Q: I have a 10-foot ligustrum tree in my front yard. It has been having trouble for more than a

year. Last year, we had a soil sample checked for nematodes. There were some present, but

not enough to cause the branches to die one after the other. What else can be causing this?

 

A: Ligustrum is a tough plant, one even brown-thumbed gardeners can grow. But it does become more susceptible to problems once it gets old. When branches die back, it usually signals some kind of root problem, and it's more than a little frustrating to callers that we tell them it can be too much water or too little. But whether the soil is too wet or too dry, the result is the same: As roots die, the branches die also. With ligustrum, there are three fungal organisms that lie in wait for stress conditions. Armillaria, phytophtora and pythium move into roots when they are stressed and slowly kill the plant. First the canopy thins out. Then branches begin to die back. The last few years have provided seesaw conditions for plants: periods of drought followed by periods of heavy rainfall. Our wet winter weather put roots in moist soil at a time when they are semi-dormant and least able to utilize water. And plants that are mature and no longer actively growing do not have as much resistance to organisms that will take advantage of their vulnerability. The best a plant owner can do is to prevent water from collecting in the root zone by routing water away from the base of plants, water during drought and encourage (by pruning and light doses of fertilizer) ongoing growth.

 

LEARN ABOUT FLORIDA ECOSYSTEM The University of Florida Extension Service

 

There are no effective ways to eliminate the pathogens. They are omnipresent and a necessary part of the big natural web we live in. Where plants have been killed by these fungi, remove as much of the root material as possible. Some experts recommend waiting for several months before replanting the area and not replanting the same plant species. This is an opportunity for a new start.

 

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