On July 2, 2014, APHIS confirmed the detection of Pyrenopeziza brassicae (a fungal pathogen that causes light leaf spot or LLS) in canola and turnip plants from a farm in Oregon. Subsequently, P. brassicae has been found to be fairly widespread in 11 Brassica production fields and on weeds in the Willamette Valley. This is the first confirmed report; a previous, unconfirmed report of this pathogen in western Oregon dates to 1998.
This can be a serious pathogen on various Brassica species and is usually found on the leaves. P. brassicae can spread through the movement of contaminated or infected seed or through wind.
LLS is an important disease of brassicas in temperate regions. The disease is considered of minor impact, with blemishes and discoloration that reduce the market value of vegetable brassicas, although canola is highly susceptible. Climate conditions and timing of planting of susceptible cruciferous crops may not be conducive to LLS development in U.S. production regions outside Oregon.
The potential effects of this pathogen in Oregon are unknown.
Control of P. brassicae includes; use of resistant cultivars, debris management, protectant fungicide application, rotation to non-cruciferous crops and control of susceptible cruciferous weeds.
Under IPPC standards, Pyrenopeziza brassicae is considered to be a pest that is present: only in some areas in the United States.