Search Results

You are looking at 1 - 3 of 3 items for

  • Author or Editor: D. J. Wehner x
Clear All Modify Search

Abstract

The adhesives gum arabic, Methocel A-15, Pelgel, Solka Floe, and 2 experimental materials were evaluated for their effect on germination and early seedling growth of ‘Kentucky 31’ tall fescue (Festuca arundinacea Schreb.), and ‘Adelphi’ Kentucky bluegrass (Poa pratensis L.) and for their ability to retain a limestone seed coating. The adhesives did not adversely affect seed germination, turf quality, and early growth of seedlings of either species. Seedling growth of ‘Adelphi’, however, was enhanced by Methocel A-15 when compared to the control. Adhesive effectiveness for the retention of a limestone seed coating was in the order: Methocel A-15 > Pelgel > Solka Floe > AP-1 = AP-2.

Open Access

Abstract

The effects on Kentucky bluegrass (Poa pratensis L.) turf quality of mowing with either a mulching mower or a conventional rotary mower, having clippings re moved or returned, were determined. Turf that received 0, 150, or 300 kg N ha–1 yr–1 was mowed at 5 cm either biweekly, weekly, or twice weekly. Turf quality, weed encroachment, and thatch buildup were monitored. Highest quality was found where turf was mowed twice weekly with a conventional rotary mower with clippings returned and received 300 kg N ha–1 yr–1. Quality ratings for turf mowed with the mulching mower were equal to or significantly lower than ratings for turf mowed with a conventional rotary mower with clippings returned on 13 of the 17 rating dates. Thatch buildup and weed encroachment responded to N level, with more thatch and fewer weeds at the highest N level.

Open Access

Cucurbit downy mildew caused by the oomycete Pseudoperonospora cubensis (Berk. And Curt) Rostov is a major disease of cucumber (Cucumis sativus L.) (Palti and Cohen, 1980) globally. Chemical control of downy mildew is necessary to achieve high yields in the absence of adequate host plant resistance. Most of the currently grown cultivars have some resistance to downy mildew. Before the resurgence of the disease in 2004, host plant resistance was sufficient to control the disease without fungicide use, and downy mildew was only a minor problem on cucumber. There are currently no cultivars that show resistance at a level equal to that observed before 2004. However, differences in resistance exist among cultivars, ranging from moderately resistant to highly susceptible. In this study, we evaluated the disease severity and yield of four cucumber cultivars that differed in disease resistance and were treated with fungicide programs representing a range of efficacy levels. The experiment was a split plot design with six replications and four years. Disease was evaluated as chlorosis, necrosis, and reduction in plant size on a 0 to 9 scale. Cultigen had a large effect in all four years. Fungicide has a smaller effect on resistance component traits and a larger effect on yield traits. The effects of cultivar resistance and fungicides appear to be additive until a threshold where maximum yield is reached. Highly resistant cultigens such as PI 197088 required only the least effective fungicides to achieve highest yields, whereas moderately resistant cultigens required a more effective fungicide to reach a similar level of yield. Susceptible cultigens did not achieve high yield even with the most effective fungicide treatments. It is likely that, even as highly resistant cultivars are released, growers will need to continue a minimal fungicide program to achieve maximum yield.

Free access