HORTSCIENCE, V OL. 32(3), JUNE 1997 427 Abstracts Contributed Papers (Poster and Oral) Workshops Colloquia 94th Annual International Conference of the American Society for Horticultural Science Salt Lake City, Utah, USA 23–26 July 1997 The Abstracts that follow are arranged by type of session (Posters first, then Orals, Colloquia, and Workshops). The Poster abstract numbers correspond to the Poster Board number at which the Poster will be presented. To determine when a paper is to be presented, check the session number in the Program Schedule or the Conference at a Glance charts. The Author presenting the paper is indicated by an asterisk. 48 POSTER SESSION 1A (Abstr. 001–006) Culture & Management—Small Fruit/ Viticulture 001 Nitrogen Transformation in Low pH Soils for Cranberry Teryl R. Roper* and Armand R. Krueger, Dept. of Horticulture, University of Wisconsin–Madison, Madison, WI 53706 Cranberry plants exclusively utilize ammonium forms of nitrogen. Nitrifi cation of applied ammonium and subsequent leaching through sandy soils is a potential problem for growers. Peat, sand, and striped soils were collected in cranberry beds in central Wisconsin and soil pH was adjusted to 3.5, 4.5, or 5.5. Twenty-fi ve grams of dry soil was placed in fl asks and half the fl asks were sterilized. Distilled water was added to half of the samples, and the other half received 15 N-labeled ammonium. Flasks were incubated at 20°C for up to 70 days. Striped soils showed no nitrifi cation at pH 3.5 or 4.5 during the 70 day incubation. At pH 5.5, nitrifi cation began at 20 days and was almost complete at 70 days. Nitrifi cation did not occur at any pH in sandy soils. This research suggests that ammonium fertilizer applied to cranberry is likely taken up before nitrifi cation would occur. 002 Living Mulch for Strawberry Production Fields C.L. Gupton*; USDA-ARS, Small Fruit Research Station, P.O. Box 287, Poplarville, MS 39470 Annual ryegrass (Lolium multifl orum), which grows prolifi cally during the strawberry production season in the Gulf South, has the potential to serve as a living mulch if its growth is controlled. Sublethal dosages of Embark, a plant growth regulator, and the herbicides Poast and Rely were determined on ryegrass. Growth retardation was rated from 0 = none to 6 = dead. In 1993, all Poast dos- ages (1/8X – 1X, where X = 8 ml • L –1 ) were lethal. Embark regulated ryegrass growth, but its study was discontinued because of the unlikelihood that it could be labeled for use on strawberries. Results of the 1994 study suggested that prime oil in the spray may cause an inordinate amount of vegetative browning. In 1995, three levels of oil (1/256X, 1/64X, and 1/32X, where X = 8 ml • L –1 ) were