Nov. i6, 1914I Pecan Rosette 155 



It will be noted from the results of these experiments in transplanting 

 that of the healthy trees set after resetted trees nearly all subsequently 

 contracted the disease, while of those set after healthy trees only about 

 half subsequently showed symptoms of the disease. This would point 

 toward the conclusion that some relation exists between pecan rosette 

 and the soil, either directly through the soil itself or through its previous 

 infection by rosetted trees. 



Furthermore, it has been shown that of rosetted trees set after healthy 

 trees in the same locality or replanted in entirely different situations, a 

 very high percentage of the trees and often all recovered. This would 

 tend to indicate that the soil relation is the direct cause of rosette rather 

 than infection of the soil with parasitic organisms from previously 

 diseased trees. 



Top soil and subsoil were taken separately in March, 191 3, from the 

 immediate vicinity of trees in the last stages of rosette at Belleview 

 and at Tallahassee, Fla. This soil was shipped to Washington D. C, 

 and in early June, 17 normal, recently germinated pecan seedUngs were 

 set in each of the four soil types. At the same time a like number of 

 seedlings were set in the garden soil ordinarily used in the Department 

 greenhouses. In both cases the top soil was a sandy loam. The Belle- 

 view subsoil was almost clear sand, while the Tallahassee subsoil was 

 a pasty red clay. Observations were frequently made throughout two 

 seasons, but no symptoms of rosette appeared in any case. Of course, 

 a test of this kind with a small quantity of soil in a porous 8-inch pot 

 must be rather inconclusive with reference to any effect of the chem- 

 ical ingredients of the soil, but it was thought that if the rosettte were 

 caused by any organisms living in the soil surely there would be a chance 

 of at least some of the trees contracting the disease. Even from this 

 point of view two seasons under observation are not sufficient, but taken 

 in connection with the other rosette work the evidence at this stage of the 

 experiment is perhaps worthy of record as tending to indicate the non- 

 ' parasitic nature of the disease. 



GERMINATION OF NUTS 



In order to determine the communicability of the rosette, pecan nuts 

 matured in the fall of 1912 on rosetted trees were planted in moist sand 

 in one of the Department greenhouses in Washington, D. C. As they 

 came up they were potted in garden soil and kept under observation 

 during the spring, summer, and fall of 1913, and the summer of 1914. 

 The nuts were obtained under the following conditions: 



Of 12 nuts obtained directly from a rosetted branch, 9 germinated. Of 

 10 from a tree, most of which showed rosette, 9 germinated. Both lots 

 were from the seedling orchard of Dr. W. P. Williams, Blackshear, Ga. 



