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Kenneth Cropper, Gregg Munshaw, and Michael Barrett

turf species temporarily affected. Another technique of reducing herbicide usage is through cultural control methods. One of the most studied cultural control methods for crabgrass is mowing. Dernoeden et al. (1993) found a mowing height of 8.8 cm

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R. Precheur, C. Welty, R.M. Riedel, and M.R. Breth

Pumpkins rank third in acreage among Ohio's fresh market vegetables. Recently, increasing incidence of insect-vectored viruses have threatened the economic potential of this crop. Studies were initiated in 1992 to obtain information on abundance of insect pests, to evaluate the effect of insecticides, reflective mulch and row covers on pest density and yield of marketable fruit. In 1994 and 1995, statewide virus surveys were conducted to determine virus types infecting the pumpkin crop. In 1992 the greatest insect injury of concern was cucumber beetle feeding on fruit rinds, Insecticides lowered pest density, but there was no effect on marketable yield. In 1993, yield of virus-infected fruit was lower were reflective mulch was used than where rowcovers or foliar insecticides were used. Marketable yield and virus incidence in 1994 were not affected by reflective mulch, rowcovers or stylet oil due to the late arrival of the virus. In 1995, aphid infestations at three locations were significantly lower on plants on reflective mulch than on plants on bare ground. Results of the 1994 virus survey showed that watermelon mosaic virus (WMV) was the most common virus in Ohio pumpkins. The watermelon mosaic developed late in the season and fruit deformity was not severe enough to affect marketable yield. There was some incidence of cucumber mosaic and squash mosaic virus but zucchini yellow mosaic virus was not detected in 1994. Results of ELISA testing of samples collected in August/September 1995 at 27 farms were 18 farms positive for watermelon mosaic virus, 5 sites positive for squash mosaic, 4 sites positive for papaya ringspot and 1 site positive for zucchini yellow mosaic.

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Larry J. Gut, Peter H. McGhee, and Ron Perry

The relationship between the extent of burrknots on apple rootstocks and dogwood borer (DWB) [Synanthedon scitula Harris] infestation, and the efficacy of a cultural management strategy for this pest were studied in heavily infested plots at the Michigan State University Clarksville Horticulture Experiment Station. Spearman rank correlation Rho values of 0.85 and 0.75 in consecutive years of the study substantiated a strong positive correlation between the number of larvae present in the rootstock and the surface area of the rootstock covered by burrknots. Cultivar type affected the level of the DWB infestation in the rootstock. Larval densities were 8- to 10-times higher in Mark rootstocks when the grafted scion was `Idared' instead of `Liberty'. This cultivar related difference in larval infestation was associated with a greater number of burrknots on `Idared'/Mark compared to `Liberty'/Mark trees. Mounding of soil to cover the exposed rootstock was found to be a highly effective alternative to insecticides for DWB control. Under conditions of heavy pest pressure, this cultural control tactic provided 76% to 99% reductions in larval densities. These levels of control are comparable to or better than those reported for trunk sprays with chlorpyrifos, the most effective of currently available insecticides.

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C. Avilla, J.L. Collar, M. Duque, P. Pérez, and A. Fereres

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Ed Peachey, Robin L. Ludy, Mary L. Powelson, and Daniel M. McGrath

Field studies were conducted in 1999 and 2001 in western Oregon to determine the effect of between-row spacing on severity of white mold (Sclerotinia sclerotiorum) in snap beans. Planting density was held constant at 445,000 plants ha–1 and between-row spacing ranged from 19 to 150 cm. Disease severity and pod rot were greatest in both years of study at the 19-cm between-row spacing and declined linearly as between-row widths increased. Severity of disease in 1999 was 24%, 41%, and 88% lower at the 38-, 75-, and 150-cm between-row spacings, respectively, than at the 19-cm row spacing. In 2001, disease severity was 11%, 25%, 34%, and 51% less at the between-row widths of 38, 75, 114, and 150 cm, respectively, than at the 19-cm row spacing. Incidence of pod rot declined by 0.24% and 0.64% for each 10-cm increase in between-row width in 1999 and 2001, respectively. The fungicide vinclozolin effectively suppressed pod rot in both years at all between-row spacings. Pod yield was not influenced by between-row spacings of 19 to 114 cm, but yield was significantly lower at the between-row spacings of 150 cm. Increasing the between-row width of snap bean rows may be an effective disease management tactic to suppress white mold when fungicides are not applied or if efficacious fungicides are not available.

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Brian K. Hogendorp and Raymond A. Cloyd

Sanitation, which includes removing plant and growing medium debris, is an important component of any greenhouse or nursery pest management program. However, there is minimal quantitative information on how sanitation practices can reduce pest problems. In this study, conducted from May through Nov. 2005, we evaluated plant and growing medium debris as a source of insect pests from four greenhouses located in central Illinois. Two 32-gal refuse containers were placed in each greenhouse with a 3 × 5-inch yellow sticky card attached to the underside of each refuse container lid. Each week, yellow sticky cards and plastic refuse bags were collected from the containers and insects captured on the yellow sticky cards were identified. Insects captured on the yellow sticky cards were consistent across the four greenhouses with western flower thrips (Frankliniella occidentalis), fungus gnats (Bradysia spp.), and whiteflies (Bemisia spp.) the primary insects present each week. Insect numbers, in order of prevalence on the yellow sticky cards, varied across the four locations, which may be related to the type of plant debris discarded. For example, extremely high numbers of adult whiteflies (range = 702 to 1930) were captured on yellow sticky cards in one greenhouse each month from August through November. This was due to the presence of yellow sage (Lantana camera), bee balm (Monarda didyma), garden verbena (Verbena × hybrida), common zinnia (Zinnia elegans), sage (Salvia spp.) and fuchsia (Fuschia spp.) debris that was heavily-infested with the egg, nymph, pupa, and adult stages of whiteflies. High western flower thrips adult numbers in the greenhouses were generally associated with plant types such as marguerite daisy (Dendranthema frutescens) and pot marigold (Calendula officinalis) disposed while in bloom with opened yellow flowers, which contained adult western flower thrips. Based on the results of this study, it is important that greenhouse producers timely remove plant and growing medium debris from greenhouses or place debris into refuse containers with tight-sealing lids to prevent insect pests from escaping.

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E.R. Mitchell, Guangye Hu, and Denise Johanowicz

Collard greens (Brassica oleracea var. acephala L.) were planted in the peripheries of cabbage (Brassica oleracea var. capitata L.) fields in the spring growing seasons of 1997 and 1998 to evaluate their effectiveness as a trap crop to manage the diamondback moth (DBM) [Plutella xylostella (L.)]. The numbers of DBM never exceeded the action threshold for application of insecticides in any of thefields that were completely surrounded by collards, but did exceed the action threshold in three of the fields without collards on four sampling dates in 1998. In both years, the numbers of DBM larvae in the collards exceeded the action threshold of 0.3 total larvae/plant in eight of nine fields. Larval counts in cabbage surrounded with collards were not significantly higher than in the conventionally planted cabbage, even though the number of pesticide applications was reduced in the former. The few pesticide applications in fields surrounded by collards probably targeted the cabbage looper [Trichoplusia ni (Hübner)], which was not impeded by the collards from infesting the interior cabbage. There was no significant reduction in marketability, and damage to cabbage was similar to that in fields where collards were planted and in fields where only conventional pesticides were used. The reduced number of pesticide sprays, as well as the high concentration of host larvae in the collards, may help maintain populations of natural enemies of DBM in the agroecosystem. Planting collards in field peripheries is a potentially effective tactic to manage DBM in cabbage.

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E.R. Mitchell, Guangye Hu, and Denise Johanowicz

Collard greens (Brassica oleracea var. acephala L.) were planted in the peripheries of cabbage (Brassica oleracea var. capitata L.) fields in the spring growing seasons of 1997 and 1998 to evaluate their effectiveness as a trap crop to manage the diamondback moth (DBM) [Plutella xylostella (L.)]. The numbers of DBM never exceeded the action threshold for application of insecticides in any of the fields that were completely surrounded by collards, but did exceed the action threshold in three of the fields without collards on four sampling dates in 1998. In both years, the numbers of DBM larvae in the collards exceeded the action threshold of 0.3 total larvae/plant in eight of nine fields. Larval counts in cabbage surrounded with collards were not significantly higher than in the conventionally planted cabbage, even though the number of pesticide applications was reduced in the former. The few pesticide applications in fields surrounded by collards probably targeted the cabbage looper [Trichoplusia ni (Hübner)], which was not impeded by the collards from infesting the interior cabbage. There was no significant reduction in marketability, and damage to cabbage was similar to that in fields where collards were planted and in fields where only conventional pesticides were used. The reduced number of pesticide sprays, as well as the high concentration of host larvae in the collards, may help maintain populations of natural enemies of DBM in the agroecosystem. Planting collards in field peripheries is a potentially effective tactic to manage DBM in cabbage.

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Heather S. Costa, Julie Newman, and Karen L. Robb

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Mary H. Meyer, Rhoda Burrows, Karen Jeannette, Celeste Welty, and Aaron R. Boyson

as prevention, monitoring, cultural control, and chemical awareness/control. MGs responded to the full set of questions on IPM practices for each of five kinds of plants: fruit, vegetables, flowers, trees, and lawns. As a result, data were explored to