THIRTY-FOURTH FRUIT-GROWERS ' CONVENTION. 



87 



decay, is caused by a fungus >vhicli has been named PijtJiiacysiis 

 citrophthora. 



Another very virulent form of lemon decay, which fortunately is not 

 of very common occurrence, is that caused by a species of Sclerotinia. 

 This funous produces an abundant growth of white mould resembling 

 a mass of cotton, which grows over the lemons in storage very rapidly. 



During the past season a large amount of decay of navel oranges has 

 been caused by the so-called "black rot" or navel end rot. This is 

 not a new occurrence, but was more abundant than usual early in 

 the past season. It is caused by a black mould fungus {alternaria) 

 which is not an active parasite, but infects navel oranges to some extent 

 when 'moisture is abundant. 



PRESIDENT JEFFREY. The subject will now be discussed by 

 Mr. V. V. Leroy, of Claremont. 



]\IR. LEROY. As Professor Smith has well said, one of our great 

 troubles in the diseases that affect the orange or lemon, or citrus trees, 

 is the vast difference in the conditions which we are confronting. All 

 over this part of the country there are so many different kinds of soil, 

 different conditions of climate, that it does make a vast difference in 

 our treatment of things as to what kind of soil we have or as to the 

 climatic conditions. For that reason, when I was asked to take this 

 subject, I thought right away that the best way to get at some practical 

 points was to get a few of the most intelligent men I could from the 

 different sections representing this part of the world, and for that 

 reason I have written or spoken to a number of people scattered all over 

 Southern California, who will in turn take up some phase of this sub- 

 ject of disease of the orange tree, and there are some remedies, of course, 

 that they ma}'' propose ; and after that, if there is any more time, I might 

 say a word or two as to the experience I have had. I will first call on 

 Mr. Koethen, of Riverside, who, in some respects, I think, has had as 

 much experience as any one on this trouble. 



MR. KOETHEX. ]Mr. Chairman, Ladies and Gentlemen : Mr. Leroy 

 asked me to express my convictions concerning the characteristic 

 features of scaly bark disease. I am fully convinced that there is a very 

 strong distinction between the scaly bark disease and any other disease 

 that affects our orange trees. The characteristics are marked, and the 

 very fact that most of the others can be cured, and the scaly bark 

 disease can not be cured, as far as we know, places it in an entirely 

 different class. If you will cross-section a limb affected with scaly bark 

 gum disease,, you Avill find that the disease enters clear through the 

 wood — clear through the hard wood. I don't believe that is the case 

 with these other more superficial diseases, and although I rather hesitate 

 to differ from the opinion of so distinguished a man as Mr. Smith, I 

 would call it a much more virulent form of disease than that of the 

 lemon — much more virulent for the reason that we can not cure it; 

 and I do hope Mr. Smith wdll take up this question from the standpoint 

 of a scientist and study it, as we have been compelled to do, practically, 

 in our orchards. I don't think it is safe for us to assume that it is not 

 contagious. It may not be, but I do believe that w^e ought to treat it at 

 present as though it were contagious. 



