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Plant Pathology– Do Disease Symptoms Always Warrant Action?

Spotted, Diseased Leaf. Image Credit: Mat

Spotted, Diseased Leaf. Image Credit: Matthew Orwat

In gardening, brown or black spotted leaves are most often an indicator of disease problems or growth issues. This causes us to worry and seek answers as to why this is occurring. This is good since the first step in solving a plant growth or disease issue is diagnosis.

During Fall, the presence of brown or black spots on leaves of shade and fruit trees is usually not cause for alarm, as it might be in the spring or summer. Certain shade trees such as Southern magnolia, Japanese magnolia, various maple, persimmon and oak in the red oak group show substantial brown and black leaf spotting as Fall arrives. This is due to the fact that these leaves have been attacked by fungal pathogens and insects since Spring and resistance to damage has broken down over time. As Fall progresses, these leaves will senesce (purposeful deterioration due to age, such as at end of season) and fall to the ground. Therefore, this ugly spotting is part of natural seasonal leaf decomposition in deciduous trees.

Although Fall leaf spotting may not be something to worry about, oftentimes we run into plant problems that need quick diagnosis. Fortunately, your local Extension Office and the Plant Disease Diagnostic Clinic at NFREC exists for these situations. If you need help with plant problems, feel free to contact your local Extension Agent or Master Gardener Volunteer group and they will figure it out or send it along to the Diagnostic Clinic (small diagnostic fee if using NFREC clinic services).

If you happen to live in or near Washington County, we are launching our Second Mondays Free Plant Clinic. Staffed by knowledgeable and friendly UF / IFAS Master Gardener volunteers and your County Extension Agent, we will be available every second Monday of the month from 10am to 2pm at the Washington County Ag Center, which houses the UF / IFAS Extension Office.  We will be located in the Master Gardener Volunteer Library which is just left of the central auditorium double doors. The launch date of this plant clinic is Monday, October 11th. See you then!

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