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Seedling blight of mango (

Diseases caused by fungi in the genus Calonectria pose a significant threat to the ornamental horticulture industries in Europe and the United States. Calonectria spp. are particularly challenging pathogens to manage in ornamental production systems and the urban landscape for multiple reasons. A high level of species diversity and poorly resolved taxonomy in the genus makes proper pathogen identification and disease diagnosis a challenge, though recent molecular phylogenetic studies have made significant advances in species delimitation. From a disease management perspective, Calonectria spp. produce long-lived survival structures (microsclerotia) that contaminate nursery production systems and can survive multiple years in the absence of a susceptible plant host. Latent infection of plant material is poorly understood but likely contributes to long-distance dissemination of these fungal pathogens, including the clonal Calonectria spp. responsible for the global emergence of boxwood blight. Breeding for disease resistance represents a sustainable strategy for managing Calonectria diseases but is challenging due to the perennial nature of many ornamental plants and high levels of susceptibility in commercial cultivars. Ultimately, long-term sustainable management of Calonectria diseases will require an improved understanding of pathogen biology as well as integration of multiple disease management strategies.

Pistachio (

Chemical control represents the main effective strategy for managing Calonectria diseases in ornamental nurseries. The occurrence of fungicide-resistant strains and the European Directive on “Sustainable Use of Pesticides” has forced ornamental plant growers to establish effective integrated pest management strategies to control Calonectria infections. Here, three nursery experiments were performed to detect the best combinations of fungicides and biological control agents (BCA) to control both leaf spot, caused by six Calonectria spp. on bottlebrush and metrosideros, and stem rot, caused by Calonectria morganii on Dodonaea plants. Overall, the cyprodinil + fludioxonil mixture alone or combined with bioformulates containing Bacillus, Trichoderma, and Streptomyces spp. provided the best performance in reducing leaf spot and stem rot caused by Calonectria spp., followed by the mixture of boscalid + pyraclostrobin. Although BCA alone provided disease suppression significantly lower than the controls in most cases, these treatments were, on average, the least effective in controlling Calonectria infections. Otherwise, there were no significant increases in efficacy with fungicides plus BCA over fungicides alone. Thus, the application of boscalid + pyraclostrobin and cyprodinil + fludioxonil mixtures may also be used in large-scale applications to reduce Calonectria diseases because they effectively managed leaf and stem infections. Our comprehensive research applied previously acquired information on Calonectria disease management in nurseries, resulting in important data that affects integrated plans to fight these pathogens in accordance with European legislation.

Primosole mandarin is a promising mandarin-like hybrid of Satsuma Miho and Carvalhais mandarin that ripens very early, at the beginning of October, in southern Italy (2). During August and September 1999 and 2000 in Sicily, widespread fruit rot, affecting from 80 to 95% of the total production, was observed in a 4-year-old Primosole mandarin orchard. The fruits developed color prematurely and light brown-to-black discoloration of the rind at the stylar end. Internal symptoms consisted of a black rot of the fruit core. Sometimes the exterior of the fruits appeared healthy. No premature fruit drop was observed, and infected fruits became mummified and remained attached on the trees. Alternaria citri Ellis & N. Pierce in N. Pierce was consistently isolated from infected tissues, and the identification of the fungus was based on morphological characteristics of the conidia (1). Pathogenicity tests of single-spore isolates were carried out on surface-sterilized Primosole fruits and were repeated twice. Either a conidial suspension (2 × 104 conidia per ml) was injected into the core of fruits, or fruits were pricked at the stylar end near or through growth cracks in poorly formed navels, and the conidial suspension was placed on the wound. Thirty fruits were used per treatment, and thirty noninoculated fruits were used for controls. Following inoculation, the fruits were placed in plastic bags and kept at 30°C for 15 days. No external symptoms were observed on any of the fruits, but when cut in half, decay of the core was observed in all inoculated fruits. A. citri was reisolated from inoculated fruits, fulfilling Koch's postulates. No symptoms were observed on fruits used as controls. We believe that infection is facilitated by growth cracks at the stylar end and the sensitivity to sunburn of Primosole mandarin. To our knowledge, this is the first report of the extreme susceptibility of Primosole mandarin to Alternaria fruit rot. References: (1) G. E. Brown and J. W. Eckert. Postharvest fungal diseases. Page 37 in: Compendium of Citrus Diseases, 2nd ed. L. W. Timmer, S. M. Garnsey, and J. H. Graham, eds. The American Phytopathological Society, St. Paul, MN, 2000. (2) E. Tribulato and G. La Rosa. Italus Hortus 1:21, 1993.

In October 1997, severe leaf spotting was observed on several ornamental plants growing in different nurseries in southern Italy. These symptoms were detected for the first time on strawberry tree (Arbutus unedo L.) and water wattle (Acacia retinodes Schltdl.). In the latter species, diseased plants showed also stem canker and shoot blight symptoms. Cylindrocladium pauciramosum C.L. Schoch & Crous (teleomorph Calonectria pauciramosa) were found associated with these symptoms (2). More recently, leaf spots were found also on feijoa (Feijoa sellowiana Berg.) and on Florida hopbush (Dodonaea viscosa (L.) Jacq.) in two other nurseries located in Sicily. Infected tissues were surface-sterilized and plated on potato dextrose agar. Plates were incubated at room temperature under fluorescent cool white lights on a 12-h light/dark regime. A Cylindrocladium species was consistently associated with diseased tissues. The isolates of Cylindrocladium collected from feijoa and Florida hopbush were identified on carnation leaf agar as C. pauciramosum on the basis of their obpyriform to broadly ellipsoidal terminal vesicles, conidiophore branching pattern, and conidium morphology, as well as mating type studies with tester strains of C. pauciramosum (1,3). Koch's postulates were fulfilled by inoculating 6-month-old seedlings of the four ornamental plants with a spore suspension of the fungus (104 conidia per ml). Following inoculation, all plants were maintained in a glasshouse where the temperature was 15 to 25° C and relative humidity was 80 to 90%. After 6 to 8 days, symptoms resembling those seen in the nurseries were apparent. The Cylindrocladium species was reisolated from lesions on inoculated plants, thus confirming it to be the causal organism of these diseases. This is apparently the first report of C. pauciramosum leaf spot on these hosts. References: (1) P. W. Crous and M. J. Wingfield. Mycotaxon 51: 341, 1994. (2) G. Polizzi and P.W. Crous. Eur. J. Plant Pathol. 105:407, 1999. (3) C. L. Schoch et al. Mycologia 91:286, 1999.

Boxleaf veronica (Hebe buxifolia (Benth.) Cockayne & Allan), native to New Zealand, is an annual or perennial shrub widely cultivated in Mediterranean zones. During late spring 2003, after seasonably wet and cool weather, a downy mildew epidemic occurred on potted, overhead irrigated, 1-year-old seedlings at a commercial nursery in eastern Sicily (southern Italy). Infections affected boxleaf veronica at first, but spread to variegated boxleaf (H. buxifolia cv. variegata). Initial symptoms on the upper side of leaves were small, gray brown patches that gradually spread, eventually resulting in necrosis in the center of infected areas. At that point, brown patches were evident on both sides of the leaves. Lesions on the lower leaf surface became covered with a fairly dense, pale gray-to-brown layer of conidia and conidiophores. As the disease progressed, these spots coalesced into large and conspicuous brown lesions. The youngest, most succulent shoots withered and died. The large brown lesions on the leaves were disfiguring and affected 95 to 100% of plants in the nursery. All diseased nursery stock had to be discarded. Oospores were not observed in leaf tissues. The fungus recovered from leaves with abundant gray brown sporulation was identified as Peronospora grisea (Unger) Unger. Microscopic observations revealed conidiophores that branched dichotomously five to seven times with branch ends 6 to 10 × 2 to 3 μm, slightly curved, and tapered to a blunt apex. Hyaline conidia were ellipsoid, brownish when mature, and measured 23 to 27 × 15 to 18 μm (mean = 25.2 × 17.1 μm), falling within the range of those reported for P. grisea (1). Pathogenicity was confirmed by inoculating 10 1-yr-old seedlings (10 cm tall) by gently pressing infected leaves with abundant sporulation onto healthy leaves and maintaining inoculated plants in a humid chamber at 21°C. An equal number of noninoculated plants served as controls. After 9 to 11 days, symptoms similar to those originally observed developed onto inoculated plants, and after 12 to 15 days, grayish mildew grew on leaves. Microscopic examination of the developing mycelium confirmed that leaves were infected with P. grisea. Uninoculated control plants did not develop any symptoms. The disease was also confirmed in this way on variegated boxleaf veronica (H. buxifolia cv. variegata). Downy mildew of Hebe spp. has been recorded in New Zealand, Britain, France, Germany, and more recently, West Sussex (2). Heavy rainfall during the spring of 2003 in eastern Sicily could have favored disease development. To our knowledge, this is the first report of downy mildew of boxleaf veronica and variegated boxleaf veronica caused by P. grisea in Italy. References: (1) S. M. Francis and A. M. Berrie. Peronospora grisea. No. 766 in: Descriptions of pathogenic fungi and bacteria. CMI, Kew, Surrey, UK. 1983. (2) J. M. Whipps and C. A. Linfield. Plant Pathol. 36:216, 1987.

In the spring of 2004, during a disease survey in three nurseries of eastern Sicily, a new leaf and stem problem was observed on 20 to 40% of young (2- to 6-month-old) container-grown bay laurel (Laurus nobilis L.). Affected plants exhibited sporadic water-soaked leaf spots on leaf edges that subsequently enlarged and turned into necrotic lesions. These spots were always bordered by a dark brownish margin. Frequently, these necrotic lesions expanded into stems causing blight of young shoots. No symptoms were observed on 2- to 3-year-old plants. Small portions (1 to 2 cm) of symptomatic tissue were surface disinfested for 30 s in 1% NaOCl, rinsed in sterile distilled water, placed on potato dextrose agar (PDA), and incubated at 22 ± 2°C. A fungus consistently isolated from affected tissues was identified as Pestalotiopsis uvicola (Speg.) Bissett based on morphological characters (1). Acervular conidiomata (as much as 250 μm in diameter) appeared in cultures on PDA at 24 ± 2°C over a period of 13 days. All isolates had 4-septate fusiform to narrow ellipsoid conidia with 2 to 4 apical appendages, often aggregated, and averaging 8 μm long. Conidia ranged from 20 to 25 μm long and 6 to 7 μm wide. Basal appendage was single, attenuated, and as much as 3 μm long. Three isolates of P. uvicola were selected for pathogenicity tests. Leaves and stems of 6-week-old seedlings of bay laurel were lightly wounded with a hypodermic needle, and a PDA mycelial plug (5 mm in diameter) was placed on the surface of wounded tissues. Sterile agar plugs were placed on control plants. This method was used to inoculate 6 plants for each isolate. All plants were incubated at 95 to 100% relative humidity and 25 ± 1°C. After 7 days, leaf spots and necrotic lesions on the stem similar to those observed in nurseries were observed. Control plants remained symptomless. Koch's postulates were fulfilled by reisolation of the fungus from affected tissues. Although found in only a few nurseries, the infections could be a threat to an important production area of bay laurel in Sicily. To our knowledge, this is the first report of P. uvicola on bay laurel in the world. Reference: (1) T. R. Nag Raj. Mycotaxon 26:211, 1986.

California lilacs, or Ceanothus, are evergreen, drought tolerant, colorful ornamental shrubs belonging to the Rhamnaceae family. Ceanothus thyrsiflorus var. repens is the most common species grown in Italy. In October 2005, a severe wilting was noticed on approximately 3,000 potted, 6-month-old plants obtained from cuttings produced by a commercial nursery in Lecco Province (northern Italy). Wilting was always associated with root rot and brown discoloration at the base of the stem. No leaf spots or stem lesions were detected. A Cylindrocladium sp. was isolated consistently from crown, basal stems, and roots of symptomatic plants with potato dextrose agar. Although many crown rots are caused by Phytophthora spp., this pathogen was not found associated with rotten roots and crown plating small pieces of diseased root tissue and crowns onto selective medium. A random selection of five Cylindrocladium sp. isolates was obtained from the infected crown and basal stem. Subsequently, they were identified on carnation leaf agar (CLA) as Cylindrocladium pauciramosum C.L. Schoch & Crous on the basis of their obpyriform to broadly ellipsoidal terminal vesicles, conidiophore branching pattern, conidium, and perithecial morphology, as well as mating type with tester strains of C. pauciramosum selected isolates (1,4). All single-conidial isolates were mated with tester strains DISTEF-G87 (MAT1-1) and DISTEF-G128 (MAT1-2) of C. pauciramosum on CLA, which confirmed both mating types to be present. Two of the isolates were deposited at Fungal Biodiversity Centre, Centraalbureau voor Schimmelcultures (CBS-120145 and CBS-120146). Pathogenicity tests were performed by macerating CLA cultures of C. pauciramosum, obtained from a single-spore isolate and incorporating them on the soil surface of 20 8-month-old C. thyrsiflorus var. repens potted plants. The same number of plants was used as the control. Following inoculation, plants were well irrigated and kept in a growth chamber at 25 ± 1°C. All inoculated plants developed crown rot, basal stem rot, and root rot 25 days after inoculation. Uninoculated control plants remained healthy. C. pauciramosum was reisolated from the artificially inoculated plants. C. pauciramosum causes considerable damage to the ornamental industry in Italy, where projects have been carried out since the first record of the fungus in Europe (3). C. pauciramosum was previously detected on Ceanothus sp. in the United Kingdom (2), where foliar and stem lesions were described. To our knowledge, this is the first record of the pathogen on C. thyrsiflorus var. repens and the first report of wilting due to crown and basal stem rot. References: (1) P. W. Crous. Taxonomy and Pathology of Cylindrocladium (Calonectria) and Allied Genera. The American Phytopathological Society, St. Paul MN, 2002. (2) C. R. Lane et al. Plant Pathol. 55:582, 2006. (3) G. Polizzi and P. W. Crous. Eur. J. Plant Pathol. 105, 407, 1999. (4) C. L. Schoch et al. Plant Dis. 85:941, 2001.

The Kentia palm or Sentry palm (Howea forsteriana (C. Moore & F.v. Muell.) Becc.) is one of the most popular palms in the world. In Italy, it is suitable for growing indoors or outdoors. In September 2006, bleeding was found on the stem of a 20-year-old Kentia palm growing in a field nursery in eastern Sicily. The trunk began to bleed from cracks or fissures of the bark at 5 ft (1.5 m) from the ground level. Tissues surrounding the stem cracks were black. The plant canopy showed no symptoms. Cross-sections revealed brown rot confined to one side of the trunk where the rot was spreading inward from the surface. Infected tissues did not emanate odor of fermented fruit. Internal tissue adjacent to the rotted areas was placed on carrot agar amended with 500 μl of streptomycin sulphate and acidified (lactic acid; pH = 3.6) potato dextrose agar (PDA). A transverse section of affected palm tissues was maintained in a moist chamber for 6 days. Microscopic examinations of isolates obtained on media and sporulation from affected tissues yielded Thielaviopsis paradoxa (De Seyn.) Höhn (2). Endoconidia, measuring 3.9 (range 3 to 6) × 8.2 μm (range 6 to 14) (n = 50), were cylindrical to somewhat oval when mature, hyaline to brown, and smooth walled. Endoconiodophores were usually straight, colorless to pale brown, as much as 150 μm long, with a terminal spore-bearing cell through which spores are borne. Chlamydospores were smooth, thick walled, brown, in chains, and were 8.8 (range 5.5 to 15.0) × 15.8 μm (range 9.0 to 25.0) (n = 50). Koch's postulates were fulfilled by stem inoculation on a 20-year-old double-stem Kentia palm growing in the same field nursery. Ten mycelial plugs (5-mm diameter) obtained from 14-day-old single-spore colonies growing on PDA at 24°C were applied to 10 5-mm-diameter stem wounds. The same number of inoculations was used as a control in the other stem and treated with sterile agar plugs. Following inoculation, the mycelial plugs and the stems were wrapped with Parafilm. After 20 days, stem rots were detected only on the inoculated stem wounds, and stem bleeding was observed after 3 months. The pathogen was reisolated from symptomatic tissues. A Thielaviopsis sp. was previously reported in Florida on Kentia palm as being responsible for a frond necrosis (1). While stem bleeding seems to be a common symptom on coconut (Cocos nucifera L.), it is not commonly reported on other palm species. Only recently, T. paradoxa was detected for first time in Sicily on date palm imported from Egypt (3). To our knowledge, this is the first record of stem bleeding caused by T. paradoxa on palms in Italy, and the first record of stem bleeding and stem rot on Kentia palm. References: (1) S. A. Alfieri Jr. et al. Fla. Dep. Agric. Consum. Serv. Bull. No. 14. 1994. (2) A. R. Chase and T. K. Broschat, eds. Diseases and Disorders of Ornamental Palms. The American Phytopathological Society, St Paul MN, 1991. (3) G. Polizzi et al. Plant Dis. 90:972, 2006.

Coprosma repens A. Rich. (mirror bush, Rubiaceae) is a hardy salt tolerant shrub that is native to New Zealand where it is primarily a coastal weed. In temperate climates, many variegated varieties and hybrids of mirror bush grow extensively in gardens. In February 2007, irregular or semicircular necrotic spots, sometimes in concentric rings, were noticed on leaves of approximately 2,000 potted, 1-year-old plants of C. repens ‘Tapuata Gold’ obtained as cuttings from a nursery located in Catania Province. The symptoms were detected on approximately 60% of the plants and were localized exclusively on older leaves especially in the yellow or white border. Protein A sandwich (PAS)-ELISA showed mirror bush was positive for the Batavian lettuce strain of Tomato spotted wilt virus (antiserum to TSWV: PVAS-450 from American Type Culture Collection, Manassas, VA). Double antibody sandwich (DAS)-ELISA with polyclonal antisera to Cucumber mosaic virus, TSWV, and Impatiens necrotic spot virus confirmed the presence of only TSWV. Reverse transcription (RT)-PCR was employed to characterize the TSWV isolate. RT-PCR was carried out with primers (forward 5′-TTA ACT TAC AGC TGC TTT-3′ and reverse 5′-CAA AGC ATA TAA GAA CTT-3′) specific for the CP gene of TSWV (3). Amplification was performed in a thermal cycler (Gene Amp PCR System 24000; Perkin Elmer, Hayward, CA) by preheating at 94°C for 5 min followed by 30 cycles of 1.5 min of denaturation at 94°C, 2 min of annealing at 48°C, and 1 min for extension at 72°C. Finally, the amplified DNA was incubated at 72°C for 7 min for a final extension. All samples yielded DNA fragments of the expected size of 823 bp, which included the entire N gene. Purified PCR products were cloned and sequencing (GenBank Accession No. EU020104) was done by Sequiserve (Vatterstetten, Germany). Comparison with sequences available from the GenBank database showed 96 to 99% homology with the same region of the genome for all TSWV isolates, thus confirming the identity of the virus as an isolate of TSWV. In the Rubiaceae family, TSWV was previously detected on Galium spp., Ixora spp., Gardenia jasminoides Ellis, and Bouvardia sp. (1,2,4). To our knowledge, this is the first occurrence of this virus on a member of the genus Coprosma. The high incidence of the disease in the nursery could be due to propagation of cuttings from an infected source. References: (1) M. K. Hausbeck et al. Plant Dis. 76:795, 1992. (2) C. Jordá et al. Plant Dis. 79:358, 1995. (3) R. A. Mumford et al. J. Virol. Methods 46:303, 1994. (4) A. M. Vaira et al. Plant Pathol. 42:530,1993.

During the summer of 2006, a widespread blight was observed on 6-month-old potted plants of firewheel tree (Stenocarpus sinuatus Endl.) and 3-month-old potted plants of bay laurel (Laurus nobilis L.) growing in a nursery in eastern Sicily, Italy. On both species, symptomatic plants initially had sunken, tan lesions at ground level where white mycelia and small (1 to 2 mm in diameter), brown, spherical sclerotia typical of Sclerotium rolfsii Sacc. were formed. As the disease progressed, the mycelia extended up the stem and entire plants collapsed. A sudden wilting affecting 4-month-old potted seedlings of bird of paradise (Strelitzia reginae Aiton) and 5-month-old potted seedlings of Mediterranean fan palm (Chamaerops humilis L.) was occasionally detected in other greenhouses of the same nursery. Liverwort (Marchantia polymorpha L.) was abundantly present on the surfaces of the containers where these plants were grown. Circular and crescent-shaped patches as much as 100 cm in diameter were observed on the massed liverwort plants. In these patches, the liverwort died and sclerotia typical of S. rolfsii were dispersed on white mycelial strands. Symptomatic tissues of the ornamental plants and liverwort were surface disinfested in 1% NaOCl for 1 min, rinsed in sterile water, and plated on potato dextrose agar. Tissues consistently yielded S. rolfsii (teleomorph Athelia rolfsii (Curzi) Tu & Kimbrough) and typical sclerotia with internally differentiated rind, cortex, and medulla were produced within 6 or 7 days (3). Pathogenicity tests were performed by placing 30 sclerotia obtained from 10-day-old cultures in the soil below the crown portion on each of 2-month-old healthy seedlings of Stenocarpus sinuatus, L. nobilis, Strelitzia reginae, and C. humilis (20 seedlings per host). In addition, liverwort growing in 10 pots (7 cm in diameter) was inoculated with 30 sclerotia per pot. For each species, the same number of plants or pots served as control. All ornamental plants and liverwort were maintained in a growth chamber at 25 ± 1°C and enclosed for 7 days in polyethylene bags and then moved to a greenhouse where temperatures ranged from 24 to 28°C. The inoculation trial was repeated once. Symptoms of southern blight developed after 5 to 20 days on all inoculated plants of Stenocarpus sinuatus and sporadically (two to five plants) after 20 days on L. nobilis, Strelitzia reginae, and C. humilis. After 5 days, liverwort in all inoculated pots was colonized and plants died within 12 days. Control plants of all species remained symptomless. S. rolfsii was reisolated from symptomatic plants. S. rolfsii was reported for the first time in Sicily in 2004 on ornamental plants (2). Strelitzia reginae was previously reported as a host of Corticium rolfsii (synonym S. rolfsii) in Portugal (1). To our knowledge, this is the first report of S. rolfsii on Stenocarpus sinuatus, L. nobilis, and C. humilis. In addition, this is the first report of the susceptibility of M. polimorpha to S. rolfsii. Liverwort could provide a food source for the fungus in container-grown nursery plants. References: (1) M. R. de Sousa Dias and M. T. Lusas. Bol. Soc. Brot. 53:469, 1980. (2) G. Polizzi et al. Plant Dis. 88:310, 2004. (3) Z. K. Punja and A. Damiani. Mycologia 88:694, 1996.

Osteospermum (African Daisy or Cape Daisy) is a genus belonging to the Calendulae with a large number of perennial plant species. In February of 2007, a severe damping-off occurred on 3- to 4-month-old potted cuttings of Osteospermum ‘Impassion Rose Purple’, ‘Impassion White’, ‘Impassion Purple’, and ‘Impassion White Rose’ cultivated in a nursery in eastern Sicily. More than 30% of the plants were infected. Disease symptoms consisted of extensive water-soaked lesions at the base of the stem followed by wilt and collapse of the plant. Isolations from diseased tissues on potato dextrose agar (PDA) amended with streptomycin sulfate at 100 mg/l consistently recovered a fungus with morphological characteristics of Rhizoctonia solani. Fungal colonies were initially white, turned brown after 2 to 3 days, and produced irregularly shaped, brown sclerotia after 1 week. Microscopic examination revealed that hyphae had right angle branching patterns, were constricted at the base of the branch near the union with main hyphae, and septate near the constriction. The number of nuclei per hyphal cell was determined on cultures grown at 25°C on 2% water agar in petri plates. Mycelium was stained with 0.5% aniline blue solution (4) and examined with a microscope at ×400. The hyphal cells were all multinucleate. Anastomosis groups were determined by pairing isolates (3) with tester isolates of AG-1 IA, AG-2-2-1, AG-2-2IIIB, AG-2-2IV, AG-3, AG-4, AG-5, AG-6, and AG-11. Anastomosis was observed only with tester isolates of AG-4, giving C2 reactions (1) at a high frequency. The identification of group AG-4 within R. solani had been obtained by electrophoretic patterns of pectic enzymes (polygalacturonases) in vertical pectin-acrylamide gel stained with ruthenium red (2). All isolates of R. solani collected from infected plants were paired in all combinations on PDA plus 1% activated charcoal and examined for somatic interaction. All paired colonies merged without producing visible tufts of aerial mycelium. Absence of tufts and the lack of formation of heterokaryon at the hyphal interaction zone indicated that all isolates belonged to the same mating type with the same mating alleles (3). Pathogenicity tests were performed by placing plugs of PDA from 5-day-old mycelial cultures in the soil near the base of the stem on 20 potted, healthy, 2-month-old cuttings of Osteospermum cv. Impassion Rose Purple. The same number of plants treated with 1/cm2 PDA plugs served as controls. Following inoculation, all plants were maintained in a growth chamber at 25°C and 95% relative humidity on a 12-h fluorescent light/dark regimen. Wilt symptoms and lesions at the base of stem identical to those observed in the nursery developed 7 days after inoculation, and all inoculated plants died within 20 days. Control plants remained symptomless. R. solani AG-4 was consistently reisolated from symptomatic tissues, completing Koch's postulates. To our knowledge, this is the first report of damping-off on the genus Osteospermum caused by R. solani. References: (1) D. E. Carling. Page 37 in: Grouping in Rhizoctonia solani by Hyphal Anastomosis Reactions. Kluwer Academic Publishers, the Netherlands, 1996. (2) R. H. Cruickshank and G. C. Wade. Anal. Biochem. 107:177, 1980. (3) M. C. Juliàn et al. Phytopathology 86:566, 1996. (4) C. C. Tu and J. W. Kimbrough. Mycologia 65:941, 1973.

Lagunaria patersonii (Adr.) G. Don (cow itch tree) is native to Australia and tolerates salted winds. During July 2007, damping-off of cow itch tree was observed on 4-month-old seedlings growing in a commercial nursery in eastern Sicily, Italy. More than 20% of the seedlings showed disease symptoms. First symptoms consisting of water-soaked lesions at the seedling base that expand rapidly girdle the stem and collapse the seedling in a few days. Diseased tissues were disinfested for 1 min in 1% NaOCl, rinsed in sterile water, plated on potato dextrose agar (PDA) amended with streptomycin sulphate at 100 mg/l, and then incubated at 25°C. A fungus with mycelial and morphological characteristics of Rhizoctonia solani Kühn was consistently yielded. Fungal colonies were initially white, turned brown with age, and produced irregularly shaped, brown sclerotia. Microscopic examination revealed that hyphae had a right-angle branching pattern, were constricted at the base of the branch near the union with main hyphae, and septate near the constriction. Basidia were not observed in the greenhouses or on the plates. Hyphal cells were determined to be multinucleate when stained with 0.5% aniline blue solution and examined at ×400 magnification with a microscope. Anastomosis groups were determined by pairing isolates on 2% water agar in petri plates (3). Pairings were made with tester strains of AG-1 IA, AG-2-2-1, AG-2-2IIIB, AG-2-2IV, AG-3, AG-4, AG-5, AG-6, AG-11. Anastomosis was observed only with tester isolates of AG-4 producing both C2 and C3 reactions. The hyphal diameter at the point of anastomosis was reduced, the anastomosis point was obvious, and cell death of adjacent cells was observed. These results were consistent with other reports on anastomosis reactions (1). The identification of group AG-4 within R. solani has been confirmed by electrophoretic patterns of pectic enzymes (polygalacturonases) in vertical pectin-acrylamide gel stained with ruthenium red (2). Pathogenicity tests were conducted on potted, healthy, 3-month-old seedlings of cow itch tree. Twenty plants were inoculated by placing plugs of PDA from 5-day-old mycelial cultures near the base of the stem. The same number of plants was treated with 1 cm2 PDA plugs as control. Plants were kept at 25°C and 95% relative humidity on a 12-h fluorescent light/dark regimen. Wilt symptoms due to basal stem rot, identical to ones observed in the nursery, appeared 10 days after inoculation and all inoculated plants showed symptoms within 1 month. Control plants remained healthy. The pathogen was reisolated from symptomatic tissues, completing Koch's postulates. To our knowledge, this is the first report in the world of R. solani causing disease on L. patersonii. References: (1) D. E. Carling. Page 37 in: Grouping in Rhizoctonia solani by Hyphal Anastomosis Reactions. Kluwer Academic Publishers, the Netherlands, 1996. (2) R. H. Cruickshank and G. C. Wade. Anal. Biochem. 107:177, 1980. (3) C. C. Tu and J. W. Kimbrough. Mycologia 65:941, 1973.

Feijoa sellowiana (O. Berg) O. Berg is native to South America and grown in Italy as an ornamental plant and for its fruit. During 2006, 2007, and 2008, a severe wilting was noticed on ∼ 10,000 potted 6-month to 3-year-old plants obtained from seeds and produced by three commercial nurseries in Catania Province (southern Italy). Wilting was always associated with root rot and brown discoloration at the base of the stem. Leaf spots or stem lesions were not observed. A Cylindrocladium sp. was isolated consistently from the crown, basal stem, and roots of symptomatic plants on potato dextrose agar (PDA). Ten isolates of a Cylindrocladium sp. were obtained from single-spore colonies made from a 14-day-old culture grown on PDA and subsequently subcultured on carnation leaf agar (CLA). Cultures were incubated at 25°C under near-UV light with a 12-h light/dark regimen and examined after 7 days (1). Only fungal structures occurring on the carnation leaf tissue were examined. Isolates were identified based on morphological traits and mating type responses (2,4). Isolates were mated with opposite mating tester strains of C. pauciramosum (DISTEF-G128 [MAT1-1] and DISTEF-G87 [MAT1-2]) and C. scoparium (DISTEF-GCs7 = CBS 120892 [MAT1-1] and DISTEF-GP0 = CBS 119669 [MAT1-2]) selected from an Italian collection. Plates were parafilmed, sealed in plastic bags, incubated in a chamber at 25 ± 1°C with a photoperiod of 16 h of light and 8 h of darkness, and examined weekly until perithecia developed. Successful crosses were determined after 2 months of incubation and were regarded as those isolate combinations that produced perithecia with viable ascospores. Conidia were observed to be 30 to 60 × 3.5 to 5.0 μm while conidiophores mostly had two to three series of branches and stipes terminated in obpyriform to broadly ellipsoidal vesicles, which is characteristic of C. pauciramosum C.L. Schoch and Crous (teleomorph Calonectria pauciramosa C.L. Schoch and Crous). Fertile perithecia containing viable ascospores were similar to Calonectria pauciramosa. They were obtained only from crosses of the examined isolates with mating type testers of C. pauciramosum. Six isolates (when paired with DISTEF-G128) and four isolates (when mated with DISTEF-G87) provided fertile progeny. No perithecia were obtained in pairings of the 10 isolates with tester strains of C. scoparium. One representative isolate was deposited at the Fungal Biodiversity Centre, Centraalbureau voor Schimmelcultures (DISTEF-AS4 = CBS-120618). Koch's postulates were fulfilled by inoculating 30 6-month-old seedlings of feijoa with a spore suspension (105 conidia per ml) of one isolate of the pathogen (DISTEF-AS4) grown on CLA for 14 days. The same number of seedlings was used as a control. Following inoculation, plants were maintained in a growth chamber at 25 ± 1°C and 90 to 95% relative humidity. Wilting, crown rot, and root rot symptoms identical to those observed in the nurseries appeared within 15 to 50 days. Symptoms were not observed on the control plants. C. pauciramosum was previously reported to cause leaf spots on feijoa (3). To our knowledge, this is the first report of wilting due to crown and root rot caused by C. pauciramosum in this host. The disease is a limiting factor for feijoa cultivation in Sicilian nurseries. References: (1) P. W. Crous et al. Mycologia 84:497, 1992. (2) P. W. Crous and M. J. Wingfield. Mycotaxon 51:341, 1994. (3) G. Polizzi and V. Catara. Plant Dis. 85:803, 2001. (4) C. L. Schoch et al. Mycologia 91:286, 1999.

Thryptomene saxicola (Hook.) Schauer is an evergreen shrub native to Western Australia and a member of the Myrtaceae. In Italy, this species was recently introduced as an ornamental plant from abroad. From July of 2008 to September 2009, a new crown and root rot of T. saxicola was observed on several stocks of approximately 20,000 1- to 3-year-old potted plants. Diseased plants were obtained from a commercial nursery in eastern Sicily, Italy. They were propagated from cuttings and grown under drip irrigation. More than 30% of the plants showed disease symptoms. Infected plants were characterized by a lack of vigor. Roots and crowns were partially or completely destroyed, and as a consequence, infected plants were chlorotic and often wilted. Early in the disease development, roots and crowns showed brown lesions. Successively, mature crown lesions turned dark brown. Longitudinal sections of crown tissues revealed a discoloration of the basal stem. Diseased tissues were surface disinfested for 1 min in 1% NaOCl, rinsed in sterile water, plated on potato dextrose agar (PDA) amended with 100 mg/liter of streptomycin sulfate, and then incubated at 25°C. A binucleate Rhizoctonia (BNR) species was consistently isolated from affected tissues of plants. Phytophthora isolates were not recovered from symptomatic tissues plated on BNPRAH (benomyl, nystatin, pentachloronitrobenzene, rifampicin, ampicillin, and hymexazol) selective medium. Fungal colonies were white with floccose, aerial hyphae. Hyphal cells were determined to be binucleate when stained with 1% safranin O and 3% KOH solution (1) and examined at ×400. Anastomosis groups were determined by pairing isolates with five different tester isolates of BNR AG-A on 2% water agar in petri plates (3). Anastomosis was observed with all tester isolates. The rDNA-ITS of one isolate of BNR (DISTEF-TS1) was sequenced (GenBank Accession No. AB514570) (2). The sequence from this isolate exhibited 99% homology with BNR AG-A (GenBank Accession No. AY738628). Pathogenicity tests were conducted on potted, healthy, 1-year-old plants of T. saxicola. Forty plants were inoculated by placing 1/cm2 plugs of PDA from 5-day-old mycelial cultures near the base of the stem. The same number of plants was treated with 1/cm2 PDA plugs as controls. Plants were kept at 25°C and 95% relative humidity on a 12-h fluorescent light/dark regimen. Root and crown rots, identical to those observed in the nursery, appeared 45 days after inoculation, and 80% of the inoculated plants died within 4 months. Control plants remained healthy. Binucleate Rhizoctonia was reisolated from symptomatic tissues, completing Koch's postulates. To our knowledge, this is the first report in the world of BNR causing disease on T. saxicola. References: (1) R. J. Bandoni. Mycologia 71:873, 1979. (2) M. Hyakumachi et al. Phytopathology 95:784, 2005. (3) C. C. Tu and J. W. Kimbrough. Mycologia 65:941, 1973.

In September 2008, a new disease was noticed in eastern Sicily, Italy in a 2-year-old regrafted citrus orchard with approximately 1,500 plants of sweet orange (Citrus sinensis (L.) Osbeck cv. Tarocco Scirè) on sour orange rootstock. Symptoms on the sweet orange scion consisted of blight of vigorously growing shoots and a sooty canker on shoots and rootstock trunks, resulting in shoot dieback to the cankered area. Masses of black fungal spores appeared under the bark and on the canker surface. Abundant gummosis was frequently associated with the affected tissues. Of the 1,500 plants surveyed, 12% were infected. A Scytalidium-like fungus was isolated consistently from symptomatic tissues on 2% potato dextrose agar (PDA). Conidia were ellipsoid to ovoid, hyaline, with an acutely rounded apex, truncate base, initially aseptate, becoming brown and two-septate at maturity, (10-) 12 to 13 (-14) × (4-) 5 (-6) μm. Mycelium was branched with septate, brown hyphae that disarticulated into 0- to 1-septate phragmospores (toruloid state). Genomic DNA was extracted from mycelia of single-conidial isolates cultivated on malt extract agar. Primers V9G and ITS4 were used to amplify the nuclear rRNA operon spanning the 3′ end of 18S rRNA gene, the internal transcribed spacers, the 5.8S rRNA gene, and a part of the 5′ end of the 28S rRNA gene (1,2). Both PCR primers were used to sequence directly the entire amplicon. DNA sequences of two isolates (CBS 124887 and 124888) were deposited in GenBank (Accession Nos. GQ330902 and GQ330903, respectively). These sequences were 100% identical in more than 545 nt to GenBank Accession Nos. AY213688 and FJ648577. On the basis of morphological characters and molecular data, the fungal isolates were identified as Neoscytalidium dimidiatum (Penz.) Crous & Slippers (2,3). Pathogenicity tests were conducted on five 2-year-old potted plants of sweet orange cv. Tarocco Scirè and lemon cv. Femminello Zagara Bianca, both grafted on sour orange. Eight 5-cm mycelial plugs of a single-conidial isolate were placed in wounds made with a sterile blade in the inner bark of plant stems and branches. Inoculation wounds were wrapped with Parafilm. The same number of plants inoculated with sterile PDA plugs served as controls. Inoculated plants were maintained in a growth chamber at 25 ± 1°C and 90 to 95% relative humidity. After 2 weeks, all inoculated plants developed gummosis originating from the inoculation point. Shoot blight and death of the entire plant were observed within 6 months on all inoculated plants. No differences were observed among the two citrus species. Control plants remained healthy. N. dimidiatum was reisolated from the infected plants and identified as described. To our knowledge, this is the first record of a disease caused by N. dimidiatum on citrus in Italy. The pathogen has been previously observed to infect freeze-damaged limbs of citrus in California, inducing a disease named Hendersonula branch wilt (4). This pathogen on citrus is important mainly as a wound-invading pathogen, therefore posing a serious threat to regrafted citrus orchards. References: (1) R. Cheewangkoon et al. Persoonia 21:77, 2008. (2) P. W. Crous et al. Stud. Mycol. 55:235, 2006. (3) E. Punithalingam and J. M. Waterston. No 274 in: Descriptions of Pathogenic Fungi and Bacteria. CMI, Kew, Surrey, UK, 1970. (4) J. O. Whiteside. Page 29 in: Compendium of Citrus Diseases. The American Phytopathological Society, St. Paul, MN, 1988.

Mediterranean fan palm (Chamaerops humilis L.), one of just two autochthonous European palms, is native to the western Mediterranean Region in southwestern Europe and northwestern Africa. It can be found growing wild in the Mediterranean area. In Europe, this species is very popular as an ornamental plant. In March 2009, a widespread damping-off was observed in a stock of approximately 30,000 potted 1-month-old plants of C. humilis cv. Vulcano in a nursery in eastern Sicily. Disease incidence was approximately 20%. Disease symptoms consisted of lesions at the seedling shoot (plumule). Stem lesions were initially orange, turned brown, and followed by death of the entire plumule or eophyll. A fungus with mycelial and morphological characteristics of Rhizoctonia solani Kühn was consistently isolated from lesions when plated on potato dextrose agar (PDA) amended with streptomycin sulfate at 100 μg/ml. Fungal colonies were initially white, turned brown with age, and produced irregularly shaped, brown sclerotia. Mycelium was branched at right angles with a septum near the branch and a slight constriction at the branch base. Hyphal cells removed from cultures grown at 25°C on 2% water agar were determined to be multinucleate when stained with 1% safranin O and 3% KOH solution (1) and examined at ×400. Anastomosis groups were determined by pairing isolates with tester strains AG-1 IA, AG-2-2-1, AG-2-2IIIB, AG-2-2IV, AG-3, AG-4, AG-5, AG-6, and AG-11 on 2% water agar in petri plates (3). Anastomosis was observed only with tester isolates of AG-4, giving both C2 and C3 reactions (2). One representative isolate obtained from symptomatic tissues was deposited at the Fungal Biodiversity Centre, Centraalbureau voor Schimmelcultures (CBS No. 125095). Pathogenicity tests were performed on container-grown, healthy, 1-month-old seedlings. Twenty plants of C. humilis cv. Vulcano were inoculated near the base of the stem with two 1-cm2 PDA plugs from 5-day-old mycelial cultures. The same number of plants served as uninoculated controls. Plants were incubated in a growth chamber and maintained at 25°C and 95% relative humidity on a 12-h fluorescent light/dark regimen. Symptoms identical to those observed in the nursery appeared 5 days after inoculation and all plants died within 20 days. No disease was observed on control plants. A fungus identical in culture morphology to R. solani AG-4 was consistently reisolated from symptomatic tissues, confirming its pathogenicity. To our knowledge, this is the first report in the world of R. solani causing damping-off on Mediterranean fan palm. References: (1) R. J. Bandoni. Mycologia 71:873, 1979. (2) D. E. Carling. Page 37 in: Grouping in Rhizoctonia solani by Hyphal Anastomosis Reactions. Kluwer Academic Publishers, the Netherlands, 1996. (3) C. C. Tu and J. W. Kimbrough. Mycologia 65:941, 1973.

Five greenhouse experiments were conducted in southeastern Sicily (Italy) from 2000 to 2009 to evaluate the effectiveness of soil solarization in reducing natural infections of tomato corky root caused by Pyrenochaeta lycopersici. Tests were performed with clear, traditional, and innovative plastic films and fumigant applications. In all the trials, soil solarization was effective in controlling corky root disease relative to an untreated control. Although inducing different thermal regimes in the soil, the use of different greenhouse covering and mulching films for solarization proved effective in reducing corky root severity relative to the untreated control. Solarization reduced infections caused by P. lycopersici comparable with methyl bromide fumigation and greater than metham sodium and metham potassium. Among the tested films, green coextruded film may be most attractive because it can be left on after solarization as mulch.

Volkamer lemon (Citrus volkameriana Ten. & Pasq., Rutaceae family) is the most commonly used rootstock for some ornamental citrus (oval kumquat and calamondin), improving the aesthetic quality of the plants and their marketable value. During the winter of 2011, symptoms of stem blight were observed on approximately 10% of 12,000 1-year-old potted C. volkameriana seedlings grown in different blocks in a commercial nursery near Catania (eastern Sicily, Italy). In the same nursery, only 1% of 15,000 older seedlings (2-year-old) showed disease symptoms. Initial symptoms included gray lesions on stems and occasionally on twigs. Later, buff lesions and gum exude appeared. Symptomatic stems and twigs were usually girdled and killed. In the lesions, irregular, dark gray sclerotia (1.0 to 5 × 1.0 to 7.0 mm, average 2.5 × 3.9 mm) were produced. In high relative humidity, cottony, white mycelia on the bark surface of infected tissues were also observed. Isolations were performed by transferring approximately 300 fragments of symptomatic tissues from 15 C volkameriana seedlings, surface-sterilized with 1% NaClO for 1 min, on potato dextrose agar (PDA) amended with 100 mg/liter of streptomycin sulfate. Sclerotinia sclerotiorum (Lib.) de Bary was recovered from all infected plants. Colony type, morphology, and dimensions of sclerotia were examined on PDA at 22 ± 1°C after 10 days in the dark. Sclerotia produced on PDA measured 2.0 to 7.0 × 1.5 to 4.0 mm (average 5.6 × 2.6 mm). DNA isolation was performed with the DNA Purification Kit (Puragene-Gentra, Minneapolis, MN) following the manufacturer's instructions. Amplification and sequencing of the internal transcribed spacer (ITS) region of rDNA was performed with primers ITS1/ITS4 (2). BLAST analysis of the 550-bp segment showed a 98% homology with S. sclerotiorum strain ms85 (GenBank Accession No HQ833450.1), thus confirming identification based on morphology. Koch's postulates were fulfilled by pathogenicity tests carried out on 20 1-year-old potted C. volkameriana seedlings. Each seedling was inoculated with five mycelial agar plugs (6 mm in diameter) and five sclerotia from the edge of 10-day-old colonies on PDA and placed in wounds made with a sterile blade in the bark of stem and twigs. Inoculated wounds (10 for each plant) were wrapped with Parafilm. The same number of control plants were wounded and inoculated with sterile PDA plugs. All inoculated plants were incubated in a growth chamber at 22°C with 80 to 90% relative humidity for 14 days. Blight symptoms and lesions on the stem and twigs identical to those observed in the nursery developed on all plants with both types of inoculum. Noninoculated control plants remained symptomless. S. sclerotiorum was reisolated from all symptomatic tissues and identified by morphology as previously described, completing Koch's postulates. To our knowledge, this is the first report of S. sclerotiorum stem and twig blight on C. volkameriana. Worldwide, Sclerotinia stem and twig blight is considered a minor disease on citrus (1), but this evidence suggests that in eastern Sicily, S. sclerotiorum may be an important pathogen of young C. volkameriana seedlings in nurseries. References: (1) J. A. Menge. Page 35 in: Compendium of Citrus Diseases. 2nd ed. The American Phytopathological Society, St. Paul, MN, 2000. (2) T. J.White et al. Page 315in: PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, San Diego, 1990.

Management of Calonectria spp. infections in nurseries requires scheduled fungicide applications, particularly with methyl benzimidazole carbamates (MBCs) and sterol demethylation inhibitors (DMIs). Due to rising concerns about the occurrence of MBC resistance in different Calonectria populations and variability in prochloraz efficacy in controlling these pathogens, a detailed study on prochloraz sensitivity distributions of Calonectria isolates belonging to the Calonectria scoparia complex was carried out. In total, 105 isolates collected in two distinct periods (1993 to 1996 and 2005 to 2009) were analyzed for prochloraz sensitivity. Based on DNA sequencing and phylogenetic analyses of β-tubulin, histone H3, and translation elongation factor-1α gene sequences, 69 and 36 isolates were identified as C. pauciramosa and C. polizzii, respectively. The isolates collected more recently (group B) had a reduced prochloraz sensitivity, as indicated by greater values for the effective dose to reduce growth by 50% than those collected earlier (group A). The reduced sensitivity detected in vitro corresponded to partial loss of fungicide efficacy in controlling infections in red clover and feijoa under controlled and semi-field conditions, respectively. Frequent prochloraz application in nurseries for controlling Calonectria spp. infections is discouraged.

The efficacy of 11 fungicides was evaluated for the control of Calonectria infections on bottlebrush (Callistemon “Masotti”) and feijoa (Acca sellowiana), with special emphasis on Calonectria pauciramosa and C. morganii, which are the most destructive species in Italian ornamental nurseries. Three nursery experiments were performed with the selected fungicides in order to determine their ability to prevent leaf spot caused by C. morganii on bottlebrush and leaf spot and crown and root rot caused by C. pauciramosa on bottlebrush and feijoa. All fungicides were effective in reducing disease infections, except for cyproconazole, propamocarb + fosetyl-Al, and K phosphite that were the least effective in reducing C. morganii leaf spot. In contrast, K phosphite proved more effective in reducing crown and root rot caused by C. pauciramosa. Fungicides were also evaluated in growth-cabinet experiments for their ability to reduce incidence and severity of leaf spot on bottlebrush caused by the exotic pathogens C. pseudomexicana, C. tunisiana, C. polizzii, and C. mexicana. Copper hydroxide, fosetyl-Al, prochloraz, prochloraz + cyproconazole, and tebuconazole were always effective in reducing Calonectria leaf spot on bottlebrush. However, some differences in levels of control might be attributable to Calonectria isolate. Overall, this study clearly indicates that new fungicides can be employed for chemical management of Calonectria infections in ornamental nurseries.

Schoch, C. L., Crous, P. W., Polizzi, G., and Koike, S. T. 2001. Female fertility and single nucleotide polymorphism comparisons in Cylindrocladium pauciramosum. Plant Dis. 85:941-946. Cylindrocladium pauciramosum is well established in South America, and has recently been collected from nurseries in South Africa, Italy, and the United States. Isolates were compared with respect to the percentages of hermaphrodites and the respective mating types in the different samples. Based on these data, the effective population size could be determined for the different areas studied. All nurseries had mating type ratios significantly different from an idealized 1:1 ratio. In the South African nursery, the MAT-1 mating type was dominant, while the MAT-2 mating type dominated in other samplings. This is consistent with an introduction of a small starter population. High percentages of hermaphrodites also agreed with recent introductions into nurseries in Italy and the United States. Variability of DNA sequences of the 5′ end of the β-tubulin gene from a set of C. pauciramosum isolates from different geographic regions was low to high. Isolates from South Africa, the United States, and Australia had identical βtubulin DNA sequences; this sequence was also found in the Italian sample, along with another unique group. Finally, a group of isolates obtained from South and Central America had the highest variation of all isolates investigated, and also included isolates that shared single nucleotide variations with another species, C. candelabrum. These findings suggest that C. pauciramosum most likely has a Central or South American center of origin.

The genus Passiflora (Passifloraceae family) contains more than 500 species and several hybrids. In Italy, some of these species and hybrids are grown as ornamental evergreen vines or shrubs. During August and September 2010, a crown and root rot was observed in a stock of approximately 6,000 potted 2-year-old plants of Passiflora mollissima (Kunth) Bailey, commonly known as the banana passionflower, in a nursery located in eastern Sicily (southern Italy). Disease incidence was approximately 20%. Disease symptoms consisted of water-soaked lesions at the crown and a root rot. Successively, older crown lesions turned light brown to brown and expanded to girdle the stem. As crown and root rot progressed, basal leaves turned yellow and gradually became necrotic and infected plants wilted and died. A fungus with mycelial and morphological characteristics of Rhizoctonia solani Kühn was consistently isolated from crown lesions and brown decaying roots when plated on potato dextrose agar (PDA) amended with streptomycin sulfate at 100 μg/ml. Fungal colonies were initially white, turned brown with age, and produced irregularly shaped, brown sclerotia. Mycelium was branched at right angles with a septum near the branch with a slight constriction at the branch base. Hyphal cells removed from 10 representative cultures grown at 25°C on 2% water agar were determined to be multinucleate when stained with 1% safranin O and 3% KOH solution (1) and examined at ×400. Anastomosis groups were determined by pairing isolates on 2% water agar in petri plates (4). Pairings were made with tester strains of AG-1, AG-2, AG-3, AG-4, AG-5, AG-6, and AG-11. Anastomosis was observed only with tester isolates of AG-4 (3). Pathogenicity tests were performed on container-grown, healthy, 3-month-old cuttings. Twenty plants of P. mollissima were inoculated near the base of the stem with five 1-cm2 PDA plugs from 5-day-old mycelial plugs obtained from two representative cultures. The same number of plants served as uninoculated controls. Plants were maintained at 25°C and 95% relative humidity with a 12-h fluorescent light/dark regimen. Wilt symptoms due to crown and root rot, identical to ones observed in the nursery, appeared 7 to 8 days after inoculation with either of the two isolates and all plants died within 20 days. No disease was observed on control plants. R. solani AG-4 was reisolated from symptomatic tissues and identified as previously described, confirming its pathogenicity. Damping-off or crown and root rot due to R. solani were previously detected on P. edulis in Brazil, Africa, India, Oceania, and Australia (2). To our knowledge, this is the first report of R. solani causing crown and root rot on P. mollissima. References: (1) R. J. Bandoni. Mycologia 71:873, 1979. (2) J. L. Bezerra and M. L. Oliveira. Fitopathol. Brasil. 9:273, 1984. (3) D. E. Carling. Page 37 in: Grouping in Rhizoctonia solani by Hyphal Anastomosis Reactions. Kluwer Academic Publishers, the Netherlands, 1996. (4) C. C. Tu and J. W. Kimbrough. Mycologia 65:941, 1973.