Crop rotation with brassicas reduces <i>Phytophthora</i> populations in potato soil

Abstract

A longterm trial (5 years) is being conducted at a commercial property on land that has a history of high incidence and severity of soilborne diseases Five rotational crops (potato pasture brassica cereal and squash) are being tested for their effects on pathogen inoculum Soil applications of metalaxyl fungicide are used as a standard treatment for comparison Soil samples are taken before and after each crop rotation cycle and plated on agar media for microbial enumeration to study the changes in fungal pathogen populations After three growing seasons rotational treatment of potato and cereal BQ Mulch (Brassica crop) reduced the level of Phytophthora and other (unidentified) fungi compared with the same rotation without BQ Mulch Metalaxyl has had no effect on the soil levels of Phytophthora and Pythium spp