Multilocus phylogenetic diversity of Fusarium avenaceum pathogenic on lisianthus.

Fusarium avenaceum is a globally distributed fungus commonly isolated from soil and a wide range of plants. Severe outbreaks of crown and stem rot of the flowering ornamental, lisianthus (Eustoma grandiflorum), have been attributed to F. avenaceum. We sequenced portions of the translation elongation factor 1-alpha (tef) and beta-tubulin (benA) protein coding genes as well as partial intergenic spacer (IGS) regions of the nuclear ribosomal genes in 37 Fusarium isolates obtained from lisianthus and other host plants. Isolates that were previously identified morphologically as F. acuminatum were included as an outgroup. Phylogenetic analyses of tef, benA, and IGS sequences showed that F. avenaceum isolates were an exclusive group with strong bootstrap support and no significant incongruence among gene genealogies. Isolates from lisianthus were scattered within this clade and did not form distinct groups based on host species or locality. Pathogenicity tests of F. avenaceum isolates obtained from several other hosts showed an ability to cause disease on lisianthus, suggesting that F. avenaceum may be pathogenic on lisianthus regardless of its phylogenetic origin. These findings have management implications and suggest that any host that supports F. avenaceum may serve as a source of inoculum for lisianthus growers.

Outbreak of Black Root Rot in Catharanthus roseus Caused by Thielaviopsis basicola.

A bedding plant grower in southwest Florida reported severe losses in potted Catharanthus roseus (Madagascar periwinkle) transplanted on various dates in December 1997. Symptoms included yellowing of lower leaves, defoliation, black root rot, and plant death. Thielaviopsis basicola was consistently isolated from blackened roots on a selective medium (1). A disease survey was conducted during mid March 1998 of 7,500 periwinkle plants in the two cultivar series Pacific (cvs. Punch, Red, and White) and Cooler (cvs. Grape, Icy, Peppermint, Pink, and Raspberry). Black root rot symptoms were observed in 21 to 53% of periwinkles transplanted between 3 and 11 December, and in 0 to 19% of plants transplanted between 21 and 29 December. The two cultivar series did not appear to differ in their susceptibility to T. basicola. The fungus was consistently isolated from symptomatic periwinkle roots, from roots of chlorotic violas (Viola cornuta), and from a potting medium used for early December transplanting. Pathogenicity of isolates of T. basicola from periwinkle, viola, and the contaminated medium was investigated. Inocula were produced by growing the fungus on acidified potato dextrose agar for 18 days. Conidia, chlamydospores, and hyphae of T. basicola were suspended in deionized water (100 ml/95 mm culture plate). One milliliter of inoculum suspensions of each of the three isolates was used to inoculate 12 plants of pansy (Viola × Wittrockiana) cv. Majestic Giant Blue Shade. An equal number of plants served as noninoculated controls. In addition, 5 ml of each isolate suspension was used to inoculate three six-plant replications of periwinkle cv. Pink Cooler. Plants were incubated in a controlled environment chamber at day/night temperatures of 24/22°C with a 12-h photoperiod. After 22 days, moderate to severe root discoloration was produced in pansy by the viola isolate of the fungus, while periwinkle and potting medium isolates produced only minimal discoloration. Chlamydospores typical of T. basicola were observed in the roots of all inoculated pansies, and in the roots of one of 12 non-inoculated controls. After 38 days, periwinkle plants were rated for foliar yellowing (0 = no yellowing, to 3 = severe yellowing) and percent defoliation, and fresh weights of shoots and roots were obtained. T. basicola was recovered on the selective medium from roots of all inoculated plants and from 68% of the noninoculated controls, indicating that secondary spread had occurred. All three isolates of the fungus caused yellowing and defoliation, but only the periwinkle and potting medium isolates significantly reduced both shoot and root weights in periwinkle, compared with control plants. T. basicola has not been previously reported to cause black root rot in C. roseus, and a contaminated potting medium used during early December may have provided initial inocula for the outbreak. The unseasonably cool and rainy weather prevalent during winter 1997 and spring 1998 ("El Niño") may have also promoted the unusual appearance of the disease. Reference: (1) L. P. Specht and G. J. Griffin. Can. J. Plant Pathol. 7:438, 1985.

Reduction of Landscape Pathogens in Florida by Soil Solarization.

Two experiments were conducted during autumn 1997 and 1998 in west-central Florida to evaluate the effectiveness of soil solarization alone and in combination with the biological control agents Streptomyces lydicus (Actinovate) and Pseudomonas chlororaphis (syn. P. aureofasciens, AtEze) and the reduced-risk fungicide fludioxonil (Medallion) in managing soilborne pathogens of impatiens (Impatiens × wallerana, 'Accent Burgundy'). Naturally infested soil was solarized for 47 or 48 days during September and October using two layers of 25-µm clear, low-density polyethylene mulch, separated by an air space of up to 7.5 cm. Solarization decreased the final incidence and progress of Rhizoctonia crown rot and blight, incidence of Pythium spp. in roots, and root discoloration, and increased shoot biomass in both experiments. The technique also consistently reduced root-knot severity and population densities of Meloidogyne incognita, Dolichodorus heterocephalus, Paratrichodorus minor, and Criconemella spp. The incidence of Rhizoctonia crown rot and blight was reduced by fludioxonil, but not by the biological control agents.

Stem Blight of Eustoma grandiflorum Caused by Sclerotium rolfsii.

During a 4-week period in May through June 1996, 15% of 50 mature lisianthus (Eustoma grandiflorum) 'Maurine Blue' and 'Maurine White' plants exhibited stem blight in a landscape planting in west-central Florida. Initial disease symptoms included stem necrosis at the soil line, and yellowing and tan discoloration of leaves. As blighting of the stem progressed, infected plants wilted and died. Symptomatic stem sections from three plants were surface-disinfested in 0.5% NaOCl and placed on acidified 25% potato dextrose agar (APDA). Sclerotium rolfsii Sacc. was isolated from all three diseased stems. Pathogenicity of each of three S. rolfsii isolates was confirmed using two lisianthus 'Flamenco Blue' plants grown in 10.2-cm-diameter plastic pots containing a peat-based medium. Sclerotia produced on APDA were sprinkled on the soil surface around each plant base; 50, 100, and 5 sclerotia from isolates A, B, and C, respectively, were used (isolate C grew more slowly and produced fewer sclerotia than either A or B). Two noninoculated lisianthus served as controls. Plants were maintained in a greenhouse at minimum and maximum temperatures of ≈24 and 35°C, respectively. Plants inoculated with sclerotia from isolates A and B developed blight symptoms within 6 days. One of two plants inoculated with isolate C developed blight symptoms within 17 days, and the other remained symptomless, as did the control plants. Infection by S. rolfsii was confirmed by reisolation from symptomatic tissue. This is the first report of stem blight of lisianthus caused by S. rolfsii.

Reduction of Phytophthora Blight of Madagascar Periwinkle in Florida by Soil Solarization in Autumn.

Three field experiments were conducted in southwest and west-central Florida in 1993 through 1995 to evaluate the effectiveness of soil solarization during autumn in reducing Phytophthora blight of Madagascar periwinkle (Catharanthus roseus) caused by Phytophthora nicotianae. Plots (3.6 by 3.6 m) were infested by incorporating winter wheat seed containing P. nicotianae in the upper 15 cm of soil. Solarization was then conducted for 21 to 41 days, primarily during October, using clear, 25- or 50-µm low-density polyethylene mulch. The progress of Phytophthora blight, monitored for 31 to 42 days following planting, was significantly reduced by solarization in all experiments, and final blight incidence was reduced in two of three experiments. Solarization also reduced population densities of P. nicotianae.

First Report of Aerial Blight Caused by Pythium myriotylum on Tomato in Florida.

In September 1996 and 1997, diseased tomato seedlings were observed with symptoms of an aerial watery rot on leaves, petioles, and stems. Tomato cvs. Sanibel and 10097 from commercial fields in southwest Florida (Collier and Lee counties) and west central Florida (Manatee County) exhibited similar symptoms that occurred at an incidence of 15 to 18% about 4 weeks after transplanting and resulted in plant death. Microscopic examination of symptomatic tissue revealed the presence of mycelium and oogonia typical of Pythium spp. A fungus was consistently isolated from four plants sampled from each site onto a medium selective for Pythium spp. and maintained in pure culture on V8 juice agar at 28°C. The isolates were identified as Pythium myriotylum Drechs. based on the following morphological data: lobate sporangium, 12 to 13 µm wide; vesicle 15.4 to 19.4 µm in diameter; exit tube 54 to 90 µm long, oogonium 23 to 30 µm in diameter; and oospore 21 to 26 µm in diameter (1,2). Pathogenicity tests were conducted with two isolates from diverse regions within Florida by spray inoculating the leaves and shoots of 6- to 8-week-old tomato seedlings with a sporangial suspension of 1 × 104 sporangia per ml. Noninoculated plants served as controls. Plants had 24 h of pre- and post-dark period, day/night temperatures of 28/21°C, a 14-h photoperiod, and near 100% relative humidity in a growth chamber. The foliage of inoculated tomato plants exhibited symptoms identical to those observed in field samples 24 h after inoculation and 100% mortality within 72 h. The reisolated fungus was morphologically identical to the original isolate. Noninoculated plants remained asymptomatic. The unusual rainfall recorded at some sites, such as in Manatee County in September 1997, was 36% higher than the 40-year average and may have contributed to the incidence of this previously undescribed foliar blight. References: (1) Anonymous. C.M.I. Descriptions of Pathogenic Fungi and Bacteria No. 118. (2) T. Watanabe. Pictorial Atlas of Soil Fungi. Lewis Pub., London. p. 71.

Detection of a Severe Isolate of Impatiens Necrotic Spot Virus Infecting Lisianthus in Florida.

In May 1997, inclusions typical of a tospovirus were visualized by light microscopy in leaf tissue of lisianthus (Eustoma grandiflorum) exhibiting stunting, necrotic ringspots, leaf distortion, and systemic necrosis. Wilting and plant death were the final symptoms observed. Affected plants occurred at low incidence (<0.1%) in greenhouse-grown lisianthus in Manatee County, FL. Symptomatic tissue tested positive for impatiens necrotic spot virus (INSV) and negative for tomato spotted wilt virus (TSWV) with enzyme-linked immunosorbent assay (ELISA; Agdia, Elkhart, IN). Mechanical transmission of the virus to lisianthus and tomato was attempted by triturating 1 g of symptomatic leaf tissue in 7 ml of a buffer consisting of 0.01 M Tris and 0.01 M sodium sulfite, pH 7.3. Six plants of lisianthus cv. Maurine Blue and three of tomato (Lycopersicon esculentum) cv. Lanai at the second true-leaf stage were inoculated following abrasion of leaves with Carborundum. An equal number of controls were inoculated with buffer alone. Plants were maintained in a controlled environment chamber with a 12-h photoperiod, day/night temperatures of 21/16°C, and light intensity of 120 µE · s-l · m-2. Transmission rates were 100 and 0% to lisianthus and tomato, respectively. Chlorotic local lesions followed by chlorotic ringspots were observed in inoculated lisianthus leaves 4 days after inoculation. Stunting, leaf distortion, and necrotic ringspots appeared in noninoculated leaves of lisianthus plants within 3 to 4 weeks after inoculation. Buffer-inoculated lisianthus and all tomato plants remained symptomless and tested negative for INSV by ELISA. All symptomatic lisianthus tested positive for INSV by ELISA. The symptoms we observed in lisianthus due to infection by INSV were more severe than those previously reported in this host (1,2). The occurrence of such strains of INSV at high incidences could pose a significant threat for commercial lisianthus production. References: (1) M. K. Hausbeck et al. Plant Dis. 76:795, 1992. (2) H. T. Hsu and R. H. Lawson. Plant Dis. 75:292,1991.

Petal Blight of Sunflower Caused by Itersonilia perplexans.

In February 1999, a cut-flower grower from Florida reported post-harvest losses of approximately 25% in Helianthus annuus (sunflower) cvs. Sunrich Orange and Sunbright. Symptoms began as small, pinpoint brown lesions on the petals, which enlarged and coalesced, leading to necrosis of the entire blossom. Symptomatic petals were surface disinfested for 30 sec with 0.5% NaOCl and suspended over plates containing acidified 25% potato-dextrose agar. Petals adhered to lids of the petri dishes by the surface tension of the water on the petals. Itersonilia perplexans Derx was consistently isolated. Inoculation of sunflower with I. perplexans was achieved using three detached, mature blossoms of the cv. Sundance Kid with their pedicels placed in sterile water. Each blossom was inoculated with 3.5 ml of a spore suspension (1 × 105 spores/ml) applied as a spray. Three noninoculated control blossoms were sprayed with sterile, distilled water. Blossoms were incubated in a controlled environment chamber at near 100% RH, a constant temperature of 18°C, and a 12-h photoperiod. Three days following inoculation all of the inoculated blossoms were symptomatic, with necrosis ranging from 50 to 100% on individual petals. I. perplexans was recovered from all of the inoculated blossoms. Noninoculated controls remained symptomless, and I. perplexans was not recovered. I. perplexans has been reported to cause lesions on the cotyledons, first true leaves, and the hypocotyl region of sunflower seedlings in Canada and Uruguay (1,2). However, this is the first report of post-harvest petal blight in sunflower caused by I. perplexans and the first report in the United States of infection of sunflower by I. perplexans. References: (1) W. E. Sackston. Can. Phytopath. Soc. 1952:22, 1953. (2) W. E. Sackston. Phytopathology. 48:108, 1958.

Introduction of Tomato Yellow Leaf Curl Virus in Florida and Implications for the Spread of This and Other Geminiviruses of Tomato.

In July 1997, symptoms characteristic of tomato yellow leaf curl virus (TYLCV-Is) were observed on one tomato plant in a field in Collier County, Florida, and on several tomato plants in a retail garden center in Sarasota, Florida. Amplification with three sets of primers, analysis of amplified fragments using restriction enzyme digestion, and hybridization with a clone of TYLCV-Is indicated that TYLCV-Is was present in symptomatic plants. The sequence of a 1,300-bp amplified fragment was 99% identical to TYLCV-Is from the Dominican Republic and 98% identical to an isolate from Israel. It appears that TYLCV-Is entered the United States in Dade County, Florida, in late 1996 or early 1997. Subsequently, infected tomato transplants produced for retail sale at two Dade County facilities were rapidly distributed via retail garden centers throughout the state. Infected plants purchased by homeowners and placed in and around homes appeared to be the source of TYLCV-Is for nearby commercial nurseries and production fields. It appears that transplants have played a role in the movement of this and probably other geminiviruses. A number of regulatory procedures, as well as field management practices, were implemented in the 1997-98 production season to minimize the movement of TYLCV-Is within and out of the state.

Outbreaks of Stem and Leaf Blight of Eustoma grandiflorum Caused by a Phomopsis sp. in Florida.

Between November 1997 and May 1998, numerous lisianthus (Eustoma grandiflorum) cultivars exhibited severe stem and leaf blight at two pot-flower production sites in Hillsborough and Dade counties, FL. Blight occurred in mature plants and ranged in incidence from 3 to 5% in Dade County and from 40 to 80% in Hillsborough County. Initial stem necrosis was rapidly followed by leaf blight and production of numerous dark pycnidia in diseased tissue. As stem blight progressed, infected plants collapsed and died. Pycnidia contained biguttulate, 7.2 × 2.2-µm spores typical of Phomopsis alpha conidia; beta conidia were not observed. A Phomopsis sp. was isolated consistently when pycnidia from symptomatic stems were placed on acidified 25% potato dextrose agar after surface-disinfestation in 0.5% NaOCl; only alpha conidia were observed in culture. Pathogenicity was confirmed using a suspension of hyphae, pycnidia, and conidia made by comminuting one 95-mm-diameter acidified carnation leaf agar plate containing a 4-week-old colony of the Phomopsis sp. in 100 ml of deionized water. Six plants of lisianthus 'Maurine Blue' (three wounded at the crown, three nonwounded) each were inoculated with 10 ml of the fungal suspension. An equal number of noninoculated lisianthus (three wounded, three nonwounded) served as controls. After inoculation, plants were maintained in a greenhouse with average high and low temperatures of 38 and 25°C, respectively. Stem and leaf blight symptoms were observed in two of three wounded plants and in all nonwounded plants within 11 and 15 days after inoculation, respectively. Infection by a Phomopsis sp. was confirmed by reisolation from symptomatic tissue. Although this Phomopsis sp. has been detected previously in lisianthus exhibiting leaf and stem lesions (1), this report establishes the ability of the of the fungus to act as a primary pathogen and to cause extensive losses in this crop. Reference: (1) Alfieri et al. 1994. Diseases and Disorders of Plants in Florida. Bull. No. 14. Division of Plant Industry, Gainesville, FL.

Reduction of Defoliation in Citrus Caused by Mycosphaerella citri with a Novel Biocompatible Fungicide.

A novel, biocompatible fungicide, CD-2346, was evaluated for management of defoliation associated with greasy spot (Mycosphaerella citri Whiteside) in orange (Citrus sinensis (L.) Osbeck) and grapefruit (Citrus × paradisi Macfad.). This product contains potassium bicarbonate, potassium carbonate, urea, and a surfactant. CD-2346 (7.0 kg/ha) and a half-rate combination of CD-2346 + benomyl (0.55 kg/ha) were compared with a higher rate of benomyl (1.1 kg/ha) and commercial standards of oil (petroleum distillate FC-435-66 [70 to 93.5 liters/ha]) or oil (46.8 liters/ha) + copper sulfate (2.2 to 2.8 kg/ha). Fungicide efficacy was assessed using the area under the defoliation progress curve (AUDPC) and final defoliation in entire trees or final greasy spot severity in individual leaves. All fungicide treatments reduced the AUDPC, and all but benomyl reduced either final defoliation percentage or disease severity in individual leaves. CD-2346 and the reduced-rate combination of CD-2346 + benomyl were generally equal or superior to the full rate of benomyl in decreasing the AUDPC; CD-2346 + benomyl was equivalent to oil in reducing the AUDPC. Oil and CD-2346 treatments similarly reduced final defoliation, but oil + copper sulfate was superior to CD-2346 in reducing the AUDPC and final greasy spot defoliation or severity.

Evaluation of Application Methods of Metam Sodium for Management of Fusarium Crown and Root Rot in Tomato in Southwest Florida.

Experiments were conducted during 1992 to 1995 to evaluate the effectiveness of application methods of metam sodium (MS; sodium N-methyldithio-carbamate) for the management of Fusarium crown and root rot (FCRR) caused by Fusarium oxysporum f. sp. radicis-lycopersici in mulched and staked tomatoes (Lycopersicon esculentum Mill.) grown on raised beds in commercial fields in southwest Florida. Efficacy of MS was compared with soil-injection of methyl bromide-chloropicrin (MBC), the current industry practice for production of tomatoes in Flor-ida. The incidence of FCRR was consistently high in nontreated plots (80 to 100%), but disease severity varied by site, and yields were reduced by 10 to 57% at sites with high disease severity when compared to sites treated with MBC at 336 to 448 kg/ha. Application of MBC reduced FCRR incidence in all experiments. Chemigation with MS at 701 or 935 liters/ha into mulched beds using either one or two drip irrigation tubes placed on the soil surface, and soil injection of MS at 935 liters/ha, failed to reduce the disease. The application of MS at 935 liters/ha to the soil surface prior to bed formation produced variable results. Rotovation of MS at the same rate into preformed beds consistently produced reductions in the incidence of FCRR equivalent to those achieved by MBC.

Distribution of Xylella fastidiosa in Oaks in Florida and Its Association with Growth Decline in Quercus laevis.

A survey of more than 200 trees has documented the widespread occurrence of Xylella fastidiosa in Florida oak populations. The pathogen was detected readily via enzyme-linked immunosorbent assay in oaks exhibiting decline or leaf scorch symptoms and was infrequently detected in asymptomatic trees. It was also associated with reduced growth in Quercus laevis as measured by current-year shoot length. The occurrence of X. fastidiosa in Q. laevis and the evidence for its occurrence in Q. incana represent first reports for these oak hosts. The role of X. fastidiosa in oak decline scenarios deserves further attention.

Premature Fruit Drop in Saw Palmettos Caused by Colletotrichum gloeosporioides.

Saw palmetto (Serenoa repens) is a palm species that grows naturally in the southeastern coastal plain of the United States and is most abundant in Florida. Extracts from saw palmetto fruit are sold worldwide in pharmaceutical and dietary supplements in a market valued at $2 billion per year. Lesions on blossoms and fruit and premature fruit drop were first observed in 1996. In 1997, premature fruit drop resulted in 100% loss of fruit in saw palmetto in central and south Florida. In 1998, fruit loss was 8 to 59%. A fungus was consistently isolated from diseased saw palmetto spadices and fruit and identified as Colletotrichum gloeosporioides based on morphological, immunological, and genetic characteristics. Inoculation of spadices of container-produced saw palmettos with C. gloeosporioides resulted in similar disease symptoms and subsequent reisolation of the causal agent. The cross-infection potential of isolates was demonstrated by infection of other hosts. This is the first report of C. gloeosporioides causing disease on saw palmetto.

Effects of solarization and ammonium amendments on plant-parasitic nematodes.

The effects of soil solarization and ammonium bicarbonate or ammonium sulfate against plant-parasitic nematodes on yellow squash (Cucurbita pepo) and on vinca (Catharanthus roseus) were evaluated at two sites. Solarization for 3 weeks in the spring suppressed population levels of Belonolaimus longicaudatus, Criconemella spp., and Dolichodorus heterocephalus throughout the growing season on both crops at both sites. Levels of Meloidogyne incognita were suppressed initially, but population densities increased by the end of the crop in several cases. In one site, numbers of Paratrichodorus minor resurged following solarization to levels that were greater than those present in unsolarized control plots. The effect of solarization was not enhanced by combination with ammonium amendments, but, in one site, application of ammonium bicarbonate or ammonium sulfate resulted in lower numbers of B. longicaudatus than in the unamended control. Additional research and improved efficacy of candidate amendments are required before they can be successfully integrated with solarization for nematode management. Efficacy of solarization against plant-parasitic nematodes was achieved despite a relatively short (3 weeks) solarization period.

The independence of physical attractiveness and symptoms of depression in a female twin population.

The relationship between physical attractiveness and symptoms of depression was investigated in a general population simple of 1,100 female twins. Photographs were rated by 4 raters. Symptoms of depression were measured by the Depression sub-scale of the SCL-54, by a self-rating based on the DSM-III-R, and by an MD diagnosis based on a structured interview (SCID). No relationships between ratings of physical attractiveness and symptoms of depression were found.

Comparative validity of seven scoring systems for the instrumental activities of daily living scale in rural elders.

Lawton and Brody's eight-item Instrumental Activities of Daily Living (IADL) scale is used often with elderly patients but scored in several different ways. We scored the IADL with seven popular procedures ranging from relatively simple to complex (Guttman scores, summed and Rasch scores from dichotomous, trichotomous, and polytomous items) in a sample of rural elders (N = 231). We compared the IADL scales' prediction of concurrent cognitive functioning, depressive symptoms, psychosocial functioning, and health care use (medications, outpatient visits, inpatient days). Validity coefficients ranged from small to large among outcome variables but were highly consistent across IADL scoring procedures. Consequently, researchers and clinicians may prefer to use simpler IADL scoring procedures with this population.

The use of behavior modification with Alzheimer patients: values and limitations.

Behavior modification principles are described as they relate to patients with Alzheimer disease and related disorders. Sample cases are used to illustrate application of the principles to both an inpatient setting and a home setting. Values and limitations along with recommendations are suggested.