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Unusual Growths on Plants May be Galls

Don’t let lumps, bumps and unusual growths on leaves and stems of your landscape plants send you into a panic. They’re likely one of the many galls that look bad, but don’t harm the health and longevity of your plants.

These bizarre growths are just the plants’ response to insect feeding.  As leaves and twigs expand in spring, mites, adelgids, psyllids and other insects feed on them, causing a proliferation of growth.  The plant forms these fuzzy red patches, tall green spindles, orbs or other strange, often colorful growths, that encapsulate the insects.

A couple common galls include spindle, velvet, maple bladder, mossy rose and hackberry nipple galls that look just like their names imply.

Since these galls are not harmful, there is no need to treat.  Weather and natural predators will help keep these gall-causing insect populations under control in the future.

 A bit more information:  Crown gall on euonymus is one exception.  These galls appear near the base of the stems on the euonymus.  The growths are caused by a soilborne bacteria.  As the galls grow, they weaken the stem and can cause stunting and tip dieback.  It is believed that this bacterium also causes galls on forsythia, viburnum, highbush blueberry, American elm, hickory, maple, oak, and privet.   The only control is pruning beneath the gall and disinfecting your pruners between cuts.  Unfortunately, this usually means ground level pruning, since the galls most often occur at the base of the stems. 


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