'02 



THE CAN A D T A \ TT O T? T T T r T/IM ' R T S T 



August, 1014. 



Marketing Early Tomatoes. Metirs. M. O. Field & Son*, Grimtby, Ont. 



into the main limbs and trunk. Here it 

 may form large cankers and through 

 cracks in the diseased bark, the yellow- 

 ish liquid will ooze in large drops. Large 

 limbs or even trunks may be girdled in 

 this way and destroyed. In the east this 

 form of the disease is most common in 

 pear trees, but in the northwestern States 

 and British Columbia it frequently as- 

 sumes this form on many varieties of ap- 

 ples and causes immense loss. In years 

 of epidemic it may spread like a blight- 

 ing flame from orchard to orchard car- 

 rying destruction with it. While it is 

 too early to say how this disease may' act 

 under Nova Scotian conditions, it does 

 not seem probable that the disease will 

 assume this virulent form. Observations 

 so far seem to show that usually the in- 

 jury is confined to the blighting of the 

 current season's growth, which, while 

 it does not seriously injure the tree, may 

 totally destroy the crop. 



In the summer when the tree begins 

 to ripen up its wood, holdover cankers 

 are formed on limbs and trunk at the 

 base of diseased shoots. These have 

 the characteristic water soaked appear- 

 ance when fresh and are usually separ- 

 ated from the healthy tissue by a crack 

 or fissure. 



The forms of the disease then are — 

 blossom, twig body and holdover blight. 

 Rody blight is the most serious form of 

 the disease, but does not appear to be 

 prevalent in Nova Scotia. The blossom 

 blight, which destroys the crop, but 

 does not kill the tree, is the form we 

 have to fight. 



SPREAD OF THE DISEASE. 



The principal agent for the spread of 

 blight is the bees, that carry it around 

 frorn flower to flower at blossoming time. 

 Aphids, leaf-hoppers, plant bugs and 



other sucking insects are attracted to the 

 sweet juice that oozes from diseased tis- 

 sue and becoming aff^ected from this 

 source, are important carriers of this 

 disease. In Ontario it has been found 

 that the Fruit Bark Beetle (Eccoptogas- 

 ter rugulosus) is often responsible for 

 carrying the' disease into the body of the 

 tree. Sap suckers and humming birds 

 may also have something to do in carry- 

 ing the disease from place to place. One 

 of the most potent and dangerous meth- 

 ods of blight dissemination is by the use 

 of infected pruning tools. Persons who 

 cut out diseased limbs without disinfect- 

 ing after each cut are liable to aggravate 

 the disease instead of controlling it. 



TKEES AND VAEIETJES AFFECTED. 



Besides the apple, pear and quince, 

 certain wild and ornamental plants are 

 known to be affected. The mountain- 

 ash, the hawthorn and the shad bush 

 are the chief of these. A disease known 

 as "wither tip" of poplar is often mis- 

 taken for fire blight, but bears no rela- 

 tion to it whatever. 



While all varieties of apples may be 

 attacked, they present a very wide varia- 

 tion in their degree of susceptibility to 

 the disease. So far we have found the 

 disease is most prevalent on the Nonpar- 

 iels though it has also been noticed on 

 Gravenstein and Baldwin. Further in- 

 vestigation will doubtless show other 

 varieties attacked. 



CONTROL OF THE DISEASE. 



The disease may be partially controlled 

 by killing the insects that spread it 

 about. While we cannot hope to get at 

 the bees, we can destroy the others by 

 the use of Black Leaf 40, either alone or 

 with flour paste, applied when the leaves 

 are about the size of mouse ears. This 



method, however, is and must always 

 remain only a partial one. The only 

 cure for the disease is cutting out the 

 diseased limbs. This should be down 

 to about a foot below the diseased part, 

 and the lools used in cutting must be 

 disinfected after each cut. For this pur- 

 pose corrosive sublimate is used in the 

 strength of i-iooo of water. Tablets can 

 be obtained at the drug store, one tablet 

 of which dissolved in a pint of water will 

 give the desired strength. This must 

 be u.scd in a wooden or glass vessel as it 

 corrodes metals. The most convenient 

 method is to use a small glass bottle or 

 flask whi<h can be kept in the pocket. 

 Attach an ordinary bath sponge to the 

 wrist by a string and keep wet with 

 liquid from the bottle. By this method 

 the pruning shears can be swabbed off 

 after each cut without loss of time, and 

 both hands are free to be used when nec- 

 essary. In cutting out hold-over cankers, 

 the bark for two or three inches around 

 the diseased area should be removed and 

 after drying the wound should be paint- 

 ed over with coal tar or white lead. For 

 disintccting purposes, formalin, one pint 

 diluted to three gallons, may be substi- 

 tuted for, corrosive sublimate. 



Careless cutting is worse than useless, 

 and puts an orchard in worse shape than 

 before. It must be understood that this 

 disease cannot be destroyed by spray- 

 ing. No more than a diseased bone can 

 be cured by the application of an oint- 

 ment to the skin, can this disease be de- 

 stroyed by sprays. Surgery is the only 

 remedy, and must be fearlessly done. 

 Better cut out a little too much at first, 

 than to have to continue the operation 

 indefinitely. I know of nothing in the 

 whole realm of plant pathology that of- 

 fers such opportunities for cooperative 

 effort as in the control of P'ire Blight. 

 With other diseases you can spray and 

 obtain good results regardless of your 

 neighbors, but with Fire Blight your 

 work will be rendered useless if a source 

 of infection exists near by. 



Injury from Root Killing 



Editor, The Canadian Horticulturist, 

 -r— We are getting numerous inquiries 

 concerning trees which leaf out and then 

 die more or less suddenly. These are 

 the customary symptoms of root killing, 

 although a great many fruit growers do 

 not seem to be aware of this form of win- 

 ter injury. We have investigated a 

 number of cases of this kind, and always 

 with the same results. If any of your 

 correspondents have been losing trees in 

 this way, we shall be glad to send a man 

 to investigate the same and report. At 

 a later date we shall be glad to inform 

 your readers more fully as to the results 

 of our studies. — J. W. Crow, O.A.C., 

 Guelph. 



