Root-knot eelWorh. 103 



mentioned in larval and male condition to the second in every state, 

 that is, larval, male, or female, has led to repeated and grave error ; 

 and the gourd- or pear- shaped females should always be searched for 

 carefully, though, even in the absence of these, it is entirely presumable 

 that the formers of the " root-knot " galls will be the H. radicicola. 



' Prevention and Kemedies. — These at present appear, as a certainty, 

 and at a paying (or indeed practicable) rate of outlay, to have eluded 

 the most careful research. Some good it is considered may be done in 

 special growing (as where one kind of crop can be kept thoroughly in 

 hand, in limited space, or under glass, or in pots), by use of what are 

 called trap-plants. That is, by sowing some small crop which is an 

 object of attraction to the Eehvorms, such especially as Lettuce, some- 

 times known as Salad, and keeping watch on these until it is found 

 that galls are forming on the roots, then removing them, and destroy- 

 ing them with the contained pests. But in this treatment the utmost 

 care must be taken in removal of the "trap-plants," for if they are 

 drawn from the soil, however carefully, some of the galls, and with 

 them the Eelworm tenants, will be likely to remain behind. 



Such matters of precaution as carefully destroying all infested 

 roots, and on no account letting them be thrown to rubbish heaps ; 

 also avoiding use of soil in which infested plants have grown; and also 

 taking care that such infested soil is not carried about on garden tools, 

 or on boots of garden labourers, or wheels of barrows, are all measures 

 of at least lessening spread of the infestation. Also it has been found 

 that the "root-knot" is worse in long cultivated and fully fertilized 

 and thoroughly pulverized areas, than in compact and virgin soils. 

 Such of these points, however, as seemed serviceable for general use, 

 have been alluded to, with authorities given, in my preceding Report, 

 and those who wish to study the subject in minute detail will find 

 excellent information, both with regard to the Eelworms, their habits, 

 and such means of counteracting their ravages as are known, in the 

 works mentioned below.* 



The following observations refer entirely to a long and careful 

 series of experiments tried by the observer, from whom I received the 

 infested Tomato roots mentioned in my Sixteenth Report. From the 

 losses sustained by him, both in Tomato and Cucumber growing on the 

 very large scale carried on in his houses, extending over many acres, 



* ' A Preliminary Report upon the Life-history and Metamorphoses of a Eoot- 

 gall Nematode, Heterodem radicicola, etc.,' by Geo. F. Atkinson.— A Science Con- 

 tribution from the Agricultural Experiment Station, Auburn, Alabama, U.S.A., 

 December, 1889. 



'The Root-knot Disease, &c.,' by J. C. Neal, Ph.D., M.D., U. S. Department of 

 Agriculture. Washington : (jovernment Printing Office, 188'.). 



