Plant and Pest Observations
Pine needle scale. Pine needle scale infestations on white spruce were noted. This insect can affect many conifer species, including Norway and Colorado spruce, Austrian, Scots, and Mugo pines. Pine needle scale has two egg hatches - one in early spring (~ 305 GDD) and another in July (~1349 GDD). Pine needle scale is more commonly found in Christmas tree plantations than in landscaping settings, with some Austrian pine populations having dense infestations.
Boxwood leaf miner. Cold winter temperatures did not impact boxwood leaf miner activity in northwest Ohio. The invasive insect has produced yellowing on many boxwoods this season. There are ongoing breeding efforts to develop resistance to the pest in North Carolina.
Lesser celandine herbicide control strategies. Controlling lesser celandine using herbicides, particularly glyphosate, can be challenging. Timing applications with full flowering may be most effective but requires long-term monitoring due to the plant's underground storage systems. Burndown herbicides like Scythe have been used anecdotally but typically require multiple applications and early spring treatment before leaves emerge to prevent carbohydrate translocation.
Box tree moth (BTM). BTM pheremone traps will be deployed from April 15th through October in Ohio with several BEHT members monitoring for BTM in their counties this year. Traps will be deployed in counties that have recorded the presence of BTM and those that have not. A current quarantine map can be found in this BYGL Alert.
Challenges with a phenology model for BTM were shared, particularly noting that the current model may not be accurate for the U.S. due to differences in diapause behavior compared to European models. BTM caterpillars overwinter in diapause and are activated by day length rather than temperature, making traditional phenology calculations based on temperature unreliable. More research is needed to understand when the phenological clock starts for BTM, with the model being refined by researchers.
Learn more about BTM in these three, recently published Ohioline Fact Sheets:
- Box Tree Moth: Range and Spread - https://ohioline.osu.edu/factsheet/ent-0099
- Box Tree Moth: Detection - https://ohioline.osu.edu/factsheet/ent-0100
- Box Tree Moth: What Should You Do? - https://ohioline.osu.edu/factsheet/ent-0101
Other observations. Potential black vine weevil damage, sooty mold, frost on saucer magnolias, star magnolias with fewer blossoms than usual. Eastern Spruce Gall adelgid mature galls were found on a white spruce trees.
Beware of volcano mulching! Volcanos are erupting across Ohio! The phenomenon is particularly damaging to affected trees - elevating root systems and stressing trees. Check out this past BYGL alert on mulching matters and this BYGL Alert, too. The conversation concluded with a mention of ISA's public service announcements about the dangers of volcano mulching. A review of scientific literature on mulch depth can be found at this ISA link.
Contributing Buckeye Environmental Horticulture Team Members:
For more information on each team member, visit: https://beht.osu.edu/people. Additional contact information for each member can be found on their county website by visiting: countyname.osu.edu (ie. pike.osu.edu).
- Ann Chanon, Lake County
- Ashley Kulhanek, Medina County
- Beth Scheckelhoff, Putnam County
- Carri Jagger, Morrow County
- Curtis Young, Van Wert County
- Joe Boggs, Hamilton County
- TJ Wells, Washington County
