Effects of Host Resistance and Inoculum Density on the Suppression of Fusarium Wilt of Watermelon Induced by Hairy Vetch

Plant Disease ◽  
2007 ◽  
Vol 91 (1) ◽  
pp. 92-96 ◽  
Author(s):  
X. G. Zhou ◽  
K. L. Everts
Keyword(s):  
Fusarium Wilt ◽  
Citrullus Lanatus ◽  
Inoculum Density ◽  
Disease Suppression ◽  
Management Tool ◽  
Infested Soil ◽  
Hairy Vetch ◽  
Inoculum Level ◽  
Resistance Level ◽  
Bacterial Populations

Hairy vetch (Vicia villosa) used as a soil amendment is a newly described potential management tool for the suppression of Fusarium wilt of watermelon (Citrullus lanatus). However, the effect of inoculum density and the level of resistance in the host on the level of suppression are not understood. In this study, hairy vetch-induced wilt suppression was evaluated in the greenhouse on 12 watermelon cultivars with different levels of wilt resistance and in 16 naturally infested soil samples collected from commercial watermelon fields. Wilt suppression occurred in all but two cultivars and with the trend that suppression increased as the level of resistance in cultivars increased. Fusarium wilt suppression was 22, 53, and 63% in hairy vetch-amended soil compared with nonamended soil on cultivars ranked as susceptible, moderately resistant, and highly resistant, respectively. Suppression also occurred in nine of the soils that contained populations of Fusarium oxysporum f. sp. niveum below 1,100 CFU/g of soil. However, at this level or higher, significant wilt suppression was not observed. The magnitude of disease suppression decreased with the increase of inoculum in the soils. The induced wilt suppression appeared to be correlated with an increase in bacterial populations in soil. Hairy vetch-induced suppression to Fusarium wilt in watermelon is dependent on the resistance level of cultivars and is overcome by high inoculum level of F. oxysporum f. sp. niveum in soil.

Histopathology comparison and phenylalanine ammonia lyase (PAL) gene expressions in Fusarium wilt infected watermelons

2008 ◽  
Vol 59 (12) ◽  
pp. 1146 ◽  
Author(s):  
P.-F. L. Chang ◽  
C.-C. Hsu ◽  
Y.-H. Lin ◽  
K.-S. Chen ◽  
J.-W. Huang ◽  
...  
Keyword(s):  
Fusarium Wilt ◽  
Phenylalanine Ammonia Lyase ◽  
Citrullus Lanatus ◽  
Spontaneous Mutation ◽  
Limiting Factors ◽  
Lower Percentage ◽  
Post Inoculation ◽  
Infested Soil ◽  
Gene Expressions ◽  
Shoot Base

Fusarium wilt disease of watermelon (Citrullus lanatus (Thunb.) Matsum & Nakai), caused by Fusarium oxysporum f. sp. niveum (FON), is one of the limiting factors of worldwide watermelon production. In this study, a Fusarium wilt resistant watermelon JSB, which was derived from a spontaneous mutation of the susceptible Sugar Baby (SB), was used to investigate histopathology. The number and diameter of xylem vessels in the root (10 mm below the shoot base) of resistant JSB plants were significantly higher than those in susceptible SB plants. At 9 days post inoculation (dpi), using the plate assay on Nash-PCNB media, FON could be recovered from 86% of the roots in the symptomless plants of both watermelon lines, and from 55% and 64% of the stem segments (5 mm above the shoot base) in resistant and susceptible plants, respectively. In paraffin and free-hand tissue sections, at 8, 13, and 35 dpi, the xylem of roots and stems close to the soil surface in resistant watermelon JSB plants was also colonised by FON, but to a much lower percentage than the susceptible SB ones. No colonisation below the middle of stems was observed in the resistant JSB plants. The susceptible plants grown in infested soil were all dead by 35 dpi, while the resistant plants remained healthy. These observations suggest that reducing FON colonisation in the vascular systems of the host may contribute to the resistance in JSB. Furthermore, the higher expression of the phenylalanine ammonia lyase (PAL) gene in JSB induced by FON and the effects of PAL inhibitor on the resistance of JSB suggested that PAL is involved in resistance of watermelon to Fusarium wilt pathogen.

Suppression of Fusarium Wilt of Watermelon Enhanced by Hairy Vetch Green Manure and Partial Cultivar Resistance

2006 ◽  
Vol 7 (1) ◽  
pp. 23 ◽  
Author(s):  
X. G. Zhou ◽  
K. L. Everts
Keyword(s):  
Fusarium Wilt ◽  
Green Manure ◽  
Fruit Yield ◽  
Management Tool ◽  
Hairy Vetch ◽  
Vicia Villosa ◽  
Combined Use ◽  
Triploid Watermelon ◽  
Marketable Fruit ◽  
Soil Fumigants

Hairy vetch (Vicia villosa Roth) green manure is a newly-described potential management tool for Fusarium wilt of watermelon, but control is insufficient when watermelon, especially triploid watermelon, is grown in severely infested soils. A field experiment in a split-split-plot design was conducted over two years to evaluate efficacy of hairy vetch green manure alone and in combination with a moderately wilt-resistant (MR) triploid watermelon cultivar for wilt suppression compared with preplant soil fumigants. Either the soil-incorporated hairy vetch winter cover crop or the MR cultivar was effective in reducing wilt incidence, promoting plant vine growth, and increasing fruit yield. However, neither approach alone resulted in disease reductions sufficient to obtain an acceptable level of marketable fruit yield. An additive effect was observed when both treatments were combined and was greater than that obtained with the fumigants methyl bromide or metam sodium. Stem colonization by Fusarium oxysporum f. sp. niveum was lower following hairy vetch green manure than in fallow treatments, and was lowest in the MR cultivar grown in green-manured plots. The combined use of hairy vetch green manure and a MR cultivar can enhance suppression of Fusarium wilt in triploid watermelon. Accepted for publication 25 February 2006. Published 5 April 2006.

scholarly journals Effect of Incorporation of Brassica spp. Residues on Population Densities of Soilborne Microorganisms and on Damping-off and Fusarium Wilt of Watermelon

Plant Disease ◽  
2008 ◽  
Vol 92 (2) ◽  
pp. 287-294 ◽  
Author(s):  
Samuel M. C. Njoroge ◽  
Melissa B. Riley ◽  
Anthony P. Keinath
Keyword(s):  
South Carolina ◽  
Fusarium Wilt ◽  
Methyl Bromide ◽  
Field Experiments ◽  
Citrullus Lanatus ◽  
Total Concentration ◽  
Management Tool ◽  
Damping Off ◽  
Amended Soils ◽  
Brassica Spp

Incorporating Brassica spp. residue to reduce populations of soilborne fungi and manage damping-off and Fusarium wilt of watermelon (Citrullus lanatus var. lanatus) was studied in two field experiments. Treatments included incorporating flowering Brassica napus cv. Dwarf Essex canola or B. juncea cv. Cutlass mustard and laying black polyethylene mulch at incorporation or 1 month after incorporation, methyl bromide, and a nontreated control. In both years, glucosinolates were identified and quantified in the shoots and roots of the flowering plants. In both years, the total concentration of glucosinolates incorporated per square meter was significantly higher for B. juncea than for B. napus. Isothiocyanates were inconsistently detected in the amended soils and none were detected more than 12 days postincorporation. After incorporation in 2004 and 2005, amended plots had higher populations of Fusarium oxysporum and Pythium spp. than the methyl bromide treatment, and in some treatments, populations were higher than in the control. Fluorescent Pseudomonas spp. were not suppressed in amended soils, and their populations were significantly higher in some amended treatments than those in methyl bromide-treated soils or nontreated control soils. Incidence of damping-off and severity of Fusarium wilt on seedless watermelon cv. Tri-X 313, which is susceptible to Fusarium wilt, were not consistently lower in brassica-amended soils or methyl bromide-treated plots than in nontreated control plots. Therefore, under spring conditions and methods used in this study, neither biofumigation nor methyl bromide fumigation in coastal South Carolina was an effective disease management tool for two soilborne pathogens of watermelon.

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 Grafting to Manage Soilborne Diseases in Heirloom Tomato Production

HortScience ◽  
2008 ◽  
Vol 43 (7) ◽  
pp. 2104-2111 ◽  
Author(s):  
Cary L. Rivard ◽  
Frank J. Louws
Keyword(s):  
United States ◽  
Fusarium Wilt ◽  
Bacterial Wilt ◽  
Management Program ◽  
Organic Production ◽  
Management Tool ◽  
Infested Soil ◽  
Tomato Production ◽  
Soilborne Diseases ◽  
Wilt Incidence

Organic heirloom tomato production is limited in the southeastern United States by foliar and soilborne diseases, thermal stress, and weathered soil structure. Heirloom cultivars command a premium market, but tolerance to disease and abiotic stress is often poor. Organic growers need research that supports the advantages of market niches afforded by heirloom tomatoes through the development of integrated systems to manage pests and reduce risks of associated crop losses or low yields. Two major soilborne diseases common in the southeast, bacterial wilt (caused by Ralstonia solanacearum) and fusarium wilt (caused by Fusarium oxysporum f.sp. lycopersici), were effectively managed using susceptible heirloom scions grafted onto resistant rootstock. In naturally infested soil, bacterial wilt incidence for nongrafted ‘German Johnson’ was 79% and 75% in 2005 and 2006, respectively. ‘German Johnson’ showed no symptoms of bacterial wilt in either year when grafted onto the resistant genotypes CRA 66 or Hawaii 7996. Fusarium wilt incidence was 46% and 50%, respectively, in nongrafted and self-grafted ‘German Johnson’ controls. When ‘Maxifort’ rootstock was grafted with ‘German Johnson’, no symptoms of fusarium wilt were seen, and plants with ‘Robusta’ rootstock had an intermediate level of disease (29%). An evaluation of commercially available rootstock was carried out in three separate experiments in diverse organic production systems to determine yield impacts with low disease pressure. ‘Maxifort’ rootstock significantly increased yield in one location (P = 0.05), but ‘Maxifort’ and ‘Robusta’ rootstock did not consistently impact yield at the other two locations. Grafting is an effective management tool for organic growers in the southeast United States to reduce risk of crop loss resulting from soilborne diseases and will be a valuable component in an integrated pest management program.

scholarly journals Cellulase Activity as a Mechanism for Suppression of Phytophthora Root Rot in Mulches

2011 ◽  
Vol 101 (2) ◽  
pp. 223-230 ◽  
Author(s):  
Brantlee Spakes Richter ◽  
Kelly Ivors ◽  
Wei Shi ◽  
D. M. Benson
Keyword(s):  
Root Rot ◽  
Phytophthora Cinnamomi ◽  
Cellulase Activity ◽  
Enzyme Concentration ◽  
Disease Suppression ◽  
In Vitro Assays ◽  
Infested Soil ◽  
Phytophthora Root Rot ◽  
Standard Curve

Wood-based mulches are used in avocado production and are being tested on Fraser fir for reduction of Phytophthora root rot, caused by Phytophthora cinnamomi. Research with avocado has suggested a role of microbial cellulase enzymes in pathogen suppression through effects on the cellulosic cell walls of Phytophthora. This work was conducted to determine whether cellulase activity could account for disease suppression in mulch systems. A standard curve was developed to correlate cellulase activity in mulches with concentrations of a cellulase product. Based on this curve, cellulase activity in mulch samples was equivalent to a cellulase enzyme concentration of 25 U ml–1 or greater of product. Sustained exposure of P. cinnamomi to cellulase at 10 to 50 U ml–1 significantly reduced sporangia production, but biomass was only reduced with concentrations over 100 U ml–1. In a lupine bioassay, cellulase was applied to infested soil at 100 or 1,000 U ml–1 with three timings. Cellulase activity diminished by 47% between 1 and 15 days after application. Cellulase applied at 100 U ml–1 2 weeks before planting yielded activity of 20.08 μmol glucose equivalents per gram of soil water (GE g–1 aq) at planting, a level equivalent to mulch samples. Cellulase activity at planting ranged from 3.35 to 48.67 μmol GE g–1 aq, but no treatment significantly affected disease progress. Based on in vitro assays, cellulase activity in mulch was sufficient to impair sporangia production of P. cinnamomi, but not always sufficient to impact vegetative biomass.

scholarly journals QTL Mapping Identifies Novel Source of Resistance to Fusarium Wilt Race 1 in Citrullus amarus

Plant Disease ◽  
2019 ◽  
Vol 103 (5) ◽  
pp. 984-989 ◽  
Author(s):  
Sandra E. Branham ◽  
Amnon Levi ◽  
W. Patrick Wechter
Keyword(s):  
Fusarium Wilt ◽  
Citrullus Lanatus ◽  
Recombinant Inbred Lines ◽  
The United States ◽  
Chromosome 9 ◽  
Mapping Study ◽  
Sources Of Resistance ◽  
Race 1 ◽  
Genetic Source ◽  
Genetic Mapping Study

Fusarium wilt race 1, caused by the soilborne fungus Fusarium oxysporum Schlechtend.: Fr. f. sp. niveum (E.F. Sm.) W.C. Snyder & H.N. Hans (Fon), is a major disease of watermelon (Citrullus lanatus) in the United States and throughout the world. Although Fusarium wilt race 1 resistance has been incorporated into several watermelon cultivars, identification of additional genetic sources of resistance is crucial if a durable and sustainable level of resistance is to be continued over the years. We conducted a genetic mapping study to identify quantitative trait loci (QTLs) associated with resistance to Fon race 1 in segregating populations (F2:3 and recombinant inbred lines) of Citrullus amarus (citron melon) derived from the Fon race 1 resistant and susceptible parents USVL246-FR2 and USVL114, respectively. A major QTL (qFon1-9) associated with resistance to Fon race 1 was identified on chromosome 9 of USVL246-FR2. This discovery provides a novel genetic source of resistance to Fusarium wilt race 1 in watermelon and, thus, an additional host-resistance option for watermelon breeders to further the effort to mitigate this serious phytopathogen.

scholarly journals Induction of Soil Suppressiveness Against Rhizoctonia solani by Incorporation of Dried Plant Residues into Soil

2006 ◽  
Vol 96 (12) ◽  
pp. 1372-1379 ◽  
Author(s):  
Masahiro Kasuya ◽  
Andriantsoa R. Olivier ◽  
Yoko Ota ◽  
Motoaki Tojo ◽  
Hitoshi Honjo ◽  
...  
Keyword(s):  
Rhizoctonia Solani ◽  
Mycelial Growth ◽  
Inhibitory Effect ◽  
Volatile Substance ◽  
Disease Suppression ◽  
Plant Residues ◽  
Infested Soil ◽  
Antagonistic Bacteria ◽  
Damping Off ◽  
Soil Suppressiveness

Suppressive effects of soil amendment with residues of 12 cultivars of Brassica rapa on damping-off of sugar beet were evaluated in soils infested with Rhizoctonia solani. Residues of clover and peanut were tested as noncruciferous controls. The incidence of damping-off was significantly and consistently suppressed in the soils amended with residues of clover, peanut, and B. rapa subsp. rapifera ‘Saori’, but only the volatile substance produced from water-imbibed residue of cv. Saori exhibited a distinct inhibitory effect on mycelial growth of R. solani. Nonetheless, disease suppression in such residue-amended soils was diminished or nullified when antibacterial antibiotics were applied to the soils, suggesting that proliferation of antagonistic bacteria resident to the soils were responsible for disease suppression. When the seed (pericarps) colonized by R. solani in the infested soil without residues were replanted into the soils amended with such residues, damping-off was suppressed in all cases. In contrast, when seed that had been colonized by microorganisms in the soils containing the residues were replanted into the infested soil, damping-off was not suppressed. The evidence indicates that the laimosphere, but not the spermosphere, is the site for the antagonistic microbial interaction, which is the chief principle of soil suppressiveness against Rhizoctonia damping-off.

scholarly journals Uncovering the Host Range for Maize Pathogen Magnaporthiopsis maydis

Plants ◽  
2019 ◽  
Vol 8 (8) ◽  
pp. 259 ◽  
Author(s):  
Dor ◽  
Degani
Keyword(s):  
Host Range ◽  
Citrullus Lanatus ◽  
Shoot Biomass ◽  
Pcr Analysis ◽  
Plant Residues ◽  
Infested Soil ◽  
Pathogenicity Test ◽  
Green Foxtail ◽  
Fungal Dna ◽  
Shoot Weight

The fungus Magnaporthiopsis maydis is a soil-borne, seed-borne vascular wilt pathogen that causes severe damage to sensitive Zea mays L. (maize) hybrids throughout Egypt, Israel, India, Spain, and other countries. It can undergo virulence variations and survive as spores, sclerotia, or mycelia on plant residues. Maize, Lupinus termis L. (lupine) and Gossypium hirsutum L. (cotton) are the only known hosts of M. maydis. Identification of new plant hosts that can assist in the survival of the pathogen is an essential step in restricting disease outbreak and spread. Here, by field survey and growth chamber pathogenicity test, accompanied by real-time PCR analysis, the presence of the fungal DNA inside the roots of cotton (Pima cv.) plants was confirmed in infested soil. Moreover, we identified M. maydis in Setaria viridis (green foxtail) and Citrullus lanatus (watermelon, Malali cv.). Infected watermelon sprouts had delayed emergence and development, were shorter, and had reduced root and shoot biomass. M. maydis infection also affected root biomass and phenological development of cotton plants but caused only mild symptoms in green foxtail. No M. maydis DNA was detected in Hordeum vulgare (barley, Noga cv.) and the plants showed no disease symptoms except for reduced shoot weight. These findings are an important step towards uncovering the host range and endophytic behavior of M. maydis, encouraging expanding this evaluation to other plant species.

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