Jacobs, Karel
MacDonald, J.D.
Berry, Allison M.
Costello, Larry

The Effect of Low Oxygen Stress on Phytophthora cinnamomi Infection and Disease of Cork Oak Roots

Date created
The incidence and severity of Phytophthora cinnamomi Rands root disease was quantified in cork oak (Quercus suber L.) roots subjected to low oxygen (hypoxia) stress. Seedling root tips were inoculated with mycelial plugs of the fungus and incubated in ≤1, 3-4, or 21 percent oxygen for 5 days. Ninety-four percent of roots became necrotic in the ≤1 percent oxygen treatment, compared to 60 and 46 percent in the 3-4 and 21 percent oxygen treatments, respectively. Root colonization and necrosis did not differ significantly between treatments. Fifty percent of inoculated roots remained asymptomatic in the atmospheric oxygen treatment, compared to 6 percent of roots in the near anoxic treatment. The asymptomatic roots were characterized by continued tip extension growth and lateral root formation above the inoculation point. Hypoxia increased the likelihood that roots became diseased, but not the severity of symptoms
Alternate Title
USDA Forest Service Gen. Tech. Rep. PSW-GTR-160. 1997