Ploetz Randy C, Schaffer Bruce, Vargas Ana I, Konkol Joshua L, Salvatierra Juanpablo, Wideman Ronney
University of Florida, Tropical Research and Education Center, 18905 SW 280th Street, Homestead 33031-3314.
Phytopathology. 2015 Apr;105(4):433-40. doi: 10.1094/PHYTO-07-14-0196-R.
Laurel wilt, caused by Raffaelea lauricola, is a destructive disease of avocado (Persea americana). The susceptibility of different cultivars and races was examined previously but more information is needed on how this host responds to the disease. In the present study, net CO2 assimilation (A), stomatal conductance of H2O (gs), transpiration (E), water use efficiency (WUE), and xylem sap flow rates were assessed in cultivars that differed in susceptibility. After artificial inoculation with R. lauricola, there was a close relationship between symptom development and reductions in A, gs, E, WUE, and mean daily sap flow in the most susceptible cultivar, 'Russell', and significantly greater disease and lower A, gs, E, WUE, and sap flow rates were usually detected after 15 days compared with the more tolerant 'Brogdon' and 'Marcus Pumpkin'. Significant differences in preinoculation A, gs, E, and WUE were generally not detected among the cultivars but preinoculation sap flow rates were greater in Russell than in Brogdon and Marcus Pumpkin. Preinoculation sap flow rates and symptom severity for individual trees were correlated at the end of an experiment (r=0.46), indicating that a plant's susceptibility to laurel wilt was related to its ability to conduct water. The potential management of this disease with clonal rootstocks that reduce sap flow rates is discussed.
由月桂拟层孔菌（Raffaelea lauricola）引起的月桂枯萎病是鳄梨（Persea americana）的一种毁灭性病害。此前已对不同品种和品系的易感性进行了研究，但关于这种寄主对该病害的反应还需要更多信息。在本研究中，对不同易感性的品种评估了净二氧化碳同化率（A）、水分气孔导度（gs）、蒸腾作用（E）、水分利用效率（WUE）和木质部液流速率。用月桂拟层孔菌人工接种后，在最易感品种‘Russell’中，症状发展与A、gs、E、WUE和日均液流减少之间存在密切关系，与更耐病的‘Brogdon’和‘Marcus Pumpkin’相比，通常在15天后检测到更严重的病害以及更低的A、gs、E、WUE和液流速率。在各品种间通常未检测到接种前A、gs、E和WUE的显著差异，但Russell的接种前液流速率高于Brogdon和Marcus Pumpkin。在实验结束时，单株树木的接种前液流速率与症状严重程度相关（r = 0.46），表明植物对月桂枯萎病的易感性与其导水能力有关。本文还讨论了利用降低液流速率的无性系砧木对该病进行潜在管理的方法。
