The weather has its own agenda. The nasty, bitter winter of 2018-2019 is one many of us would like to forget.
Every morning I would think to myself, "one day closer to spring."
It was slow in coming but spring finally got here, only to be another season we would like to forget. The grass did turn green and the flowers burst into bloom but the cold and endless rain just would not quit.
Nature also has its own agenda with a twist. It has to adjust to the environment – which includes weather! The result this year was winter kill and damage to more trees and shrubs then normal.
Partial winter kill or weak growth appeared on the large Ginkgo at the Arboretum. About 30% of the leaves are the normal size. The other leaves are dwarf in size and will grow larger with the summer sun. Our Japanese Maples took a real hit at the Arboretum. Of our 15 spectacular trees on the grounds, only two survived. If your Japanese Maple was partially damaged, cut off the dead branches and if the tree is not to deformed give it a chance to leaf out and fill in. If the tree does not fill in, it will need to be replaced.
The large majestic Sycamores in the area are struggling to leaf out. This tree is normally late to show growth. Tiny leaves are struggling to grow only to be set back further by a fungus disease called Anthracnose. This disease damages leaf cells, causing some small leaves to fall prematurely. Large, healthy trees will recover slowly when the summer sun gets here.
Colorado Blue Spruce are winter hardy here and their decline was not from the cold but from the cold wet springs and high humidity during the summer months, which favor a fungus disease called needle cast. The wet spring weather is what this fungus needs to take hold, causing more needles to turn brown and fall off lower branches. Older trees are the hardest hit. Normally, you should not trim up lower branches on conifers; however, this is the exception. As the lower branches turn brown and die they should be cut off close to the trunk. Better air circulation will help slow down this disease, but not stop it.
The devastation of the ash tree population will continue due to the Emerald Ash Borer. If you are treating your ash trees you must continue treatments yearly. Large trees must be treated by a professional arborist and they will be able to answer your specific questions.
One hardy shrub that was killed back severely was burning bush. Large, established plants show die back up to 90%. If your bush appears dead on top, it probably is. Cut all the dead branches back to the new green growth at the bottom. Hopefully the root system is still strong and will send energy to what shoots are still alive. If there is no green at the bottom, the bush will need to be removed. Other shrubs showing damage this year at the Arboretum are weigelia, viburnum, azalea, forsythia and boxwood. Some shrubs will be cut back and others will need to be removed.
Our gardens are another setback story. The warm season crops like tomatoes, peppers, green beans, sweet corn, cucumbers and zucchini could be producing fresh vegetables as much as a month later than normal. What does that mean? It means no local sweet corn or tomatoes by the 4th of July. Any large batches of salsa or pickles may not be done until the end of August or September. What we need are warm days, warm nights, full sunny days and gentle summer rains. Like I said, the weather has its own agenda. Time will tell.
Margo Hansen is the director of programs at Bickelhaupt Arboretum.