22 



BULLETIN 837, U. S. DEPARTMENT OF AGEICTTLTUBE. 



The burning was closely related to the thrift of vines, the stage 

 of grape growth when sprays were applied, the weather during and 

 following spray aplications, and the method of mixing materials. 

 Weak vines and those bearing too heavy crops were most seriously 

 burned. Spray applications just before and after bloom caused 

 more injury than later applications. Excessively wet and cloudy 

 weather during and following spray applications appeared to in- 

 crease burning. When either of the ingredients of Bordeaux was 

 added to the other without being diluted, increased burning resulted. 



From the above observations it is concluded that Bordeaux mixture 

 should not be used in the arsenate of lead-soap combination on the 

 Ives variety at any time and that in applying the combination with 

 Bordeaux to Concords and Catawbas the above factors influencing 

 foliage injury should be kept in mind. The arsenate of lead-soap- 

 lime mixture was safe wherever used, even on the Ives variety. The 

 injury from spray materials appears to be cumulative from season 

 to season. The combinations of spray materials and factors influ- 

 encing grape foliage injury warrant further experimentation. 



Dusting for Control of Grape-Berry Moth. 



Much interest is centering in the application of insecticides and 

 fungicides in dust form as compared with the liquid application. 

 In an attempt to avoid all spray residue on grapes at harvest time, 

 grape-dusting experiments were conducted in 1916, 1917, and 1918. 

 The final infestation in check plats adjacent to the dusted plats was 

 so light as to give inconclusive results except in 1916. The plan of 

 the 1916 experiments and the results recorded are presented in 

 Table IX. 



Table IX.- 



-Dusting experiment for control of grape-berry moth, Schonhardt 

 Vineyard, Venice, Ohio, 1916. 





Dust and spray mixtures 

 used and dilutions. 



Spra tions PhCa " Counts of infested grapes at harvest, Oct. 13, 1916. 



Plat 

 No. 



3 to 5 



days 

 after 

 grapes 

 bloom, 

 June 

 29. 



When 

 second- 

 brood 

 larva? 

 begin to 

 hatch, 

 Aug. 4. 



Num- 

 ber of 

 vines 

 exam- 

 ined. 



Num- 

 ber of 

 clus- 

 ters 

 exam- 

 ined. 



Num- 

 ber of 

 grapes 

 exam- 

 ined. 



Num- 

 ber of 

 clus- 

 ters 

 in- 

 fested. 



Num- 

 ber of 

 grapes 

 infest- 

 ed. 



Per- 

 cent- 

 age of 

 grapes 



in- 

 fested. 



1 



Arsenate of lead powder, 2* 

 pounds to 50 gallons; Bor- 

 deaux, 3-3-50; faundry soap, 

 2 pounds to 50 gallons. Li- 



X 



















Dust mixture, arsenate of lead 

 powder 10 per cent, hy- 

 drated lime 90 per cent 



X 



x 



8 



6 

 8 



211 



215 

 239 



6,330 



6,450 

 7,170 



211 



202 

 239 



2,978 



1,194 



5,668 



47.04 



2 

 3 



Arsenate of lead powder, 2J 

 pounds to 50 gallons; Bor- 

 deaux, 3-3-50: laundry soap, 

 2 pounds to 50 gallons 



X 



18.51 

 79.05 













