MB. R. THOMPSON — ON PEACH- AND NECTAKINE-TltEES. 147 



many substances by which trees can be readily killed — for instance, 

 common salt applied to the roots. This . substance would soon 

 kill the whole tree, but so quickly that it would be seen that 

 some such substance had been applied. Any ignorant person 

 could kill plants outright by certain applications ; but great skill 

 and abundant opportunities would be requisite to mitigate the 

 doses so as not to kill instantly, but cause a lingering, weakly 

 growth, by small doses frequently applied ; and this could not be 

 done without stirring the soil of the border in a way that would 

 lead to certain discovery. 



It can be seen that the branches have been done over with a 

 composition; but it is only such as is usually applied against 

 insects, with impunity. The ingredients were soft soap, tobacco- 

 water, sulphur, and water, with a little glue and loam to make the 

 mixture adhere. The proportions were by no means too strong ; 

 besides, it was applied after the foliage had dropped, whereas the 

 weakly shoots must have been produced in the course of the 

 summer, whilst the leaves were in action to elaborate sap ; for 

 through the leaves, the shoots, and all the solid parts of the tree, 

 even an oak, the sap must pass in a fluid state. 



Nothing could have affected these trees in such a peculiarly 

 injurious way except some kind of mildew. Of this I have no 

 doubt. The species of mildew are very numerous, and of late 

 have proved very destructive, — for example, that causing the vine- 

 disease, or vine-mildew {O'iditmi TucJceri), and another the potato- 

 disease (Botrytis infestans). These, and particularly the latter, 

 have produced disastrous effects ; and that which attacks the roots 

 of trees is allied to these ; it is probably the Byssus, or Bacodium 

 BhizopJiila of the Erench, which they say occurs more frequently 

 than is generally supposed, and attacks the roots of peaches, 

 apples, and roses, and many other plants, and kills them. They 

 describe it as one of the most perfidious enemies which we know ; 

 nothing announces its presence but death. I cannot however 

 pretend to determine the name of the species of mildew which 

 unfortunately attacked the trees at Chatsworth. 



Note. 



At the request of Mr. Thompson, specimens of the young wood 

 and roots of the several trees, and soil in which they were growing, 

 were submitted to Mr. Berkeley, together with a sample of the 

 compost which is used on the borders in the peach-house. The 

 condition of the first has been sufficiently described by Mr. 



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