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Pomona College Journal oe Economic Botany 



The History and Control In the Limoneira Orchard 



BY JAMES D. CULBERTSON,* ASSISTANT MANAGER 



"During the summer and fall months of 1908 we became suspicious of 

 a new and strange trouble affecting the lemons in the Limoneira orchard. 

 It was evidently a fungus, and although confined mostly to the ripening 

 fruit, nevertheless the incipient stages were plainly noticeable on many of 

 the half-grown lemons that were still green. Of the ripe fruit a great 

 many of the lemons were rendered unsalable and thrown away, while thou- 

 sands of others were thrown into the lower grades by the disfigurement re- 

 sulting from this "rust" or "brown-speck" as some called it. On the greener 

 fruit it appeared as tiny black specks, like minute pin-pricks, while on the 

 half-ripe and ripe lemons these specks were usually a reddish brown, and 

 many of them had increased in size varying from the smallest speck visible 

 under a hand-lens to the size of pock-marks, or even larger. Each spot 

 formed a marked depression in the rind, and not infrequently they would 

 merge into one another until in some instances covering the entire lemon, 

 leaving only a brown "mummy" hanging where the healthy yellow fruit 

 had been. Traces of this trouble had been noticed ofT and on for several 

 years, but the amount of fruit affected by it was so insignificant in relation 

 to the whole that its presence at first occasioned not even a comment, so that it 

 is not known when it made its first appearance. 



By the spring of 1909, however, we began to realize that the percentage 

 of infected fruit was a commercial consideration in itself, not to speak of 

 possible future increase in loss. The new crop was being gathered from 

 the trees and everywhere throughout the 300-acre orchard the presence of 

 this trouble was more evident than ever. Specimens of affected fruit were 

 sent to various sources for identification. Trees containing the worst affected 

 lemons were usually below the normal in vigor of leaf and twig, and often 

 chloratic and subject to gum disease. In some cases we wondered if this 

 first trouble could be a part of the cause, as we later learned that it was. 

 But on even the healthiest trees it was nearly always possible to find some 

 of both the green and yellow lemons affected with the characteristic minute 

 spots. 



While waiting for reports on the specimens sent out it happened that Dr. 

 A. F. Woods, then Assistant Chief of the Bureau of Plant Industry, and Mr. 

 G. Harold Powell of the same Bureau, were making a trip through Southern 

 California and paid us a visit. It was the 20th of April. When taken to the 

 orchard, without hesitation, they pronounced our trouble "wither-tip", scien- 

 tifically known as Collet otrichum gloeosporioidcs, a fungus parasite of Citrus 

 known and dreaded in Florida for 15 years. While we had noted only its 

 effects on the fruit our attention was called by these gentlemen to numerous 

 dead twigs, to yellow and brown spotted leaves, and also to countless small 

 blackened and dried lemons that had probably been attacked and killed by the 

 fungus, when otherwise healthy, before they were larger than small beans. 

 These were charact eristic of "wither-tip" ravages in Florida, and the presence 



*Graduate of Pomona College. 



