The doldrums of muggy, moist, cloudy weather is certainly a touchstone of late June and early July this year with disparate results.
Lawns are emerald green, crops in the field are so much more vigorous than this time last year, and ornamental plants such as bottlebrush buckeye, tricolored beech, flower plantings including the wonderful new petunias, and many others truly shine. On the other hand, disease time bombs are detonating and being set in motion.
These diseases include Diplodia tip blight of pine from fungi that infected tips in May now curling new growth on Scots and Austrian pines, and bacterial fireblight showing up where wet and warm weather during bloom in April caused blossom infections and now blighted shoots.
They also include powdery mildew of dogwood and rose black spot showing up now, and downy mildews sure to emerge soon from latent infections occurring in recent days and weeks. In fact, Sally Miller from Ohio State University’s Ohio Agricultural Research and Development Center (OARDC) in Wooster recently reported that the dreaded downy mildew of cucumber is present in Northeast Ohio.
This serious disease of genera in the Rosaceae, such as apple, pear and pyracantha (Malus, Pyrus, Pyracantha), gets a big head start in springs that are humid and wet and when temperatures are in the 65-70 degree range during bloom. In fact, these types of conditions during pear bloom effectively wiped out the pear industry in Ohio in the early 1900s.
In spring, if these ideal conditions for infection (from bacteria in overwintering cankers) are met, then shoot and trunk infections follow and fireblight can be severe, resulting in serious shoot dieback and even plant death.
This year, we are observing widely divergent levels of fireblight throughout Ohio, with most severe infections reported from Northwest Ohio.
This divergence is almost certainly due to specific environmental conditions during bloom in different areas of the state. Again, the key is moist, warm weather during bloom to get fireblight off to a roaring start.
Unfortunately, fireblight is difficult to control, though pruning, especially during the dormant season, limiting succulent new growth to the extent possible, and use of bacteriacides such as copper sulphate can help.
Many common ornamental landscape plants have a major value-added aspect to them of being good to eat, and vice-versa many common food plants are uncommonly ornamental. Blueberries have great fall color. Sassafras leaves, ground to a fine powder are the file that gives the mucilaginous texture to file gumbo. Asparagus is heavenly — and has beautiful tiny lily-like yellow flowers and, of course, airy and frilly foliage of great finery.
With that in mind, you need to get on your calendar that this edible landscaping program at the Secrest Arboretum of OARDC will be on Oct. 8.
Why do you need to know this now? Because — those who plan — can. If you plan ahead, you can get a reduced rate for the workshop by providing a recipe, and a further reduction by producing an edible sample from this recipe, for the plant loving and food loving attendees — and for the follow-up Secrest Arboretum cookbook, ArborEatum, which will then be sold as a fund raiser at Plant Discovery Day next May.
Ginkgo (Ginkgo biloba)
Ginkgoes are a fine example of a tree that not only has tremendous value as an Ohio green industry standby, but also is great natural story.
The genus Ginkgo is of ancient lineage, originating 250 million years ago or more in the Permian period, long before flowering plants. Its early relatives were extinct seed ferns and the surviving ginkgo species, Ginkgo biloba, is not closely related to any currently living plants, though alone with cycads ginkgoes produce motile sperm cells and thus have some evolutionary linkage to these cycads.
Ginkgoes are considered gymnosperms (“naked seeds”) rather than angiosperms (true flowering plants) since their seeds are not protected and enclosed by an ovary wall like true flowering plants which have seeds enclosed in fruits.
Of course, female ginkgoes do have fruitlike reproductive structures (named “golden apricots” or “silver apricots” by some), the fleshy part which is quite malodorous, in fact vomit-grade malodorous.
The seeds inside are prized in Oriental cuisines, though eaten sparingly since they do have toxins that can be dangerous to all, and some individuals are especially sensitive to ginkgo seeds.
Ginkgoes are also highly valued for medicinal properties, and ginkgo plantations that harvest leaves are used to produce ginkgo products including those touted, with some evidence that they have some effects as memory aids. At least I think I remember reading this somewhere. Oh, yes, the New England Journal of Medicine.
Horticulturally, ginkgoes are quite popular as trees of veneration worldwide, from Buddhist temples to the Morton Arboretum in Chicago, from the Old Lion ginkgo at Kew Botanic Gardens to the street tree ginkgoes outside the Jake where the Indians play in Cleveland (yes, it is now Progressive Field officially, but to me it will always be the Jake).
Ginkgoes are good urban survivors if they are male and not therefore subject to ground-level pruning somewhere down the road when the smells arise from falling pukeballs. Always plant male cultivars — unless you want to collect ginkgo “fruits.” If you do collect, wear gloves; these fruits also produce a urushiol-like chemical a la poison ivy.
Ginkgoes are large trees, growing to 60 feet or over 100 feet and over 150 feet in remnant native Chinese groves. There are a number of cultivars these days, from upright ginkgoes, to dwarves such as ‘Troll’ to ‘Variegata’ with lovely cream-white variegation.
Natural streamside survivors, ginkgoes do best with moist, but well-drained acid soils. Ginkgoes have relatively few diseases or pests, and of course, at the end of the season, the wonderful sometimes quite synchronous falling of the lemon-yellow leaves on an October or November day is spectacular.
And ginkgoes have quite a literary connection, from the story of Goethe and the Ginkgo to these words of uneasy mortality from the former U.S. poet laureate Howard Nemerov (as reprinted in a new book Ginkgo by Peter Crane):
Late in November, on a single night
Not even near to freezing, the ginkgo trees
In one consent, and neither to rain nor to wind
But as though to time alone: the golden and the green
Leaves litter the lawn today, that yesterday
Had spread aloft their fluttering fans of light
What signal from the stars? What senses took it in?
What in those wooden motives decided
To strike their leaves, to down their leaves,
Rebellion or surrender? and if this
Can happen thus, what race shall be exempt?
What use to learn the lessons taught by time,
If a star at any time may tell us: Now.
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 firstname.lastname@example.org or call 330-466-0270. Please include your phone number if you write.