46 



A " Withe?' Tip" of Plum Trees 



The progress of the disease to the end of the month is shown in the 

 table: 



June 26 



3. Rot extends 2-10 mm. 

 from the wound 



4. No change 



5. No change 



6. More than half the sur- 

 face discoloured ; numer- 

 ous minute pustules 

 present 



7. Rot extends 4-10 mm. 

 from the wound 



S. About half the surface 

 discoloured; no pus- 

 tules 



9. No change 



10. Nearly half the surface 

 affected; no pustules 



June 28 



Three-quarters of surface 

 discoloured, numerous 

 small grey pustules pre- 

 sent 



No change 



No change 



Whole of the surfare dis- 

 coloured and bearing 

 numerous pustules 



Three-quarters of the sur- 

 face affected; numerous 

 pustules 



Whole surface affected ; 

 numerous pustules 



No change 



Nearly the whole of the sur- 

 face is discoloured and 

 bears numerous small 

 pustules 



June 30 



Whole surface discoloured 

 and bearing pustules; skin 



sulcate 



No change 



No change 



The other plum of tins pair is 

 attached to the inoculated 

 one by a thickened pad of 

 hyphae and a discoloration 

 extends over it for 2-5mm. 

 from the point of contact 



Both plums had fallen to the 

 ground 



Surface sulcate; a hyphal 

 pad attaches the other 

 plum to the affected one, 

 though former shows no 

 rot 



No change 



Whole surface affected; no 

 hyphal pad and the other 

 plum is not attached and 

 is not infected 



The later stages of the disease in the same plums are shown in the 

 next table: 



July 3 



Inoculated plum much 

 shrunken and sulcate 

 Drop of gum at woimd; 

 slight discoloration 



5. No change 



0. Inoculated plum much 

 shrunken and sulcate; 

 three-quarters of the 

 surface of the second 

 plum is discoloured and 

 bears numerous jjustules 



7. (Plum fallen) 



8. Inoculated plum shrun- 

 ken and sulcate; the 

 other is discoloured over 

 three-quarters of its sur- 

 face 



9. Drop of gum at wound 

 10. Inoculated ])lum shrun- 

 ken and sulcate; no rot 

 on the other 



July 11 



Inoculated plum fallen; the 



other shows no rot 

 No further change 



No change 



Both plums dry and shrivel- 

 led; stalk of inoculated 

 plum brown to base, stalk 

 of the other brown nearly 

 to base 



Both dry and shrivelled; 

 pustules p7'esent; stalks 

 brown to base 



No rot 



Hyphal pad present at point 

 of contact of the two 

 plums aiul the rot is in- 

 vading the second plum 



July 20 



The plum not inoculated 



still healthy 

 The gum has dried; black 



spot 2 mm. diam. round 



wound 

 No change 

 Stalks of both brown to base; 



gum is issuing from the 



apex of the spur 



No further evident change 



No rot 



Both shrunken and wrinkled; 

 surfaces bear numerous 

 pustules; stalks brown to 

 base 



