8 ALFRED E. CAMERON. 



Series II. 



Kil-Tone. 



Arsenate of Lead. 



Bordeaux Mixture and Arsenate of Lead. 



Arsenate of Lead. 



Sulphur and Lead Arsenate Mixture. 



Arsenate of Lead. 

 As will be observed, the field was divided into two blocks in both of which there 

 were six plots of twenty rows, each plot measuring 0*89 acre except, the last arsenate 

 of lead plot, which had only fifteen rows and measured 0*68 acre. 



On 2nd June the field was examined for flea-beetles. The numbers had been greatly 

 reduced, but an adjacent field of potatoes, which had not been treated, was badly 

 infested with this small pest. It would appear that the beetles had been repelled 

 to this neighbouring field. On some of the plants a few Aphides, Rhopalosiphimi 

 solani, were observed at work, but not in sufficiently great numbers to cause uneasiness 

 or to make it worth while to go to the expense and trouble of a special treatment. 

 At this stage the Kil-Tone plots compared favourably with the others as regards 

 insect control, and indeed, so far as observation could be trusted, this proprietary 

 preparation seemed to give quite satisfactory results. 



On 24th June a rather curious phenomenon was observed. The potato plants 

 were now in blossom, but the flowers had died off- quickly on all the plots except 

 on the controls sprayed with arsenate of lead. What was the exact significance of 

 this cannot be stated, but that there was no ultimate detrimental effect is shown 

 by the yields, which were greater on all these plots than on the controls. On 

 this date too there was a slight recrudescence of the flea-beetle, especially noticeable 

 on the sulphur plots, but after the treatments had been applied they were 

 effectively repelled. Perhaps their increase on these plots was due to 

 the fact that the dust does not adhere to the foliage for such a long time as the wet 

 sprays, and therefore more frequent applications would have to be made to maintain 

 its efficiency. 



On 7th July, in addition to Epitrix cucumeris, there was present in appreciable 

 numbers another species of flea-beetle, Epitrix fuscula, Cr., which, according to 

 Dr. Smith,* is supposed to be rarely found in New Jersey. The recurrence of the 

 flea-beetle at this period led me to the belief that there is a second brood, if not a 

 third, in this State, for after a decided diminution a second time there was an increase 

 on 26th August on the late crops in the southern regions. These periods of great 

 infestation alternating with periods of absence of attack are generally characteristic 

 of multi-brooded species. 



As regards fungous diseases, cases of early blight were very rare on the first crop, 

 and late blight was not observed, but on the second crop, in August, early bhght 

 seemed to be rather general, appearing first when the plants were yet small. 



During the early days of August the so-called " old-fashioned potato beetle," 

 Epicauta vittata, appeared suddenly in the fields of South Jersey, stripping the vines 

 of all leaves that were yet green. This was considered peculiar, in view of the fact 



♦Smith (J. B.). — Ann. Kept. New Jersey State Museum ; Insects. Trenton, 1910, p. 352. 



