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Fungal plant pathogens can present major problems for most crop species. Currently, control of fungal diseases relies heavily on the use of fungicides. However, there are problems associated with fungicide use, including potential toxicity to non-target organisms and the development of resistance in the target fungus. New strategies are being sought to reduce fungicide use. One area of active research is the potential use of antifungal proteins from various fungal species as alternatives or complements to traditional fungicides. An antifungal protein, Efe-AfpA, from the fungal endophyte Epichloë festucae was previously found to protect plants from the pathogen Clarireedia jacksonii, the causal agent of dollar spot disease. Here we report that Efe-AfpA also has inhibitory activity against other important plant pathogens. These results suggest that it may be possible to develop Efe-AfpA as a biofungicide to target a broad range of destructive plant pathogens. [ABSTRACT FROM AUTHOR]

Colletotrichum cereale is an ascomycete inhabitant of cool-season Pooideae grasses. The fungus has increased in frequency over the past decade as a destructive pathogen of Poa annua and Agrostis stolonifera turfgrass. Colletotrichum cereale exists as two lineages, designated clades A and B, but little is known about the distribution of these clades in natural environments, or what role these subdivisions may play in the trajectory of disease outbreaks. In this study, our objective was to determine the frequency of C. cereale clades A and B. To rapidly discriminate between the two C. cereale clades, a real-time PCR assay was developed based on the Apn2 gene. A collection of 700 C. cereale pathogens and endophytes from twenty Pooideae grass genera were genotyped. 87% of the collection was identifed as part of clade A, 11.7% as part of clade B, and 1.3% was a mixture. Colletotrichum cereale from turfgrass hosts in North America were most commonly members of clade A (78%). The overabundance of clade A in turfgrass isolates was directly attributable to the dominance of this lineage from southern sampling sites, irrespective of host. In contrast, 111 C. cereale turfgrass isolates collected from northern sampling sites were evenly distributed between clades A and B. Only 28% of C. cereale from A. stolonifera at northern sampling sites were part of clade A. These data show that environmental factors such as geographic location and host identity likely played a role in the distribution of the major C. cereale clades in North American turfgrass. [ABSTRACT FROM AUTHOR]

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]

Many cool-season grasses have symbiotic relationships with Epichloë (Ascomycota, Clavicipitaceae) fungal endophytes that inhabit the intercellular spaces of the above-ground parts of the host plants. The presence of the Epichloë endophytes is generally beneficial to the hosts due to enhanced tolerance to biotic and abiotic stresses conferred by the endophytes. Many Epichloë spp. are asexual, and those infections always remain asymptomatic. However, some Epichloë spp. have a sexual stage and produce a macroscopic fruiting body, a stroma, that envelops the developing inflorescence causing a syndrome termed "choke disease". Here, we report a fungal and plant gene expression analysis of choke stroma tissue and asymptomatic inflorescence tissue of Epichloëfestucae-infected strong creeping red fescue (Festuca rubra subsp. rubra). Hundreds of fungal genes and over 10% of the plant genes were differentially expressed when comparing the two tissue types. The differentially expressed fungal genes in the choke stroma tissue indicated a change in carbohydrate and lipid metabolism, as well as a change in expression of numerous genes for candidate effector proteins. Plant stress-related genes were up-regulated in the stroma tissue, suggesting the plant host was responding to the epiphytic stage of E. festucae as a pathogen. [ABSTRACT FROM AUTHOR]

Sand size can affect the ability to incorporate topdressing into the turf canopy and thatch on golf course putting greens; unincorporated sand interferes with mowing and play. This 3-year field trial was initiated to determine the effects of sand size on sand incorporation, surface wetness, and anthracnose (caused by Colletotrichum cereale Manns sensu lato Crouch, Clarke, and Hillman) of annual bluegrass [Poa annua L. f. reptans (Hausskn) T. Koyama] maintained as a putting green. The experimental design was a randomized complete block with four replications; treatments included a non-topdressed control and three topdressing sands (medium-coarse, medium, or medium-fine) applied every 2 weeks at 0.15 L⋅m-2 during the summer. Topdressing with medium-coarse sand was more difficult to incorporate than the medium and medium-fine sands, resulting in a greater quantity of sand collected with mower clippings. Analyzing the particle distribution of sand removed by mowing confirmed that coarser sand particles were more likely to be removed in mower clippings. Surface wetness measured as volumetric water content (VWC) at the 0- to 38-mm depth zone was greater in non-topdressed plots than topdressed plots on 35% of observations. Few differences in VWC were found among sand size treatments. Turf responses to topdressing were not immediate; however, as sand accumulated in the turf canopy, topdressed plots typically had lower anthracnose severity than non-topdressed turf after the first year. Additionally, topdressing with medium and medium-fine sands produced similar or occasionally lower disease severity than topdressing with medium-coarse sand. The lack of negative effects of medium and medium-fine sands combined with better incorporation after topdressing and less disruption to the putting surface should allow golf course superintendents to apply topdressing at frequencies and/or quantities needed during the summer to maintain high-quality turf and playing conditions. [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]

Many cool-season grasses have symbiotic relationships with Epichloë (Ascomycota, Clavicipitaceae) fungal endophytes that inhabit the intercellular spaces of the above-ground parts of the host plants. The presence of the Epichloë endophytes is generally beneficial to the hosts due to enhanced tolerance to biotic and abiotic stresses conferred by the endophytes. Many Epichloë spp. are asexual, and those infections always remain asymptomatic. However, some Epichloë spp. have a sexual stage and produce a macroscopic fruiting body, a stroma, that envelops the developing inflorescence causing a syndrome termed "choke disease". Here, we report a fungal and plant gene expression analysis of choke stroma tissue and asymptomatic inflorescence tissue of Epichloë festucae -infected strong creeping red fescue ( Festuca rubra subsp. rubra ). Hundreds of fungal genes and over 10% of the plant genes were differentially expressed when comparing the two tissue types. The differentially expressed fungal genes in the choke stroma tissue indicated a change in carbohydrate and lipid metabolism, as well as a change in expression of numerous genes for candidate effector proteins. Plant stress-related genes were up-regulated in the stroma tissue, suggesting the plant host was responding to the epiphytic stage of E. festucae as a pathogen., Competing Interests: The authors declare no conflicts of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.

The fungus Colletotrichum cereale incites anthracnose disease on Poa annua (annual bluegrass) turfgrass. Anthracnose disease is geographically widespread throughout the world and highly destructive to cool-season turfgrasses, with infections by C. cereale resulting in extensive turf loss. Comprehensive research aimed at controlling turfgrass anthracnose has been performed in the field, but knowledge of the causal organism and its basic biology is still needed. In particular, the lack of a reliable greenhouse-based inoculation protocol performed under controlled environmental conditions is an obstacle to the study of C. cereale and anthracnose disease. Our objective was to develop a consistent and reproducible inoculation protocol for the two major genetic lineages of C. cereale. By adapting previously successful field-based protocols and combining with components of existing inoculation procedures, the method we developed consistently produced C. cereale infection on two susceptible P. annua biotypes. Approximately 7 to 10 days post-inoculation, plants exhibited chlorosis and thinning consistent with anthracnose disease symptomology. Morphological inspection of inoculated plants revealed visual signs of the fungus (appressoria and acervuli), although acervuli were not always present. After stringent surface sterilization of inoculated host tissue, C. cereale was consistently re-isolated from symptomatic tissue. Real-time PCR detection analysis based on the Apn2 marker confirmed the presence of the pathogen in host tissue, with both lineages of C. cereale detected from all inoculated plants. When a humidifier was not used, no infection developed for any biotypes or fungal isolates tested. The inoculation protocol described here marks significant progress for in planta studies of C. cereale, and will enable scientifically reproducible investigations of the biology, infectivity and lifestyle of this important grass pathogen.