DANGEROUS INTERNATIONAL FOREST TREE DISEASES 



107 



Table 1. — Rating of susceptibility of trees and shrubs to Phymato- 

 trichum o rani vo rum root rot 



Hosts 



Susceptibility rating by- 



Streets 



Tabenhaus and 

 Ezekiel 



Wright and Wells 



Moderate. 

 Slight 



Ailanthus altissi?na (Mill.) Very. 



Swingle. 



Prunus armeniaca L do 



Fraxinus vebjtina Torr Slight 



F. pennsylvanica Marsh 



Catalpa speciosa Warder 



Juniperus virginiana L 



Gymnocladv.s dioicus (L.) K 



Koch. 



Populus deltoides Bartr 



Ulmus americana L _ 



U. crossifolia Nutt 



U. pu mila L 



Celtis occi dent ali s L 



Juniperus faccida Schlecht 



«/. scopulorum Sarg 



Robinia pseudoacacia L 



Gleditsia triacanthos L 



High. 



do. 



Verv. 



Verv. 



Very. 

 __do. 



Morus alba yar. tatarica Moderate... 



Slight. 

 ...do_. 



Eleagnus angustifolia L 



Madura pomijera (Raf.) Scheid. 



Diospyros virginiana L 



Pinus nigra Arnold 



P. taeda L 



P. ponderosa Laws 



Caragana arborescens Slight 



Sapindus drummondii Hook. & 



Arn. 



Celtis laevigata Willd J 



Platanus occidentalis L ' Slight 



Tamarix sp j do 



Juglans major (Torr.) Heller I do 



/. nigra L ! Moderate. 



Chilopsis linearis (Cay.) Sweet. _ ; Resistant- 



Moderate 



High 



Slight 



Resistant- 

 Extreme.. 



High 



Resistant. 

 Extreme.. 

 Resistant. 

 _._do____ 



Slight.. _ 

 Extreme. 

 do.. 



High 



Resistant. 

 do... 



Moderate.. 



do 



Susceptible. 



do 



Slight 



Extreme 



Resistant. 



do___ 



Moderate. 



High. 



Intermediate 

 Do. 



Intermediate 



Do. 

 Resistant 

 Susceptible 



Do. 



Do. 

 Intermediate 

 Susceptible 

 Resistant 



Resistant 

 Susceptible 



Do. 

 Intermediate 

 Susceptible 



Do. 



Intermediate 

 Susceptible 



Do. 

 Slight 

 Resistant 



Intermediate 



Intermediate 

 Resistant 



Control. — Losses from root rot in agricultural crops can be lessened 

 to some extent by soil acidification, deep cultivation, crop rotations 

 with monocots such as wheat, and addition of organic matter. For 

 trees and shrubs in shelterbelts. no definite reduction is possible ex- 

 cept perhaps by alternate planting of resistant with less resistant 

 trees in a checkerboard pattern. Plants grown in root-rot areas should 

 not be shipped elsewhere to similar climatic zones. 



Literature: 



Shear. C. L. The life history of the Texas root rot fungus, Ozonium 

 omnivorum Shear. Jour. Agr. Res. 30: 475-477. 1925. 



Streets. R. B. Phymatotrickwm (Cotton or Texas) root rot in 

 Arizona. Univ. Ariz. Tech. Bui. 71 : 299-410. 1937. 



Taubenhaus, J. J"., and Ezekiel, W. X. A rating of plants with ref- 

 erence to their relative resistance or susceptibility to Phymato- 

 trichum root rot. Tex. Agr. Expt. Sta. Bui. 527, 50 pp. 1936. 



687-137 O— 63 8 



