Is there a beetle that eats the roots of Calla Lilies?
I have a beautiful Calla lily but when starting to plant it I found some sort of beetle in the soil. And the roots of the Calla are mushy but the roots and fibers are white and healthy looking. The mushy parts of the bulbs are just mush. What can this be?
Madison County North Carolina
From what you described, it is more likely that your calla lily (Zantedeschia) is suffering from a rhizome rot or bacterial soft rot caused by a fungus or bacterium. If you planted your calla lily was exposed to temperatures below 50 degrees Fahrenheit over an extended period of time, this can lead to the deterioration of the rhizomes as well.
If the damage to the rhizome (botanically a horizontal stem, but often colloquially called a 'root') is considerable, it is better to dispose of it. Make sure that your calla lilies are planted in moist, but well-drained soil. Porous, loamy soil that doesn't pool when watered or when it rains is better to prevent rot.
Application of a copper fungicide at bud break can work to control fungus and mildew, but this only works as a preventative measure. Once the fungus has attacked, there isn't much that can be done to fix it. The better thing to do is to provide adequate soil drainage in the first place.
Calla lily rhizomes aren't usually known to be attacked by beetles. The pests that would normally attack calla lilies would be aphids, spider mites, slugs, and thrips, but these pests attack calla lily leaves--not rhizomes. One conspicuously red species of beetle, the lily leaf beetle (Lilioceris lilii), has been known to attack calla lilies, but such attacks are rare. Also such attacks by this beetle are on calla lily leaves--not the rhizomes.
If you want to know what species of beetle you found with your calla lilies, your local cooperative extension in your city or county may have a program for submitting (dead) specimens for identification free of charge to you.
Have a Safe and Great Gardening Weekend,