scholarly journals Identification of Resistance to Fusarium oxysporum f. sp. niveum Race 2 in Citrullus lanatus var. citroides Plant Introductions

HortScience ◽  
2012 ◽  
Vol 47 (3) ◽  
pp. 334-338 ◽  
Author(s):  
W. Patrick Wechter ◽  
Chandrasekar Kousik ◽  
Melanie McMillan ◽  
Amnon Levi
Keyword(s):  
North America ◽  
Fusarium Oxysporum ◽  
Fusarium Wilt ◽  
Citrullus Lanatus ◽  
Plant Introductions ◽  
Major Disease ◽  
Seedling Inoculation ◽  
The World ◽  
Potential Sources ◽  
Race 2

Fusarium wilt (FW) is a major disease of watermelon in North America and around the world. Control of this disease is difficult because the soilborne causal agent Fusarium oxysporum f. sp. niveum (Fon) produces chlamydospores that remain infectious in the soil for many years. Although various levels of resistance to Fon Races 0 and 1 exist in watermelon cultivars, no resistance to Race 2 or 3 has been reported. In this study, we used seed and seedling inoculation procedures to screen 110 U.S. PIs of wild watermelon (Citrullus lanatus var. citroides) for resistance to Race 2 FW. Of these 110 accessions, 15 showed significantly higher resistance to Fon Race 2 than that found in the watermelon cultivars Sugar Baby or Charleston Grey as well as in the C. lanatus var. citroides PI 296341 that was reported to contain resistance to FW. PI 271769, another C. lanatus var. citroides that was previously reported as containing resistance to FW, is among the 15 resistant accessions described here. These 15 accessions are potential sources for resistance to Race 2 FW in watermelon breeding.

scholarly journals Race 3, a New and Highly Virulent Race of Fusarium oxysporum f. sp. niveum Causing Fusarium Wilt in Watermelon

Plant Disease ◽  
2010 ◽  
Vol 94 (1) ◽  
pp. 92-98 ◽  
Author(s):  
X. G. Zhou ◽  
K. L. Everts ◽  
B. D. Bruton
Keyword(s):  
Fusarium Oxysporum ◽  
Host Range ◽  
Fusarium Wilt ◽  
Citrullus Lanatus ◽  
Genetic Difference ◽  
Infested Soil ◽  
Reference Isolate ◽  
New Race ◽  
Race 2 ◽  
Highly Virulent

Three races (0, 1, and 2) of Fusarium oxysporum f. sp. niveum have been previously described in watermelon (Citrullus lanatus) based on their ability to cause disease on differential watermelon genotypes. Four isolates of F. oxysporum f. sp. niveum collected from wilted watermelon plants or infested soil in Maryland, along with reference isolates of races 0, 1, and 2, were compared for virulence, host range, and vegetative compatibility. Race identification was made on the watermelon differentials Sugar Baby, Charleston Gray, Dixielee, Calhoun Gray, and PI-296341-FR using a root-dip, tray-dip, or pipette inoculation method. All four Maryland isolates were highly virulent, causing 78 to 100% wilt on all differentials, one of which was PI-296341-FR, considered highly resistant to race 2. The isolates also produced significantly greater colonization in the lower stems of PI-296341-FR than a standard race 2 reference isolate. In field microplots, two of the isolates caused over 90% wilt on PI-296341-FR, whereas no disease was caused by a race 2 isolate. All four isolates were nonpathogenic on muskmelon, cucumber, pumpkin, and squash, confirming their host specific pathogenicity to watermelon. The Maryland isolates were vegetatively compatible to each other but not compatible with the race 2 isolates evaluated, indicating their genetic difference from race 2. This study proposes that the Maryland isolates belong to a new race, race 3, the most virulent race of F. oxysporum f. sp. niveum described to date.

scholarly journals Cucurbit Rootstocks Resistant to Fusarium oxysporum f. sp. niveum Remain Resistant When Coinfected by Meloidogyne incognita in the Field

Plant Disease ◽  
2019 ◽  
Vol 103 (6) ◽  
pp. 1383-1390 ◽  
Author(s):  
Anthony P. Keinath ◽  
W. Patrick Wechter ◽  
William B. Rutter ◽  
Paula A. Agudelo
Keyword(s):  
Fusarium Oxysporum ◽  
Fusarium Wilt ◽  
Meloidogyne Incognita ◽  
Interspecific Hybrid ◽  
Citrullus Lanatus ◽  
Root Knot Nematode ◽  
Progress Curve ◽  
Triploid Watermelon ◽  
Race 2 ◽  
Southern Root Knot Nematode

Interspecific hybrid squash (Cucurbita maxima × Cucurbita moschata) rootstocks used to graft watermelon (Citrullus lanatus var. lanatus) are resistant to Fusarium oxysporum f. sp. niveum, the fungus that causes Fusarium wilt of watermelon, but they are susceptible to Meloidogyne incognita, the southern root knot nematode. A new citron (Citrullus amarus) rootstock cultivar Carolina Strongback is resistant to F. oxysporum f. sp. niveum and M. incognita. The objective of this study was to determine if an interaction between M. incognita and F. oxysporum f. sp. niveum race 2 occurred on grafted or nongrafted triploid watermelon susceptible to F. oxysporum f. sp. niveum race 2. In 2016 and 2018, plants of nongrafted cultivar Fascination and Fascination grafted onto Carolina Strongback and interspecific hybrid squash cultivar Carnivor were inoculated or not inoculated with M. incognita before transplanting into field plots infested or not infested with F. oxysporum f. sp. niveum race 2. Incidence of Fusarium wilt and area under the disease progress curve did not differ when hosts were inoculated with F. oxysporum f. sp. niveum alone or F. oxysporum f. sp. niveum and M. incognita together. Fusarium wilt was greater on nongrafted watermelon (78% mean incidence) than on both grafted rootstocks and lower on Carnivor (1% incidence) than on Carolina Strongback (12% incidence; P ≤ 0.01). Plants not inoculated with F. oxysporum f. sp. niveum did not wilt. At the end of the season, Carnivor had a greater percentage of the root system galled than the other two hosts, whereas galling did not differ on Fascination and Carolina Strongback. F. oxysporum f. sp. niveum reduced marketable weight of nongrafted Fascination with and without coinoculation with M. incognita. M. incognita reduced marketable weight of Fascination grafted onto Carnivor compared with noninoculated, nongrafted Fascination. In conclusion, cucurbit rootstocks that are susceptible and resistant to M. incognita retain resistance to F. oxysporum f. sp. niveum when they are coinfected with M. incognita.

scholarly journals First Report of Fusarium oxysporum f. sp. niveum Race 2 as Causal Agent of Fusarium Wilt of Watermelon in Indiana

Plant Disease ◽  
2005 ◽  
Vol 89 (1) ◽  
pp. 108-108 ◽  
Author(s):  
D. S. Egel ◽  
R. Harikrishnan ◽  
R. Martyn
Keyword(s):  
United States ◽  
Fusarium Oxysporum ◽  
Fusarium Wilt ◽  
Citrullus Lanatus ◽  
The United States ◽  
Mineral Salts ◽  
First Report ◽  
Race 1 ◽  
Race 2 ◽  
Greenhouse Assay

Fusarium oxysporum f. sp. niveum race 1 is uniformly distributed throughout watermelon (Citrullus lanatus (Thunb.) Matsum. & Nakai) growing regions, but F. oxysporum f. sp. niveum race 2 has a limited known distribution in the United States (Texas, Florida, Oklahoma, Maryland, and Delaware) (3,4). Since the spring of 2001, commercial watermelon fields in Knox and Gibson counties in southwestern Indiana have been observed with symptoms of one-sided wilt and vascular discoloration typical of Fusarium wilt. Race 2 of F. oxysporum f. sp. niveum was suspected as the casual agent since the diseased watermelon cultivars are considered resistant to races 0 and 1. Two isolates of F. oxysporum obtained from wilted watermelon plants in two different commercial fields and one isolate obtained from a wilted seedling in a transplant house were compared for pathogenicity in a greenhouse assay. Known isolates of F. oxysporum f. sp. niveum races 0, 1, and 2 were obtained from Don Hopkins (University of Florida, Apopka), Kate Everts (University of Maryland/University of Delaware, Salisbury, MD), and Ray Martyn (Purdue University, West Lafayette, IN), respectively, and were used for comparison. All isolates were grown in shake cultures in a mineral salts liquid medium. (1). After 72 hr, the predominately microconidal suspensions were filtered through cheesecloth and adjusted to 1 × 105 conidia/ml with the aid of a hemacytometer. A concentration of 1 × 105 condia/ml was shown previously to cause the desired disease reaction in the standard cultivars. Seedlings of the differential cvs, Black Diamond (universal susceptible), Charleston Gray (race 0 resistant), and Calhoun Gray (race 0 and 1 resistant) were grown in a 1:1, (v:v) sand/ vermiculite mixture to the first true-leaf stage after which the plants were uprooted and the roots carefully washed prior to root dip inoculation. Subsequent to inoculation, seedlings were planted in a sand/vermiculite/ peat mixture (4:1:1, [v:v:v]) with four seedlings to a 15-cm-diameter pot. The experimental design was a randomized complete block with five replications. Two isolates from the commercial field plants caused an average of 100% wilt on cv. Black Diamond, 95% wilt on cv. Charleston Gray, and 80% wilt on cv. Calhoun Gray, resulting in a designation of race 2. The isolate from a commercial transplant house resulted in 100, 60, and 15% wilt, respectively, on the three standard cultivars resulting in a race 1 designation. The presence of F. oxysporum f. sp. niveum race 2 in Indiana is significant because Indiana currently ranks fifth in the United States in watermelon production and there are no commercially available cultivars that possess resistance to race 2. To our knowledge, this is the first report of F. oxysporum f. sp. niveum race 2 in Indiana and the first report of race 2 from the Midwest region of the United States. Race 2, first described from the United States in 1985 (2), has now been confirmed in six states. References: (1) R. Esposito and A. Fletcher. Arch. Biochem. Biophys. 93:369, 1961. (2) R. Martyn, Plant Dis. 69:1007, 1985. (3) R. Martyn, Plant Dis. 71:233, 1987. (4) X. Zhou and K. Everts. Plant Dis. 87:692, 2003.

scholarly journals First Report of Fusarium Wilt Caused by Fusarium oxysporum f. sp. niveum Race 2 in Georgia Watermelons

Plant Disease ◽  
2008 ◽  
Vol 92 (6) ◽  
pp. 983-983 ◽  
Author(s):  
B. D. Bruton ◽  
W. W. Fish ◽  
D. B. Langston
Keyword(s):  
Fusarium Oxysporum ◽  
Fusarium Wilt ◽  
Citrullus Lanatus ◽  
Fusarium Species ◽  
Block Design ◽  
Genetic Resistance ◽  
Morphological Characteristics ◽  
First Report ◽  
Race 1 ◽  
Race 2

Watermelon (Citrullus lanatus (Thunb.) Matsum. & Nakai) is the number one specialty crop grown in Georgia, a state that ranks fourth nationally in watermelon production. In the last 5 years, Fusarium wilt caused by Fusarium oxysporum f. sp. niveum (Fon) has been the greatest yield-limiting disease of watermelon in Georgia. In 2004, a seedless-watermelon field of ‘Regency’ and ‘Tri-X 313’ in Berrien County, GA exhibited approximately 40% of wilted plants. Affected plants also exhibited strong discoloration in the crown xylem. Plant samples (cultivars unknown) from a similarly affected field were also tested from Crisp County, GA. Xylem tissue was excised from the main stem of eight diseased plants in the area between the second and third internode, surface sterilized for 1 min in 1% NaOCl, rinsed with 80% ethanol, and plated onto water agar amended with 100 μg/liter of streptomycin sulfate. Fungi with the morphological characteristics of Fusarium oxysporum (4) were consistently recovered from the diseased tissue of all eight plants. The isolates were hyphal tipped and maintained in vials of sterile artificial potting mix until ready for use (1). Isolates were grown on Esposito and Fletcher medium (2) for 10 days, filtered through cheesecloth, and adjusted to 1 × 106 spores/ml. Reference isolates of race 1 and 2 were used as comparisons for race determination of the unknowns. In each of four studies, plants at the two-leaf stage were removed from potting mix, washed gently, and their roots were uniformly trimmed to 2.5 cm. Before repotting, the seedlings were subjected to a 2-min root-dip in the respective spore-containing media. In each study, approximately 40 plants of each watermelon differential were inoculated with the respective isolates. In disease scoring, each plant was considered a rep. ‘Black Diamond’ is susceptible to races 0, 1, and 2; ‘Charleston Gray’ is resistant to race 0; ‘Calhoun Gray’ is resistant to races 0 and 1, and PI-296341-FR (3) is resistant to races 0, 1, and 2 of Fon. Four plants were planted per 15-cm plastic pot, maintained in an air-conditioned headhouse for 24 h, and then placed in the greenhouse in a randomized complete block design. After 30 days, all plants were rated as to healthy, wilted, or dead plants. From eight isolates tested, one isolate from each county was determined to be Fon race 2 on the basis of its ability to wilt/kill a high percentage of the race 1 resistant differential, i.e., ‘Calhoun Gray’. Mean disease percentages for the isolates from each of the two counties on the watermelon differentials were 95 and 100% on ‘Black Diamond’, 68 and 80% on ‘Charleston Gray’, and 70 and 86% on ‘Calhoun Gray.’ Because of apparent genetic drift within our PI-296341-FR population, we determined that these data were not useful for identifying race 2. In fact, we observed a range of 17 to 80% wilt/death in the PI-296341-FR over a total of four studies that included a known race 2 isolate (Calg 13(15); E. Vivoda). To our knowledge, this is the first report of race 2 in Georgia and it increases the number of states to seven in which race 2 has been identified. Five of the top 10 watermelon-producing states have now reported race 2 of Fon for which there is no genetic resistance within commercial cultivars. References: (1) B. D. Bruton et al. Plant Dis. 84:907, 2000. (2) R. Esposito and A. Fletcher. Arch. Biochem. Biophys. 93:369, 1961. (3) R. D. Martyn and D. Netzer. HortScience 26:429, 1991. (4) P. E. Nelson et al. Fusarium Species: An Illustrated Manual for Identification. Pennsylvania State University Press, University Park, 1983.

scholarly journals Marker Development for Differentiation of Fusarium oxysporum f. sp. Niveum Race 3 from Races 1 and 2

2021 ◽  
Vol 22 (2) ◽  
pp. 822
Author(s):  
Owen Hudson ◽  
Sumyya Waliullah ◽  
James C. Fulton ◽  
Pingsheng Ji ◽  
Nicholas S. Dufault ◽  
...  
Keyword(s):  
South Carolina ◽  
Fusarium Oxysporum ◽  
Fusarium Wilt ◽  
Conventional Polymerase Chain Reaction ◽  
Detection Methods ◽  
Limiting Factors ◽  
Pcr Marker ◽  
Primer Sets ◽  
Race Differentiation ◽  
Race 2

Fusarium wilt of watermelon, caused by Fusarium oxysporum f. sp. niveum (FON), is pathogenic only to watermelon and has become one of the main limiting factors in watermelon production internationally. Detection methods for this pathogen are limited, with few published molecular assays available to differentiate FON from other formae speciales of F. oxysporum. FON has four known races that vary in virulence but are difficult and costly to differentiate using traditional inoculation methods and only race 2 can be differentiated molecularly. In this study, genomic and chromosomal comparisons facilitated the development of a conventional polymerase chain reaction (PCR) assay that could differentiate race 3 from races 1 and 2, and by using two other published PCR markers in unison with the new marker, the three races could be differentiated. The new PCR marker, FNR3-F/FNR3-R, amplified a 511 bp region on the “pathogenicity chromosome” of the FON genome that is absent in race 3. FNR3-F/FNR3-R detected genomic DNA down to 2.0 pg/µL. This marker, along with two previously published FON markers, was successfully applied to test over 160 pathogenic FON isolates from Florida, Georgia, and South Carolina. Together, these three FON primer sets worked well for differentiating races 1, 2, and 3 of FON. For each marker, a greater proportion (60 to 90%) of molecular results agreed with the traditional bioassay method of race differentiation compared to those that did not. The new PCR marker should be useful to differentiate FON races and improve Fusarium wilt research.

scholarly journals The Root Rot-Fusarium Wilt Complex of Peas

1963 ◽  
Vol 16 (1) ◽  
pp. 55 ◽  
Author(s):  
A Kerr
Keyword(s):  
Fusarium Oxysporum ◽  
Fusarium Wilt ◽  
Root Rot ◽  
Fungal Pathogens ◽  
South Australia ◽  
Pythium Ultimum ◽  
Wilt Symptom ◽  
Intensive Cropping ◽  
Race 2

At least four fungal pathogens are involved in the root rot-Fusarium wilt complex of peas which is a serious problem following intensive cropping of peas in South Australia. The pathogens are Fusarium oxysporum f. pisi race 2 Snyder & Hansen, F. solani f. pisi Snyder & Hansen, Pythium ultimum Trow, and Ascochyta pinodella L. K. Jones. In susceptible pea cultivars there is a marked interaction between F. oxysporum and P. ultimum. P. ultimum alone causes initial stunting from which plants gradually recover; F. OX1Jsporum alone probably CRuses little damage; both fungi together CRuse initial stunting followed by severe wilt symptom about 6 weeks after sowing and death 2 weeks later. The importance ofF. solani and A. pinodella has not been fully determined, but they probably cause only minor damage.

scholarly journals Transmission of Fusarium oxysporum f. sp. fragariae Through Stolons in Strawberry Plants

Plant Disease ◽  
2019 ◽  
Vol 103 (6) ◽  
pp. 1249-1251 ◽  
Author(s):  
A. M. Pastrana ◽  
D. C. Watson ◽  
T. R. Gordon
Keyword(s):  
North America ◽  
Fusarium Oxysporum ◽  
Fusarium Wilt ◽  
First Generation ◽  
Soilborne Pathogen ◽  
Infected Mother ◽  
Long Distance ◽  
San Andreas ◽  
Mother Plants ◽  
Long Distance Movement

Fusarium wilt of strawberry, caused by the soilborne pathogen Fusarium oxysporum f. sp. fragariae, is a growing threat to the strawberry industry worldwide. Symptoms of the disease typically include stunting, wilting, crown discoloration, and eventual plant death. When Fusarium wilt was discovered in California, the disease was not known to occur anywhere else in North America. Long distance movement of the pathogen would most likely occur through transport of infected plants, which seems plausible if strawberry plants can sustain infections without showing symptoms of disease. The results of this study document that F. oxysporum f. sp. fragariae can move through stolons of infected mother plants and colonize first-generation daughter plants. The pathogen can also move through stolons from first to second-generation daughter plants. Daughter plants of both generations were always symptomless. The pathogen was recovered from both roots and petioles of infected daughter plants. Similar results were obtained for two cultivars known to be susceptible to Fusarium wilt, Albion and Monterey. Transmission through stolons from mother to daughter plants also occurred in the resistant cultivar, San Andreas, but less frequently than in Albion and Monterey.

scholarly journals Potential of non-pathogenic Fusarium oxysporum isolates for control of Fusarium wilt of tomato

2005 ◽  
Vol 30 (4) ◽  
pp. 409-412 ◽  
Author(s):  
Juliano C. da Silva ◽  
Wagner Bettiol
Keyword(s):  
Fusarium Oxysporum ◽  
Fusarium Wilt ◽  
Antagonistic Activity ◽  
Healthy Plant ◽  
Conidial Suspension ◽  
Vascular Wilt ◽  
Tomato Seedling ◽  
Seedling Roots ◽  
Race 2 ◽  
Cultivation Substrate

This study was done to evaluate the efficiency of non-pathogenic Fusarium oxysporum isolates (141/3, 233, 233/1, 245, 245/1, 251, 251/2, 251/5, and 257) in controlling vascular wilt caused by F. oxysporum f. sp. lycopersici, race 2 (isolates C-21A, TO11, and TO245) in tomato (Lycopersicon esculentum) cv. Viradoro seedlings. In order to determine the effect of non-pathogenic F. oxysporum isolates in tomato plants, the root system of 30-day-old seedlings was immersed in conidial suspensions (10(6) ml-1) of each isolate and the seedlings were transplanted to a cultivation substrate. Thirty-five days after transplanting it was observed that the non-pathogenic F. oxysporum isolates were not pathogenic to the cv. Viradoro nor did they affect seedling development. The efficiency of the non-pathogenic F. oxysporum isolates in controlling Fusarium wilt was determined by immersing the tomato seedling roots in the conidial suspension (10(6) ml-1) of each isolate and then transplanting them into substrates previously infested with isolates of F. oxysporum f.sp. lycopersici, race 2 (10(5) conidia ml-1 of substrate). Evaluations were performed 35 days after transplanting, for severity in scale with 1=healthy plant to 6=dead plant or plant showing vessel browning and wilted leaves up to the leader shoot and seedling height. The non-pathogenic F. oxysporum isolates were efficient in reducing the severity of the disease and maintaining normal plant development. These results provide evidence of the antagonistic activity of non-pathogenic F. oxysporum isolates in controlling vascular wilt caused by F. oxysporum f. sp. lycopersici race 2 in tomato.

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