter, and APSD and FURR applications were made with applicators mounted on the planter. APSD applications were shanked 3-4 inches to each side and level with the seed pieces; granules were applied as 1-inch bands with Gandy applicators, and liquid formulations were diluted in water to a volume of 1 pt, then applied at a pressure of 40 psi with TeeJet 491635 nozzles. FURR applications were made in the planter shoe and directly behind the seed pieces; granules were placed as 1-inch bands, and liquid formulations were applied with TeeJet 8004F nozzles. On 1 Jun, PESD applications wre made 2 rows at a time with tractor-mounted Gandy and liquid applicators in a manner similar to that of APSD. In 1 treatment, granules of a Temik-Phorate combination were applied over the rows, then incorporated with a Lilliston cultivator. On 6-8 Jun, tuber samples were harvested from the 2 center rows of each replicate (from ca 15 ft/row). All tubers were washed and examined for wireworm feeding, and the percentages, by weight, of tubers damaged were determined. ‘Damage’ was defined as any injury as severe as described in Sec. 51.1560 and 51.1564 of the U.S. Standards for Grades of Potatoes. All percentages were transformed to arcsine percentage and analyzed by analysis of variance (split-plot design) and DMRT. Materials that were not applied by all 4 application methods were not included in the analysis.

The test was conducted at the Oregon State University Columbia Basin Experiment Station in a solid-set, sprinkler-irrigated field. The soil type was Ephrata sandy loam (Xerollic Camborthids) with an organic content of less than 1%. On Apr 5, five soil samples were taken at each of ten sites in the test area (ca 3 acres) with a 5 1/2 inch posthole digger to a depth of at least 18 inches. Three wireworms were found in 50 samples. The soil temperature was 12°C at 6 inches and 10°C at 12 and 18 inches. The test was a split block design. There were four different application methods; pre-plant broadcast, at-plant sidedress, in seed furrow, and postemergence sidedress. Each block was divided into two subblocks, each subblock having its own untreated check. Each replicate measured 40-ft long and 4 rows (11.3 ft) wide (34-inch row spacing). Each treatment of insecticide was replicated 4 times in a randomized complete block design within each subblock. On Apr 25, the broadcast materials were applied. Granular materials were broadcast with a hand-operated Cyclone grass seeder, and the EC formulations were applied with a CO2 hand-held, 2-row sprayer with a boom consisting of four Teejet (No. AL80015) nozzles. EC formulations were diluted in water to a volume of 1 pt and applied at a rate of ca. 12.8 gal/acre at a pressure of 30 psi. The plots were rototilled to a depth of 4 to 6 inches within 1 hr after application. Then on Apr 26-27 and May 1-2, potato seed pieces were planted with a 2-row planter. The at-plant sidedress and seed piece furrow applications were made during the planting operation with applicators mounted on the planter. For sidedress application, the granules were shanked 3-4 inches to each side and level with the seed pieces In 1-inch bands with Gandy applicators, and the EC formulations were diluted in water to a volume of 1 pt when applied at a pressure of 40 psi with Teejet No. 4916-35 nozzjes attached to the rear of the shanks. For furrow applications, the granules were placed in 1-inch bands through the planter shoe, level with and directly behind the seed, and EC formulations were applied with Teejet No. 8004F nozzles in the rear of the planter shoe. In addition, 6-inch band applications were made by applying the chemicals ahead of the planter shoe: for granules, a deflector was attached to the end of the delivery hose so as to produce a 6-inch band; for EC materials, the height of the nozzle, Teejet No. 8004F, was adjusted to deliver a 6-inch band. On Jun 2, postemergence sidedressed materials were applied with a two row tractor mounted Gandy and EC applicators, in a manner similar to the at-plant sidedressed materials. On Oct 3-5, tuber samples were harvested from the two center rows of each replicate (ca 15 ft/row). All tubers were washed and examined for wireworm damage and the percentages, by weight, of tubers injured and culled because of wireworms were determined. “Injured#x201D; was defined as any penetration of a tuber by a wireworm. “Culled#x201D; was defined as any injury severe enough to meet the description of “damage#x201D; in Sec. 51.1560 and 51.1564 of the U. S. Standards for Grades of Potatoes. Because of significant differences in percentages of injured and culled tubers in the untreated check plots between subblocks, all the percentages were converted to percent control so the treatments could be compared with each other. These percentages were then transformed to arcsine percentage and analyzed by analysis of variance (split-plot design) and Duncan's multiple range test. Materials that were not applied by all 4 application methods and those that were applied in 6-inch bands were not included in the analysis.

The soil type was Ritzville Series, silt loam, with less than 0.5% organic matter. On March 16 and 17 soil samples were taken with a posthole digger to a depth of at least 18 inches to estimate the wire-worm population. Five wireworms were found in 40 samples in an area of ca. 10 acres, a calculated density of 1.1 wireworms/sq ft (the upper 95% confidence limits). Individual plots were 6 rows wide (34 inches apart) and 50 ft long. Treatments applied as separate experiments were preplant broadcast, at-plant furrow, and at-plant band. Each treatment was replicated 4 times in a randomized complete block design. For the preplant broadcast treatments applied May 11 and 12, granules were broadcasted with a hand-operated grass seeder, or EC formulations were applied with a hand-held, 2-row sprayer with a boom consisting of 4 Teejet (No. 8001) nozzles. EC formulations were diluted in water to a volume of 1 qt and applied at a rate of ca. 12.8 gal/acre at a pressure of 30 psi. The plots were rototilled to a depth of 4-6 inches within 2 hr after application. The two other treatments were applied after the potatoes were planted May 13. On May 13 and 14 the furrow treatments were applied in the seed-piece furrows left uncovered (by raising the discs of the planter) when the grower planted the seed pieces.