Peter J. Landschoot

Gray leaf spot of perennial ryegrass turf in Pennsylvania

A severe foliar disease of unknown etiology occurred on perennial ryegrass (Lolium perenne) turf during the summer of 1991 in southeastern Pennsylvania. Symptoms began as small brown lesions and rapidly progressed to a foliar blight on both seedling and mature perennial ryegrass. Isolation from diseased leaf tissue yielded a high percentage of Pyricularia grisea colonies. Inoculation of 4- and 20-wk-old plants resulted in symptoms very similar to naturally infected perennial ryegrass. Plants 4 wk old were more severely diseased than 20-wk-old plants, and necrosis of leaf tissue was more extensive at 29 C than at 22 C (.)

Inhibition of Pythium spp. and Suppression of Pythium Blight of Turfgrasses with Phosphonate Fungicides

Pythium aphanidermatum and other Pythium spp. cause Pythium blight of turfgrasses in the United States. Phosphonate fungicides suppress Pythium blight when applied preventatively, but efficacy may vary with product, rate and timing of application, and host species. The objectives of this study were to assess the inhibitory effects of phosphorous acid on Pythium spp. in vitro, and determine if active ingredient and formulation of phosphonate fungicides provide similar levels of Pythium blight suppression on perennial ryegrass and creeping bentgrass when applied at equivalent rates of phosphorous acid. Phosphorous acid EC50 values (effective concentration that reduces mycelial growth by 50%) for P. aphanidermatum isolates ranged from 35.6 to 171.8 μg/ml. EC50 values for isolates of six other Pythium spp. were between 38.7 and 220.8 μg/ml. In 2004 and 2005, all phosphonate treatments provided significant suppression of Pythium blight symptoms on creeping bentgrass and perennial ryegrass relative to the untreated control. No differences in percentage of blighted turf occurred among phosphonate treatments when applied at equivalent rates of phosphorous acid in either year of the study, regardless of active ingredient, formulation, or turfgrass species.

Effects of Dew Removal and Mowing Frequency on Fungicide Performance for Dollar Spot Control

Dollar spot (Sclerotinia homoeocarpa) is a severe disease problem on creeping bentgrass (Agrostis stolonifera) fairways. The objective of this study was to evaluate the effects of dew removal and mowing frequency on fungicide performance for dollar spot control. In 2009 and 2010, an experiment involving daily dew removal or no dew removal, mowing frequency (2, 4, and 6 days week-1), and fungicides (chlorothalonil, propiconazole, and iprodione) was conducted on creeping bentgrass maintained as a fairway. Daily dew removal resulted in fewer dollar spot infection centers (IC) compared with not removing dew during late summer 2009 and 2010 for all mowing-frequency and fungicide treatments. As mowing frequency increased from 2 to 6 days week-1, dollar spot IC decreased when averaged across all fungicide treatments. For all fungicides, daily dew removal increased the number of days needed to reach a 15-IC plot-1 point of reference when compared with fungicide treatments in which dew was not removed. The number of days required to reach 15 IC varied with fungicide, mowing frequency, and year the test was conducted. Results demonstrate that dollar spot control with fungicides can be extended when daily dew removal is employed and, in some cases, when mowing frequency is increased on dew-covered turf. Benefits of dew-removal practices on dollar spot and fungicide performance can vary with weather conditions, fungicide, threshold level, and possibly other factors.

Tolerance to simulated ice encasement and Microdochium nivale in USA selections of greens-type Poa annua

Abstract Lack of winter hardiness is a limitation to the use of annual meadowgrass (Poa annua f. reptans) on golf course putting greens in northern climates. Our objectives were 1) to assess the tolerance of 13 selections of annual meadowgrass to simulated ice encasement (SIE) and pink snow mould (PSM, Microdochium nivale); 2) to determine if these tolerances were interrelated or related to plant concentrations of water soluble carbohydrates (WSC); and 3) to determine if tolerance to SIE can be associated with accumulation of toxic substances. Samples of the annual meadowgrass selections were taken from an experimental green at University Park, Pennsylvania, on four dates from 23 Nov. 2005 until 27 Mar. 2006. Samples of creeping bentgrass (Agrostis stolonifera L.) ‘Penn A-4’ were included for comparison in studies on SIE and WSC. Samples were vacuum-sealed in plastic bags at 1°C for SIE and inoculated with three isolates of M. nivale for PSM tolerance. Small, but significant, differences were found among annual meadowgrass selections after 23 days of SIE, but all selections were dead after 33 days. Significant differences were detected in foliar blighting after inoculation with M. nivale, regrowth relative to uninoculated control being three times higher in the most tolerant than in the most susceptible selections. In late November, two annual meadowgrass selections contained significantly more WSC than did creeping bentgrass, but this was not correlated with tolerance to SIE or PSM, which were also not interrelated. A separate experiment with increasing duration of SIE to one of the annual meadowgrass selections and ‘Penn A-4’ showed that the critical exposure periods were 25–30 and 42–47 days, respectively. The concentrations of the phytotoxic compounds butan-l-ol and ethyl butyrate were two- to three-times higher in annual meadowgrass than in creeping bentgrass.

Summary of Mehlich-3 P Data from Home-Lawn Soil Tests in Pennsylvania

InDISCRIMINATE USE of P-containing fertilizer on runof-prone turfgrass sites is thought to contribute to the contamination of ground and surface water (Soldat and Petrovic, 2008). Consequently, several states have enacted laws restricting the use of P fertilizers, and others are considering similar legislation. A bill restricting P and N fertilizer on turfgrass was recently introduced in Pennsylvania, and implications of the proposed legislation are currently being discussed with stakeholders. Although soil testing is primarily performed to assess nutrient status in crop and turfgrass systems, some researchers have used soil-test summaries to examine trends in nutrient management practices and the status of soil P in cropland and lawns at the regional scale (Sims, 2000). Soldat and Petrovic (2008) stated that little published data on trends in soil P concentrations exist for turfgrass sites, and such information would be beneicial to validate predictions made for lawns and other turf areas. he objective of this study was to determine soil-test P concentrations in Pennsylvania home lawns based on unsolicited soil samples submitted to Penn State’s Agricultural Analytical Services Laboratory (AASL). Data from Pennsylvania home-lawn soil samples submitted to AASL between 1 Jan. 2004 and 31 Dec. 2009 were assembled into a spread sheet and summarized. Samples were submitted by homeowners and professional lawn fertilizer applicators via test kits distributed from county extension oices in Pennsylvania. he distribution of test kits was on a request basis, and no attempt was made to solicit soil samples from homeowners and professional applicators for this study. Instructions for collecting soil samples are included in the kits and call for a sampling depth of 5.1 to 7.6 mm, 12 or more cores per sample from each sampling site, and discarding all grass and thatch from cores. All soil samples were processed and analyzed at AASL according to methods listed by Wolf and Beegle (1995). Phosphorus was extracted from soil samples using Mehlich-3 Published in Applied Turfgrass Science DOI 10.2134/ATS-2014-0048-BR