Bulletin 229, Diseases of Citrus in Florida


by the use of chemical hydrated lime and powdered bluestone
has recently come into prominence among fruit growers. The
chemical hydrated lime is an exceedingly fine hydrate, so called
because it is used largely in the chemical industries. The use of
this kind of hydrated lime gives a much better bordeaux mixture
and eliminates the difficulties of securing and slaking quick-
lime and the necessity for setting up a series of stock and di-
lution barrels and other cumbersome equipment. The required
amount of ingredients can be weighed out and poured into the
tank screen and washed into the tank by the inflowing water
according to the method just described for the use of stock so-
lutions. The use of chemical hydrated lime, which is an ex-
ceedingly finely divided product free from grit and containing a
much higher percent of calcium hydroxide than the ordinary
hydrated lime of the building trade, will undoubtedly supplant
the use of quicklime and ordinary hydrated lime in the commer-
cial preparation of bordeaux mixture.
 LIME-SULPHUR SOLUTION
 Lime-sulphur solution has the properties of both a fungicide
and an insecticide when used at certain strengths. Lime-sul-
phur is used in the citrus grove chiefly to control rust mites,
red spiders, and scab. Concentrated solutions are obtainable
from two sources and are usually distinguished as commercial
lime-sulphur and home-made lime-sulphur. Within late years,
lime-sulphur has been put on the market in dry form to elim-
inate the freight on the water.
 Commercial liquid lime-sulphur is a concentrated product
which is more expensive than the home-made product but keeps
better and eliminates the trouble of making and storing the
home-made solution. It is also more convenient to handle and
varies less in its strength. These concentrated solutions are
generally used at dilutions of 1 part to from 25 to 40 parts of
water for scab control and of 1 part to from 50 to 65 parts of
water for rust mite control. For scale control on trifoliate
orange and other trees that shed their leaves and become com-
pletely dormant, a dilution of 1 part to 8 of water is customary.
These dilutions are usually made on the basis of a concentration
of 320 Baum6 as shown by the hydrometer reading. The com-
mercial brands of lime-sulphur solution will vary in concentra-
tion or density from 31 to 34 degrees Baum6 and the concentra-