380 



far the most general and persistent enemy of hops, in 1882 the 

 damage done was said to amount to i 750 ooo and over 200 ooo 

 was spent in labour; either quassia and soft soap or nicotine and 

 soft soap are the best remedies, for they in no way harm the 

 foliage; the strig maggot (Diplosis Humuli, nov. sp.), very promi- 

 nent during 1909; the clay-coloured weevil (Othiorhynchus picipes, 

 Curtis); the hop jumper or frog-fly (Euacanthtis interruptus, L.). 

 Only one acarid occurs in sufficient numbers to do any harm, 

 namely the red spider (Tetranychus Altheae}. One very important 

 hop pest is the eelworm (Heterodera Schachtii A. Schur.), causing 

 " nettle head." It is probable also that the common eelworm (Ty- 

 lenchus devastator, Kiihn) plays some important part in the dying 

 back of hops. It must take years of patient research, it is assumed 

 before the part they play can be definitely settled. In all cases 

 of Tylenchus attack in hops which the author has observed in recent 

 years the fungus Fuso ma parasitic a has been present and it is a quest- 

 ion whether the latter is the direct cause of disease or whether 

 the eelworm makes the plant susceptible to this fungus. With the 

 insect and acarid enemies of the hop, growers can deal, but with 

 eelworm attack they are quite unable to stem the rapid tide of 

 disease that is reported now flowing. Science, it is stated, can do 

 nothing until much more is known of the bionomics of these mi- 

 nute nematode worms. 



However, The methods of prevention and treatment sugge- 

 sted are the following: i) The application of lime, for it has 

 been noticed that this and other eelworm attacks are most fre- 

 quent in soils deficient in lime, and that an application of it to 

 infected soil has proved of benefit; 2) the use of sulphate of potash 

 at the rate of from 2 to 3 cwt. per acre, this undoubtedly affects 

 the parasites in the soils, not only just around the affected hill, 

 but also around those near it; 3) collection of the parasites by 

 means of "trap" plants, the young plants may then be dragged up 

 and destroyed, a second sowing should be made at once and treated 

 in the same way. It appears that buckwheat attracts the eelworm. 



F. V. THEOBALD. The Insect and other Allied Pests of Or- 

 chard, Bush, and Hothouse Fruits. Wye, 1909, pp. xvi-559, 

 figs 328; E. S. j?., XXI, Dec. 1909. 



This book is said to be written solely with the object of placing 

 before fruit growers, gardeners, and amateurs an account of the 



