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It's raining limbs
There are several abnormalities that can happen in the landscape and confuse an unknowing homeowner. Some of these things are even brushed off and just ignored, or it is just assumed that "it's normal." But every now and then there is the homeowner that wants an answer for every little thing that goes on in the yard. What's strange is that I usually like these people. They have that in-born desire to learn and a need to know why things happen. Every fall it is typical that one or two people will call with the problem of a tree dropping twigs. While it is true that some trees, like the hackberry or silver maple, are thought to be trashy because of the limb litter that they drop throughout the year; the case may not always be so open and shut. Mother Nature is more creative than that.  Twig girdlers are commonly found on pecan, hickory, persimmon, and elm. They also attack oaks, honeylocust, hackberry, poplar, dogwood, sourwood, and various fruit trees. It is not uncommon to see the ground under infested trees almost covered with twigs that have been cut off. This affects the beauty and aesthetic quality of ornamental plantings. The fruiting area of heavily infested pecan trees is often greatly reduced, resulting in low nut yields the following year and sometimes longer. This type of injury causes the development of many offshoots that adversely affect the symmetry of the tree. Pecan nurseries located close to heavily infested woodlots occasionally suffer considerable loss from girdled seedlings. Adult twig girdlers emerge from late August to early October. They feed on tender bark near branch ends and mate before laying eggs and girdling twigs. Twigs are girdled because the larvae are unable to survive in living twigs. The girdling extends through the bark and well into the wood in a complete circle around the stem and leaves only a thin column of the center wood attached, which breaks easily. Twigs from 1/4 to 1/2 inch in diameter are most commonly girdled. Damaged twigs that fall have a spear-shaped point at the end; like it has been run through a pencil sharpener. Eggs are laid during or after the cutting process, but never before the beetle makes part of the cut. Eggs are inserted singly beneath the bark or slightly into the wood, usually near a bud scar or adjacent to a side shoot. The number of eggs per twig normally ranges from 3 to 8 but may range up to 40. Adults live 6 to 10 weeks. Each female deposits 50 to 200 eggs which hatch in about 3 weeks. The small larvae overwinter in the dead twig either in the tree or on the ground. Larvae grow rapidly in the spring and tunnel toward the severed end of the twig, feeding only on the woody portion and leaving the bark intact. The mature larva closes off the gallery with shredded fibers to form a pupation chamber, where it will transform into an adult. Pupation occurs during August and September and lasts 12 to 14 days. The newly developed adult chews a circular hole in the bark to emerge. The best way to control the nuisance is to remove the fallen limbs from the yard. Since these limbs contain the next generation it is necessary to get them out of the landscape. Just throw them into your neighbor's yard.... or maybe not! There is, however, a bit of good news at the end of this story. Only one generation occurs per year and now is the time to be looking for the fallen limbs. So the next time that you are wandering in the yard, pick up a limb and go impress some friends with your supreme horticultural knowledge. C Date: 9/24/07
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