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Robert T. Eddy and Clifford S. Sadof

Horticulture businesses will be encouraged to hire qualified individuals with disabilities due to the enactment of the Americans with Disabilities Act of 1990. Maintaining a safe workplace is a considerable challenge due to the use and storage of restricted-use pesticides. In a vocational training program, two persons with mental disabilities were trained to be effective Integrated Pest Management scouts using systematic teaching procedures. Trainees acquired employable skills while providing a service that enabled management to reduce use of conventional pesticides on a greenhouse poinsettia crop by up to 65%.

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Raymond A. Cloyd and Clifford S. Sadof

A 2-year greenhouse study was conducted to evaluate the seasonal population dynamics and use of an action threshold for western fl ower thrips (Frankliniella occidentalis) in cut carnation (Dianthus caryophyllus). An action threshold of 20 thrips/card/week was adopted to time insecticide applications. The highest numbers of thrips were caught on blue-colored sticky cards from May through September whereas the lowest thrips numbers were present from November through March 1994 and 1995. Thrips numbers based on sticky card counts, from December through March for both years were below the action threshold and as a result, no insecticides were applied. Thrips abundance on blue sticky cards was significantly correlated with both numbers of thrips in fl owers and a subjective ranking of fl ower quality. Seasonal patterns of both insecticide use and numbers of damaged fl ow- ers closely followed patterns of thrips abundance found on blue sticky cards. Our findings are the first to demonstrate, based on a case study over a 2-year period, that routinely scouting for thrips throughout the year can lead to fewer insecticide applications and thus possible cost savings in labor and insecticide purchases. This study suggests that sticky cards can be an effective tool for reducing insecticide applications in regions of the U.S. where there are seasonal fl uctuations of thrips abundance.

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Carlos R. Quesada and Clifford S. Sadof

Insecticidal soap and horticultural oil have the potential to kill individuals within populations of soft-bodied insect pests by suffocation. However, scientific literature is inconsistent about the efficacy of insecticidal soaps and petroleum-based oils against armored scale (Hemiptera: Diaspidae) and soft scale (Hemiptera: Coccidae). We examined the efficacy of horticultural oil and insecticidal soap against armored and soft scales at different developmental life stages. Studies were conducted in the laboratory and field with two species of armored scale [pine needle scale (Chionaspis pinifoliae) and oleander scale (Aspidiotus nerii)] and two species of soft scale [calico scale (Eulecanium cerasorium) and striped pine scale (Toumeylla pini)]. All insecticide applications were made at a rate of 2 gal per 100 gal water. Our laboratory results suggested that horticultural oil and insecticidal soap killed both calico scale (73% and 93%, respectively) and oleander scale (67% and 78%, respectively) when insecticides targeted 1-day-old scales. Scale insects built up tolerance to both materials over time after they settled. However, our field data indicated that horticultural oil had high control of settled armored scale [oleander scale (90%) and pine needle scale (83%)], but failed to control settled soft scale [stripe pine scale (5%)]. Insecticidal soap reduced armored scale [oleander scale (54%)]. Neither horticultural oil nor insecticidal soap significantly reduced populations of adult armored or soft scales compared with a control. Overall, horticultural oil killed a greater percentage of armored scales than soft scales, whereas insecticidal soap gave greater control against soft scales. We suggest that differences were driven by chemical properties of both insect integuments and insecticides. The waxy cover of an armored scale might reduce penetration of polar insecticidal soap whereas polar integument of a soft scale might impede infiltration of the lipophilic horticultural oil. Consequently, timing application to crawler stage is important for effective management of armored or soft scale with horticultural oils and insecticidal soaps.

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Justin M. Vitullo and Clifford S. Sadof

This study evaluated azadirachtin and imidacloprid for their ability to reduce injury by Japanese beetles [Popillia japonica (Coleoptera: Scarabaeidae)] on floribunda-type roses (Rosa sp. ‘Acadia Sunrise’), either applied to foliage or as a soil drench. Roses were arranged in field plots and exposed to resident adult beetle populations. Insecticides were evaluated in field and laboratory trials. Laboratory assays of leaves collected from plants 14 days after soil applications of azadirachtin were less preferred by adult beetles than those collected from untreated controls. Plants in field trials that received soil treatments of either imidacloprid or azadirachtin had defoliation levels that were <8% throughout the entire season, whereas untreated control plants were 20% defoliated. Addition of foliar sprays to soil applied insecticides provided no added protection to foliage. Rose blooms were more difficult to protect with both foliar and soil-applied insecticides. Bloom injury of untreated controls varied between 20% and 30%, while plants receiving soil applications of azadirachtin varied between 0.2% and 18%. Soil applications of imidacloprid provided somewhat better protection of blooms with injury ranging between 0.2% and 8%. Foliar applications of azadirachtin gave no added protection to blooms of plants treated with imidacloprid. Adding carbaryl foliar treatments every 2 weeks improved control to <2% injury, a level that was comparable to weekly application of carbaryl. The potential for using soil-applied azadirachtin to reduce the need for foliar applications of carbaryl in rose gardens is discussed.

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Raymond A. Cloyd and Clifford S. Sadof

Greenhouse studies were conducted from 1996 to 1998 to determine the efficacy of spinosad, and acephate, against western flower thrips (Frankliniella occidentalis Pergande) on transvaal daisy (Gerbera jamesonii H. Bolus ex. Hook f). In addition, the number of natural enemies inside and outside the greenhouse was determined. Studies were arranged in a randomized complete-block design with four blocks and four treatments per block. Three rates of spinosad, 50, 100, and 200 mg·L-1 (ppm), and one rate of acephate, 600 mg·L-1 were used in all three studies. Plants were artificially inoculated at bloom with 10 adult western flower thrips. The number of live and dead thrips was counted from each plant. In all three studies, both spinosad and acephate controlled thrips. However, there was more variation in the average number of live thrips for acephate than spinosad across years. In all treatments fewer live thrips and more natural enemies were found on plants outside the greenhouse than inside the greenhouse. This suggests that placing plants outdoors allows the natural enemies of thrips to colonize plants and provide supplemental control.

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Raymond A. Cloyd and Clifford S. Sadof

Greenhouse studies were conducted to determine the efficacy of two granular systemic insecticides, acephate (Pinpoint 15G) and imidacloprid (Marathon 1G), against western flower thrips (Frankliniella occidentalis Pergande) on Transvaal daisy (Gerbera jamesonii H. Bolus ex. Hook. f). These studies were arranged in a randomized complete-block design with four blocks and four treatments per block. Two rates of acephate (0.75 g/16.5-cm pot and 1.0 g/16.5-cm pot) and one rate of imidacloprid (1.3 g/16.5-cm pot) were used in two studies. Plants were artificially inoculated with five adult western flower thrips at the prebloom stage. Plants were evaluated each week for flower quality (1 = complete injury or flower distortion to 5 = no injury), thrips density per flower, and number of plants flowering in each plot. Both studies showed that the acephate treated plants had the best flower quality, lowest numbers of thrips, and greatest number of plants flowering compared to imidacloprid and the check. These studies demonstrate that granulated acephate exhibits some activity in flower tissue and may assist growers in managing western flower thrips in floricultural crops.

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Carlos R. Quesada, Adam Witte and Clifford S. Sadof

Scale insects (Hemiptera: Coccoidea) are among the most economically important pests of ornamental plants. Soft scales (Coccidae) are phloem-feeding insects that produce large amounts of honeydew. By contrast, armored scales (Diaspididae) feed on the contents of plant cells and produce a waxy test that covers their bodies. We studied two species of armored scales [pine needle scale (Chionaspis pinifoliae) and oleander scale (Aspidiotus nerii)] and two species of soft scales [calico scale (Eulecanium cerasorum) and striped pine scale (Toumeyella pini)] to compare efficacy of selected insecticides. In addition, we assessed how the duration of first instar emergence might influence insecticide efficacy. Several reduced-risk insecticides (chlorantraniliprole, pyriproxyfen, spiromesifen, and spirotetramat), horticulture oil, and two broad-spectrum insecticide standards (bifenthrin and dinotefuran) were evaluated. Efficacy of insecticides was consistent within each scale family. Bifenthrin and pyriproxyfen were the only insecticides that killed soft scale insects. By contrast, all insecticides killed armored scales when the crawler stage was the target of application. Armored and soft scales may differ in susceptibility to pesticides because of likely differences in the chemical composition of their integuments and covers. Finally, we found that the effectiveness of a single application of insecticide declined by >15% when the duration of the crawling juvenile period was increased from 1 to 4 weeks. Increases in duration of a scale crawling period decreased the efficacy of a pesticide application.

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Clifford S. Sadof, Robert J. O'Neil, Farah M. Heraux and Robert N. Wiedenmann

More than 500 Master Gardeners in Indiana and Illinois were taught alternatives to the use of insecticides in workshops that focused on biological control of insect pests in home gardens. Gardeners also learned to conduct experiments in their backyards and were encouraged to participate in a summer research program that tested specific control methods. Workshop participants were surveyed before the workshop, and in two successive growing seasons to measure changes in their pest management practices. Overall, a significant percentage of gardeners stopped applying insecticides for up to two consecutive growing seasons after attending workshops. In addition, the adoption of biological control by participants appeared to be linked to their insecticide use and willingness to participate in the research process. A significant increase in the adoption of biological control was noted among garden researchers who did not use insecticides before the workshop or had reduced insecticide use following the workshop. No such change was noted for gardeners that did not conduct research. The relative contributions of workshop participation and hands-on research experience in pesticide reduction and biological control adoption are discussed.