Like melanose, rain splash is the primary means of black The spores in Florida are formed on dead twigs, some fruit symptom types and in the leaf litter, where spores are present all year. Most citrus cultivars and species are susceptible to black spot. While still concentrated in Collier and Hendry counties, citrus black spot areas expanded to Lee and Charlotte counties recently. Residual activity of strobilurins is shorter thanĬopper, so more frequent applications are needed. Strobilurin-containingįungicides can be used if phytotoxicity is problematic but follow the same In early June also serves as the first greasy spot application. To maintain rind quality on these fruit for the fresh market. Off-season fruit complicate timing, and it will be difficult This is most important for grapefruit, which is the most susceptible cultivar. Needed every 21 days from early May until fruit become resistant in early July. Without residue estimation, copper applications to the whole canopy are TheĬopper model improves copper application timing by estimatingĬopper residue on the fruit surface, leading to better control of melanose and otherĭiseases. Long residual activity, but fruit expansion and rainfall erode the protection. Leaf and fruit lesions do not spread disease and are a dead endįor the fungus because no spores are produced.Ĭopper is highly economical for melanose control because of With cool temperatures, the fungus needs up to 24 hours of Infection only needs 10 to 12 hours of leaf wetness at temperaturesīetween 70 and 80 F.

Melanose is not usually severe without extended leaf wetness Is not a major dieback of twigs, melanose inoculum should return to lower Fortunately, high numbers of spores only occur for a year. Since there were few dead twigs, but a freeze or HLB can cause young blocks toīe affected. Historically, groves under 10 years old had less melanose Hedging reduces dead wood and lowers disease pressure, although some dead twigs will remain. citri also infects live twigs, which produce spores upon twig death. The melanose-causing fungus ( Diaporthe citri)rapidly colonizes and sporulates on small twigs formed from freeze damage and other causes of shoot dieback, including HLB. Enable is especially effective for mid- to late-season rind blotchĬontrol, but do not follow it with Amistar Top since they share the same modeĭead twigs (< 0.25 inch) in the canopy are the greatest indicator of melanose risk. Not use more than one application of a strobilurin alone or in a mixture withinĪ season. June because they are also effective for melanose management. These fungicides are most appropriate in late May to early (FRAC 3) are also effective control options with or without oil if phytotoxicity Strobilurin-containing fungicides or the demethylation inhibitor fungicide Enable Petroleum oils are a good alternative or additive to copper for controlling Practices with copper include applying it on moderately warm days without anyĪdditives, particularly petroleum oils, at 2 pounds per acre or less.įor processing oranges, where the goal is to retain leaves, With petroleum oils, copper can cause rind defects during the summer months. Was observed because the temperatures were low ( 94 F) and dry conditions promote copper phytotoxicity on fruit. In 2019, the trend of fewer problems with foliar fungalĭiseases for Florida citrus continued, which was good news for the industry.ĭespite the El Niño conditions during the spring, little postbloom fruit drop (PFD) Some of the fruit show signs of early coloring, which may lead to premature fruit drop. Citrus canker on Valencia fruit demonstrates how serious lesions can be when inoculum is high.

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