Silvia M. Wolcan

More than 75% of the area dedicated to celery (Apium graveolens var. dulce) production in Argentina (over 120 ha) is annually cultivated in greenhouses in the green belt area surrounding the city of La Plata. Celery showing symptoms of rapid decline, delayed growth, chlorotic leaves, discolored vascular tissue and stunted root systems have been observed in this area since the late 1990s. Recently Fusarium oxysporum f. sp. apii (Foa) was identified as the causal agent (Lori et al., 2008). As three races of the pathogen are known to induce Fusarium yellows of celery worldwide (Puhalla, 1984), pathogenicity tests were conducted on two differential cultivars to identify the pathogenic race present in Argentinian crops. Isolates were obtained from diseased celery plants, identified as F. oxysporum morphologically and the forma specialis apii was assigned by pathogenicity tests on celery cv. Golden Boy as previously described (Lori et al., 2008). Seven strains of Foa were tested on cultivars Tall Utah 52-70 (re...

In autumn 2007, leaves of Gerbera jamensonii with typical symptoms of downy mildew were collected in Buenos Aires province, Argentina. Based on symptoms and the morphology of the fungus, the pathogen was identified as Bremia lactucae. This is the first report of downy mildew on gerbera in Argentina.

Sclerotium rolfsii is recorded for the first time causing collar dry rot on Impatiens walleriana (Balsaminaseae) in Argentina.

A powdery mildew caused by Oidium subgen. Striatoidium (Neoerysiphe sp.) on Aloysia citriodora in Argentina is described. This is the first report of powdery mildew on Aloysia spp.