April, 1921. 



SCIENTIFIC AGRICULTURE 



169 



simple way. The primary one germinates and sends 

 out a hypha or tube of variable length, which, growing 

 vertically upwards becomes swollen at its extremity 

 and produces a conidium similar to the one from which 

 it was derived. In some cases a tertiary conidium is 

 formed from the secondary one, should unsuitable con- 

 ditions still be met with, the conidium in each case 

 being smaller than its predecessor. 



It is now necessary to return once more to the condi- 

 tion in which we find the host filled with chlamydo- 

 spores or hyphal bodies, in order to consider the for- 

 mation of the asexual or sexual resting spores — known 

 technically as azygospores and zygospores — which are 

 formed when very adverse conditions are met with. 

 The pa.ssage to the resting condition may be accom- 

 plished by a wholly non-sexual process in which case 

 we get an azygosporc : or else a sexual spore, or zygo- 

 spore, may be formed by the fusion of the contents of 

 two hyphae. In either case the product is a spore hav- 

 ing very thick walls and capable of withstanding great 

 extremes of temperature and humidity. Most fungi 

 are carried over the winter by means of these spores. 

 In the spring when conditions are favorable, they ger- 

 minate in the same manner as the eonidia did and send 

 out germ tubes bearing upright eonidiophores, at the 

 tip of which are borne the eonidia. 



Thus we see that there are really four kinds of spores. 

 First, eonidia, which are typically summer spores and 

 by means of which the fungus is spread; secondly, 

 chlamydospores or thin-walled resting spores, useful in 

 tiding the fungus over short periods ; and thirdly, 

 thick-walled spores, known as zygospores, if they have 

 been formed b.v a sexual process, or azygospores. if no 

 fusion has taken place previous to their formation. 

 These last two types of spores are formed when a long 

 period of adver.se conditions is encountered. 



This, in brief, is the life history of a typical member 

 of the Eutomophthoraceae, the most important family 

 of entomogenous fungi we have. 



Methods of Spreading Entomogenous Fungi 

 Artificially. 



Befoj-e a fungous disea.sc can lie of any great use in 

 combatting insect outbreaks it must lend itself readily 

 to artificial .spread and mu.st have the power, under 

 suitable weather conditions, of inoculating those in- 

 sects with which it comes in contact. There are many 

 diseases known, which, although they may be present 

 in small amounts each year, yet never reach a state of 

 epidemic and cannot be spread ai-tificially. Such fungi 

 can never be of much use to the mycoentomologist. 

 Years of experimenting have shown quite clearly that 

 of all the entomogenous fungi knoAvn, only a very small 

 percentage are of use from an economic standpoint. 



The methods of spreading fungous diseases of this 

 type are very varied — varying greatly with the insect 

 attacked, the species of fungus and the country in 

 which they are found. A method which might be pro- 

 ductive^of good results when used in Florida might be 

 a "total failure in Canada and because a certain method 

 has been tried successfully on one species of fungus 

 does not prove that it will be equally successful on 

 another. Each special disease has to be studied inten- 

 sively in its native habitat and carefully experimented 

 with before it is safe to say whether it is amenable to 

 artificial dissemination or not. 



Briefly, the four most generally used methods of 

 spreading entomogenous fungi are as follows: 



(1) Where the eonidia are suspended in water and 

 sprayed on the insect-infested trees. 



(2) "Where insects which have been artificially inocu- 

 lated with the disea.sc are liberated in the field" among 

 healthy ones. 



(3) Where portions of trees (leaves, twigs, pieces of 

 bark, etc.) bearing the fungus, are fastened to trees in- 

 fested with the insects to be inoculated. 



(4) Where the spores are mixed with the food and 

 infection takes place through the alimentary canal. 



Wool Grading as it Affects Canadian Wool Sales 



A. A. MacMlLLAN. Live Stock Branch. Ottawa. 



The responsibility of establishing suitable grades for 

 Canadian wools has continued to remain a feature of the 

 aeti^^ties of the Sheep Division of the Live Stock 

 Branch. During the period of the war, when prices were 

 continually rising and when prices for lower grades of 

 wool approximated very closely those of finer grades, 

 there was not the same necessity for close grading, but in 

 1919, when prices began to drop, it was apparent that 

 the .standard for Canadian grades rf wool must be made 

 stricter: othei-wise grade rejections on the part of pur- 

 cha.sers would result in cancellation of .same. Befoi-e 

 commencing grading in 1920 it was decided to bring the 

 grades up to a very high level. This was accomplished, 

 the result being that throughout the entire season there 

 were no cancellations of sales owing to questionable 

 grading, and the establishment of grades that met trade 

 demands played an important part in 1920 sales. 



Canadian wools are now cla.ssified into eleven main 

 grades which include combing and clothing lengths. 

 Owing to the effect of climate, soil and .system of man- 

 agement the grades are again separated for sale pur- 

 poses into two main divisions. Wools east of Fort Wil- 

 liam are known as Eastern Domestic, whereas, those 



west of Fort William are known as Western Domestic 

 and Range Wools. Owing to alkali and soil drifting in 

 Manitoba and parts of Saskatchewan and to the affect 

 of burnt off land in British Columbia, a further sub- 

 division was made in these provinces, on the ba.sis of 

 brightue-ss, the grades being subdivided into Bright, 

 Semi-Bright and Dark. Grading as carried out in 1920 

 allowed each province to reap the full benefits of the 

 selling qualities of their i-espective wools. This was 

 made possible largely as a result of the consolidation of 

 the grading work at Weston, Guelph and Lenuoxville. 

 Field grading, although educative to farmers locally, 

 made it difficult to maintain uniformity of grades, 

 which is now essential if Canadian wools are to stand 

 up in competition both on the Canadian, Unite 1 States 

 and British markets. Farmers now have a more or less 

 general knowledge of the various grades and there was 

 no good reason why consolidated grading slmuld not be 

 effected. Besides making for greater uniformity it per- 

 mits of blending certain wools from a number of pro- 

 vinces into one grade when otherwise there would not be 

 enough from any one province to make it worth while. 

 The subdivision within the grades permits farmers with 



