May 9th brought an unusual day of snow squals and temperatures in the upper 20’s damaging tender buds and causing confusion in the plant world. While the chestnuts in the arboretum orchards suffered some freeze damage the trees have recovered as of late June. The more mature trees have male catkins present and the female flowers are visible. A few more weeks and chestnut pollen will be on the breeze.
In years past, this time of year is a flurry of activity, planting seedlings, mowing to try and stay ahead of the grass, inoculating trees, and closely watching flower development in preparation for pollination work. We are very busy this year as well. Over 700 young chestnut trees have been inoculated in the Arboretum orchards at Penn State and 2,400 more have been inoculated using the small stem assay (SSA) method in the shadehouse.
The oldest SSAs are 3 weeks old and the effects can be seen as some of the more susceptible seedlings have died from the inoculation. Over the summer up to 50% of the inoculated B3F2 seedlings should succumb to the inoculations. The remainder B3F2s will be planted in the arboretum in fall of 2020 and spring 2021.
More grafts have been made, and a lot has been learned on what works, what doesn’t, and where we can improve. Dr. Hill Craddock from University of Tennessee, Chattanooga gave a grafting tutorial to some TACF staff which should improve the success moving forward. In preparation for next grafting season hundreds of chestnut seedlings have been planted for use as root stock. The successful grafts will be kept in the shadehouse on campus this year before being planted in a portion of the chestnut orchards in the Arboretum @ Penn State.