1 li« Si/irr- Leaf Dineme, TIT 



iiiofiilalioiis |ioil'()inu'(l in ii. .soincwlitit .similar iiiaiitior .since then have 

 };iven nctiiit-ivc results. TIuls hranclics of yoiin<i Victoria plum tree.s 

 were ,sna|)|ii'(l aero.s.s and filter licin;,' Icll in tiii.s coiidil ii)ii lor some 

 months, spores were inserted in the wounds without inducinj; siivi^'iiif;. 

 Other hranidu's \v(M'e cut olT to within two inches of the main stem and 

 after leaviu"; the ends exposed for various periods, sjjores were inserted, 

 also witii nefjative results. 



Inoeidatioiis with spores of Slcrcitni piiriiiironii carried out, however, 

 under conditions more favourable for infection have nevertheless been 

 followed by silverinp of the foliajie in a considerable innnber of cases. 

 The method of inoculation was as follows: 



'Pile nuiin stem of a younf; healthy plum tree was cut back, and a little 

 above the exposed surface a sporo])hore of Slerenm purpiireym was sus- 

 pended from a pin after an interval during which the siirfacc was left 

 open to the weather or protected fiom it by means of a tube. A wad of 

 dump col I on wool was placed over t he s|)orophon' to cause it to deposit 

 spores freely, and the whole was enclosed in a ij;lass tube fastened to the 

 top of the stem by means of plasticine. With this ari'an<;cmeid, a heavy 

 s|)orc de|iosit fell on the end of the stem under conditions favourable 

 for f:!crminati()n and infection. The experiment was varied in different 

 ways the end of the stem was sawn and covered with yas tar oi' Stock- 

 holm tar ill some eases, in others the sawn or smoothed surfac(> was hdt 

 without treatment by an antiseptic. The follow ini; ai'e details of (he 

 e\|ieriments carried out durinj.' 19115 II. 



( I ) The main stem of a standard Victoiia tree .'5 4 years old was cut 

 back with a saw to within two feet of the ground on J)ecembcr '2ii<\, 

 I'.) I.'!, and the surface td\i'red with gas tar. This remained exposed 

 until .laiiiiary ."ilst, l!MI, when a sporophorc of Slerewn purpurevm , 

 taken fiom a silvered plum tree, was placed over it and covered with a 

 Hterilized tube as described above. The fungus was removed two days 

 later and the lube re]ilaced. On May l.'Uh a branch arising an inch 

 below the iiiiiciilated surface, was heavilv silvei'cd although other 

 branches below this were normal. Hy .lidy other branches had become 

 silvei'cd and by the middle of Sept(Mnber the whole tree was affected. 



("J) .\ stamlaril C/.ar. ."> I years old, treated as in (1) e.\ce|)t that (he 

 cut cui'faee was left untouched. On May IHth. 1911, a branch arising 

 '1\ inches below the ]ilace of inoculation was silvered and the cut surface 

 was gumming and eovei'ed with a greyish mve<'lium, Sihcring did not 

 extend much in this tree, only one ot hei- branch beenming alTeeted 

 before the auliimu. 



