Citrus Fungus Issues

Greasy Spot

Greasy spots are fungus that oftentimes appear as yellow-brownish spots on the underside of a leaf. Use liquid Copper fungicide to stop the fungus from spreading. In Minnesota, this has been a big problem for me, even more so than the pests.

topside of citrus leaf with greasy spot
Topside of citrus leaf with greasy spot
underside of citrus leaf with greasy spot
Underside of citrus leaf with greasy spot
deeply afflicted key lime tree from greasy spots
Deeply afflicted key lime tree from greasy spots. This tree never had a fair chance. I started applying copper fungicide way too late. All older growth is diseased. Thankfully new growth closer to the base of the tree was not impacted. I pruned the sickly branches away. Infected leaves will be the first to go when leaf drop occurs.

Sooty Mold

Sooty Mold is a type of citrus fungus commonly found in hot, humid environments. It’s far less likely to be found in arid climates.

Sooty mold occupying many leaves all across this Ponkan Mandarin. The scaley, reflective, black nastiness is sooty mold.
Sooty mold occupying many leaves all across this Ponkan Mandarin. The scaley, reflective, black nastiness is sooty mold.

 

Treatment

Greasy spots can be treated through a couple applications of copper fungicide. Read the directions on the package on how much to add in your sprayer reservoir. Dilute with water. My particular cooper fungicide has a blue color added to it so it’s easy to tell which plants and leaves on those plants have been sprayed.

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Other Potential Problems