25. Wilkinson, J. Ford. Preparation of stocks for propagation. Rpt. North. Nut Grow. Assoc. 28:65-66. 1937. A Root Disease of Persian Walnut G. FLIPPO GRAVATT, _U. S. Plant Industry Station, Beltsville, Md._ On three recent trips to southern Europe I noted large numbers of dying Persian (English) walnuts, _Juglans regia_, in France and Switzerland and scattered trees in other countries. Dying of Persian walnuts from a root disease of undetermined cause has been reported from various European countries for many years. The extensive dying of mature Persian walnut in a number of areas in southern France is very serious. Farmers and orchardists are discouraged from planting the Persian walnut even though it is a very profitable tree when not attacked by the root disease. In area after area I noted that the farmers had scattered their Persian walnut trees, separating them as much as possible or planting them along the boundary of fields instead of in orchard plantings. They had found too frequently that solid plantings of walnut die from the root disease. The total number of Persian walnuts in southern France has decreased alarmingly in the last sixty years. In Tessin Province in Switzerland many unhealthy Persian walnuts were noted this past summer showing the same symptoms as in southern France. Studies By French and Italian pathologists have indicated that the fungus _Phytophthora cinnamomi_ is the most likely cause of this dying of walnuts. I was informed that it is worse on soils inclined to be wet or poorly drained at certain times of the year, conditions favorable for attack of many hosts of this Phytophthora. The work reported by B. S. Crandall and me in Phytopathology, March 1945, showed there was a rather direct relation between soil conditions and _Phytophthora cinnamomi_ damage to black and Persian walnut seedlings. Long periods of heavy rainfall were very favorable for an epidemic outbreak of this fungus on walnut and other nursery stock. Another species of _Phytophthora_, _P. cactorum_, has also attacked black walnuts in nurseries in eastern United States; this fungus has also been reported on Persian walnuts. We are interested in receiving reports of the dying of Persian or black walnuts in orchards or rows of trees in the Eastern half of the United States. Persian walnuts suffer from winter injury in many areas and sometimes this injury is confused with the root disease. However, where there are indications of continuing dying of walnuts year after year with a progression from one part to another of the planting, we would like to receive a report. Some root diseases are difficult to diagnose, especially when the small roots are the parts affected.