The crown gall disease of grapevines caused by Rhizobium vitis is one of the
major causes of economic losses of grape production. Recent reports have
found water-based plant extracts showing antimicrobial activity. Researchers
now investigate the water-based crude extracts from hairy vetch (Vicia
villosa) and ryegrass (Lolium perenne) for their antimicrobial activity
against R. vitis in a greenhouse as well as their ability to induce
defense-related genes in grapevines (Vitis spp.).

A total of 100 ml of each extract concentration (125, 250 and 500 g/L) was
prepared from fresh and pounded shoots and roots. These extracts were then
applied to grapevine cuttings once every 10 days. The extracts displayed
remarkable antibacterial effects, indicated by reduction of gall formation
in treated grapevines compared to the untreated vines.

The expression of several defense-related genes was also investigated and it
was found that treatment with the extracts of hairy vetch and ryegrass
induced the activity of defense-related genes. Based on these results,
extracts from tested crops can act as efficient biological plant-defense
inducers and therefore capable of serving as an alternative control strategy
for grapevine crown gall protection.

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