Wither-Tip of Citrus Trees 



(Colletotrichum gloeosporioidcs Penzig) 

 Its History, Description, Distribution, Destructiveness, and Control 



BY E. O. ESSIG* 

 HORTICULTURAL COMMISSIONER OF VENTURA COUNTY 



Common Names : Wither-tip ; Leaf-spot ; Tear-stain ; Lemon-spot ; An- 

 thracnose ; Canker. 



INTRODUCTION. 



The first observations on wither-tip in Ventura County were made by 

 Dr. Albert F. Woods, Pathologist and Physiologist in the U. S. Department 

 of Agriculture, Bureau of Plant Industry, during the month of April, 1909. 

 At that time he made very careful examinations and found that much damage 

 was being done by its attacks. The leaf-spot, lemon-spot, red-spot, dropping 

 and discoloration of leaves, and the dropping of young fruit were all classed 

 as the results of the wither-tip fungus. 



Later in August of the same year Dr. P. H. Rolfs, who had done more 

 work on this disease than any one else, visited the orchard and pronounced 

 all of the above forms wither-tip, just as had Dr. Woods. Mr. Powell was 

 of the same opinion, so it was not strange that the management of the 

 Limoneira ranch, where these valuable observations; were made, began at 

 once to take steps to not only hold the disease in check, but to prevent the 

 conditions already occasioned by it. The work there has been pushed with 

 much interest and the results to date will be found in this article further on. 



During the summer of the year 1910, Mr. C. N. Jensen of the Whittier 

 Pathological Station made several trips into this county investigating this 

 problem, but he did not remain in the State long enough to finish his work. 

 At an inspection of the trouble in the Limoneira orchards he left the im- 

 pression, to me at least, that this fungus was not in the habit of attacking 

 strong and healthy tissues, but rather those portions of the tree which had 

 become weakened by some external or other internal factor. In a letter 

 from Dr. Coit, of the Whittier Station (following) it is made plain that 

 Mr. Jensen did recognize the fact, that under proper climatic conditions, 

 the disease did attack perfectly healthy trees. However, the impression left 

 was that much of the work on wither-tip control was of little avail and we 

 rather awaited further specific evidences of its work. These came in the 

 form of a very severe outbreak in the Havana Seedling Orange orchard 

 belonging to Mr. N. W. Blanchard of Santa Paula during the months of 

 November and December, 1910. The tops and sides of the large trees were 

 dreadfully injured by the work of the fungus, which killed fruit-bearing-wood 

 back as far as four feet from the tips of the branches. The leaves curled 

 up on the twigs and died before dropping to the ground and much of the 

 fruit dropped within a few weeks. 



•Graduate of Pomona College. 



