SPRAYING FOR CITRUS INSECTS AND MITES IN FLORIDA. 35 



caused by the insecticide alone, the blemish will be found at places 

 where the drop of spray collects on the lower surface of each fruit. 



Instead of injuring citrus trees, lime-sulphur solution has a 

 stimulating effect. The leaves become a darker green and the fruit 

 reaches a larger size. Fruit has been known to ripen at least three 

 weeks to a month earlier than other fruit of the same kind in an 

 adjoining row. The exact cause of this is not known, but the spray 

 evidently has some direct action on the leaves. Careful experiments 

 have shown that there is no known spray so beneficial to citrus trees 

 as is lime-sulphur solution. 



COST OF SPRAYING. 



The cost of spraying (Table I) necessarily varies and depends upon 

 the size of the trees, the density of the foliage, the equipment used, 

 and the nearness of the grove to the water supply. Accurate esti- 

 mates of the probable cost can be computed only after all these fac- 

 tors have been taken into consideration. Nursery trees can be sprayed 

 for one-sixth of a cent each, while the largest trees will cost as much 

 as 10 cents. Trees with dense foliage require much more insecticide 

 and a longer time to spray than those with sparse foliage, even 

 though the latter may be much larger trees. If the spraying is done 

 with a barrel pump the cost will be somewhat greater than if done 

 with a power outfit. The item of labor will be not far from 75 per 

 cent of the total cost. If the water supply is in the grove or very 

 close, the cost will be considerably less than if it is some distance 

 away. A water supply a greater distance away than half a mile is 

 not practicable, because it would require two extra teams to supply 

 one machine. This would increase the cost about 1J cents per tree. 



In computing the cost of spraying the depreciation of machinery 

 should always be included. Many inquiries were sent to citrus grow- 

 ers for information on this point. Some estimated the depreciation 

 to be as great as 25 per cent. One grower thought it would be as low 

 as 10 per cent, but it was the opinion of the majority that from 15 to 

 20 per cent would be more consistent. This appeals to the writer as 

 the proper estimate to be placed upon this phase of the cost of spray- 

 ing. The percentage of depreciation will depend almost entirely 

 upon the care that is given the machine. The length of time a ma- 

 chine will be serviceable depends much more upon the care it receives 

 than upon the amount of work it does. 



The writer has obtained from many growers the actual cost figures 

 for spraying done on a commercial basis under the average grove 

 conditions prevailing in Florida. These will assist any grower con- 

 templating a spraying program in arriving at an accurate estimate 

 of the probable cost. These statements include the depreciation of 

 machinery as well as cost of labor, team hire, insecticides, and inci- 



