Pomona College Journal of Economic Botany 37 



Not all of the fallen fruit show the effects of wither-tip at the time it 

 dropped, but if placed away in moist chambers soon develop the spots de- 

 scribed above. The infections are quite general on much of the fruit that 

 has not fallen and the amount of injured fruit may reach to several hundred 

 boxes, not counting what may develop after it has been picked and boxed 

 for shipment. 



The fact that the infection takes place before any evidence is displayed 

 upon either tree or fruit makes the pest a serious menace if one has not 

 been prepared to meet it in advance. All fruit which has become infected on 

 the tree cannot be treated in any wash that will prevent the coming out 

 of the fruiting bodies. To demonstrate this, leaves infected in the orchard 

 were soaked a short time in Bordeaux Mixture, such as is used for spraying 

 citrus trees, and placed in the moist chambers. The acervuli appeared in 

 great numbers through the residue of the Bordeaux upon the leaf. All 

 methods of control must be directed as preventive. This makes the results 

 of the first unlooked for attack very destructive to the orange grower. It is 

 well to dip the fruit, however, to prevent infection in the box or in the 

 packing house. 



The leaf-spot — "Canker" — is more common upon the lemon than upon any 

 other citrus tree in this county. In Florida it seems to work to even a 

 greater degree upon the pomelo, but such a case has not been observed here 

 yet. Neither have we ever found the withering of the twig and leaves 

 as described by Prof. Rolfs on the lemon tree. The discolored leaves, the 

 spot, and the bare twigs give us the most evident clues in the field. 



It is the dropping of the young fruit that is considered the most serious 

 work of the fungus in the lemon orchards. At times it seems as if a third 

 of the young setting lemons were dropped by it. The brown mummies on 

 the ground or still clinging to the trees are full of the wither-tip spores. 

 Much of the work being done at the Limoneira ranch is to prevent this 

 condition. The results and costs, as well as the importance of the work there 

 is to be presented in Mr. Culbertson's paper further on. Concerning the 

 dropping of the bloom due to wither-tip, Prof. Rolfs states : 



"The most serious shedding of bloom occurs as the result of an attack 

 of a parasitic fungus, Colletotrichum gloeosporioides. This is a serious trouble, 

 for only too frequently its cause is not recognized, the shedding of the bloom 

 being ascribed to one of the before-mentioned causes, or to the presence 

 of thrips or other insects. 



The first sign that we notice in connection with the wither-tip dropping 

 of bloom is that a great number of unopened flower-buds have fallen from 

 the tree. As this same effect may be the result of other causes, the mere 

 fact that we find unopened flower-buds on the ground should not be con- 

 sidered as proving that we have a case of wither-tip bloom dropping. Upon 

 closer examination, however, we find that where the bloom has dropped on 

 account of being affected with the wither-tip fungus, there are little red 

 markings upon it; and the buds or blossoms may be partially, or even 

 entirely, covered by these red patches. By examining such flower-buds or 



