59 



I believe 



Fig. 73. Canker fungus of 

 the bark of the pear. 



Fig. 72. Apple apparently suf- 

 fering from the attacks of 

 canker. 



to contaminate the healthy ones. The hands become covered with the 

 invisible spores, which may be unwittingly sown on to sound foliage 

 unless such care is exercised. When the disease is bad, it is best to mow 

 the beds, let them dry, then cover them with combustible material 

 and set fire to it. The new growth following will be clean and can 

 then be kept so. One per cent, sulphuric acid will also kill the diseased 

 foliage if sprayed on thoroughly. Bordeaux is an effective remedy. 



CANKER. 



Under the name of canker I have been accustomed to include a 

 disease differing from that ordinarily so called in Europe. There the 

 disease is, I believe, usually attributed to the genus Nectria. 



the most common bark- 

 destroying fungi on the 



apple in some other parts 



of the world are also, as 



here, not Nectria. The 



canker most commonly 



referred to in the pages 



of this Gazette is not caused by a fungus of 



that genus. 



The disease is not confined to the apple in 

 this State, but is found on the pear and quince as well. On another 

 page will be found a description of a disease of the Hawthorn, which 

 appears to be indentical with our canker of the apple. 



The following are some incomplete notes on a peculiar case of 

 canker occurring on the pear : 



The branches had been pruned, and it appeared as if the disease 

 might have started from the cuts, having, perhaps, been the result of 

 inoculation by means of the pruning shears 

 themselves. The branches had a deformity in 

 the shape of long radial swellings. At a stage 

 when the perithecia of the fungus had not 

 yet produced spores the outer bark was peel- 

 ing off in thin flakes of considerable size. 

 The perithecia were numerous and crowded, 

 and gave to the naked limbs a sooty black 

 appearance. Branches of mycelium grew 

 out from the perithecia. The perithecia 

 measured 250/x in diameter and were jet black, 

 and for the most part situated on the surface, 

 mycelium was dark-brown. 



In scars on the same branches were found spores of elliptical shape, 

 measuring 10-12 x 20-27/x, two-celled and dark brownish-green in 

 colour. It remained uncertain what was the origin of these spores, 

 and whether they were connected in any way with the perithecia. 

 These spores were borne on a dark mycelium which was in most parts 

 an aggregation of ellipsoidal cells, having a tendency to break up into 

 sporidia-like bodies. The spores were smooth on the surface. (See 

 Fig. 74.) 



X 4OO 



Fig. 74. * - ores from a case of 

 canker, -or so-called "sour 

 sap " of the pear. 



The subjacent 



