scholarly journals First Report of Koch's Postulates Completion of Sudden Death Syndrome of Soybean in Argentina

Plant Disease ◽  
2003 ◽  
Vol 87 (4) ◽  
pp. 447-447 ◽  
Author(s):  
M. Scandiani ◽  
D. Ruberti ◽  
R. Pioli ◽  
A. Luque ◽  
L. Giorda
Keyword(s):  
Sudden Death ◽  
Fusarium Solani ◽  
Colony Growth ◽  
Positive Control ◽  
Sudden Death Syndrome ◽  
Symptom Development ◽  
Koch’S Postulates ◽  
Interveinal Chlorosis ◽  
Soil Infestation ◽  
Koch's Postulates

Foliage symptoms on soybean resembling those of sudden death syndrome were detected in Argentina during 1991 and 1992 in the Pampas Region and during 1992 and 1993 in the Northwest Region. Isolations were made in 1999, 2000, and 2001 from soybean plants (Glycine max (L.) Merr.) showing these symptoms. Five isolates of fungi obtained from taproot tissue and blue sporulation on taproot exteriors were selected for further evaluation. These isolates were plated on potato dextrose agar supplemented with streptomycin (PDAS). Based on the spore morphology, colony growth rate, morphology and pigmentation on PDAS, and lack of microconidia (1) five isolates were identified as Fusarium solani f. sp. glycines. Soybean cvs. Ripley, Spencer, Pioneer 9492RR, and A6445 RG were inoculated in greenhouse tests with each of the isolates using toothpick and soil infestation methods for a total of six experiments. Isolate 171 provided by J. Rupe (University of Arkansas, Fayetteville) was tested as a positive control. Foliar symptoms typical of sudden death syndrome and similar to those in the field were observed 14 and 25 days, respectively, after inoculations using the toothpick and soil infestation methods. Lesions produced on leaves averaged 3.6 for all five isolates and 4 for the reference strain using a disease severity scale where: 1 = no symptoms; 2 = slight symptom development with mottling and mosaic on leaves (1 to 20% foliage affected); 3 = moderate symptom development with interveinal chlorosis and necrosis on foliage (21 to 50% foliage affected); 4 = heavy symptom development with interveinal chlorosis and necrosis (51 to 80% foliage affected); and 5 = severe interveinal chlorosis and necrosis (81 to 100% foliage affected). Noninoculated controls were symptomless. Differences in virulence were observed among the isolates. Based on disease symptoms in the greenhouse and cultural morphology on PDAS, the isolates were classified as Fusarium solani f. sp. glycines. Isolates recovered from symptomatic plants resembled Fusarium solani f. sp. glycines on PDAS and peptone/p-chloro-nitrobenzene agar amended with streptomycin, confirming Koch's postulates. Fusarium solani f. sp. glycines was recovered from 60% of inoculated plants. Reference: (1) K. W. Roy et al. Plant Dis. 81:1100,1997.

scholarly journals First Report and Confirmed Distribution of Soybean Sudden Death Syndrome Caused by Fusarium virguliforme in Southern Michigan

Plant Disease ◽  
2010 ◽  
Vol 94 (9) ◽  
pp. 1164-1164 ◽  
Author(s):  
M. I. Chilvers ◽  
D. E. Brown-Rytlewski
Keyword(s):  
Sudden Death ◽  
Root Rot ◽  
Field Trial ◽  
The United States ◽  
Sudden Death Syndrome ◽  
Fusarium Virguliforme ◽  
Koch’S Postulates ◽  
Interveinal Chlorosis ◽  
Koch's Postulates ◽  
Β Tubulin

Leaf lesions and root rot symptoms typical of soybean sudden death syndrome (SDS) caused by Fusarium virguliforme O'Donnell & T. Aoki were observed in commercial soybeans (Glycine max (L.) Merr.) in southern Michigan. Leaf symptoms ranged from chlorotic spots to severe interveinal chlorosis and necrosis, no foliar pathogens were noted. In 2008, isolates were collected from Berrien and St. Joseph counties. In 2009, isolates were collected from Cass, St. Joseph, Van Buren, Allegan, and Monroe counties. Pieces of roots with root rot symptoms were washed prior to surface disinfestation with 70% ethanol for 30 s and 0.5% NaOCl for 1 min and incubated on water agar (WA) in petri plates amended with 50 μg/ml of chloramphenicol for the production of sporodochia. Alternatively, spores were collected directly from nondisinfested roots expressing blue sporodochia. Single-spore cultures were derived by streaking macroconidia with a bacterial loop onto 3% WA + chloramphenicol and incubated overnight. With a dissecting microscope, single germinated macroconidia were collected with a sterile 0.2-mm-diameter insect pin and transferred to potato dextrose agar (PDA). Cultures on PDA grew slowly and developed blue-to-purple masses of sporodochia typical of F. virguliforme descriptions and similar to a representative isolate, Mont-1, grown alongside (1,2). Size of macroconidia from the six representative isolates, one from each county (including isolates derived from surface-disinfested and nondisinfested roots), and Mont-1 were determined to be within the range for F. virguliforme (42 to 56 × 5 to 6 μm), with an average of four septa per macroconidia. Identity of the representative isolates was confirmed by partial DNA sequencing of both strands of the internal transcribed spacer (ITS) region of the ribosomal RNA gene, translation elongation factor 1-α, and β-tubulin loci. All six representative isolates were identical in each of the three loci and matched with 100% similarity F. virguliforme accessions in GenBank and Fusarium-ID database searches, except for the β-tubulin locus in which a single nucleotide insertion was noted (Accession Nos. HM453328–HM453330). Sequences were 98 to 99% similar to other SDS Fusarium spp. not yet recorded in the United States. Koch's postulates were performed in the greenhouse according to Malvick and Bussey (3). Infested sorghum seed (~20 g) was placed 2 cm below soybean seed of susceptible cv. Williams 82 in plastic pots. Noninfested sorghum seed was used as a negative control and sorghum infested with Mont-1 as a positive control. Chlorotic spots developed 2 weeks after establishing the trial, and 3 to 4 weeks postinoculation, severe SDS symptoms of foliar interveinal chlorosis and necrosis and severe root rot developed. Koch's postulates were completed by reisolating F. virguliforme from a subset of infected plants. In addition, an isolate of F. virguliforme collected in 2008 was used to inoculate a 2009 field trial in East Lansing, MI with no history of SDS. Typical SDS symptoms developed in the field trial and F. virguliforme was isolated from a symptomatic plant that was identified as described above. Despite being reported across the majority of soybean-producing states, to our knowledge, this is the first confirmation and distribution report for SDS in Michigan. References: (1) T. Aoki et al. Mycoscience 46:162, 2005. (2) G. L. Hartman et al. Plant Dis. 81:515, 1997. (3) D. K. Malvick and K. E. Bussey. Can. J. Plant Pathol. 30:467, 2008.

scholarly journals Recent Outbreak of Soybean Sudden Death Syndrome Caused by Fusarium virguliforme and F. tucumaniae in Argentina

Plant Disease ◽  
2004 ◽  
Vol 88 (9) ◽  
pp. 1044-1044 ◽  
Author(s):  
M. Scandiani ◽  
D. Ruberti ◽  
K. O'Donnell ◽  
T. Aoki ◽  
R. Pioli ◽  
...  
Keyword(s):  
United States ◽  
Phylogenetic Analyses ◽  
The United States ◽  
Positive Control ◽  
Koch’S Postulates ◽  
First Report ◽  
Molecular Phylogenetic ◽  
Soil Infestation ◽  
Pathogenicity Tests ◽  
Koch's Postulates

Sudden death syndrome (SDS) of soybean was detected initially in Argentina during 1991-1992 in the Pampas Region and 1992-1993 in the Northwest Region. The first report of the fulfillment of Koch's postulates of SDS caused by Fusarium solani f. sp. glycines in Argentina was published in 2003 (3). Subsequently, analyses have shown that F. solani f. sp. glycines represents several morphologically and phylogenetically distinct species, including F. tucumaniae in Argentina and F. virguliforme in the United States (1). Isolations were made from plants that exhibited typical SDS symptoms (interveinal foliar chlorosis and necrosis leading to defoliation of the leaflets but not the petioles) from fields in Santa Fe and Buenos Aires provinces in 2001, 2002, and 2003. To determine which species are responsible for SDS in Argentina, cultures of eight slow growing isolates that developed bluish pigmentation and produced abundant macroconidia in sporodochia on potato dextrose agar were subjected to morphological and molecular phylogenetic analyses and pathogenicity tests. Morphological analyses demonstrated that three of the isolates were F. virguliforme and five were F. tucumaniae. Isolates of F. tucumaniae produced long and narrow sporodochial conidia while F. virguliforme produced diagnostic comma-shaped conidia. Molecular phylogenetic analyses of DNA sequences from multiple loci confirmed morphology-based identifications and showed that the soybean SDS pathogen in the United States, F. virguliforme, was also present in Argentina. To our knowledge, this is the first report of F. virguliforme in Argentina and of this pathogen outside the United States. Five isolates of F. tucumaniae and three isolates of F. virguliforme were used for pathogenicity tests. F. virguliforme isolate 171 provided by J. Rupe (University of Arkansas, Fayetteville) was used as a positive control. Soybean cultivars Ripley, RA 702, Pioneer 9492RR, Spencer, and A-6445RG were inoculated with each of the isolates tested in a greenhouse assay using soil infestation and toothpick methods (2). All eight isolates produced typical foliar SDS symptoms 15 to 25 days after inoculation. Severity of foliar symptoms averaged 3.3 for F. virguliforme, 2.6 for F. tucumaniae, and 3.3 for the positive control using a disease severity scale in which 1 = no symptoms and 5 = severely infected or dead plants. Under these conditions, F. virguliforme appeared to be more virulent than F tucumaniae. Noninoculated plants remained symptomless. Koch's postulates were confirmed with soybean cultivars RA 702 and A6445RG. Isolates recovered from symptomatic plants inoculated by the soil infestation and toothpick methods were identical to those used to inoculate the plant. Strains were recovered at frequencies of 100 and 60% from plants inoculated by the toothpick and soil infestation methods, respectively. To our knowledge, this is the first report of the fulfillment of Koch's postulates for F. tucumaniae and F. virguliforme in Argentina. References: (1) T. Aoki et al. Mycologia 95:660, 2003. (2) K. W. Roy et al. Plant Dis. 81:1100, 1997 (3) M. Scandiani et al. Plant Dis. 87:447, 2003.

scholarly journals First Report of Sudden Death Syndrome of Soybean in Delaware and Eastern Shore of Maryland

Plant Disease ◽  
2002 ◽  
Vol 86 (6) ◽  
pp. 696-696 ◽  
Author(s):  
R. P. Mulrooney ◽  
N. Fisher Gregory ◽  
S. D. Walker ◽  
A.-M. Webster
Keyword(s):  
Sudden Death ◽  
Sudden Death Syndrome ◽  
Spore Morphology ◽  
Eastern Shore ◽  
Koch’S Postulates ◽  
First Report ◽  
Soil Line ◽  
Foliar Symptoms ◽  
Stem Lesions ◽  
Koch's Postulates

In August and September of 2000, soybean (Glycine max (L.) Merr.) plants from two fields in Sussex County, Delaware, and one field from Somerset County on the eastern shore of Maryland exhibited typical symptoms of sudden death syndrome. The season had been wetter and cooler than normal. Leaf symptoms ranged from small chlorotic spots to elongated regions of interveinal necrosis. Leaflets dropped leaving attached petioles in the upper canopy. Severely infected plants were easily pulled from the soil and had taproots with blue sporodochia, necrotic cortical tissue, and necrosis of secondary roots (2). Initial isolations from the infected plants were made from the basal stems, discolored taproots, vascular tissue, and directly from blue sporodochia. Sections were plated on water agar (WA) amended with neomycin and streptomycin, WA with antibiotics and chloramphenicol, and acidified potato dextrose agar (PDA). The isolates were slow growing on PDA, often staining agar dark maroon, produced little aerial mycelium, and formed macroconidia in blue sporodochia. The fungus was identified as Fusarium solani (Mart.) Sacc. based on spore morphology. Plugs (5 mm) of the fungus from 14-day-old cultures were placed next to the stem just below the soil line of 14-day-old plants of soybean cvs. Essex and Lee 74. Eighteen plants of each cultivar (three per pot) were inoculated and placed on a greenhouse bench for 43 days at 21°C (±2°C). Six noninoculated control plants were also included. Plants were rated for the presence of stem lesions and foliar symptoms. Of the inoculated plants, 70% had mottling, rugosity, and leaf cupping, 6% had severe interveinal leaf necrosis, and 52% had distinct stem lesions at the soil line. Control plants were symptomless. F. solani was recovered from all symptomatic plants and presumed to be F. solani f. sp. glycines based on spore morphology, color, lack of microconidia, and symptoms (1). A more extensive test was conducted to confirm Koch's postulates. Eleven isolates of F. solani f. sp. glycines were grown as before and used to inoculate Essex soybeans as previously described. Inoculated and control plants were randomized on the greenhouse bench and watered using an individual pot irrigation system. Fifty-six days after inoculation plant height was reduced 12% compared with the noninoculated controls. Lesions produced on the lower stem and taproot of the inoculated plants averaged 4.5 cm long. Most plants had mild foliar symptoms that included mottling, rugosity, and leaf cupping. Only three plants had severe foliage symptoms. F. solani f. sp. glycines was recovered from 56% of inoculated plants, completing Koch's postulates for all 11 isolates. Noninoculated controls were symptomless. Sudden death syndrome was not observed in 2001. Soybean is an important crop in the region; 250,000 ha were harvested in 2000 on the Delmarva Peninsula, which includes the three counties of Delaware, nine eastern shore counties of Maryland, and two counties of Virginia. Sudden death syndrome could be a serious threat to profitable soybean production. To our knowledge, this is the first report of sudden death syndrome from this area and represents the most eastern occurrence of this disease reported in the United States. References: (1) K. W. Roy. Plant Dis. 81:259, 1997. (2) K. W. Roy et al. Plant Dis. 81:1100, 1997.

scholarly journals First Report of Sudden Death Syndrome Caused by Fusarium solani f. sp. glycines on Soybean in Pennsylvania

Plant Disease ◽  
1999 ◽  
Vol 83 (9) ◽  
pp. 879-879 ◽  
Author(s):  
B. W. Pennypacker
Keyword(s):  
Sudden Death ◽  
Fusarium Solani ◽  
Sudden Death Syndrome ◽  
Leaf Abscission ◽  
Interveinal Chlorosis ◽  
Foliar Symptoms ◽  
Fungus Gnats ◽  
Significant Difference ◽  
Rating Method ◽  
Soybean Plants

A small, circular patch of soybean (Glycine max) showing symptoms consistent with sudden death syndrome (SDS) (2) was noted on July 25, 1998, in a producer's field in Jersey Shore, PA. Foliar symptoms included interveinal chlorosis and necrosis, leaf cupping, and leaf abscission. The vascular cylinder of roots and stems had areas of reddish-brown discoloration. A slow-growing Fusarium sp., which produced a bluish-purple color on potato dextrose agar, was isolated from the roots of several symptomatic plants. The fungus was identified as Fusarium solani by The Fusarium Research Center, The Pennsylvania State University. Koch's postulates were tested on soybean cultivars A2506, Stine 3171, Pioneer 9305 and 9306, and Jack. Five plants per cultivar were inoculated at growth stage V1 by pouring 35 ml of a 4 × 107 spores per ml suspension on the growth mix in each pot. Five plants per cultivar were treated similarly with sterile water. Foliar symptoms of SDS began to appear 3 weeks after inoculation. Seven weeks after inoculation, symptoms of interveinal chlorosis and/or necrosis, leaf cupping, and occasional leaf abscission were apparent on the inoculated plants and on several noninoculated plants. The percentage of the plant showing symptoms was recorded and converted to the 0 to 5 scale (in which 0 = 0%, 1 = 1–10%, 2 = 11–30%, 3 = 31–40%, 4 = 41–90%, and 5= 91–100% of the leaf area affected) used by Rupe (3). Regardless of the rating method, there was a significant difference (P = 0.0001) between inoculated and noninoculated plants. There were no significant differences among cultivars. Roots of the inoculated plants were frequently discolored, in contrast to those of the noninoculated plants. F. solani was isolated from the roots of 97% of the inoculated plants and 23% of the noninoculated plants. Fungus gnats were suspected of spreading the pathogen to the noninoculated plants (1). F. solani f. sp. glycines causes SDS in soybean and its identity is confirmed by the symptoms produced on soybean (2). The symptoms produced when soybean plants were inoculated in the greenhouse were consistent with those of SDS (2) and indicate that the F. solani isolate recovered from symptomatic plants in the field was F. solani f. sp. glycines. This is the first documented occurrence of SDS on soybean in Pennsylvania. References: (1) D. W. Kalb and R. L. Millar. Plant Dis. 70:752, 1986. (2) K. W. Roy et al. Plant Dis. 81:1100, 1997. (3) J. C. Rupe. Plant Dis. 73:581, 1989.

scholarly journals First Report of Sudden Death Syndrome (Fusarium solani f. sp. glycines) of Soybean in Minnesota

Plant Disease ◽  
2003 ◽  
Vol 87 (4) ◽  
pp. 449-449 ◽  
Author(s):  
J. E. Kurle ◽  
S. L. Gould ◽  
S. M. Lewandowski ◽  
S. Li ◽  
X. B. Yang
Keyword(s):  
Sudden Death ◽  
Fusarium Solani ◽  
Growth Stage ◽  
Soybean Seed ◽  
Sudden Death Syndrome ◽  
South Central ◽  
Soil Temperatures ◽  
Glycine Max L ◽  
Pathogenicity Tests ◽  
Soybean Plants

In August 2002, soybean (Glycine max (L.) Merr.) plants exhibiting foliar and root symptoms typical of sudden death syndrome were observed in Blue Earth and Steele counties in south-central Minnesota. Leaf symptoms ranging from small chlorotic spots to prominent interveinal necrosis were present on soybean plants at the R6 to R7 growth stage. As plants matured, complete defoliation took place with only petioles remaining. Symptomatic plants had necrotic secondary roots, truncated taproots, and discolored cortical tissue at the soil line. Blue sporodochia containing macroconidia were observed on the taproot of affected plants at both locations (3,4). Multiple cultures from both locations were obtained by transferring macroconidia from the sporodochia to potato dextrose agar (PDA) and modified Nash-Snyder Medium (NSM) (3). After 14 days, isolations were made from fungal colonies exhibiting bluish pigmentation and masses of bluish macroconidia (4). The isolates grew slowly, developed a bluish color, and formed sporodochia containing abundant macroconidia on NSM. These isolates were identified as Fusarium solani (Mart.) Sacc. f. sp. glycines based on colony characteristics and morphology of macroconidia (2). Pathogenicity tests were conducted with a single isolate from each location. The isolate from Blue Earth County was inoculated as mycelia in a plug of media onto taproots of plants of susceptible cvs. Williams 82 and Spencer at the V2 growth stage. Chlorotic spots appeared on leaves after 12 days of growth at 22 to 25°C in the greenhouse. Interveinal necrosis appeared after 15 days (4). The isolate from Steele County was used to inoculate the susceptible cv. Great Lakes 3202. Sorghum seed (3 cm3) infested with mycelia of the isolate were placed 2 to 3 cm below soybean seed planted in Cone-Tainers. Noninfested sorghum seed was used as a control. Plants were maintained for 21 days at 22 to 28°C in the greenhouse. Chlorotic spots appeared on leaves of inoculated plants within 21 days after planting followed by the development of interveinal chlorosis and necrosis (1). Molecular analysis further supported the identification of the Steele County isolate as F. solani f. sp. glycines. Polymerase chain reaction with specific primers Fsg1 and Fsg2 of total genomic DNA extracted from the Steele County isolate amplified a 438-bp DNA fragment identical with that extracted from previously identified isolates of F. solani f. sp. glycines (1). In 2002, symptoms of sudden death syndrome were also reported in Olmsted, Freeborn, and Mower counties. Although studies are needed to determine the distribution of sudden death syndrome in the state, the occurrence of the symptoms at multiple locations suggests that F. solani f. sp. glycines is widely distributed in southeast and south-central Minnesota. The counties where sudden death syndrome symptoms were reported are located in the most productive soybean-growing region of Minnesota. Sudden death syndrome could be a serious threat to soybean production in this area since poorly drained, heavy, clay soils are common, and soil temperatures 18°C or less are normal before the end of May. References: (1) S. Li et al. Phytopathology 90:491, 2000. (2) K. W. Roy. Plant Dis. 81:566, 1997. (3) K. W. Roy et al. Plant Dis. 81:1100, 1997. (4) K. W. Roy. Plant Dis. 81:259, 1997.

Resistance to Soybean Sudden Death Syndrome and Root Colonization by Fusarium solani f. sp. glycine in Near‐Isogenic Lines

Crop Science ◽  
1998 ◽  
Vol 38 (2) ◽  
pp. 472-477 ◽  
Author(s):  
V. N. Njiti ◽  
T. W. Doubler ◽  
R. J. Suttner ◽  
L. E. Gray ◽  
P. T. Gibson ◽  
...  
Keyword(s):  
Sudden Death ◽  
Fusarium Solani ◽  
Root Colonization ◽  
Sudden Death Syndrome ◽  
Near Isogenic Lines ◽  
Isogenic Lines

Fusarium Solani from Ascospores of Nectria Haematococca Causes Sudden Death Syndrome of Soybean

Mycologia ◽  
1993 ◽  
Vol 85 (5) ◽  
pp. 801-806 ◽  
Author(s):  
T. S. Abney ◽  
T. L. Richards ◽  
K. W. Roy
Keyword(s):  
Sudden Death ◽  
Fusarium Solani ◽  
Sudden Death Syndrome ◽  
Nectria Haematococca

scholarly journals Characterizing the Effect of Foliar Lipo-chitooligosaccharide Application on Sudden Death Syndrome and Sclerotinia Stem Rot in Soybean

2018 ◽  
Vol 19 (1) ◽  
pp. 46-53 ◽  
Author(s):  
David A. Marburger ◽  
Jaime F. Willbur ◽  
Maria E. Weber ◽  
Jean-Michel Ané ◽  
Medhi Kabbage ◽  
...  
Keyword(s):  
Sudden Death ◽  
Plant Root ◽  
Sudden Death Syndrome ◽  
Stem Rot ◽  
Signal Molecules ◽  
Symptom Development ◽  
Sclerotinia Stem Rot ◽  
Water Control ◽  
Fusarium Virguliforme ◽  
Glycine Max L

Lipo-chitooligosaccharides (LCOs) are signal molecules produced by plant root endosymbionts and have been identified, formulated, and marketed as growth-promoting adjuvants for soybean (Glycine max [L.] Merr.). Experiments were conducted under controlled environmental conditions to characterize the effects of foliar LCO applications on early symptom development of sudden death syndrome (SDS), caused by Fusarium virguliforme, and Sclerotinia stem rot (SSR), caused by Sclerotinia sclerotiorum. Treatment factors for the SDS experiment included two soybean cultivars (Sloan and CH2105R2), two inoculation levels (noninoculated control and inoculated), and two LCO applications (control and foliar LCO application), whereas two experimental soybean lines (91-38 and 91-44) and two LCO applications (water control and foliar LCO application) were used in the SSR experiment. The LCO application did not significantly influence SDS root symptom severity or early-season growth characteristics. However, on the susceptible line (P = 0.01) and with LCO application (P = 0.03), significantly larger SSR lesions developed compared with the nontreated control and resistant line. These results suggest foliar-applied LCOs have a limited effect on early root symptom development caused by F. virguliforme but increase stem symptom development caused by S. sclerotiorum.

scholarly journals Evidence that Xylella fastidiosa Can Cause Leaf Scorch Disease of Pecan

Plant Disease ◽  
2000 ◽  
Vol 84 (12) ◽  
pp. 1282-1286 ◽  
Author(s):  
R. S. Sanderlin ◽  
K. I. Heyderich-Alger
Keyword(s):  
Xylella Fastidiosa ◽  
Carya Illinoinensis ◽  
Symptom Development ◽  
Koch’S Postulates ◽  
Leaf Scorch ◽  
Symptomatic Tissue ◽  
Koch's Postulates ◽  
Bacterial Leaf Scorch

The disease known as pecan fungal leaf scorch has been reported to be either caused by or associated with several fungi since it was first recognized in 1972. Data are presented that indicate the disease is initiated by the fastidious xylem-limited bacterium Xylella fastidiosa. X. fastidiosa was found consistently associated with fungal leaf scorch disease of pecan (Carya illinoinensis) in commercial orchards in Louisiana. It was generally not detected in symptomless trees. The disease was reproduced by inoculation of greenhouse seedlings and grafted trees with cultures of the bacterium obtained from leaves with fungal leaf scorch. The bacterium was reisolated from symptomatic tissue of inoculated pecan seedlings, but not from symptomless plants inoculated with water to complete Koch's postulates. It is proposed that the name of the disease be changed to pecan bacterial leaf scorch because fungi do not appear to be necessary for symptom development.

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