2002 APS Annual Meeting Abstracts of Presentations Abstracts submitted for presentation at the APS 2002 Annual Meeting in Milwaukee, Wisconsin, July 27–31, 2002. The abstracts are arranged alphabetically, by first author’s name. Advances in the integration of morphological and molecular charac- Several methods were used to detect aflatoxin production by various terization in Phytophthora benus: The case of P. kelmania and other Aspergillus species. Isolates (n = 786) were obtained from crops (including putative new species. Z. G. ABAD (1,3), J. A. Abad (3), and T. Creswell corn, peanut, cotton) and soils from the Mississippi Delta. Cultural methods (2,3). (1) Plant Pathogen ID. Lab.; (2) Plant Disease and Insect Clinic; (3) for assessing aflatoxin production on potato dextrose agar included yellow Dept. Plant Pathology, North Carolina State Univ. Phytopathology 92:S1. pigment (YP) production and color change with exposure to ammonia vapor Publication no. P-2002-0001-AMA. (AV). The presence of aflatoxins in culture extract was confirmed by TLC and LC-MS and quantified by ELISA and HPLC. Fifty-one percent of Phytophthora with over 70 spp is one of the most important Genera of plant isolates produced YP, and all were positive for the presence of aflatoxins. pathogens. Considerable advances in the taxonomy of this stramenopile Forty-seven percent of isolates changed color with AV, and all were positive using morphological and molecular characterization have been accom- for aflatoxins. Thus, positive YP and AV responses were highly correlated plished. Yet, correct identification to species levels and characterization of with aflatoxin production. However, both methods failed to detect aflatoxins new taxa is still a major challenge. Using our innovative morphological/ in all cultures that tested positive using ELISA, HPLC and TLC. Cultures molecular pictorial key new hosts and 3 new species have been determined that produced less than 250 ppb were typically negative by the AV method. including: P. glovera, P. bisheria (semipapillated), and P. kelmania (non A. flavus isolates positive for aflatoxins produced AFB1 and AFB2 only, papillated, named to honor Dr. A. Kelman). Additional unnamed new species whereas A. nomius and A. parasiticus produced all four aflatoxins (AFB1, are presented, including: Ph2471, Ph3552, (papillated), Ph9-001, Ph2529, AFB2, AFG1, and AFG2). Fifty-one percent of 341 soil isolates and 55% of Ph5212 (non papillated). An updated phylogenetic tree (ITS1-2 rDNA) 250 corn isolates produced aflatoxins. This study showed that YP and AV including the recently described P. europaea, P. pistaciae, P. psychrophila, methods can be used for rapid screening but are not reliable in detecting low P. ramorum, and P. uliginosa maintains the consistency of 2 main groups producers of aflatoxins. (papillated and non-papillated) and verifies the identity of our eight putative new Phytophthora species. Effect of foliar applications of neem oil and fish emulsion on bacterial spot disease and yield of tomatoes and peppers. P. A. ABBASI, D. A. Predominance and pathogenicity of fungi and stramenopiles associated Cuppels, and G. Lazarovits. Agriculture and Agri-Food, London, Ontario. with Black Root Rot of strawberries. Z. G. Abad (1,2), F. J. LOUWS (2), Phytopathology 92:S1. Publication no. P-2002-0004-AMA. G. E. Fernandez (3), and L. M. Ferguson (2). North Carolina State Univ., Raleigh, NC 27695, (1) Plant Pathogen ID. Lab.; (2) Dept. of Plant Field trials were conducted in London, Ontario during 2000 and 2001 to test Pathology; (3) Dept. of Horticulture. Phytopathology 92:S1. Publication no. the efficacy of foliar sprays of neem oil and fish emulsion, derived from the P-2002-0002-AMA. neem seed and Menhaden fish, respectively, against bacterial spot disease (Xanthomonas vesicatoria or X. axonopodis pv. vesicatoria) and yield of BRR is an important disease of strawberry around the world. From 1998 to tomatoes and peppers. Ten weekly sprays of neem oil and fish emulsion 2001 about 1300 isolates (I) were collected in 6 localities (L) in NC. Sixty (0.5%; v/v) significantly reduced disease severity on the foliage of taxa were identified. Rhizoctonia fragariae AG-A (119-I, 4-L), AG-G (55-I, inoculated field-grown tomato and pepper plants in both years. The disease 3-L), AG-I (24-I, 4-L), Pythium irregulare (285-I, 5-L), Pythium Group F incidence on fruit of these plants was reduced but the effect was not always (14-I, 3-L), Pythium HS (10-I, 3-L), Phytophthora cactorum (74-I, 2-L), significant. However, the number of lesions on pepper fruit was significantly Fusarium solani (47-I, 5-L), F. oxysporum (45-I, 5-L), F. acuminatum (21-I, less with these treatments. There was a marked increase in the yield of 5-L), Phoma sp. (12-I, 5-L) were the most common. Other known pathogens disease-free fruit on neem oil-treated pepper plants in 2000 and fish included: Ascochyta fragariae (1-I, 1-L), Macrophomina phaseolina (5-I, 3- emulsion-treated pepper plants in 2001, but none of the treatments L), Phomopsis obscurans (1-I, 1-L). Rhizoctonia binucleate AGN (3-I, 1-L) significantly increased total tomato or pepper yield. Neem oil and fish and Thielaviopsis basicola (1-I,1-L) are new reports on strawberry. emulsion had no observable phytotoxic effects on tomato or pepper foliage. Pathogenicity tests indicate the importance of R. fragariae AGA, G, I, P. These results suggest a possible use for neem oil or fish emulsion as foliar irregulare, Pythium HS, P. cactorum, Phoma sp., F. oxysporum and F. sprays to manage bacterial spot disease. solani. The diversity of Fungi and Stramenopiles in BRR disease highlights the importance of this complex in the strawberry production areas of NC. Cylindrocarpon species and other fungi isolated from bark of beech in the advancing and killing fronts of the beech bark disease epidemic in Cultural and analytical methods to determine aflatoxin production by Michigan. G. C. Adams. Michigan State University. Phytopathology 92:S1. Aspergillus species from the Mississippi Delta. H. K. ABBAS (1), R. M. Publication no. P-2002-0005-AMA. Zablotowicz (2), B. W. Horn (3), W. Xie (4), and W. T. Shier (5). (1) USDA- ARS, CG & PRU, Stoneville, MS; (2) USDA-ARS, SWSRU, Stoneville, MS; Beech bark disease is a lethal disease of Fagus grandifolia caused by the (3) USDA-ARS, NPRL, Dawson, GA; (4) University of Minnesota, interaction of the exotic beech scale, Cryptococcus fagisuga, and native and Minneapolis, MN; and (5) University of Minnesota, Mineapolis, MN. exotic species of the fungus Neonectria. A Michigan beech bark disease Phytopathology 92:S1. Publication no. P-2002-0003-AMA. monitoring and impact analysis system was established in 2001 and 2002 consisting of long-term plots across the beech resource of Michigan. Our role was to determine the presence or absence of Neonectria in bark, and to identify the species. More than eighteen plots (4 subplots/plot) in 7 counties The abstracts are published as submitted. They were formatted but were sampled, with bark collected from 12 trees/plot. The plots were rated as not edited at the APS headquarters office. having no scale, light, or heavy infestations. We developed an agar medium Vol. 92, No. 6 (Supplement), 2002 S1 selective for isolation of Cylindrocarpon anamorphs of Neonectria from Apple scab, caused by the fungus Venturia inaequalis is the most important bark. Identification of Neonectria species was based on morphology of disease of apple (Malus × domestica) worldwide. Genetic resistance to apple Cylindrocarpon isolates sporulating on alfalfa stems on water agar. scab exists in several East Asiatic species including Malus floribunda. Malus Objectives are to delineate the killing front and to determine whether the floribunda 821 is the most important source of monogenic scab resistance (Vf relative abundance and distribution of native versus exotic Neonectria gene) that was bred into nearly all commercial apple scab resistant cultivars. species affects the rate of disease spread. It was recently reported that a cluster of receptor-like genes present at the (Vf locus, are homologs to the (Cf gene of tomato. However, it was not determined which member of the cluster, either HcrVf2 or HcrVf4 was the Vf Utilization of spiral gradient endpoints to estimate fungicide resistance gene. Specific primers were designed for protein domain C of the HcrVf1, potential in alternate-row-spraying of tree fruit crops. J. E. ADASKAVEG HcrVf2 and HcrVf4. We have found that these primers amplified 2 bands in and H. Förster. Dept. Plant Pathology, Univ. of California, Riverside, CA all M. floribunda and M. × domestica varieties tested. However, another 92521. Phytopathology 92:S2. Publication no. P-2002-0006-AMA. PCR product was only present in 9 out of 10 M. floribunda examined. It was Alternate-row-spraying for control of blossom diseases of deciduous tree also present in apple scab resistant M. × domestica cultivars carrying the Vf fruit crops is a cost-saving practice used by growers in California. Criticisms gene but absent from scab susceptible cultivars. This indicates that the of this method include increased potential for resistance to develop in occurrence of fragment, matching HcrVf2, correlates closely with presence of pathogen populations. In field trials on sweet cherry, trees at full bloom were the Vf gene. treated from one side with cyprodinil using an airblast sprayer at a rate of 238 g/850 L/Ha. After drying, blossoms were collected for inoculation with Genomic fingerprinting of Rathayibacter species by amplified fragment Monilinia fructicola and for residue analysis from the sprayer-exposed sides length polymorphism. I. V. AGARKOVA (1), A. K. Vidaver (1), E. and the opposite sides of the trees. Disease incidence on inoculated anthers Postnikova (2), and N. W. Schaad (2). (1) University of Nebraska, was 61% for the non-treated, 6% for the exposed-side, and 26% for the Department of Plant Pathology, Lincoln, NE; (2) USDA ARS Foreign opposite-side blossoms, corresponding to residues of 0, 16.4, and 2 mg/L Disease-Weed Science Research Unit, Fort Detrick, MD 21702.