The Canadian Horticulturist. 125 



points, dark amber color, curving backwards, just the shape of a buftalo liorii, giving the 

 gi-ub a splendid hold while cutting its way into the wood. 



If turpentine is applied freely enough to the excrescence, tlie grub will die without 

 cutting out, and the limb will heal over, out the safest remedy is the use of the knife. 

 Burn everything cut off and apply shellac to the wound. 



If any entomologist wants to get a specimen of the mature insect, cut off the knots in 

 May, on live limbs, place them in a glass jar, and in the hot weather you will see them eat 

 their way out of the wood, slough their chrysalis and come out perfect flies. 



Answers to the above on the origin of Black Knot by James Fletcher 

 and John Craig, Central Experimental Farm, Ottaiva. 



We are pleased to learn from the letter of Mr. T. Willis ( libbs that much 

 interest is being manifested by the farmers and fruit growers throughout the 

 country with regard to the origin and dangerous character of the Black Knot, 

 so seriously affecting our plum and cherry trees. Every inducement which 

 incites a desire among orchardists to study this enemy in all its bearings, is a 

 source of congratulation, as a study of its habits cannot fail to reveal its danger- 

 ous character, nor fail to point out the only remedy known thus far, by the 

 thorough application of which it may be successfully combated. It is for this 

 reason then, viz., that of directing attention to the necessity of combined and 

 co-operative action in fighting this enemy, that it is deemed advisable by the 

 writers to review briefly the life history of this disease, stating concisely, the 

 facts upon which our belief in the fungous nature of the disease is based. 



It may be well to state here that the disease known as Black Knot was 

 carefully studied by Dr. Farlow, of Cambridge University, about twenty years 

 years ago, then and now the leading mycologist of America. We are indebted 

 to this eminent scientist for much valuable data on the manner in which it 

 grows and multiplies. Not the least important part of his investigations was 

 that which at once proved its fungous nature and the possibility of transmitting 

 the disease by inoculation from wild forms of cherries to cultivated garden and 

 orchard varieties. Dr. Farlow states in a bulletin of the Bussey Institute, 

 issued March, 1876, that "we have made direct experiments to show that the 

 spores of the knot on the choke cherry will germinate and produce the knot in 

 healthy plum trees'' He says nothing of the necessity of insect agency or 

 assistance in developing the knotty growth. 



With regard to the statement that the excrescences are entirely due to the 

 attacks of an insect, the evidence submitted by Mr. Gibbs is very unconvincing 

 to us. His description, too, of the insect shows that he has not devoted much 

 time to the study of insects. We hope that next year he will make an effort to 

 send specimens of what he believes to be the cause of black knot to the Editor 

 of the Canadian Horticulturist for identification. We will merely submit 

 two facts : (i) At Ottawa the black knot is by no means a common disease, and 

 in many instances there are no insects whatever to be found at any time in the 

 knots. 2. Where the disease is abundant, the galls are as a rule much 

 destroyed by insects. This injury is caused by various insects belonging to 



