SUMMAEY. 75 



fertilizers, especially those containing potash, except where the soil 

 already contains this in abundance. This treatment often reduces 

 nematode injury greatly, {d) Flooding the land for a period of 

 some weeks, {e) Wliere rain is not likely to interfere, plowing and 

 allowing the soil to dry out for several months. (/) Preventing, by 

 the use of embankments, ditches, etc., the washing of soil from infested 

 fields to the field which it is desired to free from the pest. The intro- 

 duction of the pest by tools, wagons, farm animals, etc., should be 

 avoided. The trap-crop methods and the use of various chemicals 

 have not proved practicable as tested by the writer. The former 

 needs, perhaps, further trial. 



(9) The ideal procedure is to develop nonsusceptible strains of 

 plants, so that the expense and trouble of exterminating the pest 

 may be avoided. Such strains may be obtained by the selection 

 of more resistant plants or by crossing with resistant strains followed 

 by the careful selection and breeding of the progeny. 



Note. — ^While this bulletin was in press, there appeared a note in 

 Science,^ by L. N. Hawldns, describing the occurrence of Heterodera 

 radicicola in the roots of Typlia latifolia near Ithaca, N. Y. 



The writer has just received from Mr. G. L. Fawcett, plant patholo- 

 gist of the Porto Rico Experiment Station, Mayaguez, P. R., speci- 

 mens of the bark near the base of a 15-year-old coffee tree. Mr. 

 Fawcett wTites: "The disease is characterized by a roughem'ng of the 

 bark at the base of the coffee tree, extending from the surface of 

 the soil upward for a foot or two. No doubt it injures the tree, but 

 such injury must be slight. I have seen no sick tree the bad condi- 

 tion of wliich could clearly be ascribed to this nematode; only a 

 small percentage of the trees in any plantation are infested. It is 

 perhaps more common in moister and more shady places. Older trees, 

 say, those of 15 years or more, are the only ones noticed with this 

 disease." The living portion of the cortex was found to be very 

 densely infested with mature females of Heterodera radicicola. It 

 seems probable that these nematodes must have passed upward 

 through the soft tissue of the cortex from some original infection in 

 the root. It is worthy of note that sometimes in herbaceous plants, 

 such as tomato, the writer has found nematodes 6 inches or more 

 above the level of the ground within the cortical tissue of the stem. 



> Science, n. s., vol. 34, no. 865, July 28, 1911, p. 127. 

 217 



