Establishment of Southern Highbush Blueberry Cultivars and Suppression of Phytophthora Root Rot Using Cover Crop and Soil Amendment Treatments

Phytophthora root rot is a major disease of blueberry that relies on cultural practices, including soil amendments, for disease management. We evaluated the effect of three cover crops on the establishment and growth of southern highbush blueberry (SHB) plants and on their ability to suppress Phytophthora root rot infection of plants grown in a field previously identified to be infested with Phytophthora cinnamomi. In the spring and fall for 3 years, six soil amendment treatments (three cover crops [ Legume, Grass, and Brassica], aged ground pine bark [ Bark], fungicide drench [ Ridomil], and none [ Control]) were applied and tilled into the soil 6 months later. After 3 years, all soil amendment treatment plots were tilled into the soil, and 2-year-old plants of three SHB cultivars were transplanted into each treatment plot and grown for 3 years. Three bioassays failed to detect the presence of P. cinnamomi in the field; therefore, we were unable to determine the effect of the cover crops on Phytophthora root rot. Plant growth measurements (leaf and flower development scores and plant vigor ratings) and final measurements (cane count, total stem length and weight, cane diameter, and root measurements) showed no differences between plants grown in the Control treatment and those grown in the three cover crop treatments ( Brassica, Grass, and Legume); however, plants in the Bark treatment scored higher than those in the Control treatment in these parameters. The results support previous reports of the beneficial effect of organic soil amendments (e.g., peat moss, sawdust, bark) on blueberries. [Formula: see text] The author(s) have dedicated the work to the public domain under the Creative Commons CC0 “No Rights Reserved” license by waiving all of his or her rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law, 2025.