150 Journal of Agricultural Research voi. iii.no. 2 



Statesboro, Albany, De Witt, Baconton, Thomasville, Cairo, Valdosta, 

 and Blackshear, Ga. ; Belleview, Palatka, Sisco, Gainesville, St. Augus- 

 tine, Jacksonville, McClenny, Glen St. Mary, Alachua, Lake City, Monti- 

 cello, Newport, and Tallahassee, Fla. ; Mt. Pleasant, Denmark, Bamberg, 

 Greenwood, Blackshear, Orangeburg, St. Matthews, Fort Motte, Cam- 

 eron, Sumter, Summerton, and James Island, S. C. ; Durham, N. C; and 

 at Eastville, Va. Besides personal observations at the places above 

 enumerated, specimens of pecans (Carya illinoensis) showing undoubted 

 symptoms of rosette have been received from a much wider territory 

 including Arizona, Tennessee, and other States. Similar symptoms 

 have been observed by the authors upon other species of hickory, notably 

 the mockemut {Carya alba (L.) K. Koch.), and the pignut (C glabra 

 (Mill.) Spach.), also upon the butternut (Juglans cinerea L.), the rock 

 walnut of Texas (Juglans rupestris Engelm.), the hackberry {Celtis 

 occidentalis L), and the common locust (Robtnia pseudacacia L.). 



Furthermore, pecan rosette does not appear to be limited to any par- 

 ticular soil type, topography, or season. We have noted many distinct 

 and undoubted cases in the deep sand of the Florida Coastal Plain with the 

 water table at 3 to 3^2 feet from the surface, farther inland in deep sand 

 or sandy loam with the water table varying from 2 to 10 feet, in sand or 

 sandy loam underlain by yellow, red, or white clay at depths varying 

 from a few inches to several feet and with a varying water table, in the 

 clay or sandy clay of washed-out hillsides, in the river bottom and alluvial 

 soils of Louisiana and Texas, in the black upland soils of Texas, in cul- 

 tivated and uncultivated land, with and without fertilization, in ex- 

 tremely rich and extremely poor soils, and in wet and dry seasons. In fact, 

 for the localities personally investigated, swamp land has presented the 

 only location so far entirely exempt. It is true that wherever the soil 

 tends to be water-soaked through a considerable portion of the growing 

 season the pecan presents an unhealthy appearance through its failure 

 to make proper growth and through the sickly yellow appearance of the 

 leaves. Under such conditions the tree usually dies sooner or later. The 

 symptoms, however, bear so little resemblance to those of rosette that 

 even the most casual observer will not confuse the two diseases. 



SYMPTOMS AND VIRULENCE OF PECAN ROSETTE 



Pecan rosette first makes itself evident through the putting out of 

 undersized, more or less crinkled, and yellow-mottled leaves (PI. XXIV, 

 figs. I and 2), particularly at the ends of the branches. The veins tend to 

 stand out prominently, giving a roughened appearance to the leaf blade, 

 and the light-green or yellowish areas which give the leaf its mottled 

 appearance occur between the veins. In these light-colored parts the 

 tissues are thinner and less fully developed than in the normal leaf, and 

 later in the season they frequently become dark reddish brown and dead. 



