Different essential oils were tested against the fungus Ascosphaera apis, the causal agent of Chalkbrood Disease of honey bees. Essential oils from lavandin (Lavandula x intermedia Emeric ex Loiseleur), coriander (Coriandrum satioum L.), laurel leaf (kurus nobilis L.), false camphor (Cinnammum glandulifera Nees), basil (Ocimum basilicum L.), tagetes (Tagetes minuta L.), rosemary (Rosmarinus officinalis L.) and eucalyptus (Eucalyptus globulus Labill.) were assayed to prove their fungistatic activity at different concentrations: 700,800 and 900 p U . Strains of Ascosphaera apis were collected from apiaries of different places of Buenos Aires province (Argentina). At all concentrations tested, coriander oil was the most effective fungistatic control while basil and tagetes oils were effective only at 800 pLL/L. No differences in effectiveness of oils were observed against the different strains of Ascosphaera apis.

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In Argentina, due to climatic conditions, Fusarium head blight (FHB) caused by Fusarium graminearum, affected the 1993/94 wheat crop. To evaluate the severity of this disease, samples of wheat where gathered from four zones of the wheat area. Sanitary conditions and mycotoxin contamination were determined. One zone (IIN) was intensely affected by FHB with 90% of samples in grade III (bad quality). No samples were grade I (good quality). The other zones were less affected falling into grade I or II (moderate quality). In all samples tested F. graminearum was the most prevalent species singly or in combination with others. Zone II N, with a DON mean level of I1.26 ppm, did not fulfil aceptability limits, whereas zones IIS, III and IV with overall means of 2.12, 1.57 and 1.0 ppm, respectively, did. Statistical analysis showed a close relation between percentage FHB and DON contamination (r:-0.71, p<0.01) in infected samples.

During the growing season 2000-2001, symptoms of rot and brown to black mummified buds were observed on artichoke plants cultivated in Arana, Buenos Aires, Argentina, an area of intensive horticulture production. The present study was undertaken in order to determine the aetiology of the disease. The fungus isolated was identified as Botrytis cinerea. Pathogenicity was confirmed by inoculating buds of globe artichoke plants and cut buds with a spore suspension. Inoculated plants and cut buds developed symptoms and spores characteristic of grey mould. B. cinerea was re-isolated from inoculated buds. This work confirms the presence the grey mould, caused by Botrytis cinerea, on artichoke in Argentina.

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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.

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