Florida Agricultural Experiment Station


dying twigs and branches did not prove to be a consistently
effective, practical or economical method of controlling this
disease in groves of any considerable size. In view of this it has
become customary to rely upon spraying in conjunction with
pruning.
 A single application of 3-3-50 bordeaux mixture plus 1 percent
 of oil as emulsion, applied shortly before the May rains set in,
 has been found by several years of experimental work to give
 an excellent control of melanose as a rule. This application, in
 ordinary years, should not be made before April 15 and should
 be completed by the fifth day of May. With the repeated dem-
 onstration of the effectiveness of bordeaux-oil emulsion as a
 combined fungicide and insecticide, spraying for the control
 of melanose and other fungous diseases of citrus trees has been
 put on a commercial basis anti the former objections to the use
 of bordeaux mixture have been largely overcome. It has been
 found that 1-40 lime-sulphur solution has but little effect in con-
 trolling melanose and that dusting with either copper or sulphur
 mixtures has failed to give satisfactory control.
 Extra Spraying for Insect Control Following Melanose Spray-
 ing:-Unfortunately, spraying with bordeaux mixture or bor-
 deaux-oil emulsion destroys the spores of the beneficial fungi
 parasitic on certain citrus insects as well as the spores of the
 fungi that are being combatted. This favors a considerable and
 usually rapid increase of scale and certain other insects, which
 may do serious damage by fall unless measures are taken to
 prevent an excessive infestation. It is largely to assist in keep-
 ing the scale-insects in check that bordeaux-oil emulsion gen-
 erally is recommended for citrus disease control instead of plain
 bordeaux mixture. The addition of the oil is also effective
 against the whitefly. Experience has shown, however, that even
 when oil emulsion is used in conjunction with the bordeaux mix-
 ture or other copper fungicide, it is usually necessary to apply
 a "follow-up" spray of oil emulsion to assist in the control of
 scale-insects. This application should be made between May 20
 and June 15, the period when the scale-insects are hatching in
 greatest numbers.
 Secondary Benefits from Melanose Spraying:-There are two
important secondary benefits from spraying with bordeaux mix-
ture or bordeaux-oil emulsion for melanose control. One is the