24 BOOT-KNOT AND ITS CONTROL,' 



West the writer has observed it, only sporadically it is true, in Utah 

 and Colorado and at one place in Nebraska. It is reported, and the 

 writer has seen specimens, from Arkansas. Oklahoma, Tennessee, 

 and Kentucky have no reports of it in the open, but it is probably 

 present to some extent, since it is found along the Ohio River in 

 West Virginia and also in northern Pennsylvania. It occurs, but not 

 in great abundance, in Delaware, Maryland, and Virginia The New 

 England States appear to be almost free from the trouble, so far as 

 outdoor plants are concerned, although it has been observed in Con- 

 necticut and Rhode Island. The most northerly points where it has 

 been observed out of doors in this country are at various points in 

 New York State, on ginseng and alfalfa; northern Indiana; Menomi- 

 nee, in the Upper Peninsula of Michigan; and the locality in Nebraska 

 already mentioned. In the last three instances all the evidence indi- 

 cates that the disease was directly imported from other localities and 

 was not indigenous to that locality. The important point is, how- 

 ever, and this will be reverted to, that this nematode is able to main- 

 tain itself in regions where the winter's cold may be very intense 



All of the localities named above are those in which the root-knot 

 nematode has been found out of doors, not merely on plants par- 

 tially protected during the winter, but in soil not at all protected 

 from the severest winter cold. In addition to these localities it is 

 almost universally present in this country in greenhouses and has 

 in a number of instances become more or less established out of 

 doors in their immediate vicinity, where it is protected by compost 

 heaps, etc., from the extreme cold. In the most northern States it 

 need not be feared that the pest will ever become widel}" distributed. 



A careful study of the distribution of the disease convinces the 

 writer that root-knot is of comparatively recent introduction in the 

 regions west of the Mississippi. Indeed, it is possible to trace its 

 arrival in parts of Texas, Arizona, and southern California, it having 

 appeared in recent years after the land had been in cultivation for 

 a long time with no signs of injury from such a pest. In Texas the 

 introduction and spread of the nematode has been accomplished 

 almost entirely by means of infected nursery stock, mainly figs, 

 mulberries, and peaches; in Arizona and California figs and the 

 Old World grape seem to be the responsible plants. The scattered 

 localities in the North where the trouble occurs often reveal, on care- 

 ful inquiry, the source of the infestation. Ginseng has been respon- 

 sible for several outbreaks, the nematodes doubtless having been 

 introduced in the moist earth in which the seeds were packed. In 

 other cases nursery stock, such as peaches or even apples, has been 

 responsi]:)le ; sometimes the soil thrown out from greenliouses has 



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