Fitness and Competitive Ability of an Azoxystrobin-Resistant G143A Mutant of Magnaporthe oryzae from Perennial Ryegrass.

Development of azoxystrobin resistance in Magnaporthe oryzae from perennial ryegrass has been reported in certain locations in the United States, and possible development of resistance in additional areas is a major concern in the golf course industry. The study was undertaken to evaluate the relative fitness and competitive ability of a field-collected azoxystrobin-resistant G143A mutant by comparing it with a wild-type strain using detached perennial ryegrass blades. A fitness comparison experiment indicated that the disease severity of the wild-type strain was significantly higher than that of the mutant; however, the mutant produced greater secondary inoculum. When inoculated with three mixed populations of resistant and wild-type strains at different ratios, the production of conidia by the wild-type strain increased and that of the mutant decreased after infection occurred in all three populations tested. In an experiment on the effect of various fungicides on the population initially containing 5% of the mutant, preventive application of azoxystrobin allowed 5% of the mutant to dominate the population after the infection. However, other non-quinone outside inhibitor fungicides and mixtures of azoxystrobin with contact fungicides eliminated the entire mutant. This study demonstrates that the wild-type strain of M. oryzae has a competitive advantage over the mutant within the environment tested. Mixtures and alternations of fungicides with different modes of actions may prevent rapid build-up of resistance in the gray leaf spot pathosystem.

Effects of Soil Type, Source of Silicon, and Rate of Silicon Source on Development of Gray Leaf Spot of Perennial Ryegrass Turf.

Silicon amendments have been proven effective in controlling fungal diseases of various crops. However, effects of silicon amendments on gray leaf spot (Magnaporthe oryzae) of perennial ryegrass are not known. Studies were conducted in controlled-environment chambers and microplots where perennial ryegrass pots were buried among perennial ryegrass turf to determine the effects of silicon amendments on gray leaf spot development. Plants were grown in two soil types: peat:sand mix (soil Si = 5.2 mg/liter) and Hagerstown silt loam (soil Si = 70 mg/liter). Both soil types were amended with two sources of silicon-wollastonite and calcium silicate slag-at 0, 0.5, 1, 2, 5, and 10 metric tons/ha and 0, 0.6, 1.2, 2.4, 6, and 12 metric tons/ha, respectively. Nine-week-old perennial ryegrass was inoculated with M. oryzae. Gray leaf spot incidence and severity were assessed 2 weeks after inoculation. Gray leaf spot incidence and severity of perennial ryegrass significantly decreased by different rates of wollastonite and calcium silicate slag applied to both soils under both experimental conditions. Tissue silicon content increased consistently with increasing amount of silicon in the soils, while disease incidence decreased consistently with increasing tissue silicon content in all four soil and source combinations under both experimental conditions. These findings suggest that silicon amendments may be utilized in integrated gray leaf spot management programs on perennial ryegrass.

VITATOPS, the VITAmins TO prevent stroke trial: rationale and design of a randomised trial of B-vitamin therapy in patients with recent transient ischaemic attack or stroke (NCT00097669) (ISRCTN74743444).

BACKGROUND: Epidemiological studies suggest that raised plasma concentrations of total homocysteine (tHcy) may be a common, causal and treatable risk factor for atherothromboembolic ischaemic stroke, dementia and depression. Although tHcy can be lowered effectively with small doses of folic acid, vitamin B(12) and vitamin B(6), it is not known whether lowering tHcy, by means of B vitamin therapy, can prevent stroke and other major atherothromboembolic vascular events. AIM: To determine whether the addition of B-vitamin supplements (folic acid 2 mg, B(6) 25 mg, B(12) 500 microg) to best medical and surgical management will reduce the combined incidence of stroke, myocardial infarction (MI) and vascular death in patients with recent stroke or transient ischaemic attack (TIA) of the brain or eye. DESIGN: A prospective, international, multicentre, randomised, double blind, placebo-controlled clinical trial. SETTING: One hundred and four medical centres in 20 countries on five continents. SUBJECTS: Eight thousand (6600 recruited as of 5 January, 2006) patients with recent (<7 months) stroke (ischaemic or haemorrhagic) or TIA (brain or eye). RANDOMISATION: Randomisation and data collection are performed by means of a central telephone service or secure internet site. INTERVENTION: One tablet daily of either placebo or B vitamins (folic acid 2 mg, B(6) 25 mg, B(12) 500 mug). PRIMARY OUTCOME: The composite of stroke, MI or death from any vascular cause, whichever occurs first. Outcome and serious adverse events are adjudicated blinded to treatment allocation. SECONDARY OUTCOMES: TIA, unstable angina, revascularisation procedures, dementia, depression. STATISTICAL POWER: With 8000 patients followed up for a median of 2 years and an annual incidence of the primary outcome of 8% among patients assigned placebo, the study will have at least 80% power to detect a relative reduction of 15% in the incidence of the primary outcome among patients assigned B vitamins (to 6.8%/year), applying a two-tailed level of significance of 5%. CONCLUSION: VITATOPS aims to recruit and follow-up 8000 patients between 1998 and 2008, and provide a reliable estimate of the safety and effectiveness of folic acid, vitamin B(12), and vitamin B(6) supplementation in reducing recurrent serious vascular events among a wide range of patients with TIA and stroke throughout the world.

Comparative Genetic Analysis of Magnaporthe oryzae Isolates Causing Gray Leaf Spot of Perennial Ryegrass Turf in the United States and Japan.

Gray leaf spot caused by Magnaporthe oryzae is a serious disease of perennial ryegrass (Lolium perenne) turf in golf course fairways in the United States and Japan. Genetic relationships among M. oryzae isolates from perennial ryegrass (prg) isolates within and between the two countries were examined using the repetitive DNA elements MGR586, Pot2, and MAGGY as DNA fingerprinting probes. In all, 82 isolates of M. oryzae, including 57 prg isolates from the United States collected from 1995 to 2001, 1 annual ryegrass (Lolium multiflorum) isolate from the United States collected in 1972, and 24 prg isolates from Japan collected from 1996 to 1999 were analyzed in this study. Hybridization with the MGR586 probe resulted in approximately 30 DNA fragments in 75 isolates (designated major MGR586 group) and less than 15 fragments in the remaining 7 isolates (designated minor MGR586 group). Both groups were represented among the 24 isolates from Japan. All isolates from the United States, with the exception of one isolate from Maryland, belonged to the major MGR586 group. Some isolates from Japan exhibited MGR586 fingerprints that were identical to several isolates collected in Pennsylvania. Similarly, fingerprinting analysis with the Pot2 probe also indicated the presence of two distinct groups: isolates in the major MGR586 group showed fingerprinting profiles comprising 20 to 25 bands, whereas the isolates in the minor MGR586 group had less than 10 fragments. When MAGGY was used as a probe, two distinct fingerprint types, one exhibiting more than 30 hybridizing bands (type I) and the other with only 2 to 4 bands (type II), were identified. Although isolates of both types were present in the major MGR586 group, only the type II isolates were identified in the minor MGR586 group. The parsimony tree obtained from combined MGR586 and Pot2 data showed that 71 of the 82 isolates belonged to a single lineage, 5 isolates formed four different lineages, and the remaining 6 (from Japan) formed a separate lineage. This study indicates that the predominant groups of M. oryzae associated with the recent outbreaks of gray leaf spot in Japan and the United States belong to the same genetic lineage.

Effects of Timing of Ethofumesate Application on Severity of Gray Leaf Spot of Perennial Ryegrass Turf.

Ethofumesate is a widely used herbicide for control of annual bluegrass (Poa annua) in perennial ryegrass (Lolium perenne) fairways on golf courses in the United States. Effect of timing of ethofumesate application on development of gray leaf spot was evaluated on perennial ryegrass turf treated with six classes of fungicide. Two applications of ethofumesate (2.28 kg a.i./ha) were made to perennial ryegrass turf maintained at a 2-cm height, at 4-week intervals, each fall (October and November 1999 and 2000) or spring (April and May 2000 and 2001). In addition, turf was treated with the fungicides, azoxystrobin, chlorothalonil, flutolanil, iprodione, propiconazole, or thiophanate-methyl at the label rates at 14-day intervals. There were significant effects (P ≤ 0.05) of ethofumesate application timing and fungicide regime on gray leaf spot development. There also were significant interactions between the ethofumesate application timing and fungicide. Severity of gray leaf spot was significantly greater in turf plots treated with ethofumesate in spring compared to turf treated in fall or nontreated control plots treated with fungicides, flutolanil, iprodione, and propiconazole that were relatively less effective in control of gray leaf spot. There was no significant difference in disease severity in turf treated with ethofumesate in fall or to turf not treated with herbicide regardless of the fungicide used. Results of this study indicate that spring application of ethofumesate contributes to development of gray leaf spot epidemics, and the application timing interacts with the classes of fungicides. This study suggests that ethofumesate should be applied only in fall for control of P. annua, particularly in golf courses with a chronic gray leaf spot problem, as part of an integrated management of gray leaf spot in perennial ryegrass fairways.

Genetic Diversity of Sclerotinia homoeocarpa Isolates from Turfgrasses from Various Regions in North America.

Sixty-seven isolates of Sclerotinia homoeocarpa, causing dollar spot disease in creeping bentgrass, annual bluegrass, Bermudagrass, and perennial ryegrass turf, collected from 23 golf courses in various geographical regions of the United States and Canada between 1972 and 2001, were characterized by vegetative compatibility, genetic diversity, and pathogenicity. Eleven vegetative compatibility groups (VCGs A to K) were identified among the isolates tested in this study, and five of them (VCGs G to K) were new. VCG B was the most predominant group, typifying 33 isolates (51%) tested. S. homoeocarpa isolates collected from golf courses in Pennsylvania belonged to seven VCGs (A, B, E, F, G, I, and K), whereas three groups were observed in those collected from New York (B, E, and G) and New Jersey (E, H, and I). Two isolates, one each from Pennsylvania and Canada, were incompatible when paired with the tester isolates in all possible combinations, and did not fall into any known VCG. An isolate collected from Canada was compatible with tester isolates from two VCGs (C and D). Genetic analyses using amplified fragment length polymorphism (AFLP) showed the presence of two genetically distinct groups, designated as major group and the minor group. The major group included 36 isolates collected from various golf courses in the United States and Canada. Two isolates collected from bermudagrass in Florida formed a separate cluster, the minor group. Isolates that belonged to the major group were further divided into two subgroups (1 and 2). Subgroup 1 consisted of all the isolates that belonged to VCGs A, E, G, H, and I. Three of the four isolates that belonged to VCG K also were clustered with isolates of subgroup 1. Subgroup 2 consisted of all the isolates from VCG B, and one each from VCGs F and K. Pathogenicity assays on Penncross creeping bentgrass showed significant differences (P = 0.05) in virulence among the isolates. Overall, a relationship between virulence and VCGs was observed, in which certain virulence groups corresponded to specific VCGs; however, such a relationship was not observed between virulence and AFLPs. Close similarity among isolates of S. homoeocarpa collected from different locations in the United States and Canada suggests that isolates of the same genotype could be involved in outbreaks of dollar spot epidemics at multiple locations.

A temperature and leaf wetness duration-based model for prediction of gray leaf spot of perennial ryegrass turf.

ABSTRACT Gray leaf spot is a serious disease of perennial ryegrass (Lolium perenne), causing severe epidemics in golf course fairways. The effects of temperature and leaf wetness duration on the development of gray leaf spot of perennial ryegrass turf were evaluated in controlled environment chambers. Six-week-old Legacy II ryegrass plants were inoculated with an aqueous conidial suspension of Pyricularia grisea (approximately 8 x 10(4) conidia per ml of water) and subjected to four different temperatures (20, 24, 28, and 32 degrees C) and 12 leaf wetness durations (3 to 36 h at 3-h intervals). Three days after inoculation, gray leaf spot developed on plants at all temperatures and leaf wetness durations. Disease incidence (percent leaf blades symptomatic) and severity (index 0 to 10; 0 = leaf blades asymptomatic, 10 = >90% leaf area necrotic) were assessed 7 days after inoculation. There were significant effects ( alpha = 0.0001) of temperature and leaf wetness duration on disease incidence and severity, and there were significant interactions ( alpha = 0.0001) between them. Among the four temperatures tested, 28 degrees C was most favorable to gray leaf spot development. Disease incidence and severity increased with increased leaf wetness duration at all temperatures. A shorter leaf wetness duration was required for disease development under warmer temperatures. Analysis of variance with orthogonal polynomial contrasts and regression analyses were used to determine the functional relationships among temperature and leaf wetness duration and gray leaf spot incidence and severity. Significant effects were included in a regression model that described the relationship. The polynomial model included linear, quadratic, and cubic terms for temperature and leaf wetness duration effects. The adjusted coefficients of determination for the fitted model for disease incidence and severity were 0.84 and 0.87, respectively. The predictive model may be used as part of an integrated gray leaf spot forecasting system for perennial ryegrass turf.

Detection of Pyricularia grisea Causing Gray Leaf Spot of Perennial Ryegrass Turf by a Rapid Immuno-Recognition Assay.

An immuno-recognition assay using a monoclonal antibody was developed to detect Pyricularia grisea, the causal agent of gray leaf spot of perennial ryegrass (Lolium perenne). In vitro assays with isolates of P. grisea from perennial ryegrass, tall fescue (Festuca arundinacea), St. Augustinegrass (Stenotaphrum secundatum), crabgrass (Digitaria sanguinalis), finger millet (Eleusine coracana), wheat (Triticum aestivum), triticale (× Triticosecale rimpaui), and rice (Oryza sativa) showed positive reactions; however, the strength of the reactions differed among isolates. Reactions were more intense with isolates from perennial ryegrass, wheat, and triticale. All P. grisea isolates from perennial ryegrass collected from various regions of the United States showed positive reactions. P. grisea was detected at antigen dilution rates of 0.5×, 0.25×, 0.13×, 0.06×, and 0.03×. Dot-blot assays with Bipolaris sorokiniana, Colletotrichum graminicola, Curvularia lunata, Microdochium nivale, Pythium aphanidermatum, Rhizoctonia solani, or Sclerotinia homoeocarpa isolated from turfgrasses were negative. In vivo assays of symptomatic leaves of perennial ryegrass plants inoculated with P. grisea also showed positive reactions, and those inoculated with B. sorokiniana, P. aphanidermatum, R. solani, or S. homoeocarpa were negative. Intensity of reaction between the monoclonal antibody and P. grisea was proportional to disease severity in perennial ryegrass inoculated with P. grisea; however, there was no reaction in dot blots of leaf tissue collected during the latent period. P. grisea was detected in perennial ryegrass samples from golf course fairways affected by gray leaf spot in Connecticut, Massachusetts, Maine, New Jersey, Pennsylvania, and Rhode Island using this procedure. The monoclonal antibody recognition system is highly sensitive to P. grisea and can be used effectively for the rapid diagnosis of gray leaf spot of perennial ryegrass turf.

Distribution of Mating Type Alleles and Fertility Status of Magnaporthe grisea Causing Gray Leaf Spot of Perennial Ryegrass and St. Augustinegrass Turf.

Isolates of Magnaporthe grisea causing gray leaf spot of perennial ryegrass (PR) (Lolium perenne) and St. Augustinegrass (SA) (Stenotaphrum secundatum) were analyzed for mating compatibility and fertility. A total of 312 isolates of M. grisea from PR and 62 isolates from SA were paired with hermaphroditic tester strains from finger millet (Eleusine coracana), rice (Oryza sativa), and wheat (Triticum aestivum). All the PR isolates belonged to a single mating type, MAT1-2. Male fertility was observed in all these isolates. Asci and ascospores were not produced regardless of their developmental stage. Of the 139 (44.6%) isolates from PR that formed perithecia with the fertile tester strains, 83 (59.7%) were highly fertile, 33 (23.7%) were intermediately fertile, and 23 (16.5%) were low in fertility. Both mating types were observed among the isolates of SA, where MAT1-1 predominated the MAT1-2 type. An equal number of male and female fertile isolates were detected among these isolates obtained from a single location; however, none of the isolates behaved as hermaphrodites. Few ascospores were produced in crosses between two isolates of SA and a finger millet tester. Of the 62 monoconidial isolates of SA tested, 19 (30.6%) isolates formed perithecia, of which 5 (26.3%) were highly fertile, 7 (36.8%) were intermediately fertile, 7 (36.8%) were low in fertility, and 43 (69.4%) were infertile. The results of this study indicate that the sexual stage may not be a significant factor contributing to the genetic variation the gray leaf spot pathogen population.

First Report of Gray Leaf Spot on Perennial Ryegrass Turf in California.

Gray leaf spot of perennial ryegrass (Lolium perenne L.) turf was first reported in the United States in 1991. The disease epidemic was primarily confined to golf course fairways in southeastern Pennsylvania (1). Subsequently, moderate to severe outbreaks of gray leaf spot occurred in perennial ryegrass fairways and roughs in numerous locations throughout the eastern and midwestern United States. In August 2001, a serious decline of perennial ryegrass turf was observed in a bermudagrass (Cynodon dactylon (L.) Pers) baseball field in Dodger Stadium in Los Angeles, CA, that had been overseeded with perennial ryegrass. The bermudagrass turf was not affected. The perennial ryegrass turf developed necrotic lesions that resulted in blighting of leaf blades. In laboratory assays, Pyricularia grisea (Cooke) Sacc., was consistently isolated from symptomatic ryegrass blades from turf samples collected from the site. Of the 12 P. grisea isolates collected from the assayed leaf blades, five isolates were selected for a pathogenicity assay. Twenty-five 'Legacy II' perennial ryegrass plants were grown from seeds in 4 × 4 in.-plastic pots, (10 × 10 cm) which were filled to 1 cm below the rim with granular calcine clay medium (Turface MVP, Allied Industrial Material Corp., Buffalo Grove, IL). Three weeks after seeding, plants were fertilized with a water-soluble 20-20-20 N-P-K fertilizer (1.3 g/liter of water) once per week. Treatments (isolates of P. grisea and a control) were arranged as a randomized complete block design with five replications. Five-week-old plants were sprayed with an aqueous suspension of P. grisea conidia (≈5 × 104 conidia per ml of sterilized distilled water with 0.1% Tween 20) using an atomizer until the leaves were completely wet. Plants sprayed with sterilized distilled water served as the control. After inoculation, individual pots were covered with clear polyethylene bags and placed in a controlled environment chamber maintained at 28°C and continuous fluorescent light (88 µE m-2 s-1). Four days after inoculation, necrotic lesions (<2 mm diameter) developed on ryegrass blades inoculated with each isolate of P. grisea. Lesions did not develop on leaves of control plants. Seven days after inoculation, the polyethylene bags were removed, and 50 symptomatic blades from each pot were collected, and disease incidence (percent infected leaves) and severity (index 0 to 10; 0 = none, 10 = >90% of the leaf blade necrotic ) were assessed. P. grisea was isolated from symptomatic leaves of plants inoculated with the fungus. Disease incidence and severity on inoculated plants were 92 to 96% and 8.8 to 10, respectively. There were no significant differences in disease incidence and severity (P = 0.05) among the isolates of P. grisea included in the test. To our knowledge, this is the first report of gray leaf spot of perennial ryegrass turf in California. Reference: (1) P. J. Landschoot and B. F. Hoyland. Plant Dis. 76:1280, 1992.

Pyricularia grisea Causing Gray Leaf Spot of Perennial Ryegrass Turf: Population Structure and Host Specificity.

Gray leaf spot is a serious disease of perennial ryegrass (Lolium perenne) turf in the United States. Isolates of Pyricularia grisea causing the disease in perennial ryegrass were characterized using molecular markers and pathogenicity assays on various gramineous hosts. Genetic relationships among perennial ryegrass isolates were determined using different types of trans-posons as probes. Phylogenetic analysis using Pot2 and MGR586 probes, analyzed with AMOVA (analysis of molecular variance), showed that these isolates from perennial ryegrass consist of three closely related lineages. All the isolates belonged to a single mating type, MAT1-2. Among 20 isolates from 16 host species other than perennial ryegrass, only the isolates from wheat (Triticum aestivum) and triticale (× Triticosecale), showed notable similarity to the perennial ryegrass isolates based on their Pot2 fingerprints. The copy number and fingerprints of Pot2 and MGR586 in isolates of P. grisea from perennial ryegrass indicate that they are genetically distinct from the isolates derived from rice (Oryza sativa) in the United States. The perennial ryegrass isolates also had the same sequence in the internal transcribed spacer (ITS) region of the genes encoding ribosomal RNA as that of the wheat and triticale isolates, and exhibited rice isolate sequence polymorphisms. In pathogenicity assays, all the isolates of P. grisea from Legacy II perennial ryegrass caused characteristic blast symptoms on Marilee soft white winter wheat, Bennett hard red winter wheat, Era soft white spring wheat, and Presto triticale, and they were highly virulent on these hosts. An isolate from wheat and one from triticale (from Brazil) were also highly virulent on perennial ryegrass and Rebel III tall fescue (Festuca arundinacea). None of the isolates from perennial ryegrass caused the disease on Lagrue rice, and vice versa. Understanding the population structure of P. grisea isolates infecting perennial ryegrass and their relatedness to isolates from other gramineous hosts may aid in identifying alternate hosts for this pathogen.

A Serious Outbreak of Blast Disease (Gray Leaf Spot) of Perennial Ryegrass in Golf Course Fairways in Pennsylvania.

Blast disease (gray leaf spot) of perennial ryegrass (Lolium perenne L.), caused by Pyricularia grisea (Cooke) Sacc., in golf course fairways in Pennsylvania, was first reported in 1991 (1). The disease was primarily confined to the southeastern region of the state. In August and September 1998, severe outbreaks of blast disease occurred in perennial ryegrass fairways in numerous golf courses in the same region in Pennsylvania. Additionally, in 1998, the disease was diagnosed in ryegrass fairways for the first time in the western region of the state, where serious disease outbreaks occurred. The disease develops on leaf blades as small, watersoaked lesions that become necrotic spots. The spots expand rapidly, and develop into gray, grayish-brown, or light brown, circular spots with purple to dark brown borders often surrounded by a yellow halo on the leaf blades. As the disease progresses, the circular necrotic spots coalesce, become irregular in shape, and cause partial (tip blight) or complete blighting of the leaf blades. The blighted blades may often appear twisted. Turfgrass loss due to the disease was over 90% in several golf courses. During the 1998 epidemics, a survey was conducted in the affected regions, which included three golf courses in western Pennsylvania and 15 golf courses in southeastern Pennsylvania. P. grisea was consistently isolated from the symptomatic ryegrass leaf blades of turf samples (12 to 28 samples per location) collected from the blighted fairways. Of the 122 isolates of P. grisea collected from the 18 golf courses, seven isolates (two from western Pennsylvania and five from southeastern Pennsylvania) were selected for pathogenicity assays. Five Pennfine perennial ryegrass plants were grown in each Cone-Tainer (4 mm in diameter) that was filled to 1 cm below the rim with granular calcine clay medium (Turface MVP; Allied Industrial Material, Buffalo Grove, IL). Three weeks after seeding, grasses were fertilized with water-soluble 20-20-20 fertilizer (1.3 g per liter of water) once a week to field capacity of the growing medium. Treatments (the isolates) were arranged as a randomized complete block with four replications (a Cone-Tainer per replication). Six-week-old ryegrass plants were atomized with an aqueous suspension of P. grisea conidia (approximately 8 × 104 conidia per ml of sterilized, distilled water) until the leaves were completely wet. Individual Cone-Tainers were placed in clear polyethylene bags, enclosed, and were placed in an incubator that was maintained at continuous 28°C and 12-h-day fluorescent light (72 µE s-1 m-2). Three days after inoculation, water-soaked lesions (<2 mm in diameter) developed on leaves of the ryegrass inoculated with each isolate of P. grisea. No lesions developed on leaves of the control plants. Seven days after inoculation, the polyethylene bags were removed, and disease incidence (percent infected leaves) was assessed. P. grisea was isolated from the necrotic lesions or the blighted leaf blades of every plant inoculated with the fungus. This is the first report of blast disease outbreak in golf course fairways in western Pennsylvania. The impact of blast disease epidemics on golf courses in the northeastern United States in 1998 was significant, and caused serious concern to turf managers. The survey indicates that blast disease of perennial ryegrass may be emerging as a new problem for the turfgrass industry in the northeastern United States. Reference: (1) P. J. Landschoot and B. F. Hoyland. Plant Dis. 76:1280, 1992.

Pathogenic and Molecular Characterization of Three Phomopsis Isolates from Peach, Plum, and Asian Pear.

Three isolates of Phomopsis, causing shoot blight of peach, shoot tissue necrosis of plum, or bud death of Hosui Asian pear, respectively, were evaluated for their pathogenicity on apple, pear, peach, and plum. Current year's shoots of 1-year-old Stayman Winesap apple, Barlett pear, Babygold-7 peach, and Bruce plum trees were inoculated with each isolate by wounding a bud and applying agar blocks bearing young hyphae. The length of cankers on shoots was measured 10, 17, and 24 days after inoculation. Cankers developed on shoots of all hosts inoculated with the peach isolate and on peach shoots inoculated with plum and Asian pear isolates. No cankers developed on apple, pear, or plum shoots inoculated with plum and Asian pear isolates. In the first experiment, 10 days after inoculation, the length of cankers on apple trees (56.0 mm) inoculated with the peach isolate was not significantly different (P ≥ 0.05) from that on peach (42.8 mm), but was significantly greater than that on plum (25.3 mm) and pear (13.1 mm). The cankers on peach were significantly longer than those on pear, but not on plum. Cankers on all four hosts were significantly different from one another 17 and 24 days after inoculation. There was no significant difference between the length of cankers on peach shoots inoculated with plum and Asian pear isolates, and they were significantly smaller than those inoculated with the peach isolate. None of the control trees developed cankers. The three isolates differed in colony morphology, and appearance of conidiomata, conidiogenous cells, and α-conidia on potato-dextrose agar. None of the isolates produced ß-conidia in culture. Multi-locus DNA fingerprint analysis and internal transcribed spacer sequence comparisons revealed similarities between the plum and Asian pear isolates but a significant difference between these two and the peach isolate. The results indicate that the Phomopsis sp. that causes shoot blight of peach has the potential to cause disease on other stone and pome fruits, and peach may also be susceptible to isolates of Phomopsis from different tree fruit hosts.

Seasonal Development of Phomopsis Shoot Blight of Peach and Effects of Selective Pruning and Shoot Debris Management on Disease Incidence.

Seasonal development of shoot blight of peach caused by a Phomopsis sp. was evaluated in Oconee, Hall, and Peach counties in Georgia from April 1994 through May 1996. The frequency of infected buds in all three locations was highest during spring (mid-March to mid-May) and fall (early September to mid-October). The frequency of infected buds was highest in Hall County, which is the northernmost sampling location, followed by Oconee and Peach counties, which are located further south. During the same period of time, the effects of selective pruning and shoot debris management on disease incidence were evaluated in orchards in Oconee and Hall counties from May 1994 through May 1996. Selective pruning of infected shoots in May and October each year, following the major periods of infection, significantly reduced disease incidence during the following seasons in both locations. Disease incidence was similar regardless of whether shoot debris were left under the tree or removed from the orchard and destroyed. Our study indicates that major periods of infection of peach shoots by the Phomopsis sp. occur in the spring during the period of bud break, and in the fall when dormant buds and leaf scars are present. Additionally, our study indicates that reduction of inoculum by selectively removing infected shoots from the trees following the major periods of infection may significantly reduce disease incidence, although it may not eliminate the disease. Removal of infected shoot debris from the orchard does not appear to be necessary following pruning.

Pathogenicity of a Species of Phomopsis Causing a Shoot Blight on Peach in Georgia and Evaluation of Possible Infection Courts.

A species of Phomopsis was isolated consistently from blighted shoots of peach trees in Georgia and Alabama. Isolates of the fungus caused characteristic cankers on current season's shoots of Babygold-7 peach trees when wounded or nonwounded dormant buds, breaking buds, and natural or artificially-created leaf scars were inoculated with conidia of the fungus. Mean canker length for the isolates was 35 mm 30 days after inoculation. No disease developed on control trees. There was no significant difference between the canker length on inoculated wounded dormant buds (59 mm) and nonwounded breaking buds (54 mm). However, cankers from both sites of inoculation were significantly longer than those resulting from inoculated artificially-created leaf scars (33 mm), natural leaf scars (33 mm), and non-wounded dormant buds (30 mm). There was no significant difference in virulence among the 5 isolates of Phomopsis sp. tested, and multi-locus DNA fingerprint analysis resulted in a similarity coefficient of 0.94 among the isolates. Additionally, results of the internal transcribed spacer (ITS) regions sequence comparisons for the isolates were consistent with the multi-locus polymerase chain reaction profiles, and the nucleotide sequences of the ITS region were identical for all 5 isolates. This is the first documentation of the pathogenicity of a Phomopsis sp. associated with shoot blight of peach in Georgia. Rapid development of disease in breaking buds indicates that they may be the primary site of invasion by the fungus. Natural leaf scars and dormant buds may also serve as possible infection courts.

Impact of open access endoscopy on early diagnosis, treatment and gastrointestinal radiology service.

The objective is to compare the endoscopic findings before and after initiation of open access and its effect on gastrointestinal radiology services. The data of endoscopic findings before open access endoscopy (July, 1989-June, 1992) and after open access endoscopy (July, 1992-June, 1995) was collected from the records of the endoscopy unit. Similarly, data of barium meals for the same periods was collected from the radiology department. An X2 test was used to compare the endoscopic findings before and after open access policy. It is found that open access endoscopy increased the workload in the endoscopy unit but at the same time reduced the number of gastrointestinal radiological procedures. It reduced the waiting period for endoscopy and this helped in making early diagnosis and initiation of appropriate treatment.

Hepatic venous outflow obstruction in patients with polycystic liver disease: pathogenesis and treatment.

Polycystic liver disease is commonly asymptomatic but may present with hepatomegaly, abdominal distension, and dull abdominal pain. Transudative ascites is a rare manifestation in these patients but may occur when portal hypertension is present resulting from associated hepatic fibrosis or after deroofing procedure of a cyst. Exudative ascites might suggest hepatic venous outflow obstruction. Four cases are described where hepatic venous outflow obstruction occurred in patients with polycystic liver disease. Three patients had orthotopic liver transplantation and one had a mesocaval shunt. Of the two patients that survived orthotopic liver transplantation both have shown considerable improvement in their symptoms. None of the patients had any confirmed procoagulant disorder. The mechanism of hepatic venous outflow obstruction in these patients seems to be mechanical compression of hepatic veins by the cysts and associated formation of thrombi in small hepatic vein tributaries. Patients with severe polycystic kidney/liver disease are at risk of hepatic venous outflow obstruction and the onset of this complication is heralded by tender hepatomegaly and presence of exudative ascites.