29 
Black or Brown Olive Scale (Lecanium olcae , Bernard), and for 
these the treatment he recommends is the kerosene emulsion or 
resin wash. Mr. Froggatt remarks of the latter scale— u Perhaps 
more oranges are rendered unfit for market by the action of this 
coccid than any other pest, except Red Scale, for, though the 
scales do not get on to the fruit themselves, they frecpiently 
cluster round the stalk, and, discharging the honey-dew, cause 
the upper half of the orange to become smothered with black 
smut ( fumagine ), which takes some time to remove.” Destroy 
the insects that deposit the sugary secretion, and the accompany¬ 
ing fungus will be starved out. Recent experiments have been 
carried out in Florida as to the best treatment, and the results 
are given in Bulletin 13 of the United States Department of 
Agriculture, on “ Sooty Mould of the Orange and its treatment” 
by Webber (1897). 
The following measures may bo recommended :— 
1. Prune otF branches badly attacked with sooty mould, and 
burn. 
2. Systematically collect and burn all water shoots at the 
beginning of each spraying season. 
3. Spray with Resin Wash. This has been found to give 
uniformly good results in Florida. The best time to 
spray is when the larvm of the scale are on the move. 
As this spray is easily washed oil by rain, it should not 
be applied during rain, nor when rain is likely to fall 
within two or three days. The dense foliage of Citrus 
trees render them rather difficult to spray, but it is a 
good practice to trim out the tree from within. As it 
is absolutely necessary to wet the under surface of the 
leaves, the operator must get under the tree and spray 
outward, as well as from the outside. Plenty of the 
material should he used, on an average from 15 to 20 
gallons per tree. 
4. Fumigation with hydrocyanic acid gas, by means of tents 
covering the trees, has been found effectual. This gas 
is an animal poison, and does not seem to be effective 
against fungi ; but in this particular instance it rids ns 
of the fungus by destroying the source of its food 
supply, viz., the scale insects. Forty-minute treatments 
have given good results. (See Appendix 2.) 
5. Fungi parasitic upon the scale insects, such as the Coccus- 
loving Microcera (Microcera coccophila ), should he 
artificially spread, in order to check the development of 
the insects. 
I have not thought it necessary to recommend measures 
adapted for the removal of sooty mould alone. Alkaline washes, 
