SECnON VI. — NATURAL ENEMIES OF THE FROGHOPPER. 85 



The most wasteful method, and at the same time that requiring 

 least labour and so applicable to a large ai'ea, consists in blowing the 

 mixture of spores and rice flour over the infested fields in the late after- 

 noon or evening by some form of hand or rotary blower. This method 

 was developed by Korer, who at the end of 1912 dusted about 508 acres 

 on one estate with about 636 lbs. of mixed rice flour and spores at a cost 

 of about 25-28 cents fl/--l/2d.) per lb. for the mixture, or about 40c. 

 ])e}i acre (these prices could not now be repeated). 



In this connection it might be mentioned that if the distributor of 

 the spores gets much of the mixture in his face it may set up a form of 

 hay-fever which is extremely unpleasant. I myself was incapacitated 

 for two days by this after shaking a bag of spores over about two acres 

 of a cane field. 



Yet another method of distributing the spores experimented 

 with by Gough and Rarer and later by myself consists in attracting the 

 adults during the night by means of lights to trays containing the 

 spores with which they become covered. For further particulars of 

 this method see under " light traps" (p. 146.) 



The final test of these various methods adopted to spread the infesta- 

 tion of the green muscardine fungus, must always be the result obtained, 

 and in this connection it must be admitted that it is extremely difficult, 

 if not impossible, to estimate accurately the effect of such treatments. 

 There is nearly always a considerable natural infestation in a field and 

 it is difficult to separate this from the results of artificial introductions. 



Under suitable conditions there is little doubt that appreciable results 

 can be obtained but should the conditions alter, as for example when 

 the weather turns dry, the whole expense of the treatment may be lost. 



Eorer and Urich in 1912 distributed spores on a field at Orange 

 (irove and found later an average of 92 dead adults per stool. ( Urich. 

 Bull. Dept. A(jr. XI. 71 p. 860). 



At Golconda Estate in 1918 we were able to produce an infection of 

 the first brood which was light but at the same time considerably 

 greater than most first brood infections. On the other hand in July 

 1918 I distributed spores in a field at Williamsville Estate where only 

 one or two dead adults could be found, and thi-ee weeks later a close 

 search failed to reveal a single infected specimen. Conditions were 

 somehow unfavourable, and not only did the artificial infection fail, but 

 even the natural infection that was starting passed away. 



Some estates distributed spores regularly for several years. Others 

 have never made any attempt to supplement the natural infection. 

 Estates in both groups have suffered severely and other estates in both 

 groups have escaped. 



The method is so dependant on external conditions that it becomes 

 a form of gamble. The outlay is however sn.iaH'' and could easily be 

 covered by most estates by the saving of a few tons of sugar. The 

 method is also technically difficult, the wrong fungus may be grown in 

 the cabinets by acc^lent. particularly if sterilization of the cabinets has 

 been faulty, while distribution in a high wind or in fields alieady heavily 

 infected naturally, will result in a loss of tlie material prepared. 



I believe that further investigation could be profitably made on the 

 use of green muscardine fungus, but the method can never be made to 

 appeal to those who are looking for a certain cure with next to no 

 expenditure of time and trouble. 



*'J'lie Usiiie Ste. Madeleine in 1!M8 sp.'iit just over two thousiuul ilollar.s on the 

 production of green muscardine fundus. 



