Secrest Arboretum: Early May, 2020: Part I

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It’s been a while since the latest Secrest Arboretum bygl-alert update on April 4: ( Here is some of what happened recently and is occurring right now at Secrest. Plant development is influenced by growing degree-days which are now at 217 for Wooster, Ohio, so although another cool down with slower development is forecast for this week, this gives an idea of what to see if you visit Secrest now. Hopefully we can avoid a major frost Friday, but 28 degrees F is forecast.


For reference, checking the website, birch leafminer emergence occurs at 215 and elm leafminer emergence will be at 219.  Wherever you are, get your outdoor, socially-distance walks and pest scouting in as the world changes rapidly as Spring progresses.


Buckeye seedling
Buckeye seedling near the Secrest Arboretum field headquarters


The Lovely Genus Aesculus. Buckeyes and horsechestnuts are fabulous as leaves and flowers emerge. Here are just a few pictures of their recent entrance to woodland, arboretum, and garden stages.


buckeye horsechestnut hybrid
Emergence of leaves and flower buds of Aesculus xcarnea O'Neill buckeye/horsechestnut hybrid on April 27, 2020 at Secrest.


Aesculus emerging
An Aesculus  bud emerging on April 27 at Secrest. The stickiness of the bud scales suggests that there is some horsechestnut in this taxon.  


Hybrid Aesculus
This Aesculus eryhroblastosus on yellow buckeye (Aesculus flava) rootstock has lovely apricot or salmon young foliage.  


The Lovely/Loathsome Nature of Cedar Rusts. Cedar apple rust and cedar quince rust has done its thing in northeast Ohio in the past weeks, as shown below on junipers at Secrest Arboretum. The large cedar apple rust galls (combinations of the Gymnosporangium juniperi-virginianae fungus and juniper tissue) and the slimy fungal growth of the cedar quince rust fungus (Gymnosporangium clavipes) have released spores that made their way to rosaceous hosts: apple/crabapple, hawthorn, serviceberry, and quince.


cedar apple rust
cedar apple rust gall with telial horns on juniper at Secrest in late April 2020


old cedar apple rust gall
Old cedar apple rust gall on juniper at Secrest in late April 2020. This gall was spent last year.



Cedar quince rust
Cedar quince rust in central Ohio in late April. Photo provided by Lisa Bowers, urban forester for the Ohio Department of Natural Resources.


The fungus that grows on the rosaceous host will not re-infest those hosts, alternating back to junipers over the coming spring and summer months.  ODNR urban forester Lisa Bowers from the central Ohio area sent some great pictures of cedar quince rust on juniper there.  Symptoms of cedar apple rust and cedar hawthorn rust occur mostly on leaves of the rosaceous hosts while the cedar quince rust will occur primarily on fruits and galled stem areas.  


cedar apple rust
Cedar apple rust on 'Taylor' juniper at Secrest from late April 2020. Note the gelatinous telial horns that are massive numbers of microscopic spores that then blew in the wind, "hoping to contact a crabapple or hawthorn.


cedar quinc rust
Cedar quince rust on 'Taylor' juniper at Secrest Arboretum in late April, 2020. Yes, different species of rust fungus can be on the same juniper!


Dawnredwoods at Secrest. The grove of this  deciduous conifer (planted in 1953) is ever prominent at Secrest even without foliage in the winter, but emerges in beauty as greening in the spring progresses.


dawnredwoods and crabapples
Dawnredwood grove at Secrest is greening up - in the background. What of the crabapples in the foreground? They are  foreshadowing of one of the features in Part II of this Secrest update.


Bagworm Clothing. One of the fascinations of bagworms is their individuality: their bags are what they do not eat. If on junipers, then its Junipers for breakfast, lunch and dinner but enough left over that they make their house out of same. So, seeing last years’ bags this year, made from last year's London planetree leaves, at Secrest last week was the ultimate in posh.


Bagworm clothed in juniper clothing


Bagworm now at Secrest. Control of eggs (growing degree days of 603) that will hatch way down the road; probably in mid to late June - unless you just prune this out. What plant did it make this bag from?


The tree from which the bagworm fed and practiced its construction skills: London planetree.


bagworm on juniper
Baworm peeking out of a juniperized bag.


Camperdown Elm Fruits. American elms and European/English elms such as Camperdown elms flower and fruit in the springtime, while lacebark elms flower and fruit in late summer and into fall. I have always enjoyed the flittering of falling American elm fruits in springtime Central Park in New York City, but I guess never noticed the developing fruits of Camperdown elm, shown below near the Children’s Garden at Secrest Arboretum.  Note: Camperdown elm (Ulmus glabra ’Camperdownii’) is typically grafted to Ulmus americana  rootstocks.   


Camperdown elm fruits
The springtime fruits of Camperdown elm at Secrest.


Camperdown elm
Camperdown elm and Laura Chatfield, Spring 2020.


Stay tuned for Secrest in early May, Part II…The Rest of the Story. 


Secrest Arboretum sign
Secrest Arboretum sign and social distancing safety comments