Submitted to: Proceedings of Florida State Horticultural Society
Publication Type: Proceedings
Publication Acceptance Date: 10/1/2004
Publication Date: 12/1/2004
Citation: Bowman, K.D., Albrecht, U. 2004. Growth comparison of citrus rootstocks after artificial infection with Phytophthora. Proceedings of Florida State Horticultural Society. 117:156-160. Interpretive Summary: Phytophthora is one of the most economically important soilborne diseases affecting Florida's citrus industry. The most effective control in the field is based on the use of tolerant rootstocks in connection with good management strategies. This study describes the application of new and improved methods for the rapid greenhouse evaluation of seven rootstocks for tolerance to Phytophtora root diseases. Two commonly used rootstocks were confirmed to be severely damaged by the disease, while four other rootstocks, including one new USDA hybrid, were more resistant.
Technical Abstract: Seedlings of the rootstocks Sun Chu Sha, Cleopatra mandarin, US-897, Sour orange, 'Pineapple' sweet orange, Carrizo citrange, and Swingle citrumelo were inoculated with citrus roots derived from a field site known to be heavily infested with Phytophthora and maintained in the greenhouse in tubs containing a commercially available potting mix. Infection with Phytophthora was quantified using enzyme-linked immunosorbent assays (ELISA), and species were identified by restriction fragment length polymorphism analysis in combination with polymerase chain reaction (PCR). Shoot length, root mass and shoot mass were significantly reduced in Carrizo, 'Pineapple', and Swingle, exhibiting overall reductions of 44%, 48%, and 50%, respectively, whereas total reductions observed for Sun Chu Sha and Cleopatra were less than 25%. Values for Sour Orange and US-897 ranged in between the two groups. Results obtained in this study are in accordance with results obtained from field trials and provide valuable information to aid in the development of new citrus rootstocks that are tolerant to Phytophthora.