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Black Dry Rot in Swedes. 



dung proved disastrous on limed land and harmless on 

 unlimed. It may be that the lime has injured — as it often 

 does — the water-holding capacity of the soil, and that the 

 roots suffered more from the drought of last summer, and so 

 were open to infection. In favour of the view that 

 the water-holding capacity has been interfered with, is the 

 fact that the adjoining grass land has suffered from over- 

 liming, and that a clay patch in the turnip field suffered less 

 than the rest. On the other hand, the roots on a patch of 

 silt — the site of an old tarn — which was much moister than 

 the rest of the field, were all badly affected. On the whole I 

 am inclined to think that the more probable connection 

 between lime a'nd th« disease is due to the effect of lime, 

 not on the host, but on the parasite. It is quite likely that 

 the micro-organism responsible for black dry rot is one 

 that flourishes only in soils well supplied with lime and so 

 kept free from acidity. 



In a letter dated January 5th Mr. Middleton informed me 

 that he had seen a good many turnips affected with this 

 disease on other farms in the Naworth district, though none 

 so bad as Tryermain. It has not been reported to me from 

 any other district. 



Dung made from roots infected by the disease should not 

 be used for growing turnips. The best plan would be to cart 

 decayed roots on to permanent grass; or, if the field 

 will not be used for growing turnips again for a number of 

 years, they may be consumed on the land as soon as the 

 disease is observed. When the crop becomes thoroughly 

 diseased stock will not touch it, and it is only fit to plough 

 in as manure. 



T. H. Middleton. 



Microscopic Investigations of Btack Dry Rot in Swedes, 



Towards the end of December, 1901, some diseased swede 

 from Tryermain Farm were submitted to me for examination. 

 These I found to be attacked by the parasite fungus Phoma, 

 an account of which I published in the Journal of the Board 



