First Report of Artichoke Downy Mildew Caused by Bremia lactucae in Argentina

Abstract

In 1999, downy mildew was detected on artichoke (Cynara scolymus L.) plants from La Plata, Buenos Aires Province. The disease was observed on various commercial varieties. Symptoms were angular interveinal chlorotic spots less than 3 cm in size. These infected areas, although not confluent, covered a wide surface and caused early death of the leaves. On the undersides of these lesions, white-grayish sporulation was abundant, consisting of sporangiophores with dichotomous branches, widened in their peaks with 2 to 7 terminal sterigmata. Sporangia were ellipsoidal, hyaline and 14 to 30 × 12 to 25 μm in size. Oospores were not observed in leaf tissues. The pathogen was identified as Bremia lactucae Regel (1). Pathogenicity was confirmed with the inoculation of healthy artichoke plants. They were incubated in a humidity chamber at 10 to 15°C, and after 16 days chlorotic spots and downy mildew colonies developed. The presence of B. lactucae was confirmed by macro- and microscopic observation and Koch's postulates were fulfilled. This is the first report of downy mildew on artichoke in Argentina. Because it is widespread in the most important artichoke-growing area in Argentina (2), downy mildew should be considered in the cultural and sanitary management of the crop. References: (1) P. Corda. Hypermedia Prot. Plantes, INRA, 1995. (2) A. Ricceti et al. Bol. Hortic. 4:4, 1996.

Most Common Fungal Diseases of Globe Artichoke (Cynara scolymus L.) Production Areas

“…In areas where globe artichoke cultivation has been carried out for many years, there is a decrease in economic efficiency caused by important plant diseases and seasonal improper climatic conditions. It has been reported by various researchers that some important fungal diseases such as Verticillium wilt (Verticillium dahliae), White mold (Sclerotinia sclerotiorum), Gray mold (Botrytis cinerea), Downy mildew (Bremia lactucae) and Powdery mildew (Leveillula taurica) cause serious problems in the globe artichoke production in the World (Oin et al, 2008;Matos 2009;Doley and Jite, 2012;Larran and et al, 2004;Sherf and Macnab, 1986;Carranza et al, 2001;Agrios 2005). The study was carried out on the presence of economically restricting diseases of the globe artichoke produced extensively in the NC and increasing the complaints of farmers.…”

First report of downy mildew caused byBremia lactucaeonGerbera jamensoniiin Argentina

“…Kenneth and Palti (1984) compiled information about the relationship between Bremia and Asteraceae and observed that Bremia affects mostly hosts of the Cynareae and Lactuceae tribes and only two genera of Astereae. In Argentina, B. lactucae has been reported affecting three members of the Asteraceae family: lettuce (Lactuaceae) (Wolcan et al 2010), escarole (Cichorium endivia, Lactuaceae) (Goldemberg and Castronovo 1960) and most recently on artichoke (Cynareae) (Carranza et al 2001). Downy mildew caused by B. lactucae is an endemic disease in lettuce, which is cultivated in the same area as artichoke, escarole and gerbera but was not noted on gerbera in this region until 2007, and was not confirmed until now.…”