THE RUST MITE. 123 



supply of new growth and a constant succession of fresh 

 and vigorous leaves. 



It seems, however, to be an established fact that the 

 fruit is less liable to rust upon low than upon high lands. 

 Groves planted upon moist, rich hammock produce, as a 

 rule, brighter fruit than those upon high, sandy pine lands. 

 This result is commonly attributed to the abundance of 

 moisture in low ground ; but it may be more directly due 

 to the denser shade afforded by a more vigorous foliage 

 and reduced radiation from a darker soil. In the native 

 wild groves, which are always densely shaded by forest, 

 neither rust nor mites are found, and the same immunity 

 is enjoyed by cultivated trees planted in similar situations. 



Preventive Measures. It is not at present possible to 

 suggest any preventive measures that can be universally 

 adopted, nor are precautions likely to avail much against 

 an enemy which already exists, even if it does not always 

 make its presence known, in almost every grove and nurs- 

 ery in the State. 



Those who advocate forest culture for the orange may 

 justly claim for it the advantage of comparative immunity 

 from rust, but a decision on the merits and demerits of this 

 and other systems of cultivation must be left to the horti- 

 culturist. 



It may, however, be proper to suggest that where isola- 

 tion is practicable, much can be accomplished toward the 

 exclusion of such pests as the rust mite and the scale in- 

 sects by properly arranged natural screens. Narrow belts 

 of original forest, with its undergrowth, may be left at 

 least on the southeast side of the grove, or, on high land, 

 the tall pines may be supplemented by hedge-rows of the 

 native holly, the jujube, or other evergreen shrubs which 

 thrive upon uplands in the South. 



Such wind-breaks not only protect the bearing trees and 



