348 



AMERICAN FORESTRY 



in the nursery before it left Japan as every branch is dis- 

 eased, making a "Witch's Broom" of the whole tree. The 

 fungus grew as the tree grew, sending its thread-like bodies 

 through the living tissues of the tree and stimulating the 

 peculiar form of growth. Both the density and the short- 

 ness of the infected tree are clearh- shown in this illustra- 

 tion. The second view shows a tree that was evidently 

 attacked after it had attained considerable size. The main 

 branch on the right is free from infection, as is shown b\- 

 the normal growah, but the broomy growths occurring in 

 several places on the left branch each show the presence of 

 an infection. It is probable that this tree was infected 

 through the leaves. 



In the third illustration are shown the infected leaves. 

 The fungus develops the spore-bearing bodies on the under 

 side of the leaves, causing them to curve downward around 

 the edges to give the spores the advantage of a sheltered 

 place to grow and ripen. The crinkled effect identifies 

 these leaves, which are quite easily distinguishable from the 

 normal leaves around them. It is quite difficult to detect 

 the spore-bearing body on the under side of the leaf even by 

 close examination, as it is very inconspicuous. A faint 

 white bloom is the only visible sign of its presence. After 

 the spores have ripened and have been released into the air, 

 to be carried about by the wind, the leaves on which they 

 developed blacken and die. This will ordinarily happen a 

 few weeks after the leaves first appear. 



In spreading from tree to tree it is probable that the leaf 

 is first attacked. The infected tree develops the spores on 

 the leaves and releases them about one week after the tree 

 blossoms, so that they are free to attack other trees when 

 the leaves are only about half-grown and are still tender 

 and easily penetrable by the thread-like growths of the 

 fungus. 



It is not known whether any of our native cherries have 

 yet been attacked by this foreign parasite. But they may 



be eventually, and the fact that they have had no opjror- 

 tunity to develop resistance might mean a serious spread of 

 the disease if it once gains a foothold. The disease would 

 have an immediate effect on trees used for fruit production, 

 inasmuch as the diseased parts of a tree produce no fruit. 

 The effect on the lumber-producing cherr\- trees would be 

 felt only in the far future. It would be impossible to use 

 for lumber a tree that was made up of thick, broomy 

 branches. In fact, it is vcn,' doubtful if a tree attacked early 

 would ever reach merchantable size. The money value of 

 the fruit and lumber-producing cherries makes care in pre- 

 venting the spread of such a disease very much worth while. 



Since blossoming time has passed and this year's crop 

 of spores has long since ripened and started on the hunt for 

 prey, there is little possibility for action that will accom- 

 plish immediate results in preventing the spread of the dis- 

 ease. All cherries should be carefully examined, however, 

 for evidence of infection. If trees or parts of trees bear few 

 or no blossoms, have a dense, broomy growth, show curled 

 leaves which blacken at the edge and fall early, the assump- 

 tion is that they are diseaesd. They should be removed as 

 soon as detected, in order to prevent any possible spread. 



Although several species of Japanese cherry are com- 

 monly infected, the Yoshiro variety {Prunns serridata, but 

 more commonly called Prumis Ycdoensis) was the most 

 commonly attacked in the Washington Park and it is 

 therefore especially to be suspected. The Asagi or green- 

 flowered variety wiU also bear watching. 



In addition to this "Witch's Broom," these same Jap- 

 anese cherry trees are affected by the injurious Asiatic 

 twig borer described in a recent number of American For- 

 estry. That two such destructive pests could enter the 

 United States on a shipment as carefully watched as this 

 second one was, is conclusive e\adence that importation of 

 living plants from abroad, even if inspection shows them 

 apparently clean, is unsafe. 



FORESTERS IN WAR WORK 



THE following interesting letter has been received from 

 one of the foresters with the Forestry Battalion, 

 Canadian Expeditionary Force, stationed in England : 

 "We are now getting so close to the end of our timber 

 at Windsor Park that I have been kept pretty busy looking 

 over new areas. It is easy to find timber but difficult to 

 to find areas suitable for an operation like ours. Most of 

 the timber I saw was small Scots pine averaging about fif- 

 teen thousand feet B. M. per acre. My last trip was to 

 Whitley Camp. I am glad to say that we have given over 

 our old system of leaving slash. Our men now bum as 

 they cut. At the same time pit props (mine timbers) arc 

 cut and the fuel wood is ])ilcd. We find that this sy-stem 

 takes but little time and has obvious advantages." 



From a forester in France: "Over here in France our 

 world is centred of course on the Western front and I ha\-e 

 not heard very much of the doings in the forestry world in 

 Canada. Occasionalh- I mi^et the local French National 

 Forest officials and I can assure you that we have many 

 interesting professional talks together. Our present log- 



ging operation, of wliich I am in charge, is on a French 

 National Forest of mixed hardwood and softwood. It re- 

 minds me very much of the lectures given by our Dean. 

 The forest authorities exercise full control over the pri- 

 vate holdings such as we are cutting upon. For instance, 

 we must clean the surface entirely of all wood and debris, 

 not leaving even a twig. Luckily the local French 

 peasants are about and they eagerly take all the refuse. 

 This is appreciated when I tell you that this winter was a 

 very severe one in France and coal was very dear and high, 

 $50.00 per ton. Interesting details of our ojjeration I will 

 reserve for your interest when I return to Canada. It is 

 impossible to jiut thcni on paper." 



The Forestry Battalion being recruited by Major 

 Lyons has sent over a company and another will be ready 

 in a few weeks. 



BALSA wood, found in Central America, is said to be 

 the lightest known wood. It is Hghter than cork and 

 has an average specific gravity of only 0.104. 



