scholarly journals Role of the Shrub Tamarix nilotica in Dissemination of Fusarium oxysporum f. sp. radicis-lycopersici

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.

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.


2006 ◽  
Vol 5 (2) ◽  
pp. 161-165 ◽  
Author(s):  
Khaled Hibar ◽  
Mejda Daami-Remadi . ◽  
Hayfa Jabnoun-Khiare . ◽  
Mohamed El Mahjoub .

2013 ◽  
Vol 53 (2) ◽  
pp. 172-176 ◽  
Author(s):  
Wojciech Szczechura ◽  
Mirosława Staniaszek ◽  
Hanna Habdas

Abstract Fusarium oxysporum f. sp. radicis-lycopersici (FORL) leading to fusarium crown and root rot is one of the most destructive soilborne diseases of tomatoes occurring in greenhouse and field crops. Physiological races of FORL were not defined but nine vegetative compatibility groups (VGCs) were identified. Infection followed by wounds and natural holes and infection is not systemic. The optimum soil temperature for pathogen development is 18°C. Infection may cause plants to wilt and die completely or infection may lower fruit quality. Fusarium oxysporum f. sp. radicis-lycopersici has the ability to produce a specific enzyme, tomatinase, which breaks down α-tomatine and protects the pathogen. In contrast tomato also has a defence system which consists of the enzymes chitinase and β-1, 3-glucanase. Tomato resistance to Fusarium oxysporum f. sp. radicis-lycopersici is determined by a single dominant gene Frl, localized on the long arm of chromosome 9. It was introduced to cultivars from Licopersicum peruvianum (L.) Mill.


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.


2015 ◽  
Vol 13 (4) ◽  
pp. e1009
Author(s):  
Ana I. Borrego-Benjumea ◽  
José M. Melero-Vara ◽  
María J. Basallote-Ureba

<p><em></em><em>Fusarium oxysporum</em> (<em>Fo</em>), <em>F. proliferatum</em> (<em>Fp</em>) and <em>F. solani</em> (<em>Fs</em>) are causal agents associated with roots of asparagus affected by crown and root rot, a disease inflicting serious losses worldwide. The propagule viability of <em>Fusarium</em> spp. was determined on substrate artificially infested with <em>Fo</em>5<em>, Fp</em>3<em> </em>or <em>Fs</em>2 isolates,<em> </em>amended with either poultry manure (PM), its pellet (PPM), or olive residue compost (ORC) and, thereafter, incubated at 30 or 35°C for different periods. Inoculum viability was significantly affected by these organic amendments (OAs) in combination with temperature and incubation period. The greatest reduction in viability of <em>Fo</em>5 and <em>Fs</em>2 occurred with PPM and loss of viability achieved was higher at 35°C than at 30ºC, and longer incubation period (45 days). However, the viability of <em>Fp</em>3 did not decrease greatly in most of the treatments, as compared to the infested and un-amended control, when incubated at 30ºC. After incubation, seedlings of asparagus `Grande´ were transplanted into pots containing substrates infested with the different species of <em>Fusarium</em>. After three months in greenhouse, symptoms severity in roots showed highly significant decreases, but <em>Fp</em>3 caused lower severity than <em>Fo</em>5 and <em>Fs</em>2. Severity reduction was particularly high at 30ºC (by 15 days incubation for <em>Fs</em>2 and by 30-45 days for <em>Fo</em>5), after PPM treatment, as well as PM-2% for <em>Fo</em>5<em> </em>and <em>Fs</em>2 incubated during 30 and 45 days at both temperatures, and with ORC (15-30 days incubation). Moreover, assessment of plants fresh weight showed significantly high increases in <em>Fo</em>5 and <em>Fs2</em>, with some rates of the three OAs tested, depending on incubation period and temperature.<br /><strong></strong></p>


HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 449D-449
Author(s):  
J.W. Scott ◽  
J.P. Jones

Lycopersicon pennellii accession LA 1277 was crossed to tomato (L. esculentum) and the F1 was backcrossed to tomato. Self-pollinated seed was saved from backcross plants and seedlings derived were inoculated with Fusarium oxysporum Schlecht f.sp. radicus-lycopersici Jarvis and Shoemaker, the causal agent of Fusarium crown and root rot (FCRR). Seed was saved from resistant plants that were self-pollinated and screened until homozygous resistance was verified five generations after the backcross. Three homozygous lines were crossed to Fla. 7547, a tomato breeding line susceptible to FCRR but resistant to Fusarium wilt races 1, 2, and 3. Subsequently, backcrosses were made to each parent and F2 seed were obtained. The three homozygous FCRR-resistant lines were also crossed to Ohio 89-1, which has a dominant gene for FCRR resistance presently being used in breeding programs. F2 seed were obtained from these crosses. These generations were inoculated with the FCRR pathogen. The resistant parents, F1, and backcross to the resistant parents were all healthy. The backcross to the susceptible parent and the F2 segregated healthy to susceptible plants in 1:1 and 3:1 ratios, respectively. Thus, the resistance from LA 1277 was inherited as a single dominant gene. This gene was different than the gene from Ohio 89-1 because susceptible segregants were detected in the F2 generation derived from the two resistant sources.


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