THIRTY-FOURTH FRUIT-GROWERS ' CON\TENTION. 



79 



exterminated there. Possibly it is exterminated. We are going to watch 

 those places for a whole year without any let-up at all. We are not 

 afraid of its breaking out at Oroville or Bakersfield. At Marysville 

 we may have to treat it again. The only trouble about the white fly 

 is in the cities. There is where the devastation occurs. If it should 

 break out in Redlands or Riverside or Los Angeles, you would lose half 

 the adornment of your yards and gardens, just as you will see to- 

 morrow night from those pictures. I am very sorry you can't be here 

 to-morrow night and hear the lecture. 



]\Ir. Teague has not come yet, and we will now listen to Prof. Ralph E. 

 ^>mith on "Health and Disease in the Citrus Tree. " 



HEALTH AND DISEASE IN THE CITRUS TREE. 



By prof. RALPH E. SMITH, or Wiiittier. 



Ladies and Gentlemen: Being asked to speak on the subject of citrus 

 tree diseases, I have chosen the topic as put on the programme somewhat 

 purposely in a rather indefinite manner, making the subject "Health 

 and Disease in the Citrus Tree," and not wording it "Citrus Diseases, 

 or Disease of Citrus Trees," or anything of that nature. My idea in 

 that was this, that the subject of citrus tree diseases is one of peculiar 

 indefiniteness or complexity; in other words, it is impossible to give a 

 satisfactory and a complete expression on the subject of citrus tree 

 diseases and classify those diseases, and describe each one minutely, 

 and in a clear way tell how to remedy it. That would be impossible 

 under California conditions, and under the conditions of the California 

 citrus business. If I was speaking in New York state or other regions 

 in the East, perhaps on apple tree diseases or diseases of the peach, 

 or something of that sort, it would be a very simple matter to take up 

 almost all the serious troubles of a tree of that sort and classify them 

 and describe them, and tell what they were and what the cause was, 

 and the remedy so far as known, and present the subject in a satis- 

 factory manner so that each one who listened, if I Avas competent to 

 speak on the subject, would feel that I had described conditions as he 

 had seen them, and that I covered the case in his particular instance, 

 and that the subject had been thoroughly presented. But the subject 

 of citrus tree diseases in California is very different from one of that 

 nature. The subject is, in its very nature, complicated and indefinite. 

 It is indefinite, because it is complicated on account of the conditions 

 under which citrus trees grow here, and the nature of the tree itself. 

 So I will make that preface to what I have to say, that the subject is 

 of this nature, as I will treat it, and I will not attempt to give a cut 

 and dried classification of the cause, nature, and effect and remedy of 

 the diseases or troubles of the citrus tree. 



To define health and disease, particularly as applied to cultivated 

 plants, is by no means easy. While we all have a general idea of the 

 conditions indicated by these terms, and conceive of the two as opposed 

 to one another, one being that which the other is not, yet a definition 

 of each and a sharp drawing of the line between them is quite difficult. 

 In the case of commercial crops, and even more especially with citrus 

 fruits, it is often true that the condition of the plant, or the nature of 



