Spring is inching forward, but our degree days, a measure of how warm it has been since the start of the year, tell the story of 2013 thus far.
These degree days (heat units) drive both flower development on trees and insect development. In Wooster on March 29, the degree days last year with all the hot days were at 220, with gypsy moths having hatched at 172 and pears, then magnolias, then most crabapples already in bloom and lilacs just about to pop at 234.
Compare this with March 29 this year with degree days stuck for some time on 34, and early bloomers such as corneliancherry dogwoods and red maples not yet sporting their first blossoms.
So, we are slow to develop to date in 2013. Nevertheless color abounds in the landscape, along streams and in woods. There is the bluish bloom of ‘Candicans’ white fir. There is the sunny yellow-orange of coltsfoot wildflowers (though they are not native) that started to bloom in late March in Northeast Ohio. There are also the leftover fruiting bodies of the bright orange cinnabar polypore fungus growing on fallen dead cherry trees near Secrest Arboretum.
I was in the warmer climes of Silverton and Clackamas County, Oregon, for a Tree School talk two weeks ago and the magnolias were blooming there, a harbinger of what we will be seeing as we move into early April here.
Walking outdoors and talking indoors continues as this spring unfurls. Here are a few items for your early Spring Almanac:
• Hemlock woolly adelgids. Another major invasive species for Ohio, the hemlock woody adelgid insect (Adelges tsugae) sucks sap and debilitates native Eastern hemlock (Tsuga canadensis) and the Carolina hemlock. This aphid-like insect from Asia was discovered in the Western U.S. in 1924 and in Virginia in 1951, from different infestation sources. The Virginia infestation is attributed to materials imported from Japan.
By 2005, the insect was reported in 16 states and was intercepted a number of times in Ohio, including in Summit and Stark counties from nursery stock imported from other states. In 2012 it was first identified in natural forest settings in Ohio in Meigs County and most recently in March at Cantwell Cliffs in Hocking Hills State Park.
This insect, easily detected from the egg masses that look a bit like tiny cotton swabs on the undersides of needles, is a major concern, as anyone who loves the gracefulness of hemlocks in our forests will attest. It is devastating where widespread, leading to tree and forest stand death. We have some beautiful forest stands in Northeast Ohio, but in southeast Ohio the hemlock cove forests are major wonders. If you have visited Cedar Falls (misnamed since hemlocks are really the featured conifer) you will know how sad it would be to lose these trees.
The Ohio Department of Agriculture and the Ohio Department of Natural Resources discovered the infestation in Hocking Hills and are now considering management options, from “soft” insecticides such as horticultural oils and insecticidal soaps, to systemic insecticides and biological controls such as insect-eating fungi and predator beetles. Let us hope that management is successful. I have seen the devastation in Virginia, North Carolina, West Virginia and Kentucky woodlands, the earlier eradicated Stark County mini-infestation from North Carolina nursery stock, and even at the Oregon Gardens recently, where the insects were feeding on arboretum specimens of our eastern hemlock.
It is the familiar story line for invasive species. Native-to-Asia hemlocks have been through the evolutionary natural selection process over time, with successive generations of surviving resistant hemlocks due to mutations and development of strong populations of natural enemies, so their hemlocks are little affected by this pest compared with our native species that are newly facing this challenge.
• Rose rosette virus. Another pest that has emerged in recent years for rosarians here in Ohio is rose rosette virus. We are seeing it on many different types of roses, including the quite popular Knockout series of roses.
First discovered in North America in Canada in 1941 on multiflora rose, this pest is really becoming a problem over the past decade in Ohio. We talked about it at the recent Summit-Portage-Stark County Master Gardener update recently at Firestone Park, or at least I had hoped to get to it when impatiens downy mildew intervened.
I remember when I first got calls about this problem years ago. Gardeners noted reddish new growth, and I replied that is normal on many roses. Then they mentioned masses of short shoots growing in a broom-like pattern and a rosette pattern of stunted growth and curled, narrow, strap-like leaves. I paid a bit more attention, but suspected growth-regulator herbicide injury, perhaps glyphosate (Roundup) injury, maybe from non-lethal doses the season before. The symptoms were quite suggestive.
Other symptoms mentioned included a proliferation of thorns, unwelcome to all, so the profile was getting curiouser and curiouser. Ultimately, we all realized this was rose rosette disease. The cause was a mystery for years, but the consensus now is that it is caused by a virus spread by a tiny eriophyid mite, the rose leaf curl mite.
We thought for a while that this disease might be a good control for multiflora rose, considered an invasive plant species in many habitats. Alas, it is not quite capable of wiping out multiflora rose in our woodlands and farmlands, but it is wiping out the ornamental beauty in many rose gardens and can kill plants.
I wish we had wonderful solutions to the problem, but there are no virusides, and eriophyid miticide programs need be really intensive and are typically used only by rose producers. The best control is the bitter pill of removing the plants from your rose gardens as soon as you get a diagnostic confirmation.
Enough of these pests. Enjoy the spring. Come to the OSU Wooster Arbor Day Celebration and the Tale of Five Oaks, complete with a Why Trees Matter Tree Benefit walk on April 20 (check out http://secrest.osu.edu).
9 a.m.: Oak planting by Doylestown Brownies in the Secrest Amphitheatre
9:45 a.m.: Oak planting at OSU’s Agricultural Technical Institute with ATI students
10:30 a.m.: Oak dedication at the Ben Stinner Memorial Garden on the OARDC Campus
11:15 a.m.: Oak planting from the City of Wooster at OARDC
Noon: Oak planting from the College of Wooster at Secrest Arboretum.
The day will include comments on OSU receiving its second Tree Campus USA certification, joining the Columbus campus in 2012. OSU is one of only six U.S. universities to receive two tree campus designations from the National Arbor Day Foundation.
Finally, though it is a bit late this year, some warm spring day, heed the words of William Wordsworth, from excerpts from his poem To My Sister:
It is the first mild day of March:
Each minute sweeter than before
The redbreast sings from the tall larch
That stands beside our door…
…My sister! (‘tis a wish of mine)
Now that our morning meal is done,
Make haste, your morning task resign;
Come forth and feel the sun…
…No joyless forms shall regulate
Our living calendar:
We from to-day, my Friend, will date
The opening of the year….
…One moment now may give us more
Than years of toiling reason:
Our minds shall drink at every pore
The spirit of the season…
…Then come, my Sister! come, I pray,
With speed put on your woodland dress;
And bring no book: for this one day
We’ll give to idleness…
Jim Chatfield is a horticultural educator with Ohio State University Extension. If you have questions about caring for your garden, write: Jim Chatfield, Plant Lovers’ Almanac, Ohio State University Extension, 1680 Madison Ave., Wooster, OH 44691. Send email to email@example.com or call 330-466-0270. Please include your phone number if you write.