THE EFFECT OF SPICE EXTRACTS ON STRAWBERRY PATHOGEN BOTRYTIS CINEREA
Botrytis cinerea, the causal agent of strawberry grey mold, has become a severe problem of horticultural farms due to its genetic variability and growing resistance to frequently used fungicides. Plant disease could induce significant losses of yields and plants thus it is necessary to discover and apply novel approaches to control strawberry pathogens. In addition, chemical plant protection products can leave undesirable residues in fruits and the environment. Plant protection should be more friendly to the environment and human than already used chemical measures. One of the alternatives could be plant-based extracts, produced from aromatic and medicinal herbs, spices, fruits. Therefore, the aim of this study was to determine the in vitro effect of cinnamon bark (Cinnamomum cassia L.) and clove bud (Syzygium aromaticum L.) extracts on B. cinerea colony growth. Experiments were carried out at LAMMC Institute of Horticulture, Lithuania. Both extracts were obtained from dried material by extraction with CO2. For in vitro assay, extracts were separately mixed with potato dextrose agar in concentrations from 200 to 1000 μl/l, poured into Petri dishes, then each dish was inoculated with 6 mm diameter B. cinerea disc and incubated at 22±2 oC in the dark for 7 days. The diameter of the pathogen colony was measured 2, 4 and 7 days after inoculation. Concentrations of the extracts, which demonstrated reduced growth of the pathogen, were considered to have an antifungal effect. The results showed that extracts of cinnamon bark and clove bud had a similar antifungal effect on B. cinerea and suppressed the growth of 100% from 600 μl/l concentrations 4 days after inoculation. At 600-1000 μl/l, no growth of the pathogen was detected for both extracts 7 days after inoculation. However, clove bud extract considered to be more effective, as the diameter of B. cinerea colonies was smaller compared to cinnamon bark extract at 200-400 μl/l concentrations. To conclude, spice extracts of cinnamon bark and clove bud demonstrated antifungal effect on B. cinerea in vitro and could possibly be applied for control of strawberry grey mold.