scholarly journals Disease Development Following Infection of Tomato and Basil Foliage by Airborne Conidia of the Soilborne Pathogens Fusarium oxysporum f. sp. radicis-lycopersici and F. oxysporum f. sp. basilici

2000 ◽  
Vol 90 (12) ◽  
pp. 1322-1329 ◽  
Author(s):  
Y. Rekah ◽  
D. Shtienberg ◽  
J. Katan

Fusarium oxysporum f. sp. radicis-lycopersici, the causal agent of Fusarium crown and root rot of tomato, and F. oxysporum f. sp. basilici, the causal agent of Fusarium wilt in basil, are soilborne pathogens capable of producing conspicuous masses of macroconidia along the stem. The role of the airborne propagules in the epidemics of the disease in tomato plants was studied. In the field, airborne propagules of F. oxysporum f. sp. radicis-lycopersici were trapped with a selective medium and their prevalence was determined. Plants grown in both covered and uncovered pots, detached from the field soil, and exposed to natural aerial inoculum developed typical symptoms (82 to 87% diseased plants). The distribution of inoculum in the growth medium in the pots also indicated the occurrence of foliage infection. In greenhouse, foliage and root inoculations were carried out with both tomato and basil and their respective pathogens. Temperature and duration of high relative humidity affected rate of colonization of tomato, but not of basil, by the respective pathogens. Disease incidence in foliage-inoculated plants reached 75 to 100%. In these plants, downward movement of the pathogens from the foliage to the crown and roots was observed. Wounding enhanced pathogen invasion and establishment in the foliage-inoculated plants. The sporulation of the two pathogens on stems, aerial dissemination, and foliage infection raise the need for foliage protection in addition to soil disinfestation, in the framework of an integrated disease management program.

Plant Disease ◽  
2001 ◽  
Vol 85 (7) ◽  
pp. 735-739 ◽  
Author(s):  
Y. Rekah ◽  
D. Shtienberg ◽  
J. Katan

The saltcedar shrub Tamarix nilotica grows as a weed in the Arava region of Israel. This weed is commonly found in cultivated fields naturally infested with Fusarium oxysporum f. sp. radicis-lycopersici, the causal agent of tomato crown and root rot. Young bushes, 20 to 40 cm tall, were randomly uprooted from different fields. The roots were cut into segments which were placed on Fusarium-selective medium. Although the plants did not show any symptoms of disease, the roots of the shrub were colonized by the pathogen. The incidence of infected saltcedar plants and level of root colonization by F. oxysporum f. sp. radicis-lycopersici decreased with increasing distance of the sampling location from a tomato field infected with crown and root rot. F. oxysporum f. sp. radicis-lycopersici was also isolated from chaff of inflorescence samples taken from mature T. nilotica shrubs. Identity of the pathogen isolates obtained from T. nilotica roots and chaff samples was verified by pathogenicity and vegetative compatibility tests. Roots of T. nilotica plants sown under greenhouse conditions in soil naturally infested with F. oxysporum f. sp. radicis-lycopersici became colonized by the pathogen. Uprooting and removing saltcedar plants throughout the season from fields not cultivated with tomatoes lowered the inoculum density of F. oxysporum f. sp. radicis-lycopersici in the soil from 611 to 6 and from 176 to 10 CFU/g of soil in the 1998-99 and 1999-2000 growing seasons, respectively. These results demonstrate that T. nilotica may contribute to the buildup of the pathogen populations in the absence of a susceptible host. Colonization of saltcedar by F. oxysporum f. sp. radicis-lycopersici is an additional mechanism for survival of this pathogen in the fields and for dissemination through the spread of infested seed or chaff of T. nilotica.


1997 ◽  
Vol 87 (7) ◽  
pp. 712-719 ◽  
Author(s):  
Talma Katan ◽  
E. Shlevin ◽  
J. Katan

Plants exhibiting symptoms of wilt and xylem discoloration typical of Fusarium wilt caused by Fusarium oxysporum f. sp. lycopersici were observed in greenhouses of cherry tomatoes at various sites in Israel. However, the lower stems of some of these plants were covered with a pink layer of macroconidia of F. oxysporum. This sign resembles the sporulating layer on stems of tomato plants infected with F. oxysporum f. sp. radicis-lycopersici, which causes the crown and root rot disease. Monoconidial isolates of F. oxysporum from diseased plants were assigned to vegetative compatibility group 0030 of F. oxysporum f. sp. lycopersici and identified as belonging to race 1 of F. oxysporum f. sp. lycopersici. The possibility of coinfection with F. oxysporum f. sp. lycopersici and F. oxysporum f. sp. radicis-lycopersici was excluded by testing several macroconidia from each plant. Airborne propagules of F. oxysporum f. sp. lycopersici were trapped on selective medium in greenhouses in which plants with a sporulating layer had been growing. Sporulation on stems was reproduced by inoculating tomato plants with races 1 and 2 of F. oxysporum f. sp. lycopersici. This phenomenon has not been reported previously with F. oxysporum f. sp. lycopersici and might be connected to specific environmental conditions, e.g., high humidity. The sporulation of F. oxysporum f. sp. lycopersici on plant stems and the resultant aerial dissemination of macroconidia may have serious epidemiological consequences. Sanitation of the greenhouse structure, as part of a holistic disease management approach, is necessary to ensure effective disease control.


Author(s):  
D. Brayford

Abstract A description is provided for Fusarium oxysporum f. sp. radicis-lycopersici. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Lycopersicon spp., including L. esculentum Mill. (tomato). Plants from several families may also be susceptible to some strains, in particular Capsicum frutescens L., Solanum melongena L. (Solanaceae), Arachis hypogea L., Astragalus glycyphyllos L., Glycine max (L.) Merr., Phaseolus vulgaris L., Pisum sativum L., Trifolium spp., Vicia faba L., (Leguminosae), Cucumis spp. (Cucurbitaceae), Beta vulgaris L. and Spinacia oleracea L. (Chenopodiaceae) (Jarvis & Shoemaker, 1978; 69, 7094; 73, 7659). DISEASE: Crown and root rot. GEOGRAPHICAL DISTRIBUTION: Australia, Belgium, Canada, Crete, France, Germany, Greece, Israel, Italy, Japan, Mexico, Spain, Sweden, The Netherlands, UK, USA. TRANSMISSION: Long range dissemination is via contaminated seed (73, 5786), diseased planting material (70, 1472) and by movement of infected soil/compost (64, 2160). Locally, conidia are readily spread by water flow, e.g. in irrigation or hydroponic systems (71, 4871, 4872, 6378). Some airborne dispersal of microconidia has been detected in glasshouses (Rowe et al., 1977), presumably resulting from splash droplet formation following sporulation on nearby plant debris. Fungus gnats have been reported to transport the fungus (73, 5534).


Agronomy ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1398
Author(s):  
Vishal Gupta ◽  
Krishna Kumar ◽  
Kausar Fatima ◽  
Vijay Kumar Razdan ◽  
Bhagwati Charan Sharma ◽  
...  

Saffron (Crocus sativus L.) is considered as one of the most expensive spices. Fusarium corm rot of saffron, caused by Fusarium oxysporum, is known to cause severe yield losses worldwide. In the present study, efficacy of biocontrol agents (Trichoderma asperellum, Pseudomonas fluorescens, Pseudomonas aeruginosa, Pseudomonas putida, Bacillus stratosphericus, Bacillus pumilus, and Bacillus subtilis) along with a chemical fungicide, carbendazim, was evaluated for managing the corm rot of saffron. Under in vitro conditions, using dual culture and poison food techniques on potato dextrose agar, T. asperellum and carbendazim significantly reduced the mycelial growth of the pathogen F. oxysporum, with the inhibition of 62.76 and 60.27%, respectively, compared with control. Under field conditions, dipping of saffron corms in carbendazim and T. asperellum exhibited maximum reduction of 82.77 and 77.84%, respectively, in the disease incidence, during the first year of experiment. However, during the second year, maximum reduction in the incidence of corm rot (68.63%) was recorded with the T. asperellum. Moreover, the population density of F. oxysporum was also significantly reduced by 60 and 80.19% while using T. asperellum after 75 and 260 days of sowing of saffron corms, compared to its population before planting of corms. In case of growth promotion traits, such as sprouting and flowering, biocontrol treatments reduced the number of days (average) of sprouting and flower emergence after sowing, compared to control.


2015 ◽  
Vol 92 ◽  
pp. 139-145 ◽  
Author(s):  
Aswathy Nair ◽  
Swati P. Kolet ◽  
Hirekodathakallu V. Thulasiram ◽  
Sujata Bhargava

Author(s):  
Borisade Omotoso Abiodun ◽  
Olofin Adeola Rosemary ◽  
M. J. Falade

Potency of cell-free culture filtrate of pathogenic Fusarium oxysporum f.sp. lycopersici as systemic defense inducer against wilt disease in tomato was tested by treating seedlings with the filtrate before pathogen challenge. Infective conidia and the cell-free culture filtrate were prepared from F. oxysporum (Sensu lato) previously isolated from wilt diseased affected plants. Growth relations of the isolates were characterized under ambient temperature (25 ± 2°C) and viability of the infective conidia of the two isolates were evaluated. Treatments were done as follows: (a) treatment of seedlings with infective conidia only (Treatment-A) (b) culture filtrate treatment only (Treatment-B) (c) treatment with culture filtrate followed by inoculation with infective conidia (Treatment-C) and (d) the control which consisted of plants sprayed with sterile distilled water only (Treatment-D). Effects of fungal conidia on tomato seed germination as well as some agronomic characters of the tomato plants and disease incidence under treatments A, B, C and D were evaluated. The growth and sporulation rates of the F. oxysporum F-isolate-1 were 12.1 mm day-1 and 6.5 x 104 conidia cm-2 colony area respectively and the values for the second isolate, F-Isolate 2 were 6.1 mm day-1 and 5.4 x 104 conidia cm-2 colony area. The germination rates of the infective conidia of F-isolate 1 and F-Isolate 2 after 24 hours incubation period at ambient temperature were 70% and 85% respectively. Treatment of tomato seeds with conidia suspension containing 1.0 x 106 had no statistically significant effects on seed germination [F(2,12)=0.148, P=0.64]; the mean percentage germination of the seeds treated with F-Isolate 1, F-Isolate 2 conidia and the control were 52%,46% and 52% respectively after five days. In the Treatment-A (Infective conidia only), F-Isolate 1 and F-isolate 2 caused 100% and 80% wilt of the plant populations at 7 weeks post-inoculation, when the tomato plants were 9 weeks old and no wilt was recorded in the control. There was no wilt recorded under Treatment-B and Treatment-C also, but there was reduced flowering and the mean percentage number of leaves showing chlorosis were significantly higher than the control [F (4, 192) =6.641, P=0.001]. When the plants were 10 weeks old, withered branches at the lower vegetal strata and the senescent leaves in the control were comparable with that recorded under Treatment-B and Treatment-C (F (4, 159) =3.563, P=0.08].


Plant Disease ◽  
2000 ◽  
Vol 84 (3) ◽  
pp. 316-320 ◽  
Author(s):  
J. Hudyncia ◽  
H. D. Shew ◽  
B. R. Cody ◽  
M. A. Cubeta

A semi-selective medium was used to examine the aerobiology of ascospores of Sclerotinia sclerotiorum in five commercial cabbage fields in eastern North Carolina. Ascospores were present in all five fields from 26 September to 30 November. However, numbers of ascospores varied greatly depending on location, sampling date, and time. In general, peak ascospore deposition occurred between 11:00 A.M. and 1:00 P.M., with the number of colonies recovered ranging from 3 to 55/dish (9 cm in diameter). Peak ascospore numbers at all locations were found from mid- to late October, but a second, smaller peak was also evident at each location in late November. Information obtained was employed to evaluate the role of wounding in infection of cabbage by ascospores of S. sclerotiorum in controlled environmental chambers. A method for production and release of ascospores of S. sclerotiorum was employed in controlled-environment chambers for the inoculation of cabbage plants with one of three representative foliar wounds: a bruise, a cut, or a non-lethal freeze. Wounding treatments were applied to 7-week-old cabbage plants, misting was added to maintain continuous leaf wetness, and ascospores were released from apothecia twice daily for four consecutive days. Spore trapping with a semi-selective medium indicated that inoculum was evenly distributed within the chambers and deposition was similar to levels recorded in the field. At 31 days after inoculation, disease incidence ranged from 0% on the control to 96% on the freeze treatments. Freeze-treated plants showed the highest disease severity throughout the entire incubation period. Mean area under the disease progress curve of severity values were 0, 0.2, 34 and 60 for the control, cut, bruise, and freeze treatments, respectively. Results indicate that freeze and bruise injuries are important factors associated with infection of cabbage by S. sclerotiorum.


2008 ◽  
Vol 7 (7) ◽  
pp. 1227-1230 ◽  
Author(s):  
M. Carmen Ruiz-Roldán ◽  
Victoriano Garre ◽  
Josep Guarro ◽  
Marçal Mariné ◽  
M. Isabel G. Roncero

ABSTRACT Knockout mutants of Fusarium oxysporum lacking the putative photoreceptor Wc1 were impaired in aerial hyphae, surface hydrophobicity, light-induced carotenogenesis, photoreactivation after UV treatment, and upregulation of photolyase gene transcription. Infection experiments with tomato plants and immunodepressed mice revealed that Wc1 is dispensable for pathogenicity on plants but required for full virulence on mammals.


1999 ◽  
Vol 50 (4) ◽  
pp. 623 ◽  
Author(s):  
P. A. Pittaway ◽  
P. A. Pittaway ◽  
Nasril Nasir ◽  
K. G. Pegg

Disease severity associated with the pathogen Fusarium oxysporum is generally thought to be proportional to the population of fungal propagules in the soil. However, results from studies using naturally infested soil are contradictory, implicating host predisposition to disease. In this study, soil was amended with chicken manure to investigate the interdependence between the activity and invasiveness of the pathogen, and the incidence of Panama disease in susceptible banana plantlets. Two soil types naturally infested with either race 1 or race 4 of the pathogen, and cultivars Lady finger and Grande Naine, were used. Pathogen activity was measured by burying root tip segments for 5 days, then calculating the frequency of isolation of Fusarium from the segments. Pathogen invasion was measured by transplanting banana plantlets into trays of amended and unamended soil for 4 weeks, then calculating the frequency of recovery of Fusarium from each pseudostem. Amending both soil types with chicken manure enhanced both pathogen invasion and disease incidence. However, pathogen activity was not correlated with either parameter. We postulate that the addition of chicken manure is predisposing banana plantlets to Panama disease, by reducing the efficacy of the host wound response.


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