F. T. Brooks and M. A. Bailey 211 



Of five additional trees treated with both farmyard manure and two 

 pounds of sulphate of iron each, applied to the roots, one recovered 

 two years after treatment. The use of sulphate of iron in this con- 

 nection will be referred to shortly. 



Thus there does not appear to be any reasonable prospect of ameli- 

 oration by manurial treatment, and, as is well known, the free use of 

 nitrogenous manures often has the effect of making jiiant tissues 

 specially susceptible to fungoid diseases. 



(b) Treatment with sulphate of iron. 

 The application of this substance, both as a dressing applied to the 

 roots and by plugging it into the stems was dealt with in the previous 

 paper of this series (2). The roots of four additional trees were treated 

 each with two pounds of this substance, two of them receiving a second 

 application, but all became worse instead of better. The experiments 

 in plugging silvered plum trees with sulphate of iron carried out by 

 Mr E. Neaverson near Wisbech, were described in a preliminary way 

 in 1913(2), and through his kindness we are enabled now to give the 

 final results of this experiment conducted by him. Of thirty-seven 

 slightly affected trees plugged in 1910, twelve recovered during 1911, 

 but by 1917 all of these had again succumbed to the disease some, 

 indeed, so badly, that they had been felled together with others which 

 had not recovered after treatment. Badly silvered trees plugged at the 

 same time showed no recovery. As some slightly silvered trees in the 

 same plantation also recovered without treatment, the above figures 

 indicate that the application of ferrous sulphate to silvered trees in this 

 way is not likely to be successful. When the treated trees were felled, it 

 was ascertained that the sulphate of iron had disappeared and had 

 presumably been absorbed into the tissues. Its toxic properties would 

 doubtless kill some of the fungus in the wood though probably only in 

 a limited zone. To ensure all parts of a tree containing the mycelium 

 of Stereum piirpureun) being permeated by a solution of ferrous sulphate 

 sufficiently strong to kill the fungus without seriously affecting the 

 living cells of the tree would be very difficult, and is likely to be more 

 completely effected by absorption through the roots than by the method 

 just described. 



(c) Treatment with the fruit-bodies of Coprinus. 



In 1913 Miss Baker announced in the Annals of Botany that she 

 had cured a silvered branch of a Victoria plum by injecting into it a 



