Red Stele Root Disease of the Strawberry Caused by Phytophthora Fragariae'

The root disease of strawberries that has been described as Lanarkshire disease (24),^ red core root (1), black stele (^), red stele, ^ and brown stele (21), first attracted attention in Lanarkshire, Scotland, about 1920 (3, 24y 25), The first published report of the occurrence of the disease in the United States was from Illinois in 1935 (4). Recent reports indicate that the disease has become widely disseminated in both the British Isles and the United States. According to the latest available references, its present distribution is as follows: In Scotland, 18 counties {18), including practically all strawberry-growing districts {2)] in England, 5 counties {18), including Kent, Hampshire, Devon, and Cornwall {11)] in the United States, lUinois (4), Maryland,^ New Jersey,^ New York,^ Michigan,^ Virginia,^ ^ Delaware,^ Indiana,^ Kentucky,^ Connecticut,^ Wisconsin,^ California {21), Oregon,^^ and Massachusetts ^^; in addition, the authors have received specimens of the disease from Arkansas, Ohio, Pennsylvania, Tennessee, and Washington. Investigations into the nature of the Lanarkshire disease were initiated soon after its discovery in Scotland. Wardlaw {2^, 25, 26y attributed the disorder primarily to poor cultural conditions that' paved the way for the entry of weak root parasites, and O'Brien and M'Naughton {17) to parasitism by endotrophic mycorrhiza. Alcock and her coworkers {1, 2, 3) first noted the association with diseased roots of oospores and sporangia that resembled those of Phytophthora, correctly deduced that this Phytophthora was the true cause of the disease, gave a brief description of it on its host plant, but did not name it ; their attempts to isolate and grow the organism in pure culture were imsuccessful. Anderson {4) first reported the black stele