在接受长期土壤浸透和周期性漫灌的加州核桃生产园内,发现根颈腐病有很高的发病率。在土壤湿透的条件下,柑桔疫霉(Phytophthora Citricola)和樟疫霉(P.cinnamomi)与核桃树的死亡率高有关,这些核桃树嫁接在加州黑核桃和 paradox 核桃(核桃×黑核桃)上,此外,在接受喷灌延长土壤湿润期的核桃接穗上也观察到柑桔褐腐疫霉(P.citropth—thora)和果苹疫霉(p.cactorum)引起的核桃枝干或骨干枝溃疡病。 In the California Walnut Production Park, which is exposed to long-term soil infiltration and cyclical flooding, there is a high incidence of root rot disease. Phytophthora citricola and P. cinnamomi are associated with high mortality in walnut trees under soil-wet conditions. These walnut trees are grafted onto California black walnuts and paradox walnuts (walnut × black walnut ). In addition, on the scion of the walnut that was spray-sprinkled to prolong the soil wetting period, the stems or bony branches of the walnut caused by citrus pCitropth-thora and p.cactorum were also observed Canker disease.