April, '15] 



YOTHERS: CITRUS SPRAYING SCHEME 



163 



sufficiently from the fruit to permit the sun to color it up. Soda-sul- 

 phur 1-50 may be added to this spraying and this will increase its ef- 

 fectiveness in killing rust mites. 



IV. Lime-Sulphur Solution, 32° Baume, 1-50 to 1-75 — November 

 or December. The object of this spraying is to kill rust mites and it 

 may or may not be necessary, depending on the abundance of the 

 mites. 



It may be necessary to spray for rust mites before No. 1 is given. 

 In case the red spider becomes abundant enough to be injurious, a 

 spraying with lime-sulphur solution should be given. It may also be 

 necessary to spray three times with the oil sprays, in which case this 

 treatment can be given in midsummer or in winter. If the red scale 

 is very abundant, two sprayings with the oil emulsions should be given 

 at intervals of about a month. 



The paraffin-oil emulsion may be made according to directions given 

 in Circular No. 168, Bureau of Entomology. In addition to the above 

 there are two miscible oils on the market in Florida which are highly 

 satisfactory. The soda-sulphur solution is made according to the 

 standard formula, 30 pounds sulphur, 20 pounds caustic soda, 20 

 gallons of water. This tests about 16° Baume and may be used 1-40 

 instead of lime-sulphur solution but it is not so effective in control- 

 ling rust mites. It has the advantage of the lime-sulphur solution in 

 that it will mix with the oil emulsions. To follow the above scheme it 

 will cost from 20 cents to 35 cents a year per tree. It costs one grower 

 20 cents for trees of about five-box capacity or 4 cents per box. An- 

 other did the work for 32 cents for eight-box trees or 4 cents per box. 

 It cost several other growers 3, 3, 6, 7, and 8 cents per box respectively. 

 A maximum figure would be 8 cents per box. 



Even though this scheme is not strictly adhered to it will result in 

 raising the grade of the fruit. The second grade will become first, the 

 third will be largely eliminated, and the culls will almost disappear. 

 The increase of production due to the increase in size of the fruit re- 

 sulting from the elimination of the rust mite will be from 12^ to 25 

 per cent, amounting approximately to two million boxes. The devital- 

 izing of the trees by the insects would be eliminated and the trees 

 would then expend their vitality to produce fruit instead of nourishing 

 insects. This would also increase the quantity and quality of the fruit 

 and make a crop more certain from year to year, which would be crop 

 insurance. It is a conservative estimate that the total benefits which 

 would be derived, if this scheme was followed throughout the state, 

 would be not far from an increase of production of a minimum of 25 

 per cent over that which is the result at the present time with a total de- 



