220 AXNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



CITRUS-CANKER ERADICATION. 



As a result ol' the vij^orous eradication cainpai'^n conducted l)y the 

 Gull" iStateti in cooperation with this bureau, citrus canker, a bacterial 

 disease of citrus trees, luis been practically eliniinatetl from the 

 greater portion of this reo:ion. Alabama, 'Mississippi, and Florida 

 arc free from any <:eneral infection, but it is probable that scattered 

 cases -will be found in them for one or more years, and scouting to 

 locate and remove such cases promptly nnist be continued. Louisiana 

 apparently has eradicated canker from the commercial producing 

 area, but many scattered infected trees are being found in isolated 

 places. Texas has practically discontinued eradication work, in c<mi- 

 pliance with a recent decision of the supreme court of that State. 



FOREST PATHOLOGY. 



PATHOLOGICAL PROBLEMS IN WOOD CONSERVATION. 



As special problems under the above rather broad heading, studies 

 nave been made on the decays and discolorations of woods used in 

 the airplane industry, from the standpoint of the inspector, and 

 studies have been continued on the effert of incipient decay on the 

 strength of airplane timber. That there is a great difference in the 

 effect of different fungi on the strength of the wood has been con- 

 clusively proved. Preliminaiy studies have been begun on the effect 

 of rot on woods used in the manufacture of chair parts, automobile 

 jDarts. etc. Experiments on the control of sap-stain, sap-rot, and 

 mold in vehicle stock have been concluded, and a report on the ex- 

 periments has been practically completed. 



FOREST-TREE DISEASES. 



The work under this head ma}- be divided into two sections: (1) 

 Work on the nursery diseases and (2) work on general forest-tree 

 diseases. 



Considerable study has been given dur'ng the past year to the rela- 

 tion of fire to the general problems of forest pathology. Fire injury 

 has been found to be responsible for the greater part of all fungous 

 infections, because fire causes wounds througii which the fungi gain 

 entrance to the tree. During the statistical studies of fungous in- 

 fection in felled trees veiy interesting data on the previous history 

 of fire injury in the great forest regions of the West have been 

 irathercd. 



