Aphid Counts Research Articles

Irish Potato, Control of Potato-Infesting Aphids, 1991

Abstract Aphid foliar and systemic experiments were arranged in a randomized complete block design replicated six times. Experiments were conducted at Preseque Isle, ME on land that was in clover in 1990. The planting dates were I 21 and 20 May respectively. The 3.0 m space between blocks and the 1.8 m space between the four-row plots were sown to oats on 28 Jun in the foliar 1 experiment. These areas were left fallow in the other experiment. All rows were planted with an assisted-feed planter 0.9 m apart and 15.0 m long and the whole 'Katahdin' seed pieces (ca. 75 g) were planted 30 cm apart. Fertilizer and hilling practices were normal for the area. Early and late blight were controlled by three foliar applications of Dithane M-45 (80 WP) (1.12 kg/ha on 18, 26 Jul, and 2 Aug) and Bravo 720 (840 g/ha on 9 and 23 Aug). Furrow j applications of insecticides were made by hand with a plastic tube applying previously weighed amounts of insecticide. Foliar insecticide applications were i made with a Century boom sprayer, three nozzles per row at 6.3 kg/cm2 pressure and 940 liters/ha. Numbers of aphids (by species) were counted on top, middle, and bottom leaves of 25 plants in the middle row of each plot. When dates of count and application were the same, aphid counts were made prior I to applications of the insecticide. Analyses of variance were calculated following transformation of the data using logi0(x + 1) for Aphid-B. Transformed means of the total number of wingless aphids were compared using DMRT and then applied to the actual means. The soil was classified as Caribou Loam, pH 5.2, Total monthly rainfall for Jun, Jul, and Aug was 3.1, 1.9, and 21.7 cm, respectively. The average temperature for each of the same 3 months was 17.1, 19.0, and 19.3 deg. C.

Hessian Fly and Aphid Control Tests on Wheat, 1991

Abstract At-planting insecticide applications were made to winter wheat seeded 1 Nov in a Dothan sandy loam in Barnwell County, SC. The experimental design was a randomized complete block with 5 replicates. The experimental unit was a plot 50 × 5.3 ft (8 rows on 8 inch spacing). Granular Di-Syston and Thimet were placed in-furrow with electric Gandy applicators. In-furrow applications of Di-Syston 8 were made with a CO2 pressurized canister connected to an aluminum manifold having 8 brass push-in fittings. Equal lengths of plastic irrigation tubing (1 mm internal diam) delivered insecticide to the open furrow at 11.1 gal/acre, 25 psi manifold pressure. Broadcast applications of Di-Syston 8 were made from a CO2 pressurized canister connected to a boom mounted in front of the double-disk openers. The system delivered 10.1 gal/acre at 25 psi through Teejet 8001 flat fan nozzles. Broadcast foliar treatments of NTN 33893 were made with a tractor-mounted CO2 pressurized boom (Teejet TX 6 nozzles, 7.3 gal/acre at 50 psi). A previously untreated set of plots was Sed with NTN 33893 on 9 Jan and a set of plots previously treated with Di-Syston 15 G in-furrow was Sed with NTN 33893 on 12 Mar. Hessian fly samples were taken by randomly uprooting 10 plants from each of 4 plots (40 plants/treatment) and dissecting them in the laboratory. Aphid counts were made from 2 random 6-inch samples per plot (8/treatment). HF activity was monitored wkly in a separate set of plots by sampling 40 leaves for egg deposition and dissecting 40 plants for larval and puparial counts. Aphid species populations were also monitored wkly in a separate set of plots. EGA and BCOA were predominant throughout the growing season. On the 3 Mar sampling date, BCOA comprised 64% of the population and EGA the remainder. Yields were taken by harvesting the middle 6 rows with an Almaco plot combine. All treatments were planted with the same seed lot.

Tobacco Aphid Control on Flue-Cured Tobacco with Foliar Insecticides, 1991

Abstract A study was conducted to evaluate various insecticides applied as foliar spray and transplant water (TPW) treatments for control of the tobacco aphid on flue-cured tobacco. Experimental plots, 1 row (4 ft) wide and 40 ft long, were established in a Chesterfield-Mayodan-Bourne sandy loam soil at the Southern Piedmont Agricultural Experiment Station, Blackstone, VA. Tobacco was transplanted on 15 May into experimental plots that were arranged in a randomized complete block design with 4 replications. Plots were separated by single, untreated, border rows and blocks were separated by vacant 5-ft alleys. Except for insect control, production practices followed recommendations of the Virginia Cooperative Extension Service. Immediately after transplanting, a measuring cup was used to apply transplant water (TPW) treatments at 4 fl oz/plant (204 gal/acre). Foliar treatments were applied on 9 Jul using a CO2-pressurized backpack sprayer that delivered 26.4 gal/acre through 3 TX-10 hollow-cone nozzles per row at 60 psi. Aphids were counted on 4 upper leaves of 10 plants/plot one day before the foliar treatment and 3, 7, and 14 DAT. On 23 Aug plant damage associated with aphid infestations was rated on a scale of 0 to 5 where 0 = no damage and 5 = most severe damage. Tobacco was harvested, cured, and yield determined. Aphid counts were transformed to log(x+l) before analysis of variance (ANOVA, SAS 1985) and significant means (P=0.05) were separated by DMRT. Actual means are presented in the table.

Insecticide Evaluation, 1991

Abstract This experiment was conducted in a 5.4 acre block of 37-yr-old trees, which measured 16.5 ft in height and 23 ft in width and were planted at a spacing of 20 × 40 ft. The experimental design consisted of 6 single-tree plots (3 'Rome Beauty,' 3 'Golden Delicious') in a randomized block design. Insecticides were applied with a Swanson DA500A airblast sprayer, which traveled at 2.4 mph and delivered a spray volume of 100 gal/acre. Dates of application were 2 Apr (delayed dormant [DD]), 9 Apr (prepink [PP]), 8 May (petal fall [PF]), 21 May (first cover [1C]), 31 May (second cover [2C]), 13 Jun (third cover [3C]), 27 Jun (fourth cover [4C]), 16 Jul (fifth cover [5C]), 30 Jul (sixth cover [6C]), 12 Aug (seventh cover [7C]), and 29 Aug (eighth cover [8C]). Other materials applied separately to all treatments were Agristrep, Bordeaux mixture, Captan, Dodine, NAA, Nova, Rubigan, Solubor, and Topsin-M. Control of RAA was evaluated by counting colonies/tree. Effect of treatments against SA was determined by counting aphids on the most infested leaf on each of five terminals/tree around the periphery of'Rome Beauty.' Control of WALH and RLH was evaluated by counting nymphs on 25 leaves selected from the periphery of trees. Treatment effect against STLM was determined by counting mines observed in 5 minutes around the periphery of trees. Control of fruit-feeding insects was determined by scoring for injury 600 picked apples/treatment (100/replication) plus up to 600 drop apples/ treatment (up to 100/replication) sampled on 17 Sep. Fruit picked from 'Golden Delicious' trees were rated for finish as 0 (no russet), 1 (enlarged and raised lenticels), 2 (1-10% russeted surface), 3 (11-25% russeted surface), 4 (26-50% russeted surface), or 5 (>50% russeted surface).

Aphid Control in Winter Canola Using Soil Insecticides, 1990-1991

Abstract Selected soil-applied granular insecticides were evaluated for control of aphids in fall-planted canola on a Faceville sandy loam soil near Plains, GA. Six lb of canola seed per acre was planted in 7-inch rows using a small-plot grain drill on 26 Oct. Plots measured 5 × 20 ft. Plots were irrigated immediately after planting. Granular insecticides were applied with Noble insecticide applicators attached to the grain drill. Plant number was measured 21 and 45 days after planting by counting all plants in 2 m of row per plot. Aphids were sampled by counting aphids on 10 or 15 plants per plot at 33, 45, and 87 days after planting. The percentage of aphid infested terminals also was sampled at bloom (6 Mar) by inspecting 100 terminals/plot. Plots were harvested with a small-plot combine on 17 May and yield was adjusted to 8% moisture content.

Cotton Aphid Control, 1990

Abstract Treatments were tested for relative efficacy against cotton aphid in nonirrigated cotton planted 2 May at Stoneville, MS (Trial 1) and 1 May at Elizabeth, MS (Trial 2). Plots of 8 rows (40 inch centers) by 30 ft, separated by 15 ft alleys, were arranged in a randomized complete block with 4 replicates. Treatments were applied by a high-clearance spray machine equipped with a compressed-air spray system. Trial 1 was applied after pretreatment counts were taken on 16 Jul and Trial 2 was applied on 27 Jul after a survey indicated a heavy aphid infestation. Total spray volume was 6 gal/acre at 5 mph and 35 psi using 2 TX10 nozzles/row. Plots within a replicate were sprayed consecutively with the boom rinsed twice and blown clear between plots. Efficacy of treatments was evaluated by counting aphids within one square inch on the under surface of a leaf in the top third, middle third, and bottom third portion of 40 randomly chosen plants/treatment.

Pyrethroid Aphicide Efficacy, 1990

Abstract Fourteen treatments of 9 candidate pesticides were tested for efficacy against cotton aphids in cotton planted 5 May. Treatments were arranged in randomized complete blocks replicated 4 times. Dimensions of each plot were 26.7 ft wide (8 rows) by 50 ft long. All plots were sprayed on 29 May with Ammo 2.5 EC (0.025 lb Al/acre) to diminish the predator population and help initiate a cotton aphid infestation. All plots were also sprayed on 8 Jun with Orthene 90 SP (0.375 lb Al/acre) for control of a tarnished plant bug infestation. Pesticide applications were made with a compressed air spray system mounted on a John Deere, model 6000 high clearance sprayer operated at 5.5 mph using Conejet, TX-8 nozzles calibrated to deliver 7.3 gal/acre at 42 psi. Applications were made on 6, 20, 27 Jul, 2, 17, and 31 Aug. Pretreatment counts of aphids were made on 3 Jul and posttreatment counts at approximately weekly intervals thereafter. Counts were made on 5 mature leaves (5-8 nodes below terminal) and 5 terminal leaves (4th fully expanded leaf from the terminal bud) in each plot. The 2 center rows of each plot (2°50 row ft samples) were harvested on 2 Oct, with an International Harvester model 622 cotton picker.

Cotton Aphid Control, 1991

Abstract This trial was initiated on 8 Aug on a stand of 'PR 75' cotton planted 20 Jun near Hollis, OK, to determine efficacy of several foliar sprays for CA. Insecticides were applied using a ground rig with a 14 ft boom calibrated to deliver 5.0 gal/acre at 30 psi. Plots were 14 × 200 ft and arranged in a randomized complete block design of 3 replicates. Plots were sprayed on 8 Aug. Sampling procedure consisted of picking 6 leaves at random from the top, middle, and bottom of plants from the middle 2 rows of each plot. Aphid counts represent estimates of aphid numbers.

Within-Plant Patterns of Therioaphis maculata on Resistant, Tolerant, and Susceptible Alfalfa Plants

Plant lines with resistance (antibiosis or antixenosis or both), tolerance, or susceptibility to the spotted alfalfa aphid, Therioaphis maculata (Buckton), were selected from the cultivar OK08 for use in studies to describe the within-plant pattern of the aphid in the foliar canopy of alfalfa. Aphid counts and damage ratings were analyzed for each node (from the crown), and profiles of averages per node for each alfalfa line were prepared to illustrate within-plant patterns. Numbers of spotted aphids per node or per stem on susceptible and tolerant plants were significantly higher than on resistant plants. After 10 d of infestation, damage ratings averaged over nodes were significantly higher for susceptible plants than for those with resistance or tolerance. On all three lines, the spotted alfalfa aphid showed a clear preference for leaf blades over petioles or stems, and the greatest numbers were consistently found on nodes nearest the plant crowns. Little upward movement on stems was evident until damage to leaf blades of lower nodes had resulted in necrosis and leaf drop.

Irish Potato, Control of Potato Infesting Aphids, 1990

Abstract Aphid-A and Aphid-B experiments were randomized complete block designs with four and six replicates respectively and were conducted at Presque Isle, ME on land that was in clover in 1989. The planting dates were 17 May and 29 May. The 3.0 m space between blocks and the 1.8 m space between the four-row polts were sown to oats on 29 Jun in the Aphid-B experiment and were left fallow in the Aphid-A experiment. All rows were planted with an assisted-feed planter 0.9 m apart and 15.0 m long and the healthy whole Katahdin seed (ca. 75 g) were 30 cm apart. Fertilizer and cultivation practices were normal for the area. Late blight was controlled by 5 foliar applications of Manex 4 L (2338 ml/ha on 27 Jul; 2806 ml/ha on 3, 9, 16, and 23 Aug). Sidedress and furrow applications of insecticides were made by hand with a plastic tube applying previously weighed amounts of insecticide. Foliar insecticide applications were made with a Century boom sprayer, three nozzles per row at 6.3 kg/cm2 pressure and 0.94 kl/ha. Numbers of aphids (by species) were counted on top, middle, and bottom leaves of 25 plants in the middle rows of each plot. When dates of count and application were the same, aphid counts were made prior to applications of the insecticide. Analyses of variance were calculated on untransformed data in the Aphid-A experiment and following transformation of the data using log10(x + 1) for the Aphid-B experiment. Means of the total number of wingless aphids were compared using DMRT. The soil was classified as Caribou Loam, pH 5.2. Total monthly rainfall for Jun, Jul, and Aug was respectively 7.3, 10.2, 14.8 cm. The average temperature for each of the same 3 mo was 17.6, 19.5 and 19.7 deg C.

Tobacco Aphid Control on Flue-Cured Tobacco with Foliar Insecticides, 1990

Abstract A study was conducted to evaluate 11 chemical treatments for the control of the tobacco aphid on tobacco grown in a Chesterfield-Mayodan-Bourne sandy loam soil at the Southern Piedmont Agricultural Experiment Station, Blackstone, Va. Tobacco was transplanted in experimental plots arranged in a randomized complete block design with 4 replications on 9 May. Five plants infested with aphids in each plot were selected and marked with spray paint. Aphid populations on the upper 4 leaves of each marked plant were counted 1 d before application and at 4, 7 and 14 DAT. Treatments were applied on 19 Jul using a CO2-pressurized backpack sprayer that delivered 25 gal/acre through 3 TX-10 hollow-cone nozzles/row at 60 psi. Aphid counts were transformed to Log10(X + 1) before analysis of variance. Actual means are presented in the table.

Control of the Greenpeach Aphid on Chrysanthemum Under Greenhouse Conditions, Spring 1989

Abstract Chrysanthemums were obtained as rooted cuttings and potted in 15 cm pots in a greenhouse at UCR and allowed 4 wk growth before use. During the growth phase, the plants were exposed to heavy populations of aphids within the greenhouse. By 4 wk, the plants had obtained a moderate amount of aphids for treatment. Only the terminal portions of the plants were used for aphid counts (3 unexpanded leaves) and marked with a twist tie around the stem at that point. Therefore, posttreatment counts would be made of the same aphids and their young if produced. Plants were assigned to treatments to ensure an equal distribution of aphids/treatment. Six plants/treatment were sprayed at 45 psi using a hand sprayer. Treated plants were held on raised benches in a greenhouse at 26.7°C and ambient relative humidity. Posttreatment counts were taken at 5 and 8 d.

Release, Dispersal, and Recovery of a Laboratory-Selected Strain of the Walnut Aphid Parasite Trioxys pallidus (Hymenoptera: Aphidiidae) Resistant to Azinphosmethyl

A strain of Trioxys pallidus Haliday, selected in the laboratory for resistance to azinphosmethyl, was mass reared and released into five commercial walnut blocks in California to determine whether the strain could survive field applications of azinphosmethyl or methidathion, persist, and parasitize the walnut aphid, Chromaphis juglandicola Kaltenbach. Approximately 75,000 parasites were reared on potted walnut trees in a University of California greenhouse in Berkeley; releases were made after azinphosmethyl applications in three sites, after methidathion application in one site, and just before a methidathion application in one site. Colonies of T. Pallidus collected from each orchard before the releases were tested with a discriminating dose of azinphosmethyl to estimate resistance levels of the wild population. Samples of T. Pallidus were collected once or twice from each block after releases were made and from adjacent walnut blocks in two sites. The samples were then tested with azinphosmethyI. The high survival rates of the parasites indicated that the strain of T. Pallidus resistant to azinphosmethyl established and persisted through the growing season in four of the five walnut blocks and dispersed to nearby nonrelease blocks in two of two site sampled. Counts of aphids and mummies support the conclusion that the laboratory selected strain survived applications of azinphosmethyl or methidathion, parasitized aphids, and persisted within the release and nearby nonrelease sites during the 1988 growing season.

Thrips Control; Effect on Plant Growth, 1989

Abstract This test was conducted to evaluate insecticides applied in-furrow for thrips control and determine the effect on plant height and earliness. The plots were 4 rows wide, 40 ft long, with 4 replicates in a randomized complete block design. Treatments were applied in-furrow at planting with a John Deere Flex 71 planter on 20 Apr. The .soil type was a Dalco Clay. Plants from the outside rows were pulled and beaten on hardware screen over a white pan and thrips and aphids counted on 25 plants/plots. Thrips and aphid counts were made on 8 and 19 May. Plant height was measured on 5 consecutive plants on each of the center rows on 25 May. Plant height was determined by measuring from the cotyledon node to the first unfolded leaf. Earliness was determined by counting white and red blooms every other day on the center 2 rows from the first week of bloom, 23 to 30 Jun. Yield was determined by brush stripping the two center rows of each plot on 27 Sep.

Control of the Melon Aphid on Chrysanthemum Under Glasshouse Conditions, 1988

Abstract Rooted chrysanthemum cuttings were potted (1/pot, 6 inch dia) 3 wk prior to use. Plants were exposed to an infestation of aphids (Aphis gossypii) in the greenhouse. Four wk post-exposure, pre-treatment counts of aphids were made. Plants were separated into 5 treatments and a control and isolated on a separate raised bench within the greenhouse. Treatments were applied to 10 plants/treatment by a hand sprayer at approximately 45-60 psi. Counts of live aphids were made 4, 10, and 15 days posttreatment on both leaves and terminal (undifferentiated leaves) portions of the mums.

Control of the Melon Aphid on Chrysanthemum Under Glasshouse Conditions, Spring 1988

Abstract Rooted chrysanthemum cuttings were potted (1/pot, 6 inch dia) 3 wk prior to use. Plants were exposed to an infestation of aphids (Aphis gossypii) in the greenhouse. Four weeks post-exposure, pre-treatment counts of aphids were made. Plants were separated into 6 treatments and a control and isolated on a separate raised bench within the greenhouse. Treatments were applied to 4 plants/treatment by a hand sprayer at approximately 45-60 psi. Counts of live aphids were made 5, 10, and 15 DAT on both leaves and terminal (undifferentiated leaves) portions of the mums.

Control of Potato Infesting Aphids, 1989

Abstract The foliar and systemic experiments were randomized complete block designs with 6 replicates each and were conducted at Presque Isle, ME. The planting dates were 23 May for the foliar application experiment and 24 May for the systemic application experiment. The 3 m space between blocks and the 1.4 m space between columns and at the sides and ends of the experiments were sown to oats on 27 Jun. Each plot consisted of 4 rows of potatoes, each row 0.9 m apart and 15.0 m long. The healthy Katahdin seed pieces ca. 75 g each were planted with a tractor-pulled, assisted-feed planter. Fertilizer and hilling practices were normal for the area. Sidedress applications of insecticides were made by hand with a plastic tube applying previously weighed amounts of insecticide. Foliar insecticide applications were made with a Century boom sprayer, 3 nozzles/row at 6.3 kg/cm2 pressure and 0.94 kl/ha. Numbers of aphids (by species) were counted on top, middle, and bottom leaves of 25 plants in the middle rows of each plot. When dates of count and application were the same, aphid counts were made prior to applications of the insecticide. Analyses of variance were calculated following transformation of the data using log10 (x + 1). Means of the total number of wingless aphids were compared using DMRT and then reconverted, Total monthly rainfall for Jun, Jul and Aug was respectively 6.0, 7.7 and 11.5 cm. The average temperature for each of the same 3 months was 16.5, 18.6 and 18.2°C.

Tobacco Aphid Control, Ontario, Canada, 1988

Abstract Experimental plots were established in a field at the Research Station, Agriculture Canada, Delhi, Ontario. Tobacco was transplanted into the field on 27 May. The experimental plots were arranged in a split plot design with 2 main plots and 3 replications. There were 6 treatments, consisting of 3 insecticides at 2 rates, and an untreated check in each main plot. Individual subplots were 76 × 14 ft and consisted of 4 rows of 38 plants in each row, the outside rows in each subplot being guard rows. Sprays were applied with a power sprayer using 3 nozzles/row: TG3-TG5-TG3 that delivered 40 gal of liquid/acre at a pressure of 15 psi and 2.5 mph speed, and TG2-TB3-TG2 nozzles that delivered 20 gal of liquid/acre at 10 psi and 3.0 mph speed. All treatments were applied evenly on full-grown, topped tobacco plants over each row in each subplot on 8 Jul. To assess aphid control, 3 leaves were collected at random from each subplot 1 d before treatment and at different dates after treatment. The number of living aphids on the leaves was counted by taking the leaves to the laboratory and examining them under a Luxo lamp magnifier. The aphid counts were transformed into logarithmic scales before ANOVA. Duncan’s multiple range test was used to separate treatment means. Means were converted to original units for presentation in the table.

Delta Aphid Test-III, 1988

Abstract Nineteen treatments were evaluated for relative efficacy against aphids on irrigated cotton planted 11-12 May on the Avery farm near Shaw, MS. Plots were 8 rows by 50 ft and were arranged in a randomized complete block design with 4 replications. Treatments were applied 1 Aug to the 4 inner rows of each plot by high clearance spray tractor equipped with a compressed air-plot spray system with 2 TX-4 nozzles/row calibrated for 5 gal/acre. Prior to this test 8 applications of insecticide had already been applied to the field as follows (rates are lb [AI]/acre); 3 applications of Orthene 75 S at 0.25; Swat 8 E at 0.15; Bidrin 8 E at 0.2; Swat 8 E at 0.25; Azodrin 5 E at 1.0. Prior to treatment, the mean number and standard error of aphids on Vb of each of 10 leaves from each of 20 plots (5 random plots/rep) from the upper third of the canopy was 469.8 and 237.1, respectively. Although the standard error was high, the minimum number of aphids/plot was greater than 40.2 aphids/leaf. Posttreatment data were collected 4 Aug by counting aphids on ½ of each of 10 leaves from each of 2 levels (4th leaf down, and one from mid-plant) per plot.

Cotton Aphid Control, 1989

Abstract Twenty treatments were tested for relative efficacy against cotton aphid in nonirrigated cotton planted 23 May. Plots of 8 rows (40 inch) centers by 30 ft, separated by 15 ft alleys, were located on the Delta Branch Experiment Station, Stoneville, MS. Treatments were arranged in a randomized complete block with 4 replicates. Treatments were applied by a high-clearance spray machine equipped with a compressed-air spray system. Trial 1 was applied on 5 Jun and Trial 2 was applied on 21 Jun. Total spray volume was 5 gal/acre at 5 mph and 40 psi using 2 TX6 nozzles/row. Plots within a replicate were sprayed consecutively with the boom rinsed twice and blown clear between plots. Efficacy of treatments was evaluated 72-h post-treatment by counting aphids within one square inch at the terminal and one square inch on the under surface of the third leaf from the terminal on 40 randomly chosen plants/treatment.