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Dollar spot disease, caused by the fungal pathogen Clarireedia jacksonii, is a major problem in many turfgrass species, particularly creeping bentgrass (Agrostis stolonifera). It is well-established that strong creeping red fescue (Festuca rubra subsp. rubra) exhibits good dollar spot resistance when infected by the fungal endophyte Epichloë festucae. This endophyte-mediated disease resistance is unique to the fine fescues and has not been observed in other grass species infected with other Epichloë spp. The mechanism underlying the unique endophyte-mediated disease resistance in strong creeping red fescue has not yet been established. We pursued the possibility that it may be due to the presence of an abundant secreted antifungal protein produced by E. festucae. Here, we compare the activity of the antifungal protein expressed in Escherichia coli, Pichia pastoris, and Penicillium chrysogenum. Active protein was recovered from all systems, with the best activity being from Pe. chrysogenum. In greenhouse assays, topical application of the purified antifungal protein to creeping bentgrass and endophyte-free strong creeping red fescue protected the plants from developing severe symptoms caused by C. jacksonii. These results support the hypothesis that Efe-AfpA is a major contributor to the dollar spot resistance observed with E. festucae-infected strong creeping red fescue in the field, and that this protein could be developed as an alternative or complement to fungicides for the management of this disease on turfgrasses. [ABSTRACT FROM AUTHOR]

Summer patch is a common and destructive root disease of turfgrasses. In this study, a newMagnaporthiopsisspecies,M. meyeri-festucae, was identified from the roots of fine fescue (Festucaspp.) turfgrasses with summer patch-like symptoms. It is described and illustrated on the basis of phenotypic characteristics and partial sequences of rDNA 18S, internal transcribed spacer (ITS), and 28S regions, and ofMCM7, RPB1, andTEF1genes. A key for all seven described species in the genusMagnaporthiopsisis provided. Distinctions between the new species and related species are discussed. Fulfillment of Koch’s postulates confirmedMagnaporthiopsis meyeri-festucaeas a pathogen causing summer patch-like symptoms of fine fescue turfgrasses. This work is the basis for future studies on biogeography, host range, and impact of summer patch pathogens on a broader scale. [ABSTRACT FROM PUBLISHER]

In North America, one of the most important root diseases of Poa and Festuca turf is summer patch, caused by Magnaporthe poae. Detection and identification of M. poae in infected roots by conventional culture-based methods is difficult and time consuming, typically taking 3 wk or longer to accomplish. In this study, a culture-independent, TaqMan real-time PCR assay was developed for the detection of M. poae from the roots of fungicide-treated and non-treated Kentucky bluegrass (Poa pratensis) turf. The assay was validated with the target pathogen, closely related fungal species and a number of other microorganisms that inhabit the same host and soil environment. This assay was more sensitive (could detect as little as 3.88 pg genomic DNA of M. poae), rapid and accurate compared to direct microscopic observation and isolation on a selective medium. The real-time PCR detection results corresponded closely to visual assessments of disease severity in the field. Utilization of this assay in diagnostic laboratories will enable turfgrass managers to more quickly and effectively detect and potentially reduce fungicide usage through early and accurate identification of the pathogen. [ABSTRACT FROM AUTHOR]

Anthracnose (Colletotrichum cereale Manns sensu lato Crouch, Clarke & Hiliman) has been a devastating disease on annual bluegrass (ABG) [Poa annua L. f. reptans (Hausskn.) T. Koyama] putting green turf over the past 15 yr. The objectives of this 2-yr field trial on ABG were to evaluate the impact of mowing height (2.8, 3.2, and 3.6 mm), mowing frequency (seven and 14 times wk-1), lightweight rolling (none and every other day), and possible interactions of those factors on anthracnose severity and golf ball roll distance (BRD). Mowing height had the greatest effect on anthracnose. Mowing at 2.8 mm increased disease severity 3 to 21% compared with mowing at 3.6 mm, while 3.2 mm was intermediate to higher and lower heights. Mowing frequency had little effect on anthracnose, although mowing 14 times wk-1 occasionally reduced disease severity 1 to 14% compared with seven times wk-1. Rolling every other day also occasionally reduced disease severity 5 to 6% under moderate disease pressure. Mowing at 2.8 mm generally provided the greatest BRD. However, similar or greater BRDs were achieved at 3.2 and 3.6 mm, using combinations of increased mowing frequency and/or rolling compared with mowing at 2.8 mm seven times wk-1 without rolling. Thus, anthracnose severity on ABG greens can be reduced by raising the mowing height as little as 0.4 mm, and BRD (≥2.9-3.2 m) can be maintained by increasing mowing frequency and/or rolling without increasing disease severity. [ABSTRACT FROM AUTHOR]

Over the past decade, the emergence of anthracnose disease has newly challenged the health of turfgrasses on North American golf courses, resulting in considerable economic loss. The fungus responsible for the outbreaks, Colletotrichum cereale, has also been identified from numerous natural grasses and cereal crops, although disease symptoms are generally absent. Here we utilize phylogenetic and population genetic analyses to determine the role of ecosystem in the advancement of turfgrass anthracnose and assess whether natural grass and/or cereal inhabitants are implicated in the epidemics. Using a four-gene nucleotide data set to diagnose the limits of phylogenetic species and population boundaries, we find that the graminicolous Colletotrichum diverged from a common ancestor into distinct lineages correspondent with host physiology (C3 or C4 photosynthetic pathways). In the C4 lineage, which includes the important cereal pathogens Colletotrichum graminicola, C. sublineolum, C. falcatum, C. eleusines, C. caudatum and several novel species, host specialization predominates, with host-associated lineages corresponding to isolated sibling species. Although the C3 lineage — C. cereale— is comprised of one wide host-range species, it is divided into 10 highly specialized populations corresponding to ecosystem and/or host plant, along with a single generalist population spread across multiple habitat types. Extreme differentiation between the specialized C. cereale populations suggests that asymptomatic nonturfgrass hosts are unlikely reservoirs of infectious disease propagules, but gene flow between the generalist population and the specialized genotypes provides an indirect mechanism for genetic exchange between otherwise isolated populations and ecosystems. [ABSTRACT FROM AUTHOR]

Anthracnose disease of cool-season turfgrasses, caused by the fungus Colletotrichum cereale, has recently emerged as one of the most significant pathogens of Poa annua. Here we investigated the utility of four repetitive transposable elements as molecular markers for the analysis of C. cereale populations. Southern blot hybridization analysis revealed lineage-specific polymorphisms and distribution patterns for these transposons. Comparative phylogenetic analysis of three nonrepetitive protein coding DNA sequences against the transposon restriction fragment length polymorphisms indicated that the transposon sequences have similar evolutionary histories to those found in the sampled C. cereale population, despite the alteration of several transposon copies by repeat-induced point mutation. The variability and ubiquity of the Ccret2A15 transposon in C. cereale genomes suggest that this element could be used as a reliable DNA marker to discriminate between lineages of the fungus, identify hybrid genotypes, and analyze genetic diversity in populations of this turfgrass pathogen. [ABSTRACT FROM AUTHOR]

Over the past several decades, breeding cool-season turfgrasses for improved disease resistance has been the focus of many turfgrass breeding programs. This review article discusses the dramatic improvements made in breeding Kentucky bluegrass (Pot pratensis) for resistance to leaf spot (caused by Drechslera poae), stem rust (caused by Puccinia graminis), and stripe smut (caused by Ustilago striiformis); perennial ryegrass (Lolium perenne) for resistance to gray leaf spot (caused by Pyricularia grisea), stem rust and crown rest (caused by Puccinia coronata); tall fescue (Festuca arundinacea) for resistance to brown patch (Rhizoctonia solani) and stem rust; creeping bentgrass (Agrostis stolonifera) for resistance to dollar spot (caused by Sclerotinia homoeocarpa); and fine rescues (Festuca spp.) for improved disease resistance. Historically, the dramatic improvements in disease resistance of the cool-season grasses have been attributed to traditional/ conventional breeding techniques; however, it is likely that functional genomics and molecular techniques will play a more significant role in the development of cultivated turfgrasses as the specific genes and mechanisms for disease resistance are identified in the future. [ABSTRACT FROM AUTHOR]

In 1989, a close association was found between single-plant progenies of strong creeping red rescue infected with the endophyte Epichloü festucae and enhanced suppression of dollar spot, a widespread foliar disease of turfgrass caused by Sclerotinia homoeocarpa. From this limited observation, extensive field evaluations were conducted on a wide range of fine rescue germplasm obtained throughout the United States and Europe to determine the frequency and magnitude of this association. In five field trials established between 1985 and 1991, endophyte-infected Chewings, hard, blue, and strong creeping red rescue cultivars, selections, and crosses consistently exhibited endophyte-mediated suppression of dollar spot, when compared with closely related endophyte-free entries. Endophyte-infected Chewings and hard rescue cultivars and selections also had greater turf density and supported less foliar mycelium of S. homoeocarpa than endophyte-free entries. [ABSTRACT FROM AUTHOR]

A field day event was used to demonstrate the value of proper pesticide application methods to turfgrass. A single fungicide was applied through four nozzle-types and four water-carrier volumes targeting a common foliar disease in turfgrass. Most golf course superintendents surveyed use the same nozzle-type for all pesticide applications, but this field study indicated better disease control from the fungicide applied through certain nozzle-types and water-carrier volumes. As a result, most superintendents intended to make improvements to their pesticide application programs, and many had a highly favorable view of including this type of research at future field day events. [ABSTRACT FROM AUTHOR]