scholarly journals First Report of Charcoal Rot Epidemics Caused by Macrophomina phaseolina in Soybean in Iowa

Plant Disease ◽  
2005 ◽  
Vol 89 (5) ◽  
pp. 526-526 ◽  
Author(s):  
X. B. Yang ◽  
S. S. Navi
Keyword(s):  
Disease Incidence ◽  
Cropping System ◽  
Premature Death ◽  
Macrophomina Phaseolina ◽  
The United States ◽  
Reference Source ◽  
American Phytopathological Society ◽  
Charcoal Rot ◽  
Integrated Crop Management ◽  
Soybean Diseases

Macrophomina phaseolina, the causal agent of soybean charcoal rot, is widely present in soil and has been reported to cause yield losses of 30 to 50%, mainly in southern soybean production regions of the United States. (2). Charcoal rot was first reported in North Dakota during 2002, suggesting a range expansion for M. phaseolina (1). Charcoal rot has been occasionally observed in Iowa in individual soybean plants, but epidemics of the disease have not been recorded. During the 2003 growing season, a severe epidemic of charcoal rot was observed throughout the state. Diseased plants were first noticed in late July and by late August, patches of diseased plants wilted and died prematurely in many fields. The pith of diseased plants had a brown discoloration in taproots and lower stems. Symptoms were observed up to the 4th or 5th nodes, typical of charcoal rot. In some plants, no discoloration was evident. In discolored plants, microsclerotia of M. phaseolina were commonly observed in the epidermis, just beneath the epidermis, and inside taproots and lower stems of wilted plants. A systematic survey was conducted between late August and early September, 2003 to determine the prevalence and severity of charcoal rot in Iowa. The disease was observed in 60% of fields surveyed in northern Iowa (north of latitude 42.5°N), 90% in central Iowa (latitude 41.6 to 42.5°N), and 20% in southern Iowa (south of latitude 41.6°N). Incidence in surveyed fields ranged from 10 to 80%. One 80-ha field in Hampton (northern Iowa) had 50% disease incidence. An incidence of 80%, with extensive premature death prior to growth stage R6 (full seed), was observed in a 16-ha field east of Huxley (central Iowa). The fungus was isolated by splitting open the tap roots of a few representative symptomatic plants from 18 fields. Tissue colonized with microsclerotia of M. phaseolina was scraped, collected in sterile petri dishes, surface sterilized in 1% sodium hypochlorite, washed in distilled sterile water, and transferred to potato dextrose agar. The plates were incubated for 2 weeks at 22 ± 1°C on laboratory benches with a 12-h photoperiod. All resulting cultures produced abundant microscleorotia of M. phaseolina similar to those described by Smith and Wyllie (3). Pycnidia were observed in two cultures. August 2003 was the driest month on record in Iowa, which may have contributed to the outbreaks of this disease. Statewide, yield in Iowa soybean during 2003 was 1,976.1 kg/ha (2,798 kg/ha in 2002). The largescale epidemic of charcoal rot may have contributed to the overall reduction in soybean productivity in Iowa in 2003 (4). Since M. phaseolina also infects corn (2), and corn/soybean rotation is the most common cropping system in Iowa, efforts are needed to address the future risk of M. phaseolina to corn and soybean. References: (1) C. A. Bradley and L. E. del Rio. Plant Dis. 87:601, 2003. (2) D. C. McGee. Soybean Diseases: A Reference Source for Seed Technologists. The American Phytopathological Society, St. Paul, MN, 1992; (3) G. S. Smith and T. D. Wyllie. Charcoal rot. Pages 29–31 in: Compendium of Soybean Diseases. 4th ed. G. L. Hartman et al., eds. The American Phytopathological Society, St. Paul, MN, 1999. (4). X. B. Yang et al. Biology and management of soybean charcoal rot. Pages 55–60. in: Proc. 15th Integrated Crop Management Conf. Iowa State University, Ames. 2003.

scholarly journals Progress of soybean charcoal rot under tillage and no-tillage systems in Brazil

2003 ◽  
Vol 28 (2) ◽  
pp. 131-135 ◽  
Author(s):  
Álvaro M. R. Almeida ◽  
Lilian Amorim ◽  
Armando Bergamin Filho ◽  
Eleno Torres ◽  
José R. B. Farias ◽  
...  
Keyword(s):  
Cropping Systems ◽  
Disease Incidence ◽  
Cropping System ◽  
Macrophomina Phaseolina ◽  
Conventional System ◽  
Survival Times ◽  
Charcoal Rot ◽  
No Till ◽  
Four Seasons ◽  
Conventional Systems

The increase in incidence of charcoal rot caused by Macrophomina phaseolina on soybeans (Glycine max) was followed four seasons in conventional and no-till cropping systems. In the 1997/98 and 2000/01 seasons, total precipitation between sowing and harvest reached 876.3 and 846.9 mm, respectively. For these seasons, disease incidence did not differ significantly between the no-till and conventional systems. In 1998/99 and 1999/00 precipitation totaled 689.9 and 478.3 mm, respectively. In 1998/99, in the no-till system, the disease incidence was 43.7% and 53.1% in the conventional system. In 1999/00 the final incidence was 68.7% and 81.2% for the no-till and conventional systems, respectively. For these two seasons, precipitation was lower than that required for soybean crops (840 mm), and the averages of disease incidence were significantly higher in the conventional system. The concentration of microsclerotia in soil samples was higher in samples collected in conventional system at 0 - 10 cm depth. However, analysis of microsclerotia in roots showed that in years with adequate rain no difference was detected. In dry years, however, roots from plants developed under the conventional system had significantly more microsclerotia. Because of the wide host range of M. phaseolina and the long survival times of the microsclerotia, crop rotation would probably have little benefit in reducing charcoal rot. Under these study conditions it may be a better alternative to suppress charcoal rot by using the no-till cropping system to conserve soil moisture and reduce disease progress.

scholarly journals Occurrence of Charcoal Rot Caused by Macrophomina phaseolina on Canola in Argentina

Plant Disease ◽  
2006 ◽  
Vol 90 (4) ◽  
pp. 524-524 ◽  
Author(s):  
S. A. Gaetán ◽  
L. Fernandez ◽  
M. Madia
Keyword(s):  
United States ◽  
Buenos Aires ◽  
Vascular Tissue ◽  
Disease Incidence ◽  
Pathogenic Fungi ◽  
Macrophomina Phaseolina ◽  
The United States ◽  
Buenos Aires Province ◽  
Charcoal Rot ◽  
Experimental Plots

Canola (Brassica napus) is an important oleaginous crop in Argentina. Approximately 16,000 ha are grown commercially in the southern region of Buenos Aires Province. In 2003, typical symptoms and signs of charcoal rot were observed on canola plants in experimental plots located at the School of Agricultural Sciences, University of Buenos Aires in Buenos Aires. Average disease incidence across three 5- to 6-month-old plants (cvs. Monty, Rivette, and Trooper) was 12% (range = 7 to 17%). Affected plants appeared in patches following the rows at pod-filling stage. Symptoms included wilted foliage, premature senescence, and death of plants. Black, spherical microsclerotia 78 to 95 μm in diameter were present in vascular tissue of basal stems and taproots. The affected plants were stunted and had unfilled pods. In advanced phases of the disease, areas of silver gray-to-black discoloration were observed in the stem cortex; many plants were killed during late-grain fill, and plants could be pulled easily from the ground because basal stems were shredded. Four samples consisting of five symptomatic plants per sample were randomly collected from experimental plots. Pieces (1-cm long) taken from taproots and basal stems of diseased plants were surface sterilized with 1% NaOCl for 2 min and then placed on potato dextrose agar (PDA). Plates were incubated in the dark at 26°C for 4 days and then exposed to 12-h NUV light/12-h dark for 6 days. Five resulting isolates were identified as Macrophomina phaseolina (Tassi) Goidanich (1) based on the gray color of the colony and the presence of microsclerotia 71 to 94 μm in diameter. Two colonies developed globose pycnidia with one-celled, hyaline, and elliptic conidia. Pathogenicity tests were conducted using four inoculated and three non-inoculated control plants potted in a sterilized soil mix (soil/sand, 3:1) in a greenhouse at 25°C and 75% relative humidity with no supplemental light. Crown inoculations were carried out by placing a disk taken from an actively growing culture of M. phaseolina into wounds made with a sterile scalpel. Control plants received disks of sterile PDA. Inoculated and control plants were covered with polyethylene bags for 48 h after inoculation. Three isolates caused disease on 7-week-old canola plants (cvs. Master, Mistral, Rivette, and Trooper). Characteristic symptoms similar to the original observations developed for all three isolates within 21 days after inoculation on 80% of inoculated plants. The pathogen was successfully reisolated from diseased stem tissue in all instances. Symptoms included leaf necrosis, stunting, decay and collapse of seedlings, and plant death. Control plants remained asymptomatic. The experiment was repeated once with similar results. To our knowledge, this is the first report of the occurrence of M. phaseolina causing charcoal rot on canola in Argentina. This pathogen has been previously reported in the United States (2,3). The results demonstrate the potential importance of this pathogen in Argentina, since two commercial cultivars (Master and Mistral) were apparently susceptible to M. phaseolina. More studies are needed to determine the presence of charcoal rot in canola-growing areas of Argentina. References: (1) Anonymous. Macrophomina phaseolina. No. 275 in: Descriptions of Plant Pathogenic Fungi and Bacteria. CMI, Kew, Surrey, UK, 1970. (2) R. E. Baird et al. Plant Dis. 78:316, 1994. (3) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, St. Paul, MN, 1989.

scholarly journals Crown Rot of Strawberry Caused by Macrophomina phaseolina in California

Plant Disease ◽  
2008 ◽  
Vol 92 (8) ◽  
pp. 1253-1253 ◽  
Author(s):  
S. T. Koike
Keyword(s):  
Disease Incidence ◽  
Pathogenic Fungi ◽  
Macrophomina Phaseolina ◽  
The United States ◽  
Crown Rot ◽  
Charcoal Rot ◽  
Crown Tissue ◽  
Original Field ◽  
Rot Disease ◽  
Eventual Collapse

In 2006 and 2007, severely diseased strawberry (Fragaria × ananassa) plants were observed in five commercial fields in southern California (Orange County). Disease generally occurred in discrete patches. Within such patches, disease incidence ranged from 10 to 75%. Symptoms consisted of wilting of foliage, drying and death of older leaves, plant stunting, and eventual collapse and death of plants. When plant crowns were dissected, internal vascular and cortex tissues were dark brown to orange brown. Fruiting bodies or other fungal structures were not observed. A fungus was consistently isolated from symptomatic crown tissue that had been surface sterilized and placed on acidified corn meal agar (LA-CMA). All isolates produced numerous, dark, irregularly shaped sclerotia that were 67 to 170 μm long and 44 to 133 μm wide. When isolates were grown on 1.5% water agar with dried and sterilized wheat straw, dark, ostiolate pycnidia and hyaline, single-celled, cylindrical conidia were produced. On the basis of these characters, all isolates were identified as Macrophomina phaseolina (1). The symptomatic plants tested negative for Colletotrichum spp., Phytophthora spp., Verticillium dahliae, and other pathogens. Inoculum for pathogenicity tests was produced by growing six isolates on CMA on which sterilized wood toothpicks were placed on the agar surface. After 1 week, toothpicks were removed and inserted 4 to 5 mm deep into the basal crown tissue of potted strawberry plants (cv. Camarosa) grown in soilless, peatmoss-based rooting medium. Ten plants were inoculated per isolate and one toothpick was inserted per plant. Ten control strawberry plants were treated by inserting one sterile toothpick into each crown. All plants were then grown in a shadehouse. After 2 weeks, all inoculated plants began to show wilting and decline of foliage. By 4 weeks, all inoculated plants had collapsed. Internal crown tissue was discolored and similar in appearance to the original field plants. M. phaseolina was isolated from all inoculated plants. Control plants did not exhibit any disease symptoms, and crown tissue was symptomless. The test was repeated and the results were similar. While M. phaseolina has been periodically associated with strawberry in California (3), to my knowledge, this is the first report of charcoal rot disease on commercial strawberry in California. Charcoal rot of strawberry has been reported in Egypt, France, India, Israel, and the United States (Florida and Illinois) (2,4). Similar to previous reports (2,4), many of the affected California fields were not preplant fumigated with methyl bromide + chloropicrin fumigants, and it is possible that under these changing production practices this pathogen may increase in importance in California. References: (1) P. Holliday and E. Punithalingam. No. 275 in: Descriptions of Pathogenic Fungi and Bacteria. CMI, Kew, Surrey, UK, 1970. (2) J. Mertely et al. Plant Dis.89:434, 2005. (3) S. Wilhelm. Plant Dis. Rep. 41:941, 1957. (4) A. Zveibil and S. Freeman. Plant Dis. 89:1014, 2005.

scholarly journals First Report of Charcoal Rot (Macrophomina phaseolina) on Soybean in Minnesota

Plant Disease ◽  
2003 ◽  
Vol 87 (2) ◽  
pp. 202-202 ◽  
Author(s):  
M. E. ElAraby ◽  
J. E. Kurle ◽  
S. R. Stetina
Keyword(s):  
Vascular Tissue ◽  
Macrophomina Phaseolina ◽  
American Phytopathological Society ◽  
Charcoal Rot ◽  
Disease Survey ◽  
Glycine Max L ◽  
Colony Color ◽  
Soybean Plants ◽  
Soybean Diseases ◽  
Black Discoloration

In August 1999, soybean (Glycine max (L.) Merr.) plants exhibiting symptoms of charcoal rot were observed near Zumbrota, MN. Symptoms included shrunken, unfilled pods, and brown, wilted leaves attached to dead petioles and stems (1). When stems of symptomatic soybean plants were split, areas of gray-to-black discoloration where present in the stem cortex (1). Black, spherical microsclerotia 77 to 90 µm in diameter and elongated microsclerotia 77 to 120 µm long (1) were found in vascular tissue. Stem tissue placed on potato dextrose agar (PDA) yielded fungal colonies identified as Macrophomina phaseolina (Tassi) Goid. based on gray colony color, colony morphology, and the presence of microsclerotia 70 to 90 µm in diameter. In 2000, M. phaseolina was isolated from plant samples gathered from 11 of 90 fields sampled in a statewide soybean disease survey. More studies are needed to determine the distribution of charcoal rot in Minnesota; however, the occurrence of symptoms at one location and the presence of M. phaseolina in soybean-growing areas of Minnesota suggest that charcoal rot may occur in susceptible soybean cultivars under favorable environmental conditions. Reference: (1) G. S. Smith and T. D. Wyllie. Charcoal rot. Pages 29–30 in: Compendium of Soybean Diseases, 4th ed. G. L. Hartmann, J. B. Sinclair, and J. C. Rupe, eds. The American Phytopathological Society, St. Paul, MN, 1999.

scholarly journals Potential Bacterial Antagonists for the Control of Charcoal Rot (Macrophomina phaseolina) in Strawberry

Horticulturae ◽  
2021 ◽  
Vol 7 (11) ◽  
pp. 457
Author(s):  
Josefina Viejobueno ◽  
Natalia Rodríguez-Berbel ◽  
Luis Miranda ◽  
Berta de los Santos ◽  
María Camacho
Keyword(s):  
Disease Incidence ◽  
Hydrolytic Enzymes ◽  
Macrophomina Phaseolina ◽  
Field Trials ◽  
Dry Mass ◽  
Dual Culture ◽  
Plant Mortality ◽  
Charcoal Rot ◽  
Rdna Sequencing

The effect of antagonistic bacteria to control Macrophomina phaseolina was evaluated under in vitro, growth chamber, greenhouse and field conditions. A total of 177 bacteria, isolated from Athrocaulon macrostachyum rhizosphere of the Lebrija marsh, were screened for their potential against M. phaseolina (causes charcoal rot in strawberry) by dual culture assay. Of these isolates, 14 most promising strains were molecularly identified by the 16S rDNA sequencing method using the EzBioCloud database. These strains were tested for in vitro hydrolytic enzymes, HCN production, and biocontrol against M. phaseolina in strawberry plants. All the 14 strains produced, at least, one hydrolytic enzymatic activity and one of them, which belongs to Brevibacterium genus (Hvs8), showed the lowest records of disease incidence (20%) and severity (0.4). With these results, greenhouse and field trials were carried out with the Hvs8 strain, compared to non-treated control. In the greenhouse assays, Hvs8 strain increased root dry mass by 30%, over the control. In the field trials, production and fruit quality were not significantly different between Hvs8 treatment and non-treated control, but plant mortality and plant mortality associated to M. phaseolina decreased by more than 24% and 65% respectively, in Hvs8 treatment. This study suggests that Brevibacterium sp. Hvs8 strain could be a candidate for controlling charcoal rot in strawberry.

scholarly journals EXPLOITATION OF NEW CHEMISTRY FUNGICIDES AGAINST CHARCOAL ROT OF SESAME CAUSED BY MACROPHOMINA PHASIOLINA IN PAKISTAN

2017 ◽  
Vol 29 (2) ◽  
pp. 257 ◽  
Author(s):  
Muhammad R. Bashir ◽  
Abid Mehmood ◽  
Muhammad Sajid ◽  
Muhammad A. Zeshan ◽  
Muhammad Mohsin ◽  
...  
Keyword(s):  
Disease Incidence ◽  
Block Design ◽  
Macrophomina Phaseolina ◽  
Colony Growth ◽  
Field Conditions ◽  
Charcoal Rot ◽  
Randomized Design ◽  
Randomized Complete Block Design ◽  
And Control ◽  
Fungal Colony

The current research was conducted to find out the most appropriate concentrations of six fungicides for the management of sesame charcoal rot caused by Macrophomina phaseolina under lab and field conditions. The treatments viz. Antracol, Topsin-M, Mancozeb, Score, Topas, Nativo and Control with concentrations of 150, 250 and 350ppm were used with three replications under completely randomized design and randomized complete block design in Lab. and field conditions respectively. The mean colony growth of all treatments expressed that Nativo exhibited minimum colony growth of (0.93 cm) as compared to Score (1.14 cm), Topsin-M (1.42 cm), Mancozeb (1.77 cm), Antracol (2.04 cm), Topass (2.33 cm) correspondingly. The interaction between treatments and concentrations (T×C) showed that  used concentrations 150 ppm, 250 ppm and 350 ppm of Nativo abundantly inhibit fungal colony growth upto 1.26 cm, 0.86 cm and 0.66 cm respectively whereas the interaction between treatments and days expressed that after day ninth the minimum colony growth (1.23 cm) was observed for Nativo as compared to all other treatments. Similarly, the interaction between concentrations and days expressed highest fungal colony growth at concentration 150 ppm on day third (2.06 cm), sixth (3.02 cm) and ninth (3.65 cm) but the interaction of treatments, days and concentrations expressed that at 150 ppm concentration, all treatments exhibited minimum colony growth (1.70 to 3.30) cm at third, sixth and ninth day as compared to 250 and 350 ppm concentration respectively with respect to control (6.90 cm). In filed conditions, Nativo exhibited minimum Mean Disease Incidence (12.55%) whereas the interaction between treatments and days showed minimum of 14.95%, 12.82% and 9.90% disease incidence by Nativo as compared to all other treatments including control (66.86%, 77.57% and 87.22%) after day tenth, twenty and thirty. It was concluded that Nativo is significantly inhibiting the colony growth under lab and filed conditions.

scholarly journals Soybean Yield Loss Estimates Due to Diseases in the United States and Ontario, Canada, from 2010 to 2014

2017 ◽  
Vol 18 (1) ◽  
pp. 19-27 ◽  
Author(s):  
Tom W. Allen ◽  
Carl A. Bradley ◽  
Adam J. Sisson ◽  
Emmanuel Byamukama ◽  
Martin I. Chilvers ◽  
...  
Keyword(s):  
United States ◽  
Soybean Cyst Nematode ◽  
Yield Loss ◽  
Research Policy ◽  
Economic Loss ◽  
Macrophomina Phaseolina ◽  
The United States ◽  
Yield Losses ◽  
Soybean Yield ◽  
Soybean Diseases

Annual decreases in soybean (Glycine max L. Merrill) yield caused by diseases were estimated by surveying university-affiliated plant pathologists in 28 soybean-producing states in the United States and in Ontario, Canada, from 2010 through 2014. Estimated yield losses from each disease varied greatly by state or province and year. Over the duration of this survey, soybean cyst nematode (SCN) (Heterodera glycines Ichinohe) was estimated to have caused more than twice as much yield loss than any other disease. Seedling diseases (caused by various pathogens), charcoal rot (caused by Macrophomina phaseolina (Tassi) Goid), and sudden death syndrome (SDS) (caused by Fusarium virguliforme O’Donnell & T. Aoki) caused the next greatest estimated yield losses, in descending order. The estimated mean economic loss due to all soybean diseases, averaged across U.S. states and Ontario from 2010 to 2014, was $60.66 USD per acre. Results from this survey will provide scientists, breeders, governments, and educators with soybean yield-loss estimates to help inform and prioritize research, policy, and educational efforts in soybean pathology and disease management.

scholarly journals Effect of Formulations of Allyl Isothiocyanate on Survival of Macrophomina phaseolina from Strawberry

Plant Disease ◽  
2018 ◽  
Vol 102 (11) ◽  
pp. 2212-2219 ◽  
Author(s):  
Juliana S. Baggio ◽  
Manuel Chamorro ◽  
Leandro G. Cordova ◽  
Joseph W. Noling ◽  
Gary E. Vallad ◽  
...  
Keyword(s):  
Production Systems ◽  
Allyl Isothiocyanate ◽  
Macrophomina Phaseolina ◽  
The United States ◽  
Organic Production ◽  
Soilborne Pathogens ◽  
Corn Cob ◽  
Charcoal Rot ◽  
Phase Out ◽  
Research Facilities

Management of Macrophomina phaseolina, causal agent of charcoal rot in many crops worldwide, including strawberry, has become more challenging since the phase out of methyl bromide (MeBr). The search for a fumigant equally effective as MeBr to control soilborne pathogens has been extensive. Allyl isothiocyanate (AITC), a biofumigant recently registered in the United States, was evaluated at different rates, formulations, fumigant combinations, and application methods in the fall of 2014 and 2015 at two research facilities in Balm and Dover, FL. The efficacy of treatments was determined by evaluating the survival of M. phaseolina inoculum on infested corn-cob litter buried in bags 7.6 and 20.3 cm deep in the center, and 7.6 cm deep in the side, of plastic mulched raised beds. The biofumigant was shown to be more or as effective in reducing populations of M. phaseolina in the soil compared with standard fumigants, such as chloropicrin and 1,3-dichloropropene with chloropicrin. Thus, AITC is a promising biofumigant alternative for managing charcoal rot of strawberry, particularly in organic production systems, and should be evaluated for the management of other soilborne pathogens.

scholarly journals First Report of Macrophomina phaseolina Causing a Crown Rot of Strawberry in Florida

Plant Disease ◽  
2005 ◽  
Vol 89 (4) ◽  
pp. 434-434 ◽  
Author(s):  
J. Mertely ◽  
T. Seijo ◽  
N. Peres
Keyword(s):  
Methyl Bromide ◽  
Block Design ◽  
Vascular Ring ◽  
Macrophomina Phaseolina ◽  
Crown Rot ◽  
American Phytopathological Society ◽  
Charcoal Rot ◽  
Isolation Medium ◽  
Potato Dextrose Broth ◽  
First Report

Strawberry (Fragaria × ananassa Duchesne) is produced as an annual winter crop in raised, plastic-mulched beds on 2,800 ha in west central Florida. In December 2001, a grower submitted collapsed and dying strawberry plants from a commercial field to the University of Florida in Dover. The cut crowns of affected plants revealed dark brown necrotic areas on the margins and along the woody vascular ring. Macrophomina phaseolina was isolated from pieces of infected tissue cut aseptically from the crowns and placed on a medium containing 12 g of Difco potato dextrose broth, 17 g of Bacto agar, 250 mg of ampicillin, and 100 mg of streptomycin sulfate per liter of water. The fungus produced numerous, dark, oblong sclerotia in the isolation medium after 4 to 5 days incubation at 24°C under constant fluorescent lighting. In 10-day-old cultures, sclerotia ranged in size from 55 to 190 μm long by 50 to 135 μm wide (average 105 × 74 μm). Ostiolate pycnidia bearing relatively large, broadly ellipsoidal, hyaline conidia occasionally developed on the host tissue after 8 to 10 days of incubation (2). During the 2003-2004 season, M. phaseolina was isolated from dying strawberry plants taken from the original field and two additional farms. Affected plants were often found along field margins or other areas inadequately fumigated with methyl bromide. Two single-spore isolates from different fields were tested for pathogenicity on nursery runner plants (cv. Strawberry Festival) grown for 4 weeks in the greenhouse on artificial potting soil. The fungal isolates were grown on corn meal agar at 24°C for 4 days and allowed to colonize sterile wooden toothpicks placed on the medium for an additional 5 days. Prior to use, the toothpicks were sterilized by autoclaving twice in deionized water and a third time in V8 juice. Six plants were inoculated with each isolate by inserting a colonized toothpick into each crown. Sterile, V8-infused toothpicks were inserted into the crowns of corresponding control plants. The plants were incubated in a greenhouse in a randomized complete block design with two replicates of three plants each. After 3 days, 33 to 100% of the inoculated plants developed wilting in one or more leaves. All inoculated plants collapsed or died within 2 weeks of inoculation, while the control plants remained healthy during the observation period. The pathogen was readily reisolated from inoculated plants. Charcoal rot disease caused by M. phaseolina has been reported on strawberry in France, India, and Illinois (2,3). To our knowledge, this is the first report from Florida. M. phaseolina may be an emerging threat as the Florida strawberry industry transitions from methyl bromide to other fumigants in 2005. References: (1) J. Maas. Macrophomina leaf blight and dry crown rot. Page 26 in: Compendium of Strawberry Diseases. 2nd ed. J. L. Maas, ed. The American Phytopathological Society, St. Paul, MN, 1998. (2) G. S. Smith and T. D. Wyllie. Charcoal rot. Pages 29–31 in: Compendium of Soybean Diseases. G. L. Hartman et al., eds. 4th ed. The American Phytopathological Society, St. Paul, MN. 1999. (3) B. Tweedy et al. Plant Dis. Rep. 42:107, 1958.

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