14 



T BIN ID AD AND TOBA GO B ULLE TIN. [X VII I. 1. 



I was not present 

 at the application but 

 on November 20 the 

 treated cane from 

 A to B (Fig. IV) 

 appeared a little better 

 than the untreated 

 canes just to the north 

 of A, but no difference 

 could be seen between 

 the treated canes be- 

 tween B and C and 

 the untreated canes to 

 the east of this point. 



On December 11 



f 



A' 1 1 



m 



,Fi,8ld 



'106 



■RO AD 



I visited the field again 

 and counted the num- 

 ber of nymphs visible 

 on the surface of the 

 ground in the treated 

 and untreated areas. 



On 50 treated stools 

 on the bed next to the 

 trace along the western 

 edge of the field I 

 counted 102 nymphs, 

 and on 50 untreated 

 stools about 5 beds to 

 the east I found only 

 32 nymphs. 



Fig. IV. 



So that there were actually more nymphs on the treated than on 

 the untreated bed. 



It is naturally, not suggested that the treatment was responsible for 

 this, but it shows that variation between different parts of a field must 

 not be hastily credited to special treatments, and further that the 

 mixture in question cannot be said to exterminate either the nymphs 

 or the eggs. 



Eoot disease was present on both treated and untreated plots. 



COST OF APPLICATION, 



Leaving for a moment the question of the efficacy of the liquid in 

 destroying the froghopper nymphs or eggs, I made, in collaboration 

 with Mr. Borer, some experiments to get accurate information on the 

 cost on application of such a method. 



Using knapsack sprayers, we found that it was impossible to 

 moisten thoroughly the trash and ground at the base of the cane stools 

 without using at least one gallon of liquid to every 12 stools, or 

 200 gallons per acre at 2,400 stools per acre. 



We further found that the cost of application by this method could 

 not be brought much under ft2 per acre. 



So that the complete cost of one treatment of this type would be 

 per acre at least ^2 in addition to the cost of 200 gallons of liquid. 



GENERAL CONCLUSIONS. 

 If a liqu'.d C5ull be found that was thoroughly effective in destroying 

 the froghopper nymph and eggs in one, cr, at the inost, two applica- 

 tions, the method is not impossible, provided that the cost of the liquid 



