CITEUS DISEASES. 55 



ing ground. For disinfection of fields crates and other equipment, 

 the most efficient and commonly used substances are corrosive subli- 

 mate (mercuric bichloride), copper sulphate solution, and formal- 

 dehyde. Formulas and directions for use are given in .the appendix. 



GROVE DIAGRAMS. 



Most growers fail to appreciate the benefit, and even the necessity 

 of having a diagram or plan of each block of trees. The system 

 enables one to keep an exact record of individual tree production, 

 and of other important data, such as character of the fruit, in as 

 great detail as desired. Drone trees can thus be located and elimi- 

 nated, and bud-selection work is not only greatly facilitated, but 

 absolutely dependent upon some such scheme. From the disease 

 standpoint a plan enables the grower to watch more accurately his 

 sick trees. In brief a grove plan eliminates guess work, and makes 

 for general efficiency in all phases of grove activity. Several schemes 

 have been evolved, varying according to the manner of marking 

 the trees, and to the method of taking and arranging the data. Sug- 

 gestions and tentative outlines for orchard plans are given in 

 Farmer's Bulletin 794. The adoption of some plan of numbering 

 trees and taking individual tree data is most emphatically recom- 

 mended, as a scheme that will pay handsome dividends. 



TIME SPENT ON SICK TREES. 



As a general problem, which may be taken up at this point, there 

 arises the question of how much effort to expend on a sick tree before 

 removing it. Some growers, especially those with the smaller groves, 

 have a tendency to give considerable attention to attempted cures of 

 such trees, however hopeless their condition, wasting both time and 

 money. It is difficult to determine whether a tree will repay tiuK' 

 spent in cutting out diseased tissues, in excessive pruning, or other 

 corrective measures, but as a general rule it seldom pays to spend 

 more than the time and money necessary to remove them. 



A young, healthy tree properly planted and eared for, will very 

 soon more than make up in returns for the tree it replaced. This ad- 

 vice will apply ir. cases of serious foot-rot, root rot, wood rot, scaly 

 bark, and similar diseases. In undertaking that most difficult task, 

 the restoration of abandoned or neglected groves, an interplanting, with 

 the gradual removal of the old wrecks, will be found more feasible 

 than a long, costly, and generally hopeless struggle to bring back 

 the original stand to a productive condition. 



