Brood X Cicadas – Delay Tree Planting and Protect Newly Planted Trees
What & Where? Oldham is one of several Kentucky counties that will experience a large number of periodical cicadas emerging this spring. Known as Brood X, this population matures and emerges once every 17 years. While the exact timing of emergence is dependent on weather, we can expect to begin hearing them around mid-May.
Why Should We Care? Besides the annoying racket they make, cicadas are also pests of trees. They may cause damage to trees in two different ways. The first is when adult females cut slits in the undersides of small branches to lay eggs. ¼ – ½ inch diameter-sized branches are preferred. For smallest branches, this can mean branch dieback if the majority of xylem and phloem tissues are damaged. On larger twigs that survive, the damage may only be cosmetic. The second way cicadas damage trees is from root-feeding. Newly hatched cicadas fall from branches and burrow into the ground where they begin feeding on roots, sometimes causing substantial damage.
What Can Be Done? Cicadas favor newly planted oak, apple, peach, pear, hickory, and dogwood, but will also damage other species of trees. One way to avoid cicada damage is to delay planting new landscape or fruit trees until after periodical cicada activity has ended for the season. Here are a few other ideas as well:
- Young trees under 6 – 8 feet in height can be covered with netting to protect tender twigs. This should be done when cicada males first begin ‘singing’. Use netting that has mesh openings of less than one-half inch to prevent females from gaining access to branches. Net the canopy like a lollipop, and secure the covering around the trunk to prevent cicadas from climbing up to the limbs. The netting should be removed at the end of June or when cicada activity stops.
- For unprotected or larger trees — if practical, twigs with signs of egg-laying can be pruned out and disposed of in trash. This needs to be done within three weeks after egg laying has ended. Although time-consuming, it may be a viable option for trees of significant landscape value or for fruit trees. The idea here is to reduce the number of cicada nymphs so that root feeding damage is minimized. Feeding by large numbers of nymphs over several years can reduce the vigor of small trees.
- Insecticide applications generally are of limited use in protecting trees from damage, especially where cicadas are very abundant. Repeated treatment will be needed to deal with new arrivals. Orchards under a routine spray schedule should be treated about twice a week during peak cicada activity. Spray requirements will vary according to intensity of the outbreak, which can range from a few cicadas in some areas to massive numbers in others.
According to cicadamania.com, other counties where Brood X is expected to emerge this year are:
Written by Traci Missun, Oldham County Agriculture & Natural Resources Agent.