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Pomona College Journal of Economic Botany 



petals in the laboratory it can be easily demonstrated that they are affected 

 by the wither-tip fungus. By using a strong hand-lens one is able to see 

 the minute pustules in which the spores are produced. Such diseased flower- 

 buds and petals, however, differ so strikingly from those that have fallen 

 naturally, that almost every one whose attention has been called to the 

 point is able to distinguish between them, without the aid of a lens. When 

 much bloom has dropped as a result of being affected with the wither-tip 

 fungus, one almost invariably finds the typical signs of wither-tip on the 

 tree. The most prominent of these are the dying back of small sprigs, and 

 the very characteristic want of leaves on the inside of the tree. Whenever 

 one sees a tree in the orchard that has no interior foliage, it should be 

 noted as a suspicious specimen. 



The wither-tip fungus which causes the dropping of the flower-buds lives 

 over the winter in the leaves, or in the twigs of the tree, or on fallen fruit. 

 From these sources some of the spores find their way to an open bud, where 

 the fungus grows very rapidly and produces myriads of spores. Bees, flies 

 and other honey-loving insects, visit the affected blossoms, and coming 

 into contact with the fresh spores, not only carry them on their bodies 

 to almost every open blossom on the tree, but in crawling over the unopened 

 buds they convey the spores to these as well. But worse still, the insects 

 which have visited an infected tree carry the spores to other trees in the 

 grove, and from these secondary infections numerous other infections occur 

 in time ; so that hundreds of trees that were free from the wither-tip fungus 

 may become infected from one single tree with diseased Uossoms. 



DROPPING OF NEWLY-SET FRUIT 



Sometimes this fungus does not attack the bloom, but attacks the newly- 

 set fruit after the blooming period is over. Not unfrequently one may see 

 the ground under a citrus tree strewn with thousands of small fruits, every 

 one attacked by wither-tip fungus. In this case the same remedy used for 

 the shedding of bloom will be found useful." — Fla. Agrcl. Exp. Sta. Press 

 Hull. No. 84, Mar.. 1908. 



The large fruit spot described under the heading "Description" (Fig. 5) 

 shows up to a considerable degree in the packing houses. In the past little 

 attention has been given to it except to cull all infected fruit and run it into 

 the lowest grade. While many of these lemons go down before shipment the 

 bulk remain sound enough to reach the eastern markets. The principal 

 injury is due to the fact that fruit, which would be first grade except for the 

 spots, is rendered almost worthless for selling purposes. 



The "Red-spot" usually appears in the field and all infected fruit is 

 culled out by the time the fruit is ready for the pack. It has the same 

 valueless feature as has the lemon-spot in rendering the fruit unfit for 

 market. The fruit infected with this spot keeps very well, for only the rind 

 is injured. I have in my office a lemon preserved from last year, the rind 

 of which is entirely browned due to the red-spot, but the inside of which is 



