The Hop Aphis. 



81 



p. 548, may be consulted. The spray should be fine, but not so 

 fine as to become practically a mist, the object being to drive 

 the wash with sufficient force to thoroughly wet every leaf of 

 the growing plant. The -amount of wash required will vary 

 with the machine and the state of the bine. For a fully-grown 

 garden, 200-400 gallons per acre will be needed. 



Washing should begin as soon as lice are detected on the 

 young leaves. It is almost impossible to clean the garden if 

 once the aphis is allowed to get a start. In bad seasons washing 

 may have to be repeated again and again, practically continuously 

 throughout June, July, and early August. Every effort should 

 be made to get the plant clean before the hops begin to form, as 

 it is impossible to reach the aphis if once it gets a lodgment 

 inside the cones of the hop. For this reason a late attack of 

 aphis is the most dreaded by the hop-grower, because he is then 

 powerless to stamp it out, though washing right up to the time 

 of picking will keep down the numbers which enter the hop. 

 The lower leaves and laterals, and suckers about the base of the 

 plant, should be stripped away, as they harbour lice and are 

 difficult to wash. 



The cost of washing on a large scale amounts to about 20s. 

 per acre for both materials and labour, but much depends on 

 the proximity of the water supply. 



As the hop aphis in the main migrates from the sloe, damson 

 and plum to the hop, the use of the Caustic Wash, described in 

 Leaflet No. 70, on the fruit plantations in the winter will tend 

 to diminish the attack on the hops in the following summer by 

 destroying the eggs of the aphis. 



A rather stronger preparation of the wash above described is 

 equally effective against other kinds of aphis. It is particularly 

 necessary to attack those infesting the apple and plum at an 

 early stage, for they very soon cause the leaves to curl and pro- 

 tect themselves from any possible spraying. 



Other Insect Pests of the Hop. 



The Hop Flea (Haltica concinna), a near relative of the 

 common Turnip Flea Beetle, is often a serious trouble to hop- 

 growers. In early spring it attacks the young bine and devours 

 the first leaves. Towards harvest it harbours in the hops them- 



G 



