110 



BULLETIN 903, U. S. DEPARTMENT OF AGRICULTURE. 



Table XXXV. — Field experiments on inoculation of vines by wandering larva? 

 of the grape phylloxera, Walnut Creek, Calif., 1915. 



No. of 

 vine. 



Type of soil in can. 



Variety of 

 vine. 



Date of 

 planting 



can in 

 vineyard 



Date of 

 taking up 



can in 

 vineyard 



Distance 

 of vine in 

 can from 

 trunk of 

 infested 

 vine in 

 vineyard 



Result. 



1 1 



12 



3 



4 



5 



6 



7 



8 



i9 



10 



11 



12 



13 



1 14 



15 



U6 



17 



18 



19 



20 



21 



22 



23 



24 



25 



26 



27 



1 28 



29 



30 



31 



32 



33 



Silt loam 



do 



do 



do 



do 



do 



do 



Heavy black loam, 2 parts; silt, 1 part 



do 



do 



Heavy black clay loam 



do .' 



do 



Sandv silt 



do 



do 



Pure sand 



Heavy black clay loam 



Sandy silt 



Heavy black loam , 2 parts ; silt, 1 part 

 Heavy black loam, lpart; silt, lpart. 



Heavy black clay loam 



Sandy silt 



Heavy black loam, 2parts; silt, 1 part 



do 



Heavy black loam, 1 part; silt, 1 part. 



do 



Pure sand 



Sandy loam 



do 



Heavy black loam, 1 part; silt, 1 part. 



Heavy black clay loam 



Sandy silt 



Mission . . : 



Zinfandel. 

 Carignan. . 



Zinfandel. 



Carignan.. 

 >Zinfandel. 



>Carignan.. 

 Zinfandel. 



[July 



14 



db 



..do 



July 15 

 ..do.... 

 July 17 



..do 



..do.... 

 July 20 



..do 



July 21 

 ..do.... 



..do 



Julv 22 



..do 



..do.... 

 ..do.... 

 July 24 

 ..do.... 

 ...do.... 



f..do 



-L.do 



(...do.... 



/..do 



\July 27 

 f..do.... 



..do 



..do 



..do.... 

 ..do.... 

 July 29 



..do 



..do.... 



Sept. 8 

 Sept. 9 

 Sept. 17 

 Sept. 8 



...do.... 

 Sept. 9 

 Sept. 15 

 Sept. 9 

 Sept. 1.5 



...do.... 

 Sept. 9 

 Sept. 17 

 Sept. 15 



...do.... 

 Sept. 17 

 Sept. 15 



...do.... 



...do.... 



...do.... 



...do.... 

 Sept. 8 



...do.... 

 Sept. 15 



...do 



Sept. 17 



...do. . .. 



...do.... 



...do.... 



...do.... 



...do.... 



...do.... 



...do.... 



...do.... 



Feet. 



•Uninfested. 



Infested. 

 Uninfested. 



Infested. 



Uninfested. 



1 Entire vines died shortly after having been planted in vineyard, therefore can not be included in 

 results of experiment. 



Of the 27 vines which were alive when the cans were taken up, 21 

 had been planted in the phylloxera " spot " on light soil and 6 in 

 phylloxera " spots " on heavy black clay. None of the latter and only 

 4 of the former group became infested. Vine 6 was examined 

 September 9, and an infestation consisting of 1 adult radicicole 

 and about 12 larvae was found. This indicated that a single wan- 

 derer had established itself on the vine. On vine 11, on the same 

 date, there were found 3 adults and about 20 larvae. On vine 12 

 on September 17 there were 6 adults and about 200 larvae, besides 

 many eggs. On vine 13 on September 15 there were over 350 phyl- 

 loxera?, including some 50 adults. Vines 11, 12, and 13 were planted 

 around the same infested vine. In the case of vine 13 the infestation 

 was started either by a large number of wandering larvae in August 

 or more likely by one or two wanderers directly after the vine was 

 planted on July 21. Since in August the phylloxera generation 

 cycle may be passed in less than 22 days, and since each mature 

 radicicole may average 8 eggs per diem for several weeks, it would 

 have been possible for the infestation on vine 13 to have cWeloped 



