60 FUMIGATION FOR THE CITRUS WHITE FLY. 



had increased sufficiently to cause blackening of the foliage and 

 fruit before repeating the treatment. 



The extent of the damage due to the white fly is difficult to estimate. 

 After supplementing his personal observation with direct information 

 and estimates on this point from more than 50 orange growers who 

 have had experience with the pest, the author would consider 50 per 

 cent a conservative estimate of the average annual loss in white-fly- 

 infested groves. 



The consensus of opinion of the orange growers referred to is to 

 the effect that the reduction in the size of the crop alone amounts to 

 50 per cent or more, leaving out of consideration the loss through the 

 checking of the growth of trees, the retardation of ripening, the 

 expense of washing the fruit, and the impairment of its shipping 

 quality and flavor. In many cases the damage from the fly renders 

 citrus fruit growing unprofitable, although such losses are usually 

 unnecessary if proper care be given to cultivation and fertilization. 

 The beneficial effect of the fungous diseases of the white fly and the 

 economy of fumigation where the diseases are prevalent will be 

 discussed under another heading. The data at hand concerning the 

 cost of fumigation indicate that in most cases the expense would be 

 sustained by the increase in production if the losses of the white fly 

 were only 10 per cent, instead of the 50 or more as generally estimated. 



Losses from scale insects. — In calculating the benefits derived from 

 fumigation, the effect of the treatment on other citrus pests is an 

 important consideration. Fortunately the high average of humidity 

 in the citrus-growing sections of the Gulf States results in the partial 

 control of scale-insect pests which would otherwise make direct 

 remedial measures necessary for profitable crops. The thoroughness 

 of this natural control varies greatly in different groves according to 

 local conditions. Fruit infested with the purpfe or the long scale is far 

 less valuable, as a rule, than is clean fruit. If such fruit is cleaned 

 before packing, the cost is usually from 10 to 15 cents per box. In 

 the markets scaly fruit in rare instances brings as much as fruit free 

 from scale, but ordinarily it brings from 25 to 75 cents less per box, 

 even after being cleaned by hand. If not cleaned it may fail to find 

 a market at any price. When handled by orange buyers and sold 

 upon the tree, even a small percentage of scaly fruit frequently 

 results in a considerable loss in selling value of the entire crop. 



Direct information has been obtained from many orange growers 

 and shippers concerning the effect of scales upon the value of fruit. 

 The damage reported ranges from none at all to 26 per cent of the 

 total value of 'the crop. Ordinarily from 5 to 15 per cent of the crops 

 of oranges and grapefruit are sold as of an inferior grade owing to 

 infestation by the long and purple scales. One grower in Lee County 

 reported that last season (fruit shipped in December, 1906) he suffered 

 a loss of $1,500 on a crop of 1,000 boxes of oranges and 2,000 boxes of 



