Preliminary studies on development of a new environmentally friendly plant protection product against grey mould

The development of new environmentally friendly plant protection products against grey mould disease (caused by Botrytis cinerea Pers.) was started in 2010. In the Latvian State Forest Research Institute "Silava", production of coniferous biomass extracts using different solvents for extraction was performed. During 2010-2011, several laboratory investigations were carried out in the Institute of Biology, University of Latvia. Effectiveness of pine (Pinus sylvestris) and spruce (Picea abies) biomass extracts against Botrytis cinerea was tested. On the basis of coniferous extracts, 11 formulations were created and characterised. The effect of the formulations on mycelial growth of B. cinerea test cultures was tested using the fungal radial growth test. All formulations had inhibitory effect on mycelium growth (inhibition rate over 50%) at concentration 20 g L^-1 in medium. The impact of formulations on plants after spraying was evaluated using in vitro propagated strawberry plants. Chlorophyll content and chlorophyll fluorescence were estimated. Extracts did not show negative effect on the chlorophyll content and fluorescence of strawberry leaves. Field investigations on strawberry (Fragaria × ananassa Duch.) 'Senga Sengana' and primocane raspberry (Rubus idaeus) 'Gerakl' were conducted in the Pūre Horticultural Research Centre in 2011. None of tested the coniferous biomass extract formulations showed higher effectiveness than fungicide Signum® (pyraclostrobin 6.7%+ boscalid 26.7%, BASF).