CITEUS DISEASES. 



107 



due to the breaking up of the epiderm into small irregular flakes 

 or scales. That the injury is superficial is readily shown by the 

 ease with which the scales may be removed, exposing the normal 

 tissue beneath. Small fruit sometimes become misshapen, but ordi- 

 narily there is no harm other than the lowering of grades. This 

 injury is readily distinguished from scab in that raised corky areas 

 or conical projections are lacking. 



A number of possible agencies have been considered as the cause, 

 and all are probably involved at one time or another. Slight in- 

 juries when the fruit is young, rubbing against thorns or branches, 

 and the use of too strong spraying solutions cause some of the mark- 

 ings. A large percentage is thought to be due to the work of mi- 

 nute insects know^l as thrips. In Florida a fungus is commounly 

 found in connection with the scurfing, but is probably secondary. 

 The program of grove sanitation, pruning, and sulphur spraying rec- 

 ommended for other more serious troubles should keep silver scurf- 

 ing down to a minimum. 



SPLITS AND CREASING. 



Splitting is a mechanical injury due to unequal pressure between 

 the inner and outer tissues of the fruit. It is thought to be caused 

 in part at least by a succession of periods of drouth and wet weather, 

 the rind being unable to keep pace with the growth of the pulp, when 



the moisture supply is suddenly in- 

 W^-'-^-^^^j^L^^.^^ y -""^ creased after a shortage. Addi- 



'^^^^^^'^^*^ tional cultivation or irrigation dur- 



ing a drouth would probably obvi- 

 ate this trouble if it ever assumed 

 serious proportions. At present 

 only the naval orange, an unsatis- 

 factory variety, is at all subject to it. 

 Creasing (Fig. 20) is a similar 

 type of injury in which there is a 

 partial break only, tlie skin remain 

 ing whole, and the injury being ap- 

 parent by a depression of the rind 

 The cause and control ar'c the same 



Fig. 20. — Creasing of orange. 



along the line of the break, 

 as for splitting. 



