Posted online February 19, 2008
Examining genetic diversity within Phytophthora species. J. E. Blair, M. Peiman, and M. D. Coffey. Amherst College, Amherst, MA, and University of California, Riverside.
A robust phylogeny for 82 Phytophthora species has recently been established using molecular markers derived from complete genome sequence data. Additional studies are now examining the genetic diversity present inside species complexes within the genus. Here we will present some preliminary data on an analysis of Phytophthora infestans and four closely related taxa, P. mirabilis, P. andina, P. ipomoeae, and P. phaseoli. Sequence analyses of ITS data suggest that some isolates identified as P. andina and P. mirabilis cannot be distinguished from other isolates of P. infestans. We are currently examining other molecular loci, including introns and coding sequence within protein-coding genes, to verify these results. We will also present a research outline for a recently funded project examining genetic diversity within three species that are of significant interest to the floriculture industry, P. cryptogea, P. nicotianae, and P. cactorum.
Effect of Fe, Cu, Mn, Zn, and Mo on the development of Helminthosporium solani and potato silver scurf. S. Boivin (1), T. J. Avis (1), C. M. Maios (2), S. Jabaji-Hare (2), and R. J. Tweddell (1). (1) Centre de recherche en horticulture, Université Laval, Québec, QC, Canada G1K 7P4; (2) Department of Plant Science, McGill University, Sainte-Anne-de-Bellevue, QC, Canada H9X 3V9.
Silver scurf, caused by Helminthosporium solani, is a potato disease characterized by the presence of grey to tan lesions on the periderm of tubers. Control of the disease has been hampered by the development of H. solani strains resistant to thiabendazole and consequently silver scurf has emerged as an economically important disease. A recent study revealing the existence of suppressive soils against potato silver scurf suggests that soil chemical properties may affect the development of the disease. In order to further investigate the impact of soil chemicals on silver scurf development, different forms of Fe, Cu, Mn, Zn, and Mo were tested for their effect on mycelial growth and conidial germination of H. solani in vitro and on silver scurf development. The tested elements inhibited significantly H. solani development, as well as silver scurf development when applied directly on the potato tuber.
Isolate effects on the inheritance of dollar spot resistance in crosses of creeping bentgrass. S. A. Bonos and E. Weibel. Rutgers University.
Genetic resistance to dollar spot disease incited by Sclerotinia homoeocarpa F.T. Bennett is a promising component of sound integrated disease management programs. Previous research indicates that dollar spot resistance is quantitatively inherited with no evidence of major disease resistance genes; however, the response of creeping bentgrass genotypes to different isolates has not been evaluated. The objectives of this study were to evaluate the response of creeping bentgrass crosses to three different isolates of S. homoeocarpa, evaluate disease progression, determine gene action, and identify number of loci involved in resistance to individual fungal isolates. Four hundred plants of each of three reciprocal controlled crosses were established in a field trial in a randomized complete block design in the fall of 2000 and 2002. Eight backcross and four F(2) populations were also included in the 2002 trial. One hundred progeny of each cross were inoculated with one of three isolates of S. homoeocarpa, and a mixture of the three isolates and evaluated for dollar spot disease. The degree of dollar spot disease differed depending on the cross and the isolate evaluated. Backcross populations were skewed towards the recurrent parent regardless of resistance or susceptibility. Minimum loci calculations differed depending on the cross and the isolate. These results indicate the presence of different genes associated with resistance and susceptibility depending on grass genotype and fungal isolate.
Biocontrol potential of three species from the Pseudozyma genus. G. Clement-Mathieu, G. Marchand, C. Labbé, and R. R. Bélanger. Département de phytologie, Centre de Recherche en Horticulture, Université Laval, Québec, Canada G1K 7P4.
Pseudozyma flocculosa, a basidiomycetous yeast-like epiphyte, displays excellent biocontrol activity against powdery mildews, presumably by releasing flocculosin, an antifungal glycolipid. Within the Pseudozyma genus, other species produce glycolipids but their biocontrol activity is still undetermined. Recently, P. flocculosa was transformed genetically with gfp to allow its visualization under fluorescence microscopy. In situ observations of plant-pathogen-transformant interactions highlighted that growth of P. flocculosa was closely associated with infection sites of powdery mildew. In this work, we compared the biocontrol potential and the ecological development of P. antarctica, P. rugulosa and P. fusiformata to that of P. flocculosa. To this end, we developed gfp transformants for in situ observations of their behaviour on powdery-mildew infected leaves. Except for P. flocculosa, none of the species was able to colonize and degrade powdery mildew colonies. Conidial chains were unaffected by the presence of the three tested Pseudozyma spp., even in the case of P. fusiformata, known to produce a glycolipid similar to flocculosin. These results confirm the biocontrol specificity of P. flocculosa and suggest that its activity is influenced by the presence of powdery mildew which stimulates its growth.
A fungal marine pathogen and an alga: Lichen or not. D. R. Cooley (1), R. F. Mullins (1), and R. T. Wilce (2). (1) Dept. of Plant, Soil & Insect Sciences; (2) Dept. of Biology; Univ. of Mass., Amherst, MA 01003.
Pseudendoclonium submarinum, a marine green alga common on upper shores of the North Atlantic, grows normally in situ, but declines in vitro in the presence of a filamentous fungus. Pseudendoclonium collected from Ipswich, MA during a two-year period were consistently contaminated with a fungus tentatively identified as Cladosporium. Microscopic examinations of samples immediately after collection showed that the alga and fungus grew in close association. In culture, alga populations declined, became necrotic, and died, while the fungus grew producing hyphae and conidia. The fungus failed to grow in sterile algal medium in the absence of Pseudendoclonium. Scanning electron microscopy showed fungal hyphae had infiltrated intercellular areas of the algal filaments, but did not penetrate algal cells. Fungal production of an exotoxin or a cell wall degrading enzyme, which accumulated and killed algal cells in vitro thereby releasing nutrients used by the fungus, is hypothesized. Fungal ribosomal DNA sequences were obtained and compared to Cladosporium sp. in GenBank, indicating that the fungus is C. cladosporiodes.
Use of a pre-plant corm treatment to suppress Fusarium corm rot of gladiolus. W. H. Elmer. The CT Agr. Exp. Sta., New Haven, CT 06504.
Fusarium corm rot of gladiolus is caused by Fusarium oxysporum f. sp. gladioli and occurs wherever gladioli are grown. Current recommendations for control are hot water corm treatments and use of benzimidazole fungicides. Because of difficulties in obtaining good control with hot water treatments and pathogen resistance to benzimidazoles, we investigated new strategies for disease management. Several commercially available biological and chemical fungicides were combined with and without acibenzolar-s-methyl (ASM, Actigard, 50 ppm a.i.). Treatments were applied as a 20-min. corm soak before planting. The chemicals fludioxonil (Medallion), triflumizole (Terraguard), and ASM reduced disease severity by 27%, 23%, and 12%, respectively, and each treatment increased the numbers of flower spikes. No interactions were observed. All biological fungicides were ineffective. Increasing the rate of ASM to 200 and 500 ppm was associated with increased flower spikes, but phytotoxicity was noted. The proposed pre-plant corm treatments use minimal amounts of product, reduce costs, and minimize human and environmental exposure to chemicals. Currently ASM is not registered on ornamentals.
The effect of host growth on the dynamics of plant disease epidemics. F. J. Ferrandino. The Connecticut Agricultural Experiment Station, New Haven, CT 06504.
Since plants are sessile, the behavior of the host is often taken as a constant in models describing plant disease epidemics. However, plants grow and to some extent both the spatial density and the physical position of plant parts change with time. The ramifications of plant growth on plant disease development are examined for a number of illustrative cases: Verticillium wilt on eggplant and olive, powdery mildew of pumpkin, and foliar pathogens on strawberry. For the soilborne pathogen (Verticillium), the growth of the root system of the plant increases the probability of infection as roots colonize larger volumes of soil. For aerially-dispersed powdery mildew, the ability of the plant canopy to catch inoculum increases dramatically as pumpkin vines cover the ground. For splash-dispersed pathogens on strawberry the relative length scale for rain splash as compared to runner length critically determines the rate of new infections. These examples are discussed using simple mathematical models.
Black rot control in eastern organic grape production. B. Hed (1) and J.W. Travis (2). Dept. Plant Pathology, Penn State University, (1) North East, PA 16428; (2) Biglerville, PA 17307.
Black rot, caused by Guignardia bidwellii, is a major obstacle to organic grape production in the eastern United States due to the limited efficacy of fungicides permitted for organic use. Allowable materials were screened for activity against black rot on individual grapevine leaves and whole vine field plots of Vitis labrusca ‘Concord’ and ‘Niagara’ and Vitis interspecific hybrid ‘Aurore’. In greenhouse leaf inoculations, potassium bicarbonate (Armicarb O and Milstop), plant extracts and oils (EF 400, Citrex 100, GC-3, Yucca Ag-Aide 50), lime sulfur, and copper hydroxide (Champion WP) reduced leaf lesions by more than 90 percent. However, in whole vine field plots, only copper hydroxide and lime sulfur significantly reduced fruit rot. Inoculum pressure had a major effect on the performance of fungicides. Copper hydroxide and lime sulfur provided 97 and 71 percent control, respectively, under moderate inoculum pressure but only 31 and 28 percent control, respectively, when challenged with high inoculum pressure. Studies have been initiated to evaluate strategies to reduce black rot inoculum pressure.
Sand topdressing rate and frequency effects on anthracnose disease of a Poa annua putting green. J. C. Inguagiato, J. A. Murphy, and B. B. Clarke. Rutgers Univ., Dept. of Plant Biology & Pathology, New Brunswick, NJ 08901.
Sand topdressing has been reputed to increase anthracnose on putting green turf. The effect of sand topdressing rate (0, 0.3 and 0.6 L m(^–2)) and frequency (7-, 14- and 28-d) on anthracnose was evaluated using a randomized complete block design in 2006 and 2007. Treatments were applied in a factorial arrangement to Poa annua turf mowed at 3.2 mm. The topdressing rate of 0.3 L m(^–2) increased anthracnose on 12 July 2006 compared to no topdressing; however, less disease was observed at both sand rates than non-topdressed plots after 7 August 2006. Rate was inversely related to disease from 28 August to 6 September 2006. Sand applied at 0.6 L m(^–2) reduced disease compared to non-topdressed plots from 25 July to 23 August 2007. Topdressing every 7-d reduced anthracnose compared to 14- and 28-d intervals from 7 August through 9 September 2006 and on 23 August 2007. Topdressing rate interacted with frequency in August and September 2006 and August (p = 0.093 & 0.087) 2007 indicating a cumulative benefit of topdressing. These data indicate that sand topdressing generally does not increase anthracnose and can enhance disease recovery.
Structure of fungicide resistance populations of Sclerotinia homoeocarpa on golf courses. G. Jung (1), Y.-K. Jo (1), P. Koch (2), and S. W. Chang (1). (1) Department of Plant, Soil & Insect Sciences, University of Massachusetts-Amherst; (2) Department of Plant Pathology, University of Wisconsin-Madison.
Dollar spot, caused by Sclerotinia homoeocarpa, is the most prevalent and economically important turfgrass disease in North America. Increasing levels of fungicide resistance, coupled with tightening environmental scrutiny of existing fungicides, has left fewer options for dollar spot control. To reduce risk of resistance development and to manage fungicide resistance, a greater understanding of S. homoeocarpa population is needed. Our recent survey, based on in-vitro sensitivities to two systemic fungicides (thiophanate-methyl and propiconazole) using >1,400 S. homoeocarpa isolates collected from greens, fairways, and roughs of one Massachusetts and six Wisconsin golf courses, indicated that the course age and fungicide history have no correlation with the frequency of thiophanate-methyl resistant isolates in the population. In case of propiconazole, the number of fungicide applications in the previous five years was not significantly related with reduced sensitivity. To examine genetic diversity of S. homoeocarpa population, isolates collected from the fairway and green of a university research facilities in Wisconsin were tested using inter simple sequence repeat (ISSR) markers. Two genetically distinct subgroups, which are vegetatively incompatible and have different fungicide sensitivities, coexisted on the fairway and putting green.
Spatial evaluation of Neonectria spp. presently associated with beech bark disease in Maine. M. T. Kasson (1) and W. H. Livingston (2). (1) Dept. of Plant Pathology, Penn State University, University Park, PA 16802; (2) School of Forest Resources, University of Maine, Orono, ME 04469.
Beech bark disease (BBD) requires prior infestation of an exotic scale insect, Cryptococcus fagisuga, to permit infection by one or more fungi, primarily Neonectria ditissima and Neonectria faginata. Evidence to support a unidirectional progression in which N. faginata replaces N. ditissima as the dominant pathogen in the BBD complex has been shown in various studies. In 2005-06 in northern Maine, incidence of N. ditissima and N. faginata was related to BBD severity, beech mortality, and hardwood species composition. Ascospore measurements from 201 bark disks containing perithecia indicated that, once established, N. faginata dominates the BBD complex. However, stands did contain high levels (>30%) of N. ditissima if other highly susceptible tree species were present (R(^2) = 0.717) regardless of disease progression. In Maine, N. ditissima remains an important pathogen in BBD where susceptible, non-beech hosts are present.
Reduction in primary inoculum of Fusicladosporium carpophilum on stone fruit by the QoI fungicide trifloxystrobin. N. Lalancette, K. A. McFarland, and A. L. Burnett. Rutgers University, Agricultural Research & Extension Center, Bridgeton, NJ.
The influence of bloom applications of trifloxystrobin on sporulation of overwintering scab twig lesions was studied in a nectarine orchard during 2005-7. Treatments consisted of applications made at pink and bloom, bloom and petal fall, petal fall and shuck-split, or petal fall to 3 × 3 tree plots arranged in a RCBD with three replicates. Five or six sporulation assessments were conducted from May through July by removing 10-16 infected twigs from each plot and incubating them for 24 h at 25°C and RH > 95%. Conidial production was estimated using a hemacytometer. Spore production peaked between days 150 and 159 and ended by day 200. Analysis of areas under the sporulation curves showed all treatments significantly reduced primary inoculum production. The most effective treatments reduced peak sporulation by 82-92%. Concomitant reductions in fruit disease incidence and severity were also observed. These results indicate that use of anti-sporulant fungicides at bloom is an effective strategy for reducing primary scab inoculum during the subsequent fruit growth and development period.
Actigard increases fungicide efficacy against Peronospora tabacina, cause of tobacco blue mold. J. A. LaMondia. The Connecticut Agricultural Experiment Station, Windsor, CT 06095.
Blue mold, caused by Peronospora tabacina, can be economically damaging to cigar wrapper tobacco. We evaluated Actigard 50W (Acibenzolar-S-methyl) alone and in combination with a standard fungicide program for efficacy against blue mold on shade-grown wrapper tobacco in Windsor, CT. The standard fungicide program consisted of Acrobat MZ (or Forum plus Dithane), alternated with Quadris applied at label rates on six occasions at 14-day intervals. Treated and untreated 5 m by 5 m plots were replicated four times in 2003 and in 2006. Actigard treatments were applied alone or in combination with fungicides at the third, fourth and fifth spray dates at rates ranging from 1.1 g a.i./ha to 17.5 g a.i./ha. In both years, disease was greatest in non-treated plots and significantly reduced when fungicides or Actigard were used alone. The combination of three Actigard applications at 17.5 g a.i./ha down to 4.4 g a.i./ha with standard fungicides was more efficacious than either fungicides or Actigard alone (P < 0.001) in reducing blue mold lesions per plot and number of diseased leaves harvested. The combination of fungicides and Actigard at the lower rates of 2.2 or 1.1 g a.i./ha was similar to either fungicides or Actigard (17.5 g a.i./ha) applied alone. Combining low rates of Actigard with fungicide applications greatly increased efficacy and marketable yield.
Biological control of Alternaria black spot in cabbage by antagonistic bacteria. C.-T. Lo and L.-Y. Lee. Dept. of Biotechnology, National Formosa University, Yunlin, Taiwan.
Alternarial black spot is one of the common and destructive diseases of crucifers worldwide. It has been suggested that the use of antimicrobial active species and strains of the genus Bacillus and Trichoderma, or use of their metabolites, may be an alternative or supplementary method to chemical plant protection to against the alternarial diseases. In the present study we evaluated the efficacy of the Bacillus sp. and Trichoderma sp. isolated from the soils in Taiwan against black spot of cabbage caused by Alternaria brassicicola. The biocontrol agents were cultured with 1% raw mushroom for 5 days and then were filtrated with 0.2 mm filter. The effect of cell-free extract of the antagonists on alternarial black spot of cabbage was determined using a modified procedure of Xu and Ko. The results indicated that strain B9 and B10 of Bacillus licheniforms could produce the inhibition zone of size 2 diameter against A. braccicicola and strain TA1 and TA2 of Trichoderma spp. parasitize on A. braccicicola as revealed by dual plate assays conducted on potato dextrose agar plates and V-8 agar plates. In growth chamber trials, the cell free extract of the bacterial strains completely inhibited to develop black spot on cabbage leaves. However, the extract treated with the strains of Trichoderma spp. appeared the black spot on inoculation leaves as well as the untreated control (only water). The extract of bacterial agents may have the fungicidal nature of the strain B9 and B10 of B. licheniforms compared to the extract of Trichoderma strain after 5 days of incubation with 1% raw mushroom. The effective metabolites of the bacterial agents may be an antifungal protein.
Managing soilborne potato diseases in the Northeast with Brassica rotations. R. P. Lynch and R. P. Larkin. USDA-ARS New England Plant, Soil and Water Laboratory, Orono, ME 04469.
Soilborne pathogens are persistent problems in potato production systems in the northeastern U.S. Previous research has reported significant reductions in the incidence and severity of multiple soilborne diseases when Brassica crops are included in the rotation cycle. The objectives of this project are to evaluate the efficacy of selected Brassica crops in controlling soilborne potato diseases and their effects on soil microbial community characteristics. Multiple 2-year crop rotations were established on several research and commercial field sites with histories of soilborne disease. Rotations included up to six different Brassica crops that were incorporated as green manures in the first year and followed by potato the second year. Diseases assessed included stem canker, black scurf, common scab, powdery scab, and silver scurf. Significant differences were observed among the rotation crops in soil microbial community characteristics. However, in initial results, although some differences in soilborne diseases among rotations were observed, consistent disease control was not achieved with single-year Brassica crop rotations.
Amplified Fragment Length Polymorphic (AFLP) markers for the forest fungal pathogen, Neonectria ditissima. R. E. Marra. Department of Plant Pathology and Ecology, The Connecticut Agricultural Experiment Station, New Haven, CT 06511.
Neonectria ditissima is an important fungal pathogen in northeastern forests. Native to the eastern U.S., the fungus causes perennial cankers on numerous native hardwoods, with the greatest damage occurring on black birch, Betula lenta. Because of the potential impact of N. ditissima on birch and on forest dynamics, an understanding of the genetics, ecology, and natural history of this fungus is critical to the development of disease management strategies. We are developing Amplified Fragment Length Polymorphic (AFLP) markers for population genetic and mating system studies. A collection of 22 disparate isolates is being used in marker development to maximize genetic diversity. Three pairs of selective primers used to screen for AFLPs produced numerous polymorphic bands. The three marker sets were also used to measure AFLP segregation within and among nine sets of ascospore progeny from cankers collected at West Rock Ridge State Park in New Haven, CT. The applicability of this method in measuring outcrossing rates, inbreeding coefficients, population subdivision will be discussed.
Co-colonization of Theobroma cacao seedlings with bacterial and fungal endophytes. R. L. Melnick (1), B. A. Bailey (2), M. D. Strem (2), and P. A. Backman (1). (1) Dept. of Plant Pathology, Penn State University, University Park, PA 16802; (2) USDA-ARS SPCL, Beltsville, MD 20705.
Pod yield and quality of Theobroma cacao L. is drastically reduced by infection with cacao diseases. Phytosanitation and chemical controls are often costly and undesirable in an agroforestry system. Previous research has demonstrated that Trichoderma spp. can endophytically colonize cacao seedlings and activate plant defense mechanisms, and that Bacillus spp. endophytically colonizes cacao foliage and reduce disease. The objective of this study was to determine if bacterial and fungal endophytes could be successfully co-applied to cacao seedlings. Successful co-inoculation occurred both through root application of Trichoderma spp. with foliar application of bacteria as well as root application of Trichoderma spp. with seed application of bacteria. With both applications, stems and roots were endophytically colonized by both bacteria and Trichoderma spp. while leaves were only colonized by bacteria. This research opens the opportunity for co-colonization of cacao to enhance biocontrol.
The worldwide occurrence of the anther-smut fungus Microbotryum on species of the Caryophyllaceae as assessed from herbarium surveys. J. I. MENA-ALI (1), J. Antonovics (2), T. Giraud (3), B. Oxelman (4), A. Gibson, R. Yockyeng (5), M. Arroyo (6), F. Conti (7), and M. E. Hood (1). (1) Department of Biology, Amherst College, Amherst, MA 01002; (2) Department of Biology, University of Virginia, Charlottesville, VA 22904; (3) ESV, Bâtiment 362, Université Paris-Sud, 91405 Orsay cedex, France; (4) Department of Systematic Botany, Uppsala University, Uppsala, Sweden; (5) Museé national d’Histoire naturelle, Paris, France; (6) Pontificia Universidad Católica de Chile, Santiago, Chile; (7) University of Camerino, Camerino, Italy.
Invasion/infection of pathogens onto a new host can be affected by various traits of the host that limit the pathogen’s survival, reproduction and spread to more individuals in the population. The effect of these traits will in part depend on the life history of the pathogen, as well as its specificity and virulence. Microbotryum violaceum causes anther-smut disease in members of the Caryophyllaceae. Obligate pathogens with very restricting life cycles such as M. violaceum are expected to preferentially infect perennial host species. Here we greatly expand this hypothesis by surveying over 28 thousand herbarium specimens of Silene and allied genera of the Caryophyllaceae to determine the worldwide distribution of M. violaceum. These data was then examined for associations between the probability of infection and life history of the host, floral morphology, and breeding system. Our analyses expand the assumed range of the pathogen from an exclusively temperate Northern distribution to a worldwide presence, to include subtropical locations. These results are discussed in light of host distribution over a broad geographic range and the role of potential host-shifts in dispersal at an inter-continental scale.
First report of Curvularia blight of zoysiagrass in the United States. J. A. Roberts and L. P. Tredway. Dept. of Plant Path., NC State University, Raleigh, NC 27695.
Curvularia species are ubiquitous and are typically considered to be secondary pathogens or saprophytes. A foliar blight of zoysiagrass has been observed in NC since 2002. The disease is most active when temperatures are 21°C to 30°C. Leaves initially exhibit small, brown spots with dieback from the tips, followed by blighting of irregular patches 15 cm in diameter. Microscopic analysis revealed Curvularia conidia consistently associated with the disease. Twenty-one Curvularia isolates were obtained from 6 locations. Analysis of ITS rDNA sequences indicated isolates were most closely related to C. lunata and C. pallescens, and spore morphology was consistent with C. lunata. Pots of ‘Emerald’ and ‘El Toro’ zoysiagrass were inoculated with one of five C. lunata isolates in a greenhouse at 26°C. Isolates varied in aggressiveness, inducing symptoms in 1 to 3 weeks. Continued disease progress resulted in blighting similar to that observed in the field. This is the first report of Curvularia blight of zoysiagrass in the United States, it was previously reported in Japan, where it is called ‘dog footprint’.
Identification of streptomycin-resistant strains of Erwinia amylovora in New York. N. L. Russo (1), T. J. Burr (1), D. I. Breth (2), and H. S. Aldwinckle (1). (1) Department of Plant Pathology, Cornell University, Geneva, NY 14456; (2) Cornell Cooperative Extension, Albion, NY 14411.
Streptomycin is the most effective antibiotic registered for the control of fire blight on apple, a disease caused by Erwinia amylovora. Resistance surveys conducted between 2002-2006 produced the first authenticated report of streptomycin-resistant strains of E. amylovora in New York. Resistant strains were identified in two orchards in Wayne County. Resistance was based on the acquisition of the strA-strB gene pair, and not a spontaneous mutation of the streptomycin-binding site. Although common in epiphytic bacterial populations in NY, the strA-strB genes have only been associated with fire blight outbreaks in Michigan. Infected trees originated from Michigan, and it is likely bacteria were imported on infected nursery stock. Since orchard removal in 2003 no streptomycin-resistant E. amylovora have been identified in NY. The movement of infested plant material posses a great threat to the continued use of streptomycin as a routine application to control fire blight.
Organic disease management on apple. J. W. Travis and N. O. Halbrendt. Dept. Plant Pathology, Penn State University, Fruit Research and Extension Center, Biglerville, PA 17307.
Disease management programs that are effective and profitable for growers while being environmentally sound are being developed. In 2004, an organic apple demonstration orchard was established at the Penn State University Fruit Research and Extension Center, Biglerville, PA to provide the industry with the opportunity to observe ‘best’ organic practices for local apple production. The first certified organic fruit was produced and sold in 2006. The organic apple project was named PA Regional Organic Fruit Industry Transition (PROFIT). Research trials focused on the efficacy of sulfur and lime sulfur applied alone, in combination or in rotation with other organic and alternative fungicides to evaluate control of apple scab, powdery mildew, cedar apple rust and summer diseases on apples. Treatment programs with sulfur reduced the incidence of scab on shoots and fruit compared to the untreated trees. Programs based on sulfur alone or sulfur in combination with Citrex (not presently labeled for organic), lime sulfur, or Vigor Cal provided comparable control of scab incidence on shoots and the incidence and severity of scab on fruits (P < 0.05).
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