engleski

Weeds as an inoculum source of parasites for cultivated plants

The target of our research supported by Ministry of Science and Technology was to determine weed plants as a possible source of inoculum for the infection of main field crops. In extensive literature it is documented on parasites associated with weeds as alternative hosts. These alternative hosts have an important role in disease epidemiology as a source of inoculum and as a conection between two vegetations (Dinoor 1974). Weeds, either simptomless plants or plants with simptoms, were collected during a six year period (1996- 2001) in Eastern Croatia. Isolations of fungi were made from root and stem tissue using routine laboratory methods (moist chamber, PDA and CLA media, incubation under 12h dark/light regime or in dark, what depends on fungi species as well as on temperature regime). Twenty two fungi species were recorded on 36 weed species from 15 families. Fusarium genus was dominant in most of the cases. Our pathogenicity studies show that all isolated Fusarium species (F. graminearum, F. moniliforme, F. subglutinans, F. culmorum, F. oxysporum, F. proliferatum, F. poae, F. avenaceum, F. sporotrichioides) are more or less pathogenic to wheat seedlings and spikes (Ćosić and Jurković 2000, Ćosić 2001). Velvetleaf (Abutilon theophrasti Medik.) and common ragweed (Ambrosia artemiisifolia L.) are found to be the hosts of Sclerotinia sclerotiorum (Jurković and Culek 1997). In sunflower, soybean and other hosts S. sclerotiorum can be very destructive, and our preliminary research showed that the parasite isolated from velvetleaf could be even more pathogenic for sunflower than the isolate of the same parasite from main crop.

weed ; inoculum source ; cultivated plants

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