212 



Tvlietber the two varit'ties which I have iiulieatcil will succeed iii your locality, but 

 the probabilities are that they will do A'ery well as stocks, even if they should not be 

 desirable to grow for their fruit. I shall be glad to learn the course pursued by you 

 and its success. 



The Grape Phylloxera in the United States. 



May I venture to ask you to write me briefly your views of Phylloxera in the United 

 States. If, in your opinion, it is on the increase or decrease, and if there is occasion 

 for any serious alarm in any section of this country as to the future of the grape 

 crop. I desire the information for a French correspondent jirominent in the agri- 

 cultural societies of France. — [Burnet Landreth, Pennsylvania, September 19, 1891. 



Reply. — There is in this country, for the most part east of the Rocky Mountains, 

 very little to be feared from the Phylloxera, at least so far as our native vines are 

 concerned. Most of the American varieties of grapes are resistant to the root-form of 

 this insect and hence suffer little injury. The leaf-gall form is not particularly seri- 

 ous in its effect on the vdne, except in a few thin-leaved varieties. The damage done 

 by the Phylloxera in France and other parts of Europe where it has obtained a foot- 

 hold is due to the root-form exclusively. All European A'ines or varieties derived 

 from the European grape, Vitis vinifera, are especially liable to this form of attack 

 and rapidly succumb to the Phylloxera. 



The danger in this country then is confined to those localities, chiefly in California, 

 where European varieties are grown, and in the Sonoma Valley region considerable 

 difficulty has already been experienced. The remedy here will be the adoption of 

 the means which long experience has shown to be valuable in France, viz, grafting 

 susceptible European sorts on resistant American varieties, and also the use of such 

 remedial measures as experience has shown to be practically valuable. These reme- 

 dies are referred to in the publications which I have already mailed to you. In other 

 parts of the United States it will occasionally be necessary to abandon the cultiva- 

 tion of particular varieties, such as the Catawba aud Delaware. The Clinton is jiar- 

 ticularly liable to the attacks of the leaf-gall form, and occasionally the multiplica- 

 tion of the lice ui)on the leaves is so great as to seriously injure the plant. The 

 Catawba and Delaware and various hybrids with vinifera succiiml) occasionally to 

 the root form. The Cliuton stocks, however, are especially valuable on account of 

 their resistant f^ualities, since the lice are seldom found to any great extent ou the 

 roots of this variety and the vine is so vigorous a grower that a slight attack does 

 little injury. As long, therefore, as we continue to grow our native grapes, we need 

 have little fear of Phylloxera. This insect, as you doubtless know, is a native of 

 this country, and our native vines have acquired, by long association with the Phyl- 

 loxera, certain resistant qualities which are entirely wanting in the Euroiiean 

 grapes. 



With regard to Phylloxera damage to grapes grown under glass I would refer you 

 to a report by myself, published in the Annual Report of the DeiJartment of Agri- 

 culture for 1884, pp. 408-9, which you will jirobably find of interest in this connec- 

 tion.— [September 24, 1891.] 



Mites ou a Maple Aphid. 



I mail you to-day slides with mite which attacks Drejjanosiphnm acerfolii, Thomas. 

 Saw a great number of these scarlet mites each fastened at base of wing of this com- 

 mon Maple Aphid, but the Aphid is so active that I secured but three specimens. 

 Have also seen this mite ou the Hickory Callixtenus. Can you give me name of 

 mite in case you recognize it, without trouble or especial study? — [J. G. Monell, 

 Missouri, August 5, 1891. 



Reply. — * * * The mites which you send are immature aud in bad condition. 

 They evidently belong to the genus Erythnvus, but it will require better material to 

 enable a correct determination. — [August 4, 1891.] 



