96 Journal of Agricultural Research voi. vi, No. 2 



and were equally numerous on sprayed and check trees. A number of 

 growers have used various germicidal mixtures in attempts to find a 

 preparation which could be successfully employed against Citrus canker. 

 In no case have these efforts met with a sufficient degree of success so 

 that their use in canker control can be recommended. When formal- 

 dehyde is used in sufficient strength to cause the death of the leaf tis- 

 sues in a considerable area surrounding the cankers no viable organisms 

 can be found in the cankerous tissues in many cases. They are still 

 viable, however, in others, and it has also been found to be impossible 

 to cause formaldehyde to penetrate sufficiently deep into old suberized 

 limb cankers to kill the canker organisms. In the light of these tests 

 and in the light of the ineffectiveness of sprays in the control of other 

 plant diseases of bacterial origin, it is believed that there is little to be 

 hoped for in the use of germicides for protection against Citrus canker. 



Eradication. — The history of the work of eradication of Citrus 

 canker, Jittle of which has been published outside of the daily press, 

 would in itself be voluminous, and it is not the present purpose to include 

 it in this account. The early efforts toward the eradication of Citrus 

 canker were confined to the removal of diseased parts in case the trees 

 were only slightly diseased. When the trees were seriously affected, 

 however, they were severely pruned, even though this necessitated the 

 removal of nearly all of the branches. Pruned trees were then thoroughly 

 sprayed with Bordeaux mixture. It was recommended that all the 

 diseased parts which had been removed should be burned. 



After a few months' trial it was seen that by this procedure the treated 

 trees were still diseased. Further than this, adjacent trees had become 

 diseased, although they were apparently healthy at the time efforts 

 had been made to remove cankered leaves and branches from the trees 

 near by. 



Even when the work of removal had been done by skilled hands and 

 when the trees had received several applications of some fungicide to 

 protect the new growth they were still found to become cankered. 



As a result of this it was decided during the summer of 1914 that only 

 the complete destruction of the diseased trees by burning would be 

 effective. As a result of this decision the eradication campaign was 

 organized and a concerted, heroic effort is being put forth to stamp out 

 Citrus canker from the Gulf States. The intelligent observance of the 

 strictest sanitary precautions with reference to trees adjacent to those 

 which are destroyed is necessary. 



SUMMARY 



A serious disease, commonly known as Citrus canker, which affects 

 species of Citrus and Fortunella, has within the past few years been in- 

 troduced into Alabama and other of the Gulf States. It attacks fruits, 

 leaves, twigs, and larger branches, producing characteristic cankerous 



