38 



BULLETIN 828, U. S. DEPARTMENT OF AGRICULTURE. 



ments were June 19, 28, July 6, 13, 18, 28, August 3, 13, and 16. 

 Table I gives the details as to the number of plants, kind and num- 

 ber of treatments, and wilt records for each plat in the field, and figure 

 10 shows graphically the relative effect of the various treatments 

 as compared with the control plats. Photographs of plats Nos. 1, 6, 

 and 11, taken August 25, 1916 (Pis. II and IV), show the appearance 

 of the vines with all the applications of Bordeaux mixture and lead 

 arsenate, with lead arsenate alone, and also without any treatment. 

 Each stake shown in these photographs represents one case of wilt. 

 In all cases the cucumbers were picked when about 6 inches in 

 length. No new or special combinations of insecticides were used 

 in this test, as the insect control, per se, is a matter left to the Bureau 

 of Entomology. In the earlier tests, Bordeaux mixture with lead 

 arsenate gave a better control than either mixture alone, so that 

 2 pounds of lead arsenate paste were added to each 50 gallons of 

 Bordeaux mixture used in this experiment. 



Table I. — Bacterial wilt record of the spray experiment in Field Ha at East Marion, 



Long Island, 1916. 





Plat 

 No. 



New cases of wilt at different dates. 



Num- 

 ber of 

 plants 

 at the 

 start. 



Wilt for the 



season. 



Treatment. 



July- 



August — 



Total. 



Per- 

 cent- 

 age. 





11 



18 



29 



9 



15 



23 





1 



2 

 3 



4 

 5 

 6 

 7 

 8 

 9 



10 

 11 



6 



7 

 8 

 3 

 3 

 1 

 3 

 9 

 2 



7 

 11 



12 



7 



21 



26 



8 



6 



5 



12 



32 



48 

 19 



56 



50 

 48 

 52 

 58 

 21 

 30 

 36 

 41 



51 

 66 



25 



29 

 12 

 43 

 33 

 17 

 24 

 20 

 26 



IS 

 16 



11 



6 



14 

 5 

 6 

 7 



15 

 4 



14 



8 

 18 



1 



4 

 3 

 2 

 2 

 8 

 5 

 9 

 3 



2 



7 



248 



325 

 230 

 234 

 227 

 267 

 268 

 282 

 231 



260 

 264 



Ill 



103 

 106 

 131 



110 

 60 

 82 

 90 



118 



134 



137 





Bordeaux mixture pluslead arsenate: 





2-3-50-2, first two only 





2-3-50-2, first only 





2-3-50-2, all but first four 



48 

 22 



2-3-50-2, all but first 



30 



2-3-50-2, all but first and second. . 



32 



Lime and tobacco dust, all applica- 



51 



Lead arsenate, 2-50, all applications.. 



52 



Total 





60 



196 



509 



263 



108 



46 



2,836 



1,182 













It will be noted that the reduction of wilt was greater with the 

 2-3-50 Bordeaux mixture than with the 1-2-50 mixture, although 

 the number and weight of fruit picked was slightly greater for the 

 weaker mixture. The wilt records show the effect of the treatments 

 on the wilt alone, while a comparison of the number and weight of 

 fruit for the various plats shows the combined control against both 

 wilt and downy mildew (caused by Pseud,operonospora cubensis). 

 The latter disease became prevalent during the month of August 

 (fig. 3). For control of wilt the last five treatments had no appre- 

 ciable effect. Of the remaining four applications the two most 



