EXPlQRIMENT STATION REPORTS. 283 



The 50.75% of inert ingredients is probably mostly tobacco dust as 

 the percentage of actual nicotine in tobacco dust is quite low. 



Equipment and Application. The dusting material was applicnl with the 

 Ideal Power Duster. When dusting cucumbers the team was driven so 

 that the duster was dii-ectlj' over the row and each hill was dusted as the 

 machine passed over. If the vines were long enough to be in the path 

 of the wheels they were easily turned so as not to be injured by team or 

 wheels. 



The outlet was held very close to the groiuid and swung from side 

 to side so as to cover the entire hill. The leaves were easily turned up and 

 in many cases the whole vine would be lifted from the ground so that the 

 dusting material easily reached the under surfaces of the leaves. 



Because of the large size of the sciuash plants it was not possible to 

 drive over as with the cucumbers; the duster was driven along one side of 

 the row. 



Results. The under surfaces of the cucundjer leaves were well coated 

 with the dusting material, so that it was c^uite certain to come in contact 

 with any aphids that might be there. Verj- few live aphids except a few 

 of the winged form, could be found after a few hours from the time the 

 dust was applied. With the squash it was impossible to distribute the 

 dust to all parts of the plants. It is necessary to have the outlet quite 

 close to the plants. 



Conclusions. Aphids can be controlled by the dusting method when con- 

 ditions are such that the dust can be brought in contact with them. This 

 can be done with such crops as cucumbers or muskmelons, but not with 

 rank growing vine crops such as squash excepting during their earlier 

 periods of development. 



DUSTING POTATOES TO CONTROL COLORADO POTATO BEETLE. 



Materials. The dusting material used was a mixture of Dry Calcium 

 Arsenate (Corona Brand — 47% arsenic oxide) and talc. It was mixed in 

 the proportion of : 



Calcium arsenate 15% 



Talc 85% 



This makes a very fine, smooth, and easy-flowing mixture. 



Applications. The dusting was all done with the Ideal Power Duster 

 with the same outlet used for dusting trees. Four rows were dusted 

 at each trip through the field, by holding the outlet pipe close to the 

 plants and swinging it from side to side. 



Work in College Gardens. Twenty-four rows in a potato field were 

 dusted and the remainder of the field was sprayed with Calcium Ar- 

 senate at the rate of 1}-^ lbs. in 50 gallons of water. 



Results. As soon as the dusting and spraying were finished a con- 

 siderable number of plants in l)oth plots that had a noticeable number 

 of beetles on them were marked with stakes. Both jnethods were entirely 

 successful. Within two hours after the application of the dusting ma- 

 terial many of the beetle larvae were showing ffects of the poison. No 

 live larvae could be found the next morning (about eighteen hours aftei 

 application) on either plot. Although there is no definite data for this 



