Center Of Plot Research Articles

Abating pocket gophers (Thomomys spp.) to regenerate forests in clearcuts

Pocket gophers have long suppressed forest regeneration in clearcuts in western North America, despite the application of intensive and costly, large-scale abatement practices, which also kill non-target wildlife and may increase soil erosion. At four national forests in northern California, gophers (Thomomys bottae and T. monticola) on 50 clearcuts were baited with a 0.5% strychnine concentration on wheat or oat groats, which were presented as loose grains or in 1 × 2 cm paraffin pellets for added durability. The various baits and baiting regimes usually reduced gopher abundance by 50-100% within one month. However, gopher populations recovered too quickly to protect seedlings planted for forest regeneration, especially on plots baited with a mechanical burrow-builder. In some plots where abatement was most successful initially, gopher densities increased to levels exceeding those in control plots by 7-13 months later. As gopher populations recovered following abatement, active burrows first appeared at the plot peripheries and advanced toward the plot centres, suggesting that abated territorial residents were replaced by immigrants dispersing from the surrounding landscape.Whereas conventional abatement practices can reduce gopher abundance in clearcuts, the small spatial and temporal scales of application encourage reinvasion of vacated ecological space. These population responses defeat the goal of forest management by increasing gopher density in clearcuts; at the same time the conifer seedlings are vulnerable to gopher predation. Predation of conifer seedlings might be reduced by not abating gophers or by using alternative harvest regimes. These alternative strategies would avoid creating the conditions under which gophers contribute to slowing forest regeneration following timber harvests, and they would avoid the widespread and possibly long-term environmental damage caused by applying acute poisons and by using the burrow-builder.

A free‐air enrichment system for exposing tall forest vegetation to elevated atmospheric CO2

AbstractA free‐air CO2 enrichment (FACE) system was designed to permit the experimental exposure of tall vegetation such as stands of forest trees to elevated atmospheric CO2 concentrations ([CO2]a) without enclosures that alter tree microenvironment. We describe a prototype FACE system currently in operation in forest plots in a maturing loblolly pine (Pinus taeda L.) stand in North Carolina, USA. The system uses feedback control technology to control [CO2] in a 26 m diameter forest plot that is over 10 m tall, while monitoring the 3D plot volume to characterize the whole‐stand CO2 regime achieved during enrichment. In the second summer season of operation of the FACE system, atmospheric CO2 enrichment was conducted in the forest during all daylight hours for 96.7% of the scheduled running time from 23 May to 14 October with a preset target [CO2] of 550 μmol mol–1, ≈ 200 μmol mol–1 above ambient [CO2]. The system provided spatial and temporal control of [CO2] similar to that reported for open‐top chambers over trees, but without enclosing the vegetation. The daily average daytime [CO2] within the upper forest canopy at the centre of the FACE plot was 552 ± 9 μmol mol–1 (mean ± SD). The FACE system maintained 1‐minute average [CO2] to within ± 110 μmol mol–1 of the target [CO2] for 92% of the operating time. Deviations of [CO2] outside of this range were short‐lived (most lasting < 60 s) and rare, with fewer than 4 excursion events of a minute or longer per day. Acceptable spatial control of [CO2] by the system was achieved, with over 90% of the entire canopy volume within ± 10% of the target [CO2] over the exposure season. CO2 consumption by the FACE system was much higher than for open‐top chambers on an absolute basis, but similar to that of open‐top chambers and branch bag chambers on a per unit volume basis. CO2 consumption by the FACE system was strongly related to windspeed, averaging 50 g CO2 m–3 h–1 for the stand for an average windspeed of 1.5 m s–1 during summer. The [CO2] control results show that the free‐air approach is a tractable way to study long‐term and short‐term alterations in trace gases, even within entire tall forest ecosystems. The FACE approach permits the study of a wide range of forest stand and ecosystem processes under manipulated [CO2]a that were previously impossible or intractable to study in true forest ecosystems.

Control of Fall Armyworm on Sweet Corn, Spring 1996A

Abstract ‘Silver Queen’ corn was seeded in Rockdale soil on 10 Feb 1996. A randomized complete block design was employed to provide 4 replicates each for 4 treatments comprising a plot size of 4 rows, 30 feet long. Insecticide applications were initiated when 2-5% of the plants were infested with FAW. Whorl treatments were continued at approximately 7 d intervals beginning 30 Mar. Whorl applications were made with a shaker jar, 10 cm above the whorl. This jar was fitted with a screen mesh lid appropriate for granular flow. No phytotoxicity was observed with either product. Evaluations were conducted 24 hours after each treatment by extracting 5 plants from plot centers, storing in polyethylene bags and transporting to the laboratory. Each plant was dissected, larvae extracted and counted. FAW populations were not significantly reduced by any treatment as compared with untreated check plots.

Control of Fall Armyworm on Sweet Corn, Spring 1996B

Abstract ‘Silver Queen’ corn was seeded in Rockdale soil on 25 Feb 1996. A randomized complete block design was employed to provide 4 replicates each for 6 treatments comprising a plot size of 3 rows, 30 feet long. Insecticide applications were initiated when 2-5% of the plants were infested with FAW. Whorl treatments were continued on approximately 7-day intervals beginning 19 Mar. Whorl applications were made with a shaker jar, 10 cm above the whorl. This jar was fitted with a screen mesh lid appropriate for granular flow. No phytotoxicity was observed with either product. Evaluations were conducted 24 hours after each treatment by extracting 10 plants from plot centers, bagging in polyethylene bags and transporting to the laboratory. Each plant was dissected, larvae extracted and counted. FAW populations were significantly reduced by all treatment compared to untreated check plots.

EFFECT OF BORDER ROWS AND TRAP/DONOR RATIOS ON POLLEN-MEDIATED GENE MOVEMENT

One of the concerns associated with the field testing and agronomic-scale release of transgenic crops is the potential for the pollen-mediated escape of engineered genes into naturally occurring populations of wild relatives. While border rows have been used frequently to restrict the pollen-mediated escape of engineered genes from field trials, the efficacy of this approach has been little studied. To test the effectiveness of border plantings, isogenic lines of cucumber (Cucumis sativus L.) differing for the seedling marker trait blunt leaf apex (bla) were planted in four designs: 1 m2 of wild-type donor plot surrounded by a 399-m2 border of bla recipients; 1 m2 of donor plot/99 m2 border; 4 m2 of donor plot/96 m2 border; and 1-m2 of donor plot with no border. Each planting was encircled by eight 1.4-m2 satellite plots 50 m from the plot center. Progeny of plants from the satellites and borders were screened to determine the percentage of gene movement as measured by the occurrence of the dominant phenotype. Gene movement within the plot borders followed a leptokurtic distribution; there was greater movement from the 4-m2 donor plot than from the 1-m2 plot. Long-distance movement to the satellites significantly increased as the trap-to-donor ratio decreased. Although movement to individual satellites was generally consistent within a treatment, there was one instance of unusually high outcrossing to a single satellite, indicating that the effectiveness of borders was influenced by both the relative numbers of donor plants and by environmental variables.

Breeding density and nest site selection in a Goshawk Accipiter gentilis population of the Central Apennines (Abruzzo, Italy)

Information on forest vegetation structure immediately around a Goshawk's nest can indicate the minimum forest stand surface necessary to be conserved or created to favour Goshawk settlement and help solve potential conflicts between timber harvest and maintenance of a viable Goshawk population. In order to gain greater insight into this species and to contribute to a correct policy for managing forests, Goshawk nest site characteristics were examined at three levels of scale (nest/nest trees level, nest site level, landscape level). The breeding density recorded in the study area is 5.03 sites/100 km2. The nests were found on north- and east-facing slopes and in the central part of the tree canopy. The average values of crown height and surface diameter at breast height (dbh) were higher than the corresponding values recorded in nest plots. The average values of dbh, tree height, height of trunk without branches, crown height, crown length, crown breadth, crown basal area, crown volume, distance between trunks and plot centre canopy cover were significantly higher in nest plots than in control plots. Some characteristics of the nest site were consistent among nest sites even though analysis of the landscape surrounding the nest site showed a great variety of habitat composition and structure.

Potato Growth Uniformity as Affected by Subsurface Drip and Seepage Irrigation

Growth and production uniformity of potato (Solanum tuberosum L.) as influenced by conventional seepage irrigation and by subsurface drip irrigation was evaluated in field studies during two seasons in plots 16 rows (18.3 m) wide and 183 m long. Seepage irrigation water was supplied through ditches located on each side of each plot. Drip irrigation water was distributed through buried tubes placed under the beds 6.1 m apart extending the length of the rows. Water application throughout the plots was accomplished more rapidly with the subsurface drip system and water use during the two seasons was 33% less than with the conventional seepage system. Tuber yield during the first season was similar with the two irrigation systems. During the second season, plant growth, tuber development, and tuber yield were sampled on alternate rows beginning on each outside bed, at each end of each plot, and in the middle of the plots. Irrigation method and bed location among the 16 beds had little influence of potato growth and development. With water flow from north to south, plant growth, and tuber yield were significantly higher from potatoes growing at the north end, lowest in the plot center, and intermediate from potatoes growing at the south end. These data indicate that potato production with the two irrigation systems was similar.

Waste Corn as a Point Source of Inoculum for Aspergillus flavus in the Corn Agroecosystem.

Sporulation of Aspergillus flavus was detected on kernels in deposits of waste corn close to corn storage cribs and bins at 18 locations throughout Iowa in 1991 and 1992. A. flavus was detected in spore traps located 3 m from the deposits and was isolated from nitidulid beetles within the deposits or in insect traps within 3 m of the deposits. A. flavus also was isolated from asymptomatic corn kernels in the deposits and from soil beneath the deposits. Linear dispersal gradients of airborne conidia of A. flavus, sampled at distances of 2, 6, 10, and 14 m from waste corn deposits into adjacent cornfields, were detected at three sampling times between 28 July and 1 September 1992 at Cedar Rapids and Williamsburg, Iowa. Linear dispersal gradients from the deposits also were detected for A. flavus-infested nitidulid beetle species Carpophilus lugubris and Glischrochilus quadrisignatus. The incidence of A. flavus infection on corn leaves, silks, and kernels in the fields adjacent to the deposits were correlated to numbers of airborne conidia at each sampling time at both locations. In a field experiment in Ames in which waste corn was placed in the center of individual corn plots, linear dispersal of conidia of A. flavus and plant infection gradients similar to those found from natural deposits were detected at distances of 1.7 to 8.5 m from the deposits at four sampling times from 6 August to 26 September 1992. Few airborne conidia of A. flavus were detected, and no infection of leaves, silks, and kernels by A. flavus occurred in the corresponding noninfested control plots. This study showed that deposits of waste corn infested with A. flavus found in the vicinity of corn storage cribs and bins are point sources of inoculum for A. flavus in the corn agroecosystem.

Temporal and spatial changes in aphid and parasitoid populations following applications of deltamethrin in winter wheat

AbstractThe spatial and temporal effects of the pyrethroid insecticide, deltamethrin, on populations of cereal aphids and their primary parasitoids and hyperparasitoids were investigated in a large scale field experiment in winter wheat. Four hectare plots were treated at the recommended field concentration or a reduced concentration representing one twentieth of field rate. A control plot was left unsprayed. Invertebrate populations were sampled at sites within a grid layout covering the whole plots, enabling the use of geostatistical analysis. Hymenopteran populations were monitored using transparent sticky traps and suction sampling. Aphid populations were recorded by visual counts. Monitoring continued for 36 days after treatment. The full rate deltamethrin treatment resulted in initial reductions of aphid populations by 78%. Primary parasitoid and hyperparasitoid populations were reduced in suction samples by 90% and 47% respectively, when corrected for control fluctuations. The reduced deltamethrin concentration caused reductions of aphid, primary parasitoid and hyperparasitoid populations of 40, 60 and 54% respectively. Aphid population recovery over the full rate plot occurred slowly and in a ‘patchy’ manner following treatment. No significant reinvasion gradients were detected. Aphid population density recovered more rapidly in the reduced rate treatment; with initial evidence for increased densities at the plot centre. Significant patterns of reinvasion were initially detected for both groups of Hymenoptera in the full rate treatment, suggesting that reinvasion of the sprayed area was taking place from untreated surrounding reservoirs. It was concluded that experiments that examine pesticide impacts within small plots will lead to underestimates of effects on dispersive groups including parasitic Hymenoptera.

Evaluation of Various Repellents for Control of Flea Beetle on Broccoli, 1996

Abstract Broccoli (cv. Premium Crop) was planted on 13 May 1996 at the Horticulture Field Research Center in Ft. Collins, CO. Plots consisted of single 10 ft long rows with 15 in. in-row spacing, arranged in RCB design with six replications. Each plot consisted of 8 plants. Repellent treatments were applied on 20 and 30 May, and 3 and 24 June with hand-held sprayers. Plants were sprayed to the point of drip delivering a spray volume of approximately 167 ml for each plot. Insect counts were made on 21 and 31 May 4, 6, 11, 20, 24, and 28 Jun, and 1 and 11 Jul by whole plant examination of 4 plants in the center of each plot.

The Spread of Epiphytic Populations of Xanthomonas campestris pv. vesicatoria on Pepper in the Field

AbstractThe spread of the epiphytic population of Xanthomonas campestris pv. vesicatoria and the disease it causes, bacterial leaf spot, were studied in field plots of pepper near Gainesville, Florida. In the summer of 1989, the epiphytic population of X. campestris pv. vesicatoria was dispersed to the west‐northwest from point sources of diseased plants. Winds from the southeast during rainstorms were essential for the spread of bacteria in the field. In the autumn of 1989, a focus of bacterial leaf spot developed naturally near the centre of the experimental plot. The epiphytic population of X, campestris pv. vesicatoria increased sharply after a 2‐day rain accompanied with strong wind. The wind was believed to be responsible for the transport of bacteria to distances 32 m from the focus. Initially in both seasons, the epiphytic populations occurred as distinct gradients from the focal sources of diseased plants. These gradients flattened over time and the disease incidence increased to near 100%, The increase in the epiphytic populations of the pathogen to > 3.0 log10 (cfu cm−2) on healthy plants away from the foci preceded disease appearance by several weeks. Applications of cupric hydroxide plus mancozeb significantly reduced the epiphytic population of X. campestris pv. vesicatoria on pepper leaves and slowed the spread of disease in the plots.

Optimal Dose of an Antiaggregation Pheromone (3-Methylcyclohex-2-en-1-one) for Protecting Live Douglas-Fir from Attack by Dendroctonus pseudotsugae (Coleopera: Scolytidae)

The Douglas-fir beetle, Dendroctonus pseudotsugae Hopkins, anti aggregation pheromone, 3-methylcyclohex-2-en-1-one (MCH), was applied to stands of Douglas-fir, Pseudotsuga menziesii (Mirabel) Franco, at high risk for infestation to determine the lowest effective dose for protecting live trees. MCH was applied at rates of 50, 100, and 150 bubble capsules per hectare (20, 40, and 60 g/ha, respectively) in 1994, and 15, 30, and 50 bubble capsules per hectare (6, 12, and 20 g/ha, respectively) in 1995. Mean release rates throughout the beetle flight periods in 1994 and 1995 were 1.63 and 1.23 milligrams per capsule per day, respectively. For both years, catches of Douglas-fir beetles in pheromone-baited traps located at the plot centers were significantly lower on all MCH-treated plots compared with untreated plots, but there were no differences among the 3 doses of MCH. In contrast, NCR had no effect on the numbers of 3 predators [Thanasimus undatulus (Say), Enoclerus sphegeus F., and Temnochila chlorodia (Mannerheim)] collected in the traps during either year. In 1994, the percentage of Douglas-fir ≥20 cm diameter at breast height (abh) that were mass attacked was significantly lower on MCH-treated plots compared with the untreated control, and all 3 doses were equally effective. In 1995, there were no significant differences in the percentage of mass-attacked trees among the treatments. These results demonstrate that MCH applied at rates as low as 20 g/ha (50 bubble capsules per hectare) can reduce the probability that high-risk Douglas-fir will become infested.

Introduction and Spread of the Fungal Pathogen Entomophaga maimaiga (Zygomycetes: Entomophthorales) Along the Leading Edge of Gypsy Moth (Lepidoptera: Lymantriidae) Spread

The gypsy moth fungal pathogen Entomophaga maimaiga Humber, Shimazu, & Soper was first reported in North America in 1989 but did not occur in areas more recently colonized by gypsy moth, Lymantria dispar (L.). To establish this pathogen along the leading edge of spreading gypsy moth populations, 6 x 10 5 E. maimaiga resting spores were released around the bases of oaks in 0.01-ha plots in Maryland, Pennsylvania, Virginia, and West Virginia. E. maimaiga was released in 34 plots in 1991 and 7 plots in 1992, with 15 control sites in 1991 and 3 control sites in 1992. During 1991, E. maimaiga infections were found in 28 plots, with infection levels >40% in 6 plots (17.6%). Infection levels were greater in plots where E. maimaiga resting spores were watered weekly. Low levels of infection were found in 4 of the 15 control plots. In 1992, E. maimaiga infections were detected in 40 of the 41 release plots as well as in the majority of control plots. Infection levels in 1992 E. maimaiga release plots averaged 72.4 ± 10.7% (mean ± SE) and were associated with declining egg mass densities. In 1991 fungal release plots resampled in 1992, disease prevalence in 1992 was greater in plots with higher levels of infection during 1991. During 1992, epizootics (>70% infection) occurred in 24 of the 28 1991 release plots. Throughout this study, levels of E. maimaiga infection were never associated with gypsy moth egg mass density at the beginning of the season. May rainfall was positively associated with infection for each year, and optimal average temperatures for infection were 13-19°c during May and June. During 1991, E. maimaiga spread up to 350 m from centers of release plots, and in 1992, E. maimaiga was abundant 1,000 m from release plots. Because of the abundance of E. maimaiga in 1992 control plots and at 1,000 m from 1992 release plots, 228 sites were surveyed to reevaluate the distribution of this fungus. E. maimaiga was found at all sites sampled in Virginia and Maryland and in the majority of West Virginia sites, demonstrating spectacular spread by this pathogen to the south and west; E. maimaiga now occurred at the southern limit of the gypsy moth distribution in the northeastern United States. Such rapid spread was completely unexpected and has never before been documented for an entomopathogenic fungus. We hypothesize that both our E. maimaiga release sites and preexisting E. maimaiga populations to the north and east may have been sources for the fungal inoculum that spread.

Spatial Growth of Kikuyugrass (Pennisetum clandestinum)

Photographic techniques and the point-frame transect method were used to study areal growth of kikuyugrass grown in the field without competition in 1990 and 1991. The effect of cutting height on plant extension was also examined in 1991. There were no differences in sward area between eight selections planted in 1990, except on the first measurement date, but selections differed in height and number of primary and secondary stolons. Expansion was irregular in all but one selection, and the patch shape of all irregular selections was defined by the direction and number of the earliest buds to sprout from the stolons. Only two of the eight selections were planted in 1991. Cutting height affected extension from the plot center, linear plant frequency, and plant biomass. The lowest height of cut, 2.5 cm, had the least extension and frequency, the higher cut, 5 cm, was intermediate, and the unmowed plots had the highest extension and frequency. There were differences between selections in number of nodes per unit area, which resulted in differences in response to mowing. Results from a greenhouse clipping experiment showed that although root weight of stolon sections used as propagules was reduced by defoliation, starch content was not affected. The spreading ability of kikuyugrass appears to be based on its ability to branch from its stolons presumably due to reallocation of resources. Based on these results, close mowing could slow the process of kikuyugrass invasion into other turf species but is inadequate to control it.

Stand structure and dynamics of young red alder as affected by planting density

The response of stand structure and dynamics of young red alder ( Alnus rubra Bong.) was examined over a gradient in planting density. Data from three Nelder plots, representing ages 1–7 years and planting densities from 238 to 101 218 trees ha −1, were used to develop biomathematical models for dominant height, diameter, and survival. The models accounted for 88–99% of the observed variation in projected height, diameter, and survival, with planting density accounting for 0.6–2.6% of the variation in diameter and height and 7.1% of the variation in survival. Height growth rate exhibited a quadratic relationship with planting density up to 24 670 trees ha −1 and a linear relationship at greater planting densities. The natural logarithm of planting density exhibited a linear relationship with change in relative diameter and quadratic mean diameter growth rates. These functional relationships between growth rates and planting density were consistent with the concepts of competition thresholds: height and diameter growth rates were more affected by planting density at lower than at higher planting density while mortality rate increased linearly with increasing density. At high planting density, annual height and quadratic mean diameter growth were less and reached a maximum at younger ages than at low planting density. The dominant height projection function depicts a temporal ripple in maximum height growth that progresses outward over time from the high planting densities in the center of Nelder plots to the lower densities near the edge of the plots.

Widely Separated Pheromone Release Sites for Disruption of Sex Pheromone Communicationin Two Species of Lepidoptera

Experiments were conducted to determine the efficacy of synthetic pheromone components in causing disruption of attractancy of males of 2 moth species to females used as bait in traps in the centers of large field plots. For beet armyworm, Spodoptera exigua (Hubner) (Noctuidae), in tomatoes and Platynota stultana (Walsingham) (Tortricidae) in both peaches and table grapes, large, widely spaced (20 m apart) evaporators in 1-ha plots gave disruption equivalent to that provided by smaller, more closely spaced (5.5 m apart) evaporators, as long as the release rates in both cases were adjusted to the same level, ≍0.9 mg/ha/d. When evaporators releasing the same total amounts of components per hectare per day were spaced 100 m apart in 25-ha plots, a reduction in the efficacy of communication disruption was noted. Evaporators releasing ≍0.9 mg of pheromone components per hectare per day and spaced at 5.5-m intervals around the perimeters only of 1- or 4-ha plots provided communication disruption of S. exigua in tomatoes and P. stultana in grapes and peaches equivalent to that provided by evaporators releasing the same amount of components per hectare per day and uniformly distributed at 5.5-m spacings within 1-ha plots. When evaporators releasing the same amount of components per hectare per day were spaced at 5.5-m intervals around the perimeters only of 16-ha plots, a reduction in communication disruption efficacy was also noted. It was calculated that evaporators releasing ≍0.9 mg of pheromone components per hectare per day could be separated from each other and from centrally located female-baited traps by up to 100 m before a lessening of communication disruption was obtained. Mechanical devices, which we call puffers , releasing pheromone components at 840 mg/ha/d, spaced at 40-m intervals around perimeters only of 16-ha plots, and separated from female-baited monitoring traps by 200 m, provided complete disruption of communication of S. exigua in tomatoes and P. stultana in grapes and peaches.

Potential of a blend of E8,E10‐120H and E8,E10‐12Ac for mating disruption of codling moth, Cydia pomonella L. (Lep., Tortricidae)

Abstract: Dispensers of E8,E10‐12OH (codlemone), E8,E10‐12Ac (codlemone acetate), or both dispenser types were placed on the corners of 100 m2 and 300 m2 plots within apple orchards. Communication disruption of male codling moths, Cydia pomonella, was monitored with pheromone traps in the centres of these plots. In the 300 m2 plots, trap catch was reduced only by codlemone. In the 100 m2 plots, trap catch was reduced in all three treatments, fewest males were caught in plots treated with both codlemone and codlemone acetate. Males were attracted to codlemone dispensers, they were also flying actively around the tree crowns, well above the dispensers. This behaviour was not observed in treatments with codlemone acetate, where male orientation flights were directed only towards the trap in the plot centre. The antagonistic effect of each of the four geometric isomers of codlemone acetate was shown by another trap test. Addition of 20% E,E‐; E,Z‐; Z,E‐ or Z8,Z10‐12Ac decreased male attraction to traps baited with E8, E10‐12OH.

Ataenius Efficacy On A Golf Course Fairway In Muskegon County Mi, 1995

Abstract A section of irrigated bent grass fairway at Spring Lake Country Club in Spring Lake, MI, that had a history of Ataenius and Aphodius problems was divided into 36 10ft X 10ft plots. Each treatment was replicated six times. The treatments were applied on 5 Jun for Aphodius control. Six cup-cutter samples were taken from the center of each plot on 19 Jun and no Aphodius grubs were found. The same plots were retreated on 26 Jun to evaluate Ataenius grub control. Treatments 2, 3, and 4 were applied with a modified salt shaker, while treatments 1 and 5 were sprayed with a hand held CO2 pressurized boom sprayer at 50 psi with four 8008 nozzles. 175 gal/acre of finished spray was applied. On 10 Jul, six cup-cutter samples were taken from the center of each plot.

Control of Southern Armyworm with Bacillus Thuringiensis in Staked Tomato, Fall 1994

Abstract Greenhouse raised tomato seedings “Florasette” were planted 8 Sep. 1994, 18 inches within the row on six subirrigated beds, 240 ft long, 32 ft wide on 6 ft centers. Beds had been fumigated with methyl bromide + chloropicrin 67/33 at a rate of 2201b/acre and mulched with whiteside polyethylene. Each of 4, 125 ft blocks was divided into 4, 3-row plots 25 ft long plus 2.5 ft walkways. Plants were sprayed weekly with an alternating combination of Maneb 80 WP at 1 lb/acre plus Kocide 101 at 31b/acre and Bravo 720 at 1.5 pt/acre for disease control. Plants were inoculated on 5 Oct with beet armyworm and on 19 Oct with SAW on 19 Oct to supplement natural populations by applying 2-3 neonates (2-3 per plant) in Grito-O-Cobs (20-40 mesh) to foliage with a “bazooka” gun. Treatments and spray schedules are given in Tables 1 and 2. Spray was delivered weekly for 7 weeks starting in 21 Oct using a high clearance sprayer equipped with yellow hollow cone Albuz nozzles at 200 psi pump pressure. Configuration for the first 4 applications was 9 nozzles per row, one overhead and four each side calibrated to deliver 89 GPA. An additional nozzle per side drop was added for the last 3 applications to deliver 110 GPA. Larval populations were evaluated weekly from 21 Oct to 29 Nov on 6 ft of row from the center of each 3-row plot in two-plant (between-stake) units. Larvae were counted in 3 size categories: small, medium and large but only medium and large are reported. Fruit of marketable size was harvested on 21 Nov & 02 Dec and graded on a commercial table with weights and numbers recorded.

Evaluation of Selected Insecticides for Control of Bollworm and Budworm, 1995

Abstract Cotton was planted on 17 May at the Robert Fratesi farm in Jefferson County. Plots consisted of 8 rows (40 inch centers) X 50 ft. Treatments were arranged in a RCBD with 4 replications. Insecticide treatments were applied on 19 Jun, 2 Jul, and 15 Jul with a CO2 sprayer mounted on a John Deere 6000 hi-cycle. Total volume was 9.91 gpa at 25 psi using Teejet TXVS-6 nozzles on 20 inch spacings. Insect counts on the first 2 evaluation dates (19 Jul, 2 Aug) were made by whole plant examination of 14 row ft in the center of each plot. Insect counts on the last evaluation date (15 Aug) were made by randomly examining 50 squares and terminals throughout the plot.