Incidence of Cultural Practies on Incidence pf «Phytophthora nicotianae» var. «parasitica» Causing Root Rot of Lavender («Lavandula officinalis» L.)

The influence of cultural practices on the incidence of root rot of lavender (Lavandula officinalis L.), caused by Phytophthora nicotianae var. parasitica was evaluated in two trials carried out in 1996 and 1997. The effects of type of substrate, type of pot and cultivation site (open field or under shade) were evaluated on lavender plants grown in soils with and without artificial inoculation with the pathogen. Growing plants under shade significantly reduced disease incidence in both seasons. Plants in larger pots had lower disease incidence, irrespective of type of substrate, or the presence or absence of soil inoculation. The data obtained in this study highlight the importance of light, soil temperature and pot volume in the epidemiology of P. parasitica on lavender.