Diagnostics: Now and in September

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Diagnostics – why good plants go bad – is a big part of what we do at OSU Extension and a key skill for all horticulturists. I was doing a walkabout yesterday at the Secrest Arboretum just outside my office in Wooster, OH and took a few pictures. I realized that some were perfect lead-ins to the 84th Ohio Plant Diagnostic Workshop coming up on Friday, September 8 from 10am to 4pm.  For the program agenda and to register, see "More Information" below.

 

  There was a pawpaw leaf spot I had not seen before. Is it Mycosphaerellao or Cercospora? We shall see.

 

Leaf blotch on pawpaw
Foliar disease on pawpaw

 

  There was the familiar Guignardia leaf blotch disease on buckeyes and horsechestnuts (Aesculus spp.) seen every year, highly variable on different Aesculus  taxa. Note also the lack of this disease on bottlebrush buckeye. However, here is physiological leaf scorch can occur during dry periods on bottlebrush buckeye. Also note how different symptoms of this leaf scorch are from leaf blotch fungal disease.

 

Gugnardia leaf spot on Aesculus
More resistant 'Autumn Splendor' Aesculus tri-brid on leaf with highly susceptible horsechestnut-buckeye cross on right

 

 

Physiological leaf scorch on bottlebrush buckeye
Physiological leaf scorch on bottleburush buckeye with different pattern of symptoms than Guignardia leaf blotch

  There were examples on my walk for plant identification samples (#1 Question of the 25 Questions of Plant Diagnostics). Clustered terminal buds on oak. There were the seven pedicillate parts of the candelabra of seven-son flower, Heptacodium miconoides.

 

clustered buds of oak
Oaks have clustered terminal buds

 

Heptacodium with the seven points of its flower cluster
The seven points of seven-son flower

 

  There were weird diseases such as Phomopsis galls on hickory, growing in increasing numbers on a large hickory each year. There were introduced pine sawfly larvae on Pinus cembra I had not noticed before. There were small older leaves on Japanese snowbell, japonica while newer leaves were larger – why do you think that is?

 

Phomopsis fungal galls on hickory
The famous Phomopsis gall hickory tree at Secrest Arboretum 

 

Introduced pine sawfly on Swiss stone pine
Introduced pine safely on Swiss tone pine

 

Leaves and fruits of Japanese snowbell
Why are the early leaves on this Japanese snowbell so small? Tough to see, but a hint is here

 

  And then there were redbuds. Beautiful redbuds. But some beasts on the beauties: redbud leaffolder insects on everything from ‘Don Egolf’ Chinese redbuds to purple-leaved weeping redbuds.  There was a leaf spot disease on some redbuds, but not all: ‘Rising Sun’ was clear of both insects and diseases, at least on this walk.  More discussion at the workshop.  

Redbud leaffolder on Don Egolf Chinese redbud
Redbud leaffolder on 'Don Egolf' Chinese redbud

 

Leaffolder insect, frass, and damage
Redbud leaffolder, Fascista cercerisella revealed when leaves are unfolded

 

Leaf spot on redbud
Fungal leaf spot on redbud

 

'Rising Sun' redbud
'Rising Sun' redbud at Secrest Arboretum

 

  So, we shall talk about host ranges and out diseases and insects and physiological problems, both common and uncommon. We will have loads of samples and outdoor walks and indoor talks, including enough credits for core and ornamental categories  ODA pesticide recertification credits, for ISA credits, for ONLA credits, for MGV credits.

 

  Spend the day with the Tree Amigos (Boggs, Draper, Chatfield) and all the assembled experts, including yourself. Eat treats from Templeton’s Scottish bakery. Enjoy a gourmet lunch (last year medallions of beef and chicken cordon bleu, this year – who knows. All for $40. 

 

If you have questions, contact: Sarah Mays, 330-263-3831, mays.201@osu.edu, OSU Extension 1680 Madison Avenue, New York, New York (just kidding). Really:  1680 Madison Avenue, Wooster, Oh 44691

 

To see the Agenda and to register, see "More Information" below.

 

redbud leaffolder escapes the nest
Redbud leaffolder escapes a probing lens