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Nitrogen (N) is the essential plant nutrient needed by turfgrass in the greatest quantity. Urea and urea-based liquids are arguably the safest, least expensive, and subsequently most popular soluble N fertilizers. Unfortunately, urea fertilizer application to turfgrass is often subject to NH3 volatilization: a deleterious phenomenon from both environmental and agronomic perspectives. The objective of this research was to quantify the efficacy of creeping bentgrass (Agrostis stolonifera L.) golf course fairway foliar fertilization by urea-based N fertilizers as influenced by a petroleum-derived spray oil (PDSO) containing Cu II phthalocyanine colorant (Civitas Turf DefenseTM Pre-M1xed, Intelligro LLC, Mississauga, ON, Canada). In 2019 and 2020, a maintained creeping bentgrass fairway received semimonthly 9.76 kg ha–1 soluble N treatment either alone or in combination with Civitas at a rate of 27 L ha–1. In the 48 h following foliar application, fertilizer N loss as NH3 ranged from 1.3 to 5.5% and corresponded directly to fertilizer urea content but not Civitas inclusion. In the 1 to 14 d following semimonthly treatment, Civitas had either a beneficial (methylol urea and UAN) or negligible (urea) effect on canopy mean dark green color index. Once cumulative N inputs exceeded 47 kg ha–1, creeping bentgrass fairway shoot growth and N nutrition were consistently increased by Civitas complementation of commercial liquid N fertilizer. Over the 2-yr study, absolute mean percent fertilizer N recovery from plots treated by Civitas-complemented foliar liquid N treatment exceeded their 'N only' counterparts by 8.7%. [ABSTRACT FROM AUTHOR]

Cirsium arvense (Asteraceae) is known as creeping thistle in its native range in the UK and Canada thistle in its invasive North American range. Recently, the fungus Phoma macrostoma was registered in Canada as a bioherbicide in turfgrass, where it causes severe chlorosis (White Tip disease) and death of C. arvense and other broadleaved weeds. It was hypothesised that the disease originated in the UK on its thistle host and, therefore, that fungal isolates from both countries should be biologically and genetically similar. Twenty-six strains in the genus Phoma- isolated during surveys in the UK - were compared morphologically with the type culture of P. macrostoma, tested for bioherbicidal activity using the inoculum mat bioassay and genetically screened with bioherbicide-specific primers. White tip disease was found to be restricted to the eastern and southern counties of England. Phoma macrostoma was isolated consistently from diseased bleached tissues. Bioherbicidal isolates of P. macrostoma occupy a unique clade, which is phylogenetically distinct but morphologically indistinguishable from the type culture. Most isolates from the UK had the same bioherbicidal activity and similar genetic make-up as strain SRC 94-44B, the active ingredient in the registered Canadian product. The origin of all bioherbicidal strains found to date has a clear presence in both Canada and the UK, with strong genetic similarities, supporting the view of a common ancestry. Thus, on the evidence presented, the 'white tip' clade of P. macrostoma evolved in southern England. Therefore, the bioherbicide based on strain SRC 94-44B should also be eligible for registration in the UK, based on the pest risk assessment data already available. [ABSTRACT FROM AUTHOR]

Eighty-seven isolates of Colletotrichum graminicola, mostly from Agrostis palustris, were collected in grass fields, most of which were in Ontario, Canada. Specific primers were designed to amplify the mating-type (MAT) genes and, among 35 isolates tested, all yielded a band of the expected size for MAT2. For six isolates, the MAT2 PCR products were sequenced and found to be similar to that reported for MAT2 of C. graminicola from maize. Based on 119 polymorphic bands from 10 random amplified polymorphic DNA primers, analyses of genetic distances were found to generally cluster isolates by host and geographic origin. Among 42 isolates from a grass field in Ontario, significant spatial autocorrelation was found to occur within a 20-m distance, implying that this is the effective propagule dispersal distance. Although clonal propagation was observed in the 87 isolates with 67 unique genotypes, the extent of genetic variation in local populations implies some occurrence of sexual or asexual recombination.Key words: anthracnose, turfgrass, RAPD, MAT, reproduction, fungi.Quatre-vingt-sept isolats de Colletotrichum graminicola, la plupart du temps à partir d'Agrostis palustris, ont été récoltés dans des champs d'herbes, principalement en Ontario, Canada. Des amorces spécifiques ont été contruites pour amplifier les gènes des différents types de croisement (MAT) et, parmi 35 isolats vérifiés, tous produisaient une bande dont la taille correspondait à celle de MAT2. Chez six isolats, les produits PCR MAT2 ont été séquencés et se sont révélés semblables à ceux connus pour MAT2 de C. graminicola du maïs. En se basant sur 119 bandes de polymorphisme obtenues avec 10 amorces d'ADN polymorphe amplifié au hasard, la mesure des distances parcourues par les gènes a permis de regrouper de façon générale les isolats selon l'hôte et la région géographique. Avec 42 isolats provenant d'un même champ, nous avons observé une autocorrélation spatiale significative dans les limites de 20 m, ce qui serait donc la distance maximale de la dispersion des propagules. Même si une propagation des clones a été observée chez les 87 isolats qui portaient 67 génotypes uniques, l'importance des variations génétiques dans les populations locales suggère la présence de phénomènes de recombinaison sexuée ou asexuée.Mots-clés : anthracnose, gazon, RAPD, MAT, reproduction, champignons. [ABSTRACT FROM AUTHOR]

Pollen extracts from five locally-common grassland species in eastern Ontario, Canada were tested for in vitro allelopathic effect on the pollen germination of 17 sympatric target species in 1987. The flowering phenologies of the test and target species were recorded to determine if any phenologically-divergent species showed evidence of in vitro pollen-allelopathic interactions. Phleum pratense L. demonstrated pollen-allelopathic effects on all targets except Linaria vulgaris Hill. P. pratense L. also exhibited significant phenological divergence with seven of the target species. Pollen extracts from Agrostis stolonifera L., Melilotus alba Desr., and Vicia cracca L. inhibited pollen germination in some of the target species, but the results suggest that these effects were pH-mediated. The pollen extract of Erigeron annuus (L.) Pers. did not cause inhibition of pollen germination in any of the target species. Further tests with pollen extract of P. pratense and another 23 sympatric target species were performed in 1988. Pollen germination was significantly inhibited in all but two of these species: A. stolonifera and P. pratense. Hence, the pollen of P. pratense was not auto-allelopathic. The breeding system, relatively tall growth habit and relatively large quantity of pollen produced all support the in vitro evidence of P. pratense as a Pollen-allelopathic species. [ABSTRACT FROM AUTHOR]