DISTRIBUTION OF ROOT-KNOT. 23 



The A'arious families of plants represented in the foregoing list and 

 the fact that the infections were obtained easily and very pronouncedly 

 would seem to indicate that the nematode causing root-knot of the 

 plants experimented with, including some of those most generally 

 affected in the field, is not as yet very markedly differentiated into 

 strains peculiar to certain hosts. It is still possible, and indeed quite 

 likely, that had seeds of the same host as that furnishing the roots 

 from which the nematodes came been sown in the pot along with the 

 other seeds the latter would have sliown less infection than the other 

 plants. Unfortunately, however, various circumstances prevented 

 this line of experiments from being carried out. 



Observations in the field seem to bear out the results of the pot 

 experiments. The writer has been unable to detect any special adap- 

 tation to any one species of plant. Indeed, peaches were attacked 

 very badly wlien planted where cowpeas had been grown for several 

 years. Figs and the Old World grape are the plants through which 

 the parasite has been introduced into many new districts, which could 

 hardly have been done so thoroughly and rapidly if the nematode 

 had become in a manner specialized upon them. 



DISTRIBUTION OF ROOT-KNOT. 



Root-loiot was first observed by Berkeley ^ on greenliouse plants 

 in England It was next reported by Greef ^ on out-of-doors plants 

 in Germany. Since then it has been observed in many parts of 

 Germany, France, Italy, Austria, Holland, Sweden, and Russia. 

 In Africa it is abundant in parts of Algeria, occurring even in some 

 of the Saharan oases, Egypt, German East Africa, Transvaal, Cape 

 Colony, and Madagascar; in Asia it occurs widespread in India, 

 Ceylon, and to some extent in China and Japan. In the East Indies, ' 

 Java and Sumatra are badly infested. No authentic reports have 

 been received of the presence of this pest in the Philippines, but it is 

 probably to be found there. Several of the Australian States are 

 infested, and the pest is not unknown in New Zealand. In South 

 America it has been reported from Chile, Argentina, and Brazil. It 

 seems also to be widespread throughout the West Indies. In Mexico 

 it is prevalent at many points. 



In the United States the root-knot is to be found in sandy soil now 

 or previously in cultivation in most parts of North Carolina, South 

 Carolina, Georgia, Florida, Alabama, Mississippi, Louisiana, and 

 Texas, as well as at many points in California. It is not abundant 

 in New Mexico or Arizona, although proving destructive in some of 

 the irrigated chstricts of the latter. It is very evidently of recent 

 introduction there, as in many parts of Texas. In the interior of the 



I Berkeley, 1855. * Greef, 18C4. 



217 



