Fusarium Wilt of Lettuce Caused by Fusarium oxysporum f. sp. lactucae in Argentina

Abstract

The green belt area surrounding the city of La Plata, Argentina, produces more than 70% (around 280 ha) of the lettuce (Lactuca sativa L.) cultivated under greenhouse for fresh consumption in the country. In February 2011, April 2012, and December 2013, butterhead lettuce plants from cv. Lores showing wilt and stunted growth symptoms, red-to-brown discoloration of vascular tissues, and yellow leaves were found in greenhouses in La Plata. Sections of tap root, crown and stem from symptomatic plants showing dark-brown streaking of the vascular tissue were surface sterilized and isolations were made. A total of 21 monosporic isolates obtained from different lettuce production fields were identified as Fusarium oxysporum Schltdl. based on morphological characteristics (2). Vegetative compatibility group (VCG) analysis (1) was conducted on 11 of these isolates and all isolates belonged to the same VCG. To fulfil Koch's postulates, two pathogenicity tests were conducted with these 11 isolates in winter (July 2012) and summer (December 2013). Healthy 20-day-old butterhead lettuce seedlings of two cultivars (Reina de Mayo and Lores in the winter and summer tests, respectively) were inoculated by dipping the roots of each plant in a spore suspension (~3 × 105 CFU ml−1), planted in 1-liter pots containing autoclaved soil and grown in a greenhouse with only natural daylight. Control treatments were prepared by dipping the seedling roots in sterilized distilled water. All inoculated plants showed wilt symptoms 15 to 20 days after inoculation (dai) and 45 to 50 dai in the summer and winter pathogenicity tests, respectively. The delay in the appearance of symptoms observed during the winter test is consistent with the effect of planting date on the development and final incidence of Fusarium wilt of lettuce reported by Matheron et al. (3). No symptoms were observed in control treatments. F. oxysporum was re-isolated from vascular tissues of the stems of symptomatic plants and the formae speciales lactucae J.C. Hubb. & Gerik was confirmed by PCR using the specific primer pair GYCF1 and R943 (4). The identification of only one VCG for the tested isolates agrees with the hypothesis of seed transmission of the pathogen, which might explain the dissemination of Fusarium wilt of lettuce in geographically distant areas (2). Studies are being carried out to determine the race of these Argentinian isolates of F. oxysporum f. sp. lactucae. To our knowledge, this is the first report of F. oxysporum f. sp. lactucae infecting lettuce in Argentina. References: (1) J. C. Correll et al. Phytopathology 77:1640, 1987. (2) J. F. Leslie and B. A. Summerell. The Fusarium Laboratory Manual. Blackwell Publishing, Ames, IA, 2006. (3) M. E. Matheron et al. Plant Dis. 89:565, 2005. (4) G. C. Y. Mbofung and B. M. Pryor. Plant Dis. 94:860, 2010.

A new race of Fusarium oxysporum f. sp. lactucae of lettuce

“…Three races (1, 2 and 3) have been identified so far: race 1 was first described in Japan in 1967 (Matuo & Motohashi,), and was reported in the USA in 1993 (Hubbard & Gerik, ), Iran in 1995 (Millani et al .,), Taiwan in 1998 (Huang & Lo, ), Brazil in 2000 (Ventura & Costa, ), Portugal in 2004 (EPPO, ) and Argentina in 2014 (Malbrán et al ., ). Until recently, races 2 and 3 had only been reported in Japan (Fujinaga & Wada, ; Fujinaga et al ., , , ; Yamauchi et al ., ).…”

Pathogenicity of Fusarium oxysporum f. sp. lactucae in lettuce cultivars at different temperatures

“…lactucae (Matuo and Motohashi,1967) is considered the most important soil-borne pathogen of lettuce (Farr and Rossman, 2020;Matheron and Gullino, 2012). The disease was first identified in Japan in 1955 (Matuo and Motohashi, 1967) and after in California (USA) (Hubbard and Gerik, 1993), Taiwan (Li et al, 2014), Iran (Millani et al, 1999), Italy (Garibaldi et al, 2002), Brazil (Ventura and Costa, 2008;Cabral et al, 2014), Argentina (Malbrán et al, 2014), Belgium (Claerbout et al, 2018), the Netherlands (Gilardi et al, 2017a), France (Gilardi et al, 2017b), Egypt (El-Sayed et al, 2018), England, Ireland (Taylor et al, 2019), Florida (Murray et al, 2020) and Norway in 2021 (Herrero et al, 2021). The disease causes leaf yellowing and wilting of developed plants, vascular obstruction, and, finally, plant death.…”

Rapid detection of Fusarium oxysporum f. sp. lactucae on soil, lettuce seeds and plants using loop‐mediated isothermal amplification

“…lactucum, which was confirmed to be the same agent of the root rot in Japan. Fusarium wilt is a widespread lettuce disease (Fujinaga et al, 2001;Garibaldi et al, 2002;Malbrán et al, 2014), which can cause the total destruction of the crop in severe outbreaks (Garibaldi et al, 2002). In Italy, FOL causes important losses, especially in Lombardy (northwestern Italy), due to the intensive cultivation of lettuce in the same area, year after year (Garibaldi et al, 2002).…”

“…Four races have been identified within this forma specialis. Race 1, pathogenic on Patriot and Banchu Red Fire lettuce cultivars, was described in Japan in 1967 (Matuo & Motohashi, 1967) and is the most widespread race, reported in the USA, Iran, Taiwan, Brazil, Portugal, Argentina and Italy (Hubbard & Gerik, 1993;Huang & Lo, 1998;Millani et al, 1999;Garibaldi et al, 2002;Marques Ramalhete et al, 2006;Ventura & Costa, 2008;Malbrán et al, 2014). Race 2, pathogenic on Patriot and Costa Rica No.…”