Cabbage

This handout summarizes the results from clubroot resistant brassica (cabbage, broccoli, cauliflower, Napa cabbage, etc) variety trials conducted in 2015-16 on farms in the Willamette Valley of Oregon as well as in greenhouse screening trials.

Clubroot is becoming an increasing problem on Willamette Valley vegetable farms. Most cultivated brassica crops (broccoli, cauliflower, cabbage, etc.) are highly susceptible to the disease, which is caused by the soilborne fungus Plasmodiophora brassicae. In severe cases it can cause significant crop losses, and heavily infested fields may be taken out of production. Once a field is infected, eliminating the pathogen is difficult if not impossible because its thick walled resting spores have been shown to remain viable in soil for up to 18 years. As a result, once pathogen populations have developed to economically damaging levels, the goal of the farmer is to manage rather than eradicate the disease. One effective control strategy is to raise the soil pH to ≥7.2 through liming.

Myers, J.R. 2006.  Outcrossing Potential for Brassica Species, and Implications for Vegetable Crucifer Seed Crops of Growing Oilseed Brassicas in the Willamette Valley.  OSUES SR 1064.

The Cabbage Aphid can cause significant economic loses in broccoli grown in the Willamette Valley (Figure One). The feeding of the aphid on the broccoli plant may reduce yield slightly, but the real damage it causes is contamination. The cabbage aphid contaminates the harvested heads of broccoli. This can result in rejection of entire loads of broccoli by the quality assurance program of broccoli processors. Once the aphids have moved up into the developing broccoli head, it is possible to kill them, but it is no longer possible to remove them as a contaminant.

The Cabbage White Butterfly can cause damage to several cole crops in the Willamette Valley. This page provides some basic information about the pest and discusses management and controls methods. Detailed scouting and monitoring techniques are provided as well as a risk assessment for spray decisions.