About two weeks ago, I was doing some yard work around one of the prized plants of the Drapescape; specifically, a magnolia, Magnolia X brooklynensis 'Yellow Bird'. It is a hybrid cross of our eastern native cucumber magnolia, Magnolia acuminata and M. lilliflora. This year the gorgeous, incredible floral display of beautiful three-inch tall, vase-shaped blooms with butter-yellow petals, has been going on for weeks! The large elliptical-shaped leaves are 4-8 inches long and 4-6 inches wide. I meandered over underneath the Magnolia to trim up the grass and I was shocked to see holes in the young, expanding leaves! It was only the first week of May— so what in the world was wreaking holey havoc with the leaves?
'Yellow Bird' Magnolia with holes in leaves
Putting on my diagnostic hat, I carefully noted the appearance, size and any discernable pattern of holes in the leaves and in the overall damage. While some holes in the leaf were the classic “kidney bean-shape”, others appeared to be almost round. These holes were randomly scattered across some leaves, while other leaves are absolutely riddled with holes. There were no readily discernible, consistent patterns or site placements for the holes in the leaves. Some of the holes had been made earlier, as evidenced by the edges of the holes being completely healed over; yet comparatively, other holes were being freshly created because the leaf tissue damage was still open and raw.
'Yellow Bird' Magnolia with holes in leaves caused by Yellow Poplar Weevil adults
These classic damage symptoms, especially on large-leafed magnolia species, are the result of feeding by the adult Yellow Poplar Weevil (YPW), Odontopus calceatus. The YPW is also known as the sassafras or magnolia weevil, which is fascinating because if you didn’t know, magnolias and sassafras are related!! Depending upon when adults feed on the leaf, the holes may be small, due to direct feeding damage in mature leaves; contrastingly, holes can be quite large, if adults fed on young, rapidly expanding leaves. These small, black to brownish, adult snout beetles will feed on and damage hosts such tulip poplar (yellow poplar), sassafras, and magnolia.
'Yellow Bird' Magnolia with holes in leaves caused by Yellow Poplar Weevil adult feeding
I reported seeing the YPW damage, which I thought was very early, on our weekly BYGL in-service call and Joe Boggs lamented that they just don’t see the YPW down south. Then ironically, Joe reported this past week, (https://bygl.osu.edu/node/2486) an outbreak of YPW on tuliptrees in southeastern Ohio, similar to what happened in the summer of 2018!!
'Yellow Bird' Magnolia with holes in leaves caused by Yellow Poplar Weevil adult feeding
Describing the outbreak of YPW on tuliptrees, Joe noted the following behaviors of the YPW adults, “YPW have one generation per year; however, adults feed twice during the growing season. Adults spend the winter in protected sites such as the duff beneath trees. They emerge in the spring to feed, mate, and lay eggs in leaf midribs. This is the so-called "spring generation" of adults. The "summer generation" arises from the leafmining larvae. There are typically a greater number of adults in this generation compared to the spring generation meaning that most of the damage is done in early to mid-summer. Although yellow poplar weevils are finished feeding in central Ohio, the damage will remain evident throughout the season.”
'Yellow Bird' Magnolia with holes in leaves caused by Yellow Poplar Weevil adult feeding
Apparently, we are in the midst of the “spring generation” emergence in NE Ohio, which feed on the leaves, mate, and then lay eggs in leaf midribs. I have other types of magnolias scattered in the Drapescape, like Sweetbay Magnolia (Magnolia virginiana) and ‘Ann’ ‘Betty’ and ‘Jane’ of the Little Girl series Magnolias. Interestingly enough at least for right now, none of these smaller leafed species of magnolias show evidence of YPW feeding. It is limited mainly to the large leaf species, which currently are the preferred food snack of the YPW!!
'Yellow Bird' Magnolia with holes in leaves caused by Yellow Poplar Weevil adult feeding