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  • Author or Editor: R.M. Riedel x
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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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Controlled pollinations were made between five hemlock (Tsuga) species from eastern North America and Asia, resulting in over 5700 germinating seedlings. A subset of putative hybrid seedlings from each cross was tested for authenticity by various DNA marker systems. The most reliable and useful system for verifying hybrids was amplified fragment-length polymorphism (AFLP) markers. Hybridizations between the eastern North American species, T. canadensis [L.] Carriere and T. caroliniana Engelm., and the Asian species, T. chinensis (Franch.) E. Pritz., were used as a model to test the inheritance, reliability, and ease of use of these markers. Using AFLP markers, we were able to verify 58 hybrids between T. caroliniana and T. chinensis, one hybrid between T. caroliniana and T. canadensis, but could find no definitive hybrids between T. canadensis and T. chinensis. Results using other marker systems, including RAPD, SCAR, ITS, and SSR, are also presented.

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