154 



Liver Rot in North Wales, 1920-21. [May, 



less to the foliage of all but a very few varieties if properly ap- 

 plied. It will be seen that we have at present no entirely satis- 

 factory fungicide for summer use, and it is most desirable that 

 further research should be carried out to find one. 



Scab is controlled to some extent by pruning, and unless this 

 has attention spraying is much less effective than it might be. 

 On certain varieties, notably Cox's Orange Pippin, the winter 

 stage of the disease may be observed in a blistered or roughened 

 appearance of the bark of the young shoots. Such shoots should 

 be cut off during winter pruning and burned; otherwise the 

 fungus breaks through the bark later on and distributes spores 

 freely. All dead wood should also be cut out. It has been found, 

 moreover, in the pruning experiments at the East Mailing Re- 

 search Station, that scab is less troublesome on the fruit of trees 

 that have their leaders tipped every winter. This benefit is not 

 confined to varieties which show the winter stage of scab on 

 their young shoots. It is assumed, therefore, that it is due to 

 the fact that the tipping produces tougher, more vigorous leaves 

 which resist the disease. 



THE LIVER ROT EPIDEMIC IN 

 NORTH WALES, 1920-21. 



C. L. Walton, M.Sc, 

 Adviser in Agricultural Zoology, University College, Bangor. 



The epidemic of Liver Rot which devastated the lowland 

 flocks of North Wales in 1920-21 was undoubtedly the worst 

 experienced since the noted outbreak of 1879-80, although, to 

 judge by statements made by the older men, that attack was 

 even more widespread. The present notes deal solely with the 

 counties of Anglesey, Carnarvon, Denbigh and Flint. The 

 writer had carried out work in the Aberystwyth area in connec- 

 tion with this disease, more particularly regarding the life 

 history of the host snail, Limnaea truncatula * which experience 

 proved very useful in dealing with the 1920-21 outbreak. 



The parasite causing the disease is the Flatworm, Fasciola 

 hepatica, which inhabits the biliary duct, gall bladder and liver 

 of sheep, cattle, rabbits, hares, etc. This worm has a 

 complicated life history, and has as its intermediate host the 

 small fresh-water snail, Limnaea truncatula, within which it 



* See The Liver Rot of Sheep and Bionomics of Limnaea truncatula in 

 the Aberystwyth Area. Parasitology, Vol. II., December, 1917, pp. 232-266. 



