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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]

Anthracnose (Colletotrichum cereale Manns sensu lato Crouch, Clarke & Hillman) 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.sup.-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.sup.-1] occasionally reduced disease severity 1 to 14% compared with seven times [wk.sup.-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.sup.-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 ([greater than or equal to] 2.9-3.2 m) can be maintained by increasing mowing frequency and/or rolling without increasing disease severity.

Frequency and severity of anthracnose epiphytotics, caused by Colletotrichum cereale Manns Manns sensu lato Crouch, Clarke, and Hillman, on annual bluegrass (ABG) [Poa annua L. f. reptans (Hauskins) T. Koyama] putting greens have increased over the past decade. This 3-yr field study evaluated the impact of N fertilization (4.9 kg [ha.sup.-1] every 7 or 28 d), mefiuidide (ME; 0 and 0.106 kg a.i. [ha.sup.-1] [yr.sup.-1]) {N-[2,4-dimethyl-5-[[(trifluoromethyl)sulfonyl]amino] phenyl]acetamide}, trinexapac-ethyl (TE; 0 and 0.050 kg a.i. [ha.sup.-1] every 14 d) [4-(cyclopropyl-[alpha]-hydroxymethylene)-3, 5-dioxocyclohexanecarboxylic acid ethylester], verticutting (VC; 0- and 3-mm depth every 14 d), and interactions of these factors on anthracnose of ABG mowed at 3.2 mm. Nitrogen fertilization frequency had the greatest influence on disease throughout the study; N applied at 4.9 kg [ha.sup.-1] every 7 d reduced damage 5 to 24% compared to a 28-d interval. The plant growth regulators, ME and TE, frequently interacted during the last 2 yr of the study; sequential application of ME and TE reduced disease 6 to 14% compared to plots that only received one of these plant growth regulators. At advanced stages of disease, the combination of 7-d N fertilization and ME and TE application had the greatest disease reduction. Verticutting had little effect on anthracnose severity.

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 [Ccret2.sup.A15] 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.

Gray leaf spot disease, caused by Pyricularia oryzae Cavara, is an important disease in perennial ryegrass (Lolium perenne L.) turf. Host resistance is an ideal and promising approach to disease control. In this study, two diallel crosses involving six parents and eight parents, respectively, of perennial ryegrass were established to investigate the inheritance of gray leaf spot resistance. Parents and progenies were evaluated for gray leaf spot resistance in growth chamber experiments where they were inoculated with a mixture of five pathogen isolates. A field experiment was conducted on the progenies of one diallel cross. Effects of both general combining ability (GCA) and specific combining ability (SCA) were significant in both growth chamber and field tests. However, the GCA variance accounted for the major portion of the total genotypic variance. Narrow-sense heritability calculated by midparent-offspring regression ranged from 0.57 to 0.76, indicating additive gene effects were the major genetic component in control of gray leaf spot. Estimates of minimum number of genes ranged from 2.1 to 4.4, suggesting resistance to gray leaf spot was controlled by a small number of genes. All the results suggested that a breeding program basing on recurrent selection should be effective to improve the resistance to gray leaf spot in perennial ryegrass., GRAY LEAF SPOT has rapidly become one of the most important diseases of perennial ryegrass (Lolium perenne L.) in United States since its identification (Dernoeden, personal communications, 1986; Landschoot and [...]

Gray leaf spot, caused by the fungus Pyricularia grisea (Cooke) Sacc. [teleomorph Maguaporthe grisea (T.T. Herbert) Yaegashi & Udagawa], can be a devastating disease on perennial ryegrass (Lolium perenue L.). The identification and utilization of perennial ryegrass cultivars with improved resistance to gray leaf spot would reduce the need for fungicide applications. The objectives of this study were to: (i) evaluate cultivars, experimental selections, and single-plot progenies of perennial ryegrass for resistance to gray leaf spot, (it) develop populations from selected resistant parents to determine improvements in the next generation, and (iii) determine heritability and the response to selection for gray leaf spot resistance in perennial ryegrass populations. Two perennial ryegrass field experiments consisting of commercial cultivars and experimental selections, were established in 2000 and 2001 at Adelphia, NJ. Susceptibility of germplasm to gray leaf spot was evaluated following ephemeral natural outbreaks of the disease that occurred three to four weeks post seeding. Parents with improved resistance to gray leaf spot were selected based on progeny turf plot evaluations in 2000, inter-pollinated and seeded into turf plots in the 2001 experiment. Most cultivars and selections evaluated in both experiments had greater than 50% gray leaf spot disease. The high broad-sense heritability estimate (0.92) and similar response of progeny compared to selected parents indicated that parent selection based on progeny tests was a good selection method to predict the combining ability of the parents. It also proved successful in improving gray leaf spot resistance in the next generation, which will be important for the development of more disease resistant cultivars., GRAY LEAF SPOT has become a significant pathogen of perennial ryegrass. Pyricularia grisea was first associated with foliar blighting of perennial ryegrass in 1985 (Dernoeden, 1996), but was not confirmed [...]

Sand topdressing applied to annual bluegrass [Poa annua L. f. reptans (Hausskn.) T. Koyama] putting greens during the spring and summer can reduce anthracnose caused by Colletotrichum cereale Manns sensu lato Crouch, Clarke, and Hillman. However, the effects of autumn topdressing on this disease and the annual quantity of sand required to suppress anthracnose are not known. A 3-yr field study was initiated in 2010 to evaluate a 3 x 3 x 3 factorial of autumn, spring, and summer topdressing on anthracnose severity of annual bluegrass maintained at 2.8 mm. Autumn and spring topdressing was applied at 0, 1.2, or 2.4 L m-2 yr-1 and 0, 0.6, or 1.2 L m-2 yr-1 of sand was applied during summer. Linear and Cate-Nelson models were used to evaluate the response of anthracnose to annual topdressing quantity. Spring topdressing caused the greatest reduction in disease. Autumn topdressing reduced disease early each year following application, while spring topdressing provided consistent disease suppression throughout the growing season. Summer topdressing rates, similar to those applied on golf courses, reduced disease only in 2012 (mid- to late summer). Additionally, modeling the disease response against annual topdressing quantity indicated that increasing topdressing up to 6.0 L m-2 yr-1 produced a linear reduction of anthracnose on annual bluegrass. Golf turf managers should recognize that autumn topdressing will aid in anthracnose suppression; however, spring applications are more effective when anthracnose is the management objective. [ABSTRACT FROM AUTHOR]