358 



Hop " Canker " or " Growfng-off." 



[July, 



tible to " canker," a certain number of dead hills are almost 

 invariably to be found. 



Varieties Susceptible to " Canker." — Some varieties of hops 

 appear to be more susceptible than others. In the Weald of 

 Kent and Sussex. Bramlings and Tolhurst are severely attacked ; 

 Fuggles do not escape the disease, but the injury inflicted is not 

 usually so great as in the above-noted varieties. In East Kent 

 the variety Eodmersham (or Mercer's) Golding has proved par- 

 ticularly susceptible; Bramling to a less degree, while Cobbs 

 and Old Golding are little affected. 



In Worcestershire the Mathon White is very liable to the 

 disease, and in Hampshire the Farnham Whitebine. 



Influence of Soil Moisture. — While by no means confined to 

 hop-gardens on heavy, wet soils, the disease does appear to be 

 favoured by moist conditions. The general experience of hop- 

 growers is that " canker " is worse in a wet season or following 

 a wet winter. If there is a wet clayey patch in a garden, the 

 " hills " are likely to be more severely attacked there than in 

 the other part of the garden, and that side of a garden which 

 gets least sun will frequently show the greater number of dis- 

 eased hills. A grower in East Kent writes : — " My garden of 

 Rodmersham Goldings which was so severely attacked by 

 " canker " lay rather low and damp, and somewhat shaded 

 from the early morning sun; the soil is a deep loam overlying 

 brick earth. I grubbed this garden and it has not been re- 

 planted, but I planted up some Eodmersham Goldings in another 

 garden which has a lighter and sharper soil, with a gravel and 

 chalk subsoil. The plants do not crop so heavily but on the 

 other hand we have much fewer losses by dead hills or dying 

 off after the bines have reached the top wire." 



The Fungus Causing the Disease.— The constant association 

 of the Fusariurn, fungus with the disease, and the fact that this 

 fungus can be directly isolated as a pure culture from tissues of 

 the hop-plant bordering on the healthy parts supply strong 

 presumptive evidence that the fungus is the cause of the disease. 



Inoculation experiments carried out by the writers on hop 

 sets, although not conclusive (owing to the fact that some of 

 the control sets contracted the disease) give further evidence in 

 the same direction. 



Eight hop sets were inoculated with the fungus (by placing 

 on the cut surface mycelium from a pure culture) and planted 

 up in pots; all gave rise to diseased plants, six of them becoming 



