FLORIDA ,STATE HORTICULTURAL SOCIETY. 
87 
fumigation when the fly is not excessively 
abundant in a grove may be expected to 
last two, or, in some instances, three 
years, while the amount of fly escaping a 
fumigation in a badly infested grove may 
represent numerically such a large amount 
of fly that the trees may become blacken¬ 
ed by the following fall, if multiplication 
goes on unchecked by natural agencies. 
It seems probable that in very heavily in¬ 
fested groves fumigation two successive 
years can best be employed to reduce the 
fly to relatively small numbers when fu¬ 
migation once in two or three years will 
keep the fly from blackening the foliage 
and fruit. 
Mr. Scott: In Arcadia, the whitefly 
made its appearance about three years 
ago. Last winter we fumigated with 
these tents, I suppose about 1,000 or i,- 
500 trees, at an expense of $2,500.00 
which was appropriated by the county. 
This year, if the fly has been seen there, 
I haven’t seen it or heard of it. I have 
not seen a single one. 
Dr. Back: In that work, about four 
of every thousand flies escaped fumiga¬ 
tion. The percentage of fly killed in Ar¬ 
cadia is remarkable considering the ad¬ 
verse conditions. 
Mr. Scott: We had a few chinaberry 
trees that might have harbored the fly 
and we cut them down, and all the Cape 
Jasmine and privet. There was some bad 
feeling about it, but I think it is all over 
now. It was just in town that this was 
done. We took it in time so that it has 
not spread out into the county at all. 
Mr. Gillette: We use a great deal of 
spray during the summer killing the rust 
mite; that is, the sulphur solution dis¬ 
solved with caustic soda or caustic pot¬ 
ash. If the grove was full of the fungus 
you have described, would the use of this 
wash kill the fungus or have any effect 
upon it? 
Dr. Back: As most groves are 
sprayed for the mite, I do not think that 
it will. I have seen groves sprayed for 
the mite where the fungus along the edge 
of the under surface of the leaf had 
turned color and appeared to have been 
killed, although I am not positive. Since 
in spraying a tree for the mite the under¬ 
surface of the foliage is not wet to any 
extent by the spray, I doubt if the fungus 
is seriously affected. 
Mr. Porcher: If you sprayed four o*~ 
five times during the summer, what ef¬ 
fect would there probably be? 
Dr. Back: I don’t know how to an¬ 
swer that question except with this ex¬ 
ample. I know of one grove that was 
sprayed regularly throughout the sum¬ 
mer for rust mite and in September that 
grove had the finest stand of Yellow As- 
chersonia that I ever saw. 
Mr. Skinner: I might suggest that in 
spraying for the rust mite, you generally 
go at it from the top of the tree, so that 
the spray hits the upper sides of the 
leaves, and the fungi are on the under 
sides of the leaves. 
Mr. Hart: Now, about straining the 
material; I note that you say to strain 
through fine wire. Is that what you use 
altogether? 
Dr. Back: Just an ordinary wire 
strainer. We use wire strainers altogeth¬ 
er. 
