25 



In spring, during the period of ovipositiun, repellent mixtures should 

 be sprayed on the trees, followed by insecticide sprays when necessary 

 during the hatching period. In summer and autumn the fallen almonds 

 and the infested ones remaining on the tree should be collected and 

 put into receptacles screened with a 1 mm. mesh to allow the 

 emergence of parasites. 



]\1akchal (P.). Les Traitements Arsenicaux et les Traitements mixtes 

 des Arbres Fruitiers. — Ann. Service dcs Epiphvtics, Paris, vi, 

 (1918) 1919, pji. 242-280. [Received 12th November 1920.] 



In continuation of the work of previous years [R.A.E., A, vii, 

 pp. 462-464), various treatments have been given against pests of fruit- 

 trees. The substances and manner of application in use in America 

 are described and contrasted with the French methods, and many 

 formulae are given for simple insecticide and combined mixtures. 



The conclusions reached by the work achieved up to the present 

 are discussed. It is agreed that the earliest measure against Cydia 

 {Carpocapsa) pomonella (codling moth) should be given at the moment 

 of the fall of the petals, or immediately after, care being taken to fill 

 the calyx with the spray, as this is the most usual point of entry of 

 the larva into the fruit. In 1917, moths of the second generation 

 emerged on 16th August from infested apples gathered in July ; it is 

 probable that in northern France the second generation is only a partial 

 one, and less important than the first. Accurate information on this 

 point is desirable, but it is probable that the second generation 

 influences only the quahty and not the quantity of the fruit, and 

 therefore is not of much importance in cider districts. This generation 

 is controlled in America by later sprays, which, however, are forbidden 

 in France by legislation. Some growers prefer to spray apple-trees 

 when in full bloom. For pears, in which the calyx cup frequently 

 remains open, the first treatment may be made comparatively 

 late. 



Lead arsenate has pro\'ed the most successful of all insecticides, 'and 

 is used sometimes at as much as double the strength of the American 

 formula, owing to the fewer treatments that can be applied. A com- 

 mercial preparation, equivalent to 3 lb. sodium arsenate plus 9 lb. lead 

 acetate per 100 gals, water, used in Gironde in 1917, produced more than 

 double the quantity of apples compared with untreated trees when a 

 single application was given at the time the blossoms fell, and nearly 

 three times the quantity when a second application was given a fort- 

 night after the first. Lead arsenate is not only efficacious against 

 C. pomonella and C. fitncbrana (on plums), but also against foliage 

 pests, such as Cheimatobia brumata, Hyponomeuta spp., the larvae of 

 which die in 8 to 15 days after spraying, and Malacosoma nensfria, 

 which also dies within a few days. 



The action of various mixtures on the plants is discussed. It is said 

 that lead arsenate mixtures are not only harmless to the plant, but 

 even stimulate its growth. The advantage to be gained by arsenical 

 treatments is considered ; in the case of table fruit the profit to be 

 derived in consequence of better quality fruit has already been proved ; 

 it remains to be determined exactly which treatments will give the 

 maximum results that are obtained normally in the United States and 

 in Canada. 



