NOTES AND COMMENTS. 



453 



the handsome and well cultivated grounds 

 of Mr. Robson, who has one of of the neatest 

 appointed gardens in town, just alongside 

 that of Thomas Beal, who is truly said to 

 be the father of horticulture not only in the 

 town, but in the surrounding districts. 



Immediately south of the Exhibition 

 stands the beautiful new hospital, which was 

 a gift of Mr. Ross of Montreal, a former 

 resident of Lindsay. The building and the 

 location are simply magnificent, and would 

 well repay a visit. The beautiful edifice is 

 to be officially opened in a few days. 



PEAR CANKER. 



THIS is a disease which has been hitherto 

 confounded with pear blight, but 

 recent investigations prove that it is quite 

 distinct, and is caused by a well-known 

 fungus, Sphaeropsis Malorum. 



"The disease shows itself," says the 

 Delaware Bulletin 57, " on the main body 

 or on the larger limbs, as, round to elon- 

 gated, sunken areas, which are usually dark 

 or black in color. These sunken areas are 

 due to the death and dying-out of the inner 

 bark. The bark adheres firmly to the under- 

 lying wood, but commonly in the latter 

 stage of the malady, becomes cracked. 



" The dead area is usually bounded by a 

 crack, making a short line of demarcation 

 with healthy wood. The dead bark may 

 also show a number of cross fissures. These 

 areas are self-limited, or at least extend 

 slowly, but a number of adjacent areas may 

 coalesce, so as to girdle the limb or main 

 trunk, and thus kill the tree. Formerly 

 this disease has been confounded with the 

 ordinary pear blight, or fire-blight previously 

 mentioned, but the two troubles are entirely 

 distinct, both as to their character and cause. 

 Fire-blight is more diffusely spread ; in 

 other words, it is a general blackening of 

 the limbs, and does not appear in circum- 

 scribed areas on a limb or trunk. The 

 tissues also do not shrink or show cracking 



of the bark, which is so characteristic of this 



disease." 



Nature attempts to form new healthy bark 



underneath, and if some exterior application 



were effective in destroying the old fungus, 



the disease might be cured, and for this the 



following formula is recommended : formal- 



dehide, i pint ; glycerin, 2 pints ; water, 17 



pints. 



PEAR BLIGHT. 



THE cause and spread of this evil is no 

 longer so mysterious as in former 

 days. The Bulletin above quoted gives the 

 following important particulars : The 

 disease is caused by a minute germ or bac- 

 illus. This germ only needs to come in 

 contact with a blossom or be introduced into 

 the tissues of a leaf, young shoot or bud for 

 the disease to manifest itself. From that 

 point it extends slowly downwardly and 

 inwardly. 



One of the great sources of infection is 

 observed in the spring, when blighted twigs 

 are often seen to exude a milky looking 

 substance. This latter is the pear blight 

 virus in an almost pure state. If examined 

 under the microscope it is found swarming 

 with rod-shaped organisms or bacilli. From 

 this, too, the organism can be isolated and 

 grown upon artificial media, and from these 

 pure cultures, blossoms, buds, twigs and 

 leaves can be innoculated, and the trouble 

 reproduced. 



To show the relation of the milky virus 

 exuding in the spring from blighted trees to 

 spread of disease, a quantity of the latter 

 was collected on April 25th, 1902, just at 

 the time that the trees were coming into 

 bloom. This was diluted with sterile water 

 to make a turbid fluid, which the micros- 

 cope showed was swarming with pear blight 

 germs. By means of a camel-hair brush 

 dipped in the diluted virus, a number of 

 blossoms were touched in their centres and 

 infested with germs. The blossoms so in- 

 noculated were then enclosed in bags. 



