FLORIDA ,STATE HORTICULTURAL SOCIETY. 
83 
been extensively practiced but the spore-spray¬ 
ing method has now almost displaced this meth¬ 
od. If leaves are pinned, each leaf should be 
pinned, with its fungus side down, to the lower 
surface of a leaf on the whitefly-infested tree. 
Such was the position of the leaf on the tree be¬ 
fore picking, and it should again be placed in 
its original position, as the fungus will more 
readily be distributed by its natural agencies 
when in that position. 
TREATMENT WITH INSECTICIDES. 
As previously stated in the topic on the fungi, 
there are dry times, and groves out of condition, 
when the fungi will not thrive sufficiently. It 
then becomes necessary to spray or fumigate, 
keeping the fungi well spread, however, during 
the period of summer rains. 
The writer is aware that spraying with in¬ 
secticides has been more or less in disfavor. On 
the other hand, operations and experiments of 
the past year indicate clearly that effective spray¬ 
ing can be done, provided the several stages of 
development of the whitefly are taken into con¬ 
sideration and the spraying properly timed. The 
difficulties in the past have probably been that 
spraying was done at the wrong time, reinfestation 
from surrounding groves, and poor spraying. 
The difficulty of spraying so thoroughly that the 
under surfaces of all the leaves become wet with 
the spraying solutions can be overcome only in 
part, by taking special care to do the work 
thoroughly and by spraying at a pressure of ioo 
pounds or over. ^Spraying solutions are also 
more effective in hot weather. 
Spraying for whitefly can be carried on suc¬ 
cessfully during those portions of the year when 
all or nearly all of the insects are in the larval 
stages or are pupae. During the most of fall, 
beginning with October, and the whole of winter 
we have the whitefly in the stages referred to. 
During a part of April or May, following soon 
after the disappearance of the spring brood of 
adults, there is another period of about a month 
when but few adult flies and eggs are present 
and the insect is again in its larval and pupal 
stages. After May and through September all 
stages of the whitefly including the adult winged 
flies are generally present in the trees and the 
period of rains being on besides, it is not a 
good time to spray because most of the adults 
fly away and the eggs are not generally de¬ 
stroyed. 
Fumigation with hydrocyanic acid gas is rec¬ 
ommended for winter use when there are no 
eggs or adult whiteflies. 
For convenience of treatment further discus¬ 
sion of the artificial insecticides will be given un¬ 
der the two following topics. 
WINTER TREATMENT FOR WHITEFLY. 
Winter is a favorable time to treat the white¬ 
fly, because it is in its larval stages, and there 
are no adults to fly away or eggs that are diffi¬ 
cult to kill. The older larvae and cooler 
weather, however, necessitate using all insecti¬ 
cides stronger. 
There are two methods of winter treatment; 
fumigation, and spraying. Where fumigation can 
be employed, it is to be preferred. Those who 
have carried on extensive fumigation experi¬ 
ments claim that it is less injurious to the tree 
than spraying with insecticides. Quicker and 
better results can undoubtedly be obtained with 
it, especially on the larger trees where it is diffi¬ 
cult to wet all the leaves by spraying. For small 
and medium-sized trees spraying can, however, 
be made just about as effective. 
That winter spraying against the whitefly can 
be made effective has been demonstrated. The 
solution must of course be used much stronger 
in winter than in summer. The writer has irs 
mind a locality in Florida in which the growers 
organized a protective league, and assessed each 
grower one cent per year for each tree he owned. 
In this locality, namely, Florence Villa, the 
whitefly had just become started in two or three 
groves, and the results of spraying have been 
so successful that but few if any more whitefly 
larvae could be found last fall than three years 
ago. These spraying operations appear to be the 
most successful on record. The insecticide was 
a good proprietary miscible oil. Another grow¬ 
er states that he has succeeded in keeping the 
whitefly confined to a few trees in one corner of 
the grove for four or five years by thorough 
spraying with another miscible oil. For winter 
spraying 'whale-oil soap should not be used 
weaker than I pound to 4 gallons of water. 
Locality Just Becoming Infested .—Winter 
treatment should not be omitted in any locality 
in which the whitefly is just coming in and is 
confined to a limited area. Under such circum¬ 
stances there is too much at stake to delay. Co¬ 
operation should be started in the form of a 
protective league. All the growers in such a lo¬ 
cality are threatened, and no grower can afford 
to omit paying his share towards keeping the 
pest confined within its present limits as long 
as possible. It pays better to help fight the pest 
in another man’s grove than to have it in one’s 
own grove. Work should not be postponed 
with the thought that something can still be 
done in the summer, since by so doing the 
whitefly is given another chance to spread 
during its swarming period in April or May. 
Fumigate if possible, if noit, then spray thor¬ 
oughly. 
Badly Infested Localities .—Where a locality is 
completely and heavily infested, the trees should 
