52 NATUEAL CONTROL OF WHITE FLIES IN FLORIDA. 



preference of the grower and the amount of work to be done. The 

 compressed-air sprayer has a capacity of 3 gallons, and besides having 

 the advantage of bemg somewhat lighter has a valve by the use of 

 which the spray can be mstantly cut off by the operator, thus pre- 

 venting loss of solution m passmg from tree to tree. It has the dis- 

 advantage of requirmg frequent pumpmg up, and having been in use 

 for some time, this feature is apt to become a serious drawback. 

 Knapsack sprayere and barrel pumps, new or thoroughly cleaned, 

 were found less likely to cause delays in work. 



The method of procedure in the grove has differed but little from 

 that by which insecticides are applied, and is very simple. In using 

 knapsack or compressed-air sprayers it has been found very conven- 

 ient to have as many jars on hand as there are sprayers. After the 

 fungous leaves have been shaken the solution is strained directly into 

 the tank and then diluted to its capacity. The jars are then refiJled 

 ■with another supply of leaves and water and allowed to stand until 

 the contents of the first tank have been sprayed out. After the first 

 shaking, the leaves have been used to advantage a second time when 

 the supply was limited, but when an abundance of fungous leaves 

 was available it was found to be a better policy either to throw them 

 away or add fresh leaves for reasons mentioned elsewhere. Where 

 three or four sprayers were in use it was found to be of advantage 

 to have an additional man to keep the water supply replenished, 

 shake the fungus, and change the base of supplies, so as to save time 

 in traveling back and forth. 



Wlien using a barrel pump, in view of the larger amounts of water 

 necessary, it is more essential that the tub or other retainer be placed 

 near a larger supply of water. After the spore solution had been 

 prepared and strained into the barrel, the latter was filled and the 

 solution sprayed. Meanwhile the tub was again partially filled and 

 more leaves added to soak and be stirred in readiness for the next 

 barrelfui of solution. 



In spraying with knapsack or compressed-air sprayers, or in brush- 

 ing, best results were obtained by directing the spray onto the under- 

 side of the leaves of the outer, more heavily infested, shoots. 

 Experiments have shown that better infections were obtained on the 

 outer portions of the tree than on water shoots. With a barrel 

 pump two leads of hose were used to advantage, the halves of two 

 rows being sprayed as the wagon passed between the rows. 



The dipping method was fu'st used as a check on experiments with 

 other methods, but as it has been found to have a practical usefulness 

 under some conditions, it has been frequently recommended by the 

 authors to citrus growers. The water mixture is prepared as already 

 described. A clean bucket half full of the unstrained mixture is 

 held with one hand and arm in such a manner that with the other 



