FLORIDA STATE HORTICULTURAL SOCIETY 
69 
is no parasite feeding upon the rust mite, 
and I have been following it for a good 
many years. I have seen the rust mite 
since I have been in Florida; they have 
been here ever since the first Chinese or¬ 
ange was grown, and I have never been 
able to find any parasite. 
So far as using fertilizer, I have been 
following that line some, too, and there 
is absolutely no fertilizer to my knowl¬ 
edge, nor to any fertilizer man’s knowl¬ 
edge, that we can put on the ground that 
will destroy the rust mite. 
Question : What is the cause of die- 
back in an orange or grapefruit tree'? 
Can it be remedied, and how? 
Mr. Hume: I am sure that question 
will be answered during the later discus¬ 
sions, but I am calling it up now. 
'Mr. Stevens: At present, we do not 
know the cause of die-back, but it can be 
controlled in a measure by non-cultiva¬ 
tion. 
Mr. Carroll: Mr. Stevens, do you 
know of any case where a sour orange 
root has had melanose or foot-rot—I 
mean foot-rot? 
Mr. Stevens: No, I don’t know of a 
case. 
Mr. Carroll: Can you tell us why the 
sour orange, and almost the grapefruit 
root, is immune to that, and the Chinese 
or Mediterranean orange is liable to 
that disease? 
Mr. Stevens: No, I don’t know that I 
can tell that. The sweet orange is the 
more susceptible, though just why it is, 
I don’t know. 
Mr. Hume: I do not think, Mr. Car- 
roll, that question can be answered as 
to why it is. 
Mr. Carroll: I was just wondering if, 
in his research, he had arrived at any 
conclusion as to why the sour orange is 
immune, and the sweet orange suscep¬ 
tible. 
Mr. Hume: That runs all the way 
through plants, and there is no explana¬ 
tion of it offered as yet. 
Question : Has the idea that the keep¬ 
ing quality of oranges depends in part 
on the cured condition of the rind, been 
entirely given up by growers? 
Mr. Skinner: I think the experiments 
of the department answer that question 
decidedly, and their experience showed 
that the quicker the fruit is put into the 
market, the better it was. You can look 
at the maps given at other meetings, and 
the percentage of decay increased a great 
deal faster than the time. If you hold 
it forty-eight hours, you get a good deal 
more decay than if you hold it twenty- 
four hours, and my experience has been 
that the sooner you get it off, the better 
you are off. * 
Mr. McKay: That has been our ex¬ 
perience, invariably. 
