Feeding Scars Research Articles

Life cycle and host specificity ofEutinobothrus sp. (Col.: curculionidae) an agent for biological control ofSida acuta (malvaceae) in the northern territory, Australia

The biology of an undescribed weevil,Eutinobothrus sp., and its specificity toSida acuta, a serious weed in northern Australia, were studied in a quarantine facility in Australia. Sixty-eight plant species were screened and onlyS. acuta andS. rhombifolia could sustain populations ofEutinobothrus sp. Adults feed externally on the stems and oviposit in feeding scars. Larvae feed internally and pupate in the stem. Prepupae and pupae may aestivate in the stem and adults emerge with the onset of the wet season when new growth is evident.Eutinobothrus sp. was released in January, 1994 in the Northern Territory and has established.

Effects of Neem Seed Extract on Feeding Frequency of Nezara viridula L. (Hemiptera: Pentatomidae) on Pecan Nuts

ABSTRACTDifferent concentrations of neem seed extract, containing azadirachtin, were found to significantly decrease the number of feeding sites by the green vegetable bug, Nezara viridula, on pecan nuts. Application of this extract to nuts decreased the feeding scars on nuts from 6.6 per bug per 24 h to 1.9 per bug per 24 h. This decrease was independent of azadirachtin concentration suggesting that only low application rates of this substance may be necessary to significantly reduce the damage done by this insect in pecan orchards.

Insecticidal and Microbial Control of Lepidopteran Pests in Minnesota Cabbage, 1994

Abstract This study was conducted on the University of Minnesota Rosemount Agricultural Experiment Station. Cabbage was transplanted 23 Jun into plots consisting of two 25 ft (7.62 m) rows on 40 inch (1.02 m) centers. Plants were spaced 13 inches (0.33 m) apart. Ten ft (3.05 m) borders and 7 ft (2.13 m) alleys separated the plots. Treatments were arranged in a randomized complete block design with 4 replications. Treatments were applied 28 Jul, 5, 12, and 19 Aug using a moderate-clearance Spirit sprayer with 6 TX-10 hollowcone nozzles (1 overhead and 2 drop nozzles per row). The sprayer was calibrated to deliver 27 gpa (252.5 liters/ha) at 47 psi (3.3 kg/cm2) and 3 mph (4.8 km/hr). Bond sticker/extender was added to all treatments at a rate of 0.10 fl oz/gal (0.79 ml/liter). Insect counts were taken 4 and 22 Aug. Plots were harvested and evaluated for feeding damage on 25 Aug using Green’s rating scale (J. Econ. Entomol. 1969 62(4): 798-800): 1 = no feeding damage; 2 = minor feeding damage on the wrapper leaves (≤ 1% eaten); 3 = moderate feeding damage on the wrapper leaves (2-5% eaten) with no head damage; 4 = moderate feeding damage on the wrapper leaves (6-10% eaten) and minor feeding scars on the head; 5 = moderate to heavy feeding on the wrapper leaves (11-30% eaten) and moderate feeding scars on the head; 6 = >30% of the wrapper leaves eaten and numerous feeding scars on the head.

MonitoringHylobius abietis (L.) (Col., curculionidae) by baited pitfall traps in relation to planting and treatment of seedlings in a re-forested area

The method of standardized baited pitfall, traps for monitoring population ofHylobius abietis (L.) was experimentally included into the routine planting and control schedule (model area) in the Czech Republic. It is recommended to determine characteristics of the area on the basis of long-term monitoring. A short-term prognosis per site must be drawn from monitoring done from the earliest beginning of the season. However, it seems advisable to treat all the individual seedlings immediately after theyhave been planted in the area where the over-all characteristics (ascertained by monitoring) indicate generally high population levels. To base a decision for treatment on the percentage of seedlings attacked (feeding scars) per site is considered unadvisable in comparison with data obtained bymonitoring using baited pitfall traps. Insecticides for the treatment of newly planted seedlings need to be applied to two-thirds of the trunk of a seedling (including the root collar), their action should be fast enough to paralyse (kill) the weevils before they reach xylem by feeding and, furthermore, the residues should be effective up to the end of the season.

Smartbox Insecticide Applicator and Corn Rootworm Larval Control, 1994

Abstract The objective of this study was to obtain corn rootworm efficacy data for Force 3G and Fortress 5G insecticides applied through SmartBox and Noble granular applicator systems. The test plot was planted 3 May at the Iowa State University NW Research Center, located near Sutherland, IA. The research site, a silty clay soil, had been planted to a trap-crop the previous year. The experimental design was a RCB, with insecticide treatments applied to paired rows, 75 ft in length, replicated 8 times. A John Deere 7100, 2-row corn planter had been set up with the SmartBox delivery system and calibrated for application using the radar speed input device. The planter could also be set up to deliver insecticide with modified Noble metering units; SmartBox mounting cradles were removed and replaced with Noble mounting brackets. All treatments were applied at 4 mph and planter drag chains were used for insecticide incorporation. Prior to planting, previous SmartBox calibration settings were checked for accuracy. Controller (computer) settings for all Force and Fortress treatments delivered more than the + 5% allowable range. All treatments were recalibrated according the SmartBox Instruction Guide. Prior to planting, the research area was pre-flagged for treatment placements. All treatments utilizing the SmartBox system were applied and then the planter was converted for the Noble delivery system. When planting, both rows were constantly monitored to ensure that insecticide was being applied correctly. When using the SmartBox delivery system, it was observed that insecticide did not start flowing at the full rate until 5-7 paces (12-17 ft) into the plot. Seemingly, it took this long for the tractor/planter to reach 4 mph and the radar gun to give an accurate reading to the SmartBox controller. To ensure that plot measurements were taken from areas where insecticide was being dispensed at the proper rate, only the center portion of each replication was used. Following the majority of rootworm feeding (18 Jul), 5 consecutive roots were dug from each of the paired treatment rows (10 roots/treatment × 8 replications = 80 roots/treatment). Prior to transport back to Ames, roots were tagged for identification and excess soil was removed. In Ames, a pressurized water spray was used to remove remaining soil. Roots were then rated for rootworm feeding damage on the Iowa 1-6 scale (1 equal to no damage or only a few minor feeding scars, and a 6 rating equal to 3 or more nodes of roots completely destroyed). Lodging counts were taken on 31 Aug. Corn was machine harvested from 30 row-ft per treatment on 14 Oct. Weights were converted to No. 2 shelled corn at 15.5% moisture and analyzed for treatment effects. On 9 Nov, stand counts were taken in the harvested area.

Corn Rootworm Larval Control, 1994

Abstract Rootworm planting-time, soil-insecticide test plots were established at 3 IA locations in 1994. Soil types were: Ames (Chapin), silty clay loam; Nashua, loam; and Sutherland, silty clay. Plots were planted 9, 2 and 3 May, respectively, on areas that had been planted to trap crop (late-planted corn, high plant population) the previous year. A RCBD with 4 replications for the experimental and cultivation tests and 8 replications for the yield trials was used. All treatments were applied to single 50-ft length rows with 30-inch row spacing. Granular insecticide formulations were applied with modified Noble metering units mounted on a 4-row John Deere 7100 planter. Planting-time liquid formulations were applied with a compressed-air delivery system built directly into the planter; 8003E nozzles delivered 13 gpa at 23 psi. Liquid cultivation-time insecticides were applied with a small-plot bicycle sprayer. Two 8002E nozzles, 1 on each side of the corn row, were positioned to deliver either a 7 or 15-inch band width around the base of the plants; 13 gpa at 25 psi. Broadcast (30-inch band) applications of Furadan 4F were applied to single rows. A boom containing three 8002 nozzles (19-inch centers) delivered 13 gpa at 32 psi. One untreated buffer row was left on each side of a “broadcasted” row. Granular cultivation-time insecticide applications were made with electrically-driven Noble units mounted on the tool bar of a 2-row, rear-mounted cultivator. Plastic tubes, positioned directly in front of the cultivator sweeps, directed the insecticide granules to both sides of the corn row for basal treatments. Chemical phytotoxicity was checked in early Jun by taking stand counts from 1/1000 acre and measuring extended leaf heights on 10 consecutive plants (experimental tests only). Rootworm larval feeding was evaluated in Jul by digging 5 roots from each treatment row and rating them on the Iowa 1-6 scale (1 equal to no damage or only a few minor feeding scars, and a 6 rating equal to 3 or more nodes of roots completely destroyed). Lodging counts were taken at harvest time. A plant was considered lodged if the angle between the base of the plant and the ground was 45° or less. Stand counts were taken in the yield plots at harvest time. Yields were measured by hand harvesting 1/1000 acre from each treatment at Nashua and Chapin, and machine harvesting 25 row-ft at Sutherland. To determine treatment differences, data were analyzed using ANOVA and means were separated with Ryan’s Q test (REGWQ).

WARREN ROOTCOLLAR WEEVIL, HYLOBIUS WARRENI WOOD (COLEOPTERA: CURCULIONIDAE), IN CANADA: ECOLOGY, BEHAVIOR, DAMAGE RELATIONSHIPS, AND MANAGEMENT

AbstractWarren rootcollar weevil, Hylobius warreni Wood, is a pest of several conifer species and is distributed widely throughout the boreal forest in Canada. Literature on this weevil is reviewed and interpreted to provide comprehensive coverage of its ecology, behavior, and impacts, and the implications for its management. New information is provided to fill gaps in our knowledge of H. warreni. These include distribution and hosts, immature stages, sex ratios, and daily and seasonal activity patterns of adults. Sex ratios, abundance, longevity, and pedestrian dispersal behavior of adults within the forest and on trees are described from mark, release, and recapture studies conducted over several years using a newly designed interception trap. Daily trap captures are correlated with previous night temperatures and this relationship is a tool for predicting adult captures. Fecundity and oviposition behavior on the host tree are described from laboratory- and field-reared adults.Population levels of H. warreni are compared across a variety of lodgepole pine stands in Alberta. Weevil numbers within forests are described in relation to tree size and age, depth of duff material around tree bases, and stand density. Analysis of weevil feeding scars distributed at the root collar base of mature pine stems were used to describe the likely temporal pattern of population abundance and change during stand development. Information supportive of this pattern is presented from surveys in young and mature stands.A new method of assessing stands of lodgepole pine for suitability of habitat for H. warreni takes into account the cumulative nature of this weevil’s injury and reflects its temporal pattern of success in relation to stand conditions. The effects of a pre-commercial thinning treatment on H. warreni populations and its girdling injury were investigated in a 25-year-old lodgepole pine stand over an 8-year period. Compared with control plots, thinning treatment caused a 5-fold increase in weevil numbers per tree and increased the tree attack incidence by 2-fold, but resulted in an average 6% reduction in partial stem girdling of attacked trees. Information about the effects of various forest management practices on H. warreni abundance and survival is reviewed and areas requiring research are identified.

Brushing Reduces Thrips and Aphid Populations on Some Greenhouse-grown Vegetable Transplants

`Sunny' tomato (Lycopersicon esculentum Mill.), `Black Beauty' eggplant (Solanum melongena var. esculentum L. Nees.), or `Sugar Baby' watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] were nontreated, subjected to brushing (20 strokes twice daily) or drought conditioning (2 hours daily wilt), or maintained undisturbed using ebb-and-flow irrigation. One week after brushing or drought conditioning, plants were inoculated with western flower thrips (Frankliniella occidentalis Pergande) or green peach aphid (Myzus persicae Sulzer). Brushing and drought conditioning reduced plant height and shoot dry weight of all crops. Brushing of all three species generally reduced the number of thrips, as indicated by number of feeding scars or percent leaf area damaged. Drought conditioning did not affect thrips populations consistently. Undisturbed plants grown with ebb-and-flow irrigation exhibited the greatest damage from thrips. Brushing reduced the number of aphids on tomato relative to the nontreated controls. Drought did not reduce aphid populations consistently on any crop. Brushing for height control may be advantageous in an integrated pest-management program to control aphids and thrips.

Importation, releases, and establishment ofNeochetina spp. (Col.: Curculionidae) for the biological control of water hyacinth,Ecchhornia crassipes (Lil.: Pontederiaceae), in Benin, West Africa

Water hyacinth,Eichhornia crassipes (Martius) Solms-Laubach (Pontederiaceae) was first reported in Benin in 1977 and about 10 years later became the major floating water weed in the south east, obstructing boat traffic and fisheries. Water hyacinth multiplies in permanently fresh water in the swampy upper reaches of the So River and in tributaries of the Oueme River. From there it is moved by wind and water flow to the coastal lagoons. The coastal lagoons are brackish during the dry season and water hyacinth eventually dies. In 1991,Neochetina eichhorniae (Warner) (Col.: Curculionidae) of South American origin was imported from Australia via quarantine in Britain to Benin. A small infestation of the fungusBeauveria bassiana (Bals.) Vuill. (Hyphomycetes) was eliminated from the colony before release by sterilizing eggs and rearing a fungus-free generation. Between late 1991 and mid 1993, about 23,900N. eichhorniae were released at 11 localities along the Oueme River and in the head waters of the So River. Regular monitoring revealed feeding scars by adults on leaves and tunnelling by larvae in petioles at all release sites. By October 1993,N. eichhorniae had spread up to 20 km from some release sites.Neochetina bruchi Hustache was imported in 1992. A total of about 5,700 weevils has been released in six localities since mid 1992. Recoveries of offspring were made in all but one locality. Despite the negative impact of water flow, wind, penetration of salt water, and removal of infested water hyacinth by fishermen,N. eichhorniae andN. bruchi are established in Benin in a situation typical for coastal West Africa.

Insecticidal and Microbial Control of Lepidopteran Larvae in Minnesota Cabbage, 1993

Abstract This study was conducted on the University of Minnesota Rosemount Agricultural Experiment Station in cabbage seeded 9 May and transplanted 14 Jun. Plots consisted of two 25 ft (7.62 m) rows on 40 inch (1.02 m) centers. Plant spacing was set for 13 inches (0.33 m). Ten ft (3.05 m) borders and 7 ft (2.13 m) alleys separated the plots. Treatments were arranged in a randomized complete block design with 4 replications. By 26 Jul, 50% of the plants were infested with DBM larvae. On 29 Jul, pheromone traps exceeded 8 CL moths/night and eggs and small larvae for both CL and ICW were present. Treatments were applied 29 Jul, 6, 13, and 20 Aug using a moderate-clearance Spirit sprayer with 5 TX-10 hollowcone nozzles delivering 27 gpa (252.5 liters/ha) at 45 psi (3.16 kg/cm2) and 3 mph (4.8 km/hr). Bond sticker/extender was added to all treatments at a rate of 0.10 fl oz/gal (0.79 ml/liter). Larval counts were taken 11 Aug and 2 Sep. Plots were harvested and evaluated for feeding damage on 10 Sep using Green’s rating scale (J. Econ. Entomol. 1969 62:4 798-800): 1 = no feeding damage; 2 = minor feeding damage on the wrapper leaves (0-1% eaten); 3 = moderate feeding damage on the wrapper leaves (2-5% eaten) with no head damage; 4 = moderate feeding damage on the wrapper leaves (6-10% eaten) and minor feeding scars on the head; 5 = moderate to heavy feeding on the wrapper leaves (11-30% eaten) and moderate feeding scars on the head; 6 = greater than 30% of the wrapper leaves eaten and numerous feeding scars on the head.

Spoke-Injection of Liquid Insecticides for Corn Rootworm Larval Control in Iowa, 1993

Abstract Spoke-injection of liquid insecticides (100% incorporation), was compared with conventional planting- and cultivation-time applications. Plots were established at Rhodes (silty clay loam) and Nashua (loam). A RCB design, with 4 replications, was used. All treatments were applied to single 50-ft length rows with 30-inch row spacing. Granular insecticide formulations were applied with modified Noble metering units mounted on a 4-row John Deere 7100 planter. Plantingtime liquid formulations were applied with a compressed-air delivery system built directly into the planter; 8003E nozzles delivered 10 gpa at 23 psi. Liquid cultivation-time insecticides were applied with a small-plot bicycle sprayer. Two 8003E nozzles, one on each side of the corn row, were positioned to deliver either a 7, or 15-inch band width around the base of the plants; 10 gpa at 10 psi. Broadcast applications of Furadan 4F were applied to single rows. A boom containing three 8002 nozzles (19-inch centers) delivered 13 gpa at 17 psi. One untreated buffer row was left on each side of each "broadcasted" row. Granular cultivation-time insecticide applications were made with electrically-driven Noble units mounted on the tool bar of a 2-row, rear-mounted cultivator. Plastic tubes, positioned directly in front of the cultivator sweeps, directed the insecticide granules to both sides of the corn row for basal treatments. “Spoke-injection” treatments were applied within several days of planting. The spoked applicator cylinder, mounted behind a small tractor, consisted of a 7-inch high-density polyethylene rod, with a 1.5-inch brass axle. Injection points (0.19-inch diam × 1.3-inch in length) were aligned in 10 rows on the cylinder, for a total of 220 points. A tension spring forced the points into the soil. Flat steel scrapers, positioned between rows of points, kept debris from interfering with the function of the spoke injector. Liquid insecticide was injected to a depth of ca. 1 inch using CO2; 20 gpa at 50 psi. Rootworm larval feeding was evaluated by digging 5 roots from each treatment row and rating them on the Iowa 1-6 scale (1 equal to no damage or only a few minor feeding scars, and a 6 rating equal to 3 or more nodes of roots completely destroyed). To determine treatment differences, data were analyzed using ANOVA and means were separated with Ryan’s Q test (REGWQ).

Corn Rootworm Larval Control in Iowa, 1993

Abstract Rootworm planting-time, soil-insecticide test plots were established at 6 locations in 1993. Soil types were: Ames and Rhodes, silty clay loam; Nashua, loam; Newell and Waukee, clay loam; and Sutherland, silty clay. All plots were planted on areas that had been planted to trap crop (late-planted corn, heavy stand) the previous year. A RCB design, with 4 replications for the root-protection trials (registered and numbered products) and 8 replications for the yield trials (registered and EUP products) was used. All treatments were applied to single 50-ft length rows with 30-inch row spacing. Granular insecticide formulations were applied with modified Noble metering units mounted on a 4-row John Deere 7100 planter. Planting-time liquid formulations were applied with a compressed-air delivery system built directly into the planter; 8003E nozzles delivered 10 gpa at 23 psi. Chemical phytotoxicity was checked in early Jun by taking stand counts from 1/1000 acre and measuring extended leaf heights on 10 consecutive plants. Rootworm larval feeding was evaluated in late Jul and Aug by digging 5 roots from each treatment row and rating them on the Iowa 1-6 scale (1 equal to no damage or only a few minor feeding scars, and a 6 rating equal to 3 or more nodes of roots completely destroyed). Lodging counts were taken at harvest time. A plant was considered lodged if the angle between the base of the plant and the ground was 45° or less. Stand counts were taken in the yield plots at harvest time. Yields were measured by hand harvesting 1/1000 acre from each treatment. To determine treatment differences, data were analyzed using ANOVA and means were separated with Ryan’s Q test (REGWQ).

Control of Tobacco Wireworms on Fumigated and Non-Fumigated Land with Soil Insecticides, 1992:

Abstract Two tests were conducted at the Upper Piedmont Research Station near Reidsville, NC, to determine the effects of various soil pesticides on tobacco wireworms. In one test site, the land was fumigated with Telone C-17 on 11 Apr at 98.2 liters/ha, while the other site was not fumigated. The predominant soil type was Cecil loamy sand (pH 6.3). On 13 May, the fumigated test site was divided into 20 plots to form a RCB design with 5 treatments and 4 blocks, while the non-fumigated test was divided into 28 plots to form a RCB with 7 treatments and 4 blocks. Individual plots were 20 plants long (ca. 12.2 m) and 4 rows wide (1.14 m between rows). Sprays were applied using a CO2-powered sprayer fitted with five 8004 Spraying Systems flat-fan nozzles 50.8 cm (20 inches) apart on a 6.7 m (80 inch) boom at 207 kpa (30 psi) and a delivery rate of 234 liters/ha (25 gal/acre). In the fumigated test, the Temik 15 G was applied through two fertilizer shanks attached to an electrically driven, granular applicator. The shanks were positioned 12.7 cm (5 inches) on each side of the row center and 12.7 cm below the final bed surface (SHANK). In the non-fumigated test, the Temik 15 G was applied with the electrically driven, granular applicator with a single 14 inch distributing fan centered on the row (BAND). All treatments were incorporated via ridging immediately after application. Flue-cured tobacco, (K-326, a root-knot nematode-resistant variety) was transplanted on 15 May with a single row transplanter. Soil moisture was very good (13.8%) at the time of transplanting. Nineteen days after transplanting, 10 consecutive plants from row 2 in each plot were gently pulled from the soil. The roots and underground portions of the stems were visually examined and rated for wireworm damage as follows: 0 = no damage; 1 = feeding scars on root surface; 2 = feeding reaching pith with tunneling < 1 cm; 3 = pith tunneling from 1-5 cm; 4 = pith tunneling > 5 cm; and 5 = dead plant. Using this data, the avg wireworm rating and the proportion of wireworm damaged plants was calculated. Data were subjected to ANOVA and WD, K = 100. Proportion of plants infested was transformed to arcsine V proportion before ANOVA.

Control of Tobacco Wikeworms with Winter and Spring Applications of Lorsban, 1992:

Abstract Plots were established at the Border Belt Tobacco Research Station near Whiteville, NC, on 3 Mar. Plots were 22 plants long (ca 13.7 m) and 4 rows wide (1.2 m between rows) and were arranged according to a randomized complete-block design having 8 treatments and 4 blocks. The predominant soil type was Goldsboro fine sandy loam (pH 6.5). Winter treatments were made on 3 Mar and spring treatments were made on 23 Apr. Sprays were applied using a CO2-powered sprayer fitted with 5, 8004 Spraying Systems flat-fan nozzles (20 inches apart) on a 80 inch boom at 30 psi and a delivery rate of 25 gal/acre. All treatments were incorporated via ridging immediately after application. Tobacco was transplanted on 24 Apr. Soil moisture was excellent at the time of transplanting. Twenty-six days after transplanting, 10 consecutive plants from row 2 in each plot were gently pulled from the soil. The roots and underground portions of the stems were visually examined and rated for wireworm damage as follows: 0 = no damage; 1 = feeding scars on root surface; 2 = feeding reaching pith with tunneling < 1 cm; 3 = pit tunneling from 1-5 cm; 4 = pith tunneling > 5 cm; and 5 = dead plant. Using this data, the avg wireworm rating and the proportion of wireworm damaged plants was calculated. Data were subjected to ANOVA and WD, K = 100. Proportion of plants infested was transformed to arcsine √ proportion before ANOVA.

Influence of Feeding by Zeiraphera canadensis (Lepidoptera: Tortricidae) on Growth of White Spruce: Larval Density-Damage and Damage-Shoot Production Relationships

Field studies were conducted in New Brunswick, Canada to evaluate the relationship between larval density of the spruce bud moth, Zeiraphera canadensis Mut. & Free. (Lepidoptera: Tortricidae), and damage to current year's shoots of white spruce, Picea glauca (Moench) Voss, and the response of white spruce, in terms of shoot production, in the year following damage. The length of undamaged shoots was closely related to the length of buds, the length of the previous internode, and shoot basal diameter. Basal diameter explained 78-94% of the variability in shoot length in the absence of herbivory and was chosen to estimate potential growth of damaged shoots. The number of larvae per shoot, shoot size, whether shoots were broken at a feeding scar, the amount of previous herbivory, and the position of damage along shoots explained 24-87% of the variation in six damage indices (i.e. area and percentage of shoots defoliated, area and percentage of cortical tissue consumed, percentage shoot length reduction and incidence of shoot breakage) examined over 2 years and at two sites (...)

Field Corn, Corn Rootworm Larval Control, 1992

Abstract Rootworm planting-time, soil-insecticide test plots were established at 5 IA locations in 1992. Two of these locations were also used for cultivation-time insecticide tests. The soil type at Ames and Newell was loam; Crawfordsville, Sutherland, and Mt. Union was silt loam. The experimental design was a randomized complete block with 4 replications for the root-protection trials (registered and numbered products) and 8 replications for the yield trials (registered and EUP products). All treatments were applied to single 50-ft length row with 30-inch row spacing. Granular insecticide formulations were applied with modified Noble metering units that had been laboratory-calibrated to accurately deliver material at a tractor speed of 4 mph. The applicators were mounted on a 4-row John Deere Max-Emerge 7100 integral planter. Each row was constantly monitored to ensure that insecticide was being correctly applied at all times. Planter-mounted drag chains were used for insecticide incorporation. Granular cultivation-time insecticide applications were made with electrically-driven Noble units mounted on the tool barof a 2-row, rear-mounted cultivator. Plastic tubes, positioned directly in front of the cultivator sweeps, directed the insecticide granules to both sides of the corn row for basal treatments. Liquid insecticides were applied with a small-plot bicycle sprayer. Two 8003E nozzles, 1 on each side of the corn row, created the desired band width around the base of the plants. Liquid application rate was 10 gal/acre at 10 psi. Early cultivation-time applications (7-10 d prior to cultivation) consisted of a 15-inch band with no incorporation. All other liquid applications were done just prior to cultivation with a 7-inch band. Chemical phytotoxicity was checked in early Jun by taking stand counts from 1/1000 acre and measuring the height of 10 consecutive plants from each treatment. Evaluation of root damage was started in mid-Jul, but due to excessive rainfall, the root ratings were not completed until mid-Aug. Rootworm feeding was evaluated by digging 5 roots from each treatment row and rating them on the Iowa 1-6 scale (1 equal to no damage or only a few minor feeding scars, and a 6 rating equal to 3 or more nodes of roots completely destroyed). Lodging counts were taken at harvest time. A plant was considered lodged if the angle between the base of the plant and the ground was 45° or less. Stand counts (number plants per 1/1000 acre) were taken in the yield plots at harvest time. Yields were measured by hand harvesting 1/1000 acre from each treatment. To determine treatment differences, data were analyzed using ANOVA and means were separated with REGWQ.

Temporal Relationship Between Southern Pine Beetle (Coleoptera: Scolytidae) and Pinewood Nematode Infestations in Southern Pines

The incidence of feeding scars of the cerambycid vectors of the pinewood nematode (Bursaphelenchus xylophilus (Steiner and Buhrer) Nickel) on twigs of loblolly (Pinus taeda L.) and shortleaf (Pinus echinata Mill.) pines in central Louisiana was determined. Feeding scars on twigs taken from pines felled at random were compared to those on twigs taken from pines adjacent to southern pine beetle (Dendroctonus frontalis Zimmermann) infestations. Additionally, the presence of pinewood nematode in trees attacked by southern pine beetle was followed through the course of beetle development. Significantly more cerambycid feeding scars were present on twigs of trees located near the advancing edge of a southern pine beetle infestation than on twigs not adjacent or near any known southern pine beetle infestation. From 82 to 100% of the trees sampled adjacent to bark beetle infestations had been fed upon by cerambycids. Pinewood nematodes were recovered from 79% of these trees. The incidence of nematodes in the boles of trees attacked by southern pine beetles increased as immature beetles entered their later instars. The highest incidence of nematodes was from trees recently vacated by southern pine beetles. Trees killed by the southern pine beetle may thus serve as reservoirs for the pinewood nematode and its cerambycid vectors and lead to the infestation of adjacent trees and facilitate subsequent SPB colonization.

Effects of Temporary Drainage on Selected Life History Stages of the Rice Water Weevil (Coleoptera: Curculionidae) in California

Adults, eggs, first instars, and root-feeding larvae of the rice water weevil, Lissorhoptrus oryzophilus Kuschel, were experimentally confined to rice, Oryza sativa L., plants in flooded and drained fields during experiments conducted in 1989-1990. In both years, oviposition was significantly greater under flooded conditions (5.8-32 mean number of eggs per plant) than under drained conditions (0-1 mean number of eggs per plant). Scars from leaf-feeding by adults were more abundant on plants in flooded plots in both years. Lengths of feeding scars were greater on plants from the flooded plot in 1989, but scar lengths did not differ between treatments in 1990. In 1989, survival of eggs exposed to drained conditions for 7 d was greater than for eggs exposed to flooded conditions for the same period. Survival of weevil eggs in 1990 did not differ among flooded and drained treatments. In 1989, fewer larvae established on plants when drainage occurred 1 dafter transplanting than on plants that were transplanted at the same time but remained under flooded conditions. In 1990, water management, block, and the interaction (water management and block) influenced larval establishment. Survival of root-feeding larvae did not differ between flooded and drained treatments in 1989, whereas in 1990, survival declined with an increasing duration of drainage. Draining rice fields may be effective in controlling rice water weevil infestations, particularly when targeted against adults. However, earlyseason drainage conflicts with other management practices and appears to be more costly, and appropriate timing of this practice may be difficult to establish.

Control of Tobacco Wireworms with Fall, Winter, and Spring Applications, 1991

Abstract Plots were established at the Upper Piedmont Research Station (UPRS) near Reidsville, NC, on 2 Nov and at the Border Belt Tobacco Research Station (BBTRS) near Whiteville, NC, on 5 Nov. Plots were 20 plants long (ca. 40 foot) and 4 rows wide (45 and 48 inches between rows at UPRS and BBTRS, respectively) and were arranged according to a randomized complete-block design having 10 treatments and 4 blocks. Soil types were Cecil loamy sand (pH 6.0) and Goldsboro fine sandy loam (pH 6.5) for UPRS and BBTRS, respectively. Fall applications (treatments 1-3) were made on 2 Nov at the UPRS and on 5 November at the BBTRS, using a CO2- powered sprayer fitted with 5, 8004 Spraying Systems flat-fan nozzles spaced 20 inches apart on an 80 inch boom. Sprays were applied at 30 psi with a delivery rate of 25 gal/acre and incorporated to a depth of 4 to 6 inches with a spring tooth harrow. Rows were ridged within 2 hours after incorporation. Winter applications (treatments 4-6) were made on 4 Feb at UPRS and on 19 Feb at BBTRS, while spring applications (treatments 7-9) were made on 9 Apr at BBTRS and on 3 May at UPRS. Winter and spring treatments were applied as described above. Flue-cured tobaccos, var. NC 37 and var. K 326, were transplanted on 16 Apr and 10 May at the BBTRS and UPRS, respectively. Soil moisture was excellent at the time of transplanting. Three weeks after transplanting, 10 consecutive plants from one row per plot were gently pulled from the soil and the roots and stems visually examined and rated for wireworm damage as follows: 0 = no damage; 1 = feeding scars on root surface; 2 = feeding reaching pith with tunneling >1 cm; 3 = pith tunneling from 1-5 cm; 4 = pith tunneling >5 cm; and 5 = dead plant. Data were subjected to ANOVA. Proportion of plants infested was transformed to arcsine Vproportion before ANOVA.

Field Corn, Corn Rootworm Larval Control, 1991

Abstract Rootworm planting-time, soil-insecticide test plots were established at 5 locations in 1991. Two of these locations were also used for cultivation-time insecticide tests. The experimental design was a randomized complete block with 4 replications for the root-protection trials (registered and numbered products) and 8 replications for the yield trials (registered and EUP products). All treatments were applied to single 50-ft length rows with 30-inch row spacing. Granular insecticide formulations were applied with modified Noble metering units that had been laboratory-calibrated to accurately deliver material at a tractor speed of 4 mph. The applicators were mounted on a 4-row John Deere Max-Emerge 7100 integral planter. Each row was constantly monitored to insure that insecticide was being correctly applied at all times. Drag chains were used for incorporation. Cultivation-time insecticide applications were made with electrically-driven Noble units mounted on the tool bar of a 2-row, rear-mounted cultivator. Plastic tubes, positioned directly in front of the cultivator sweeps, directed the insecticide to both sides of the corn row for basal treatments. Banders positioned directly above the plant row provided whorl treatments. Liquid insecticides were applied just prior to cultivation with a small-plot bicycle sprayer. Two 8003E nozzles, one on each side of the corn row, created a 7-10 inch band around the plant base and delivered 10 gal/acre at 10 psi. Chemical phytotoxicity was checked in early Jun by taking stand counts from 1/1000 acre and measuring the height of 10 consecutive plants from each treatment. In mid-Jul, rootworm feeding was evaluated by digging 5 roots from each treatment row and rating the damage on the Iowa 1-6 scale (1 equal to no damage or only a few minor feeding scars, and a 6 rating equal to 3 or more nodes of roots completely destroyed). Lodging counts were taken at harvest time. A plant was considered lodged if the angle between the base of the plant and the ground was 45° or less. Yields were measured by hand-harvesting 1/1000 acre from each treatment. To determine treatment differences, data were analyzed using ANOVA and means were separated with REGWQ.