THE WEEKLY WEED: Canadian Horseweed (Conyza canadensis)

Canadian horseweed (Conyza canadensis, family Asteraceae) has become notorious in recent years for failing to respond to glyphosate (e.g. Roundup) in agricultural fields and landscapes.  This annual weed, which is also known as just horseweed, Canadian fleabane, coltstail, and marestail, has moved in recent years from being a plague in field crops to become a scourge in landscapes and nurseries.  Indeed, this native North America plant has become such a problem in Ohio it has been added to the state's noxious weeds list.

 

Challenges with managing this weed centers...

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Joe Boggs

Cryptomeria Scale (Fried-Egg Scale) Found in Southwest Ohio

Last week, Cindy Meyer (OSU Extension, Butler County) and I found Cryptomeria Scale (Aspidiotus cryptomeriae) on Canaan fir in a Christmas tree farm in southwest Ohio. The literature indicates this non-native armored scale may be found on the underside of needles on a wide range of conifers including true firs (Abies spp.), Douglas-fir (Pseudotsuga menziensii), hemlocks (Tsuga spp.), spruces (Picea spp.), and perhaps other conifers as well as Taxus (Taxus spp.).  However, it appears that cryptomeria scale has a distinct preference for...

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Joe Boggs
Cindy Meyer

Shrub of the Week: Chinese Leptodermis

{This Shrub of the Week article and its photos are from Paul Snyder of OSU's Secrest Arboretum at the Ohio Agricultural Research and Development Center in Wooster.}

  Have you ever had someone come to you looking for a particular plant, and then begin listing all the characteristics they are looking for? “It needs to be dwarf, have lots of flowers all summer, not be messy, and it can’t have thorns…” We have all been there, and we have all thought “With all those requirements you can’t really grow anything but perhaps poison ivy.”

  We often receive questions like this at...

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Jim Chatfield

Tree of the Week: Three-Flowered Maple

  The three-flowered maple continues to grow and thrive in my backyard and the more I see it planted at the Secrest Arboretum in Wooster, at the High Line Park in New York City, and elsewhere, the more I enjoy this tree. This Asian maple will become a small to medium-sized  tree (20-25 feet). Like its cousin paperbark maple, it has exfoliating bark but the bark is not as papery or with the cinnamon color of Acer griseum.

 

...

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Jim Chatfield

Pear Rust Revisited

  While walking in German Village in Columbus with ONLA’s Frits Risor last week we revisited the Callery pears with rust disease noted earlier this season (http://bygl.osu.edu/node/342). I wanted to see if the rust was isolated to the two trees heavily affected in June. As earlier, the two trees in question were speckled with bright orange lesions on the upper leaf surfaces, but I suspected that by now the rust fungus would have undergone sexual reproduction in the leaves with aecial spore pustules developing  on the lower leaf surfaces as would be seen with the cedar-apple rust fungus (...

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Jim Chatfield

Smorgas-gourd

  “I am ignorant of almost everything” is a favorite saying of mine, and truth be told it is an obvious truth for us all. It is what makes us so lucky to be plant lovers, since we are reminded with the new personal and universal discoveries of Nature every single day.  Know-it-alls need not apply for attendance at Nature’s banquets – though they might learn the most.  One of my recent revelations of a horticultural bent was about – gourds.  I have seen them, and have a vague sense that they are cucurbits, that is that they are in the Cucurbitaceae, the family that also includes...

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Jim Chatfield

Red-Spotted Purple

Look closely at woodland edges and you may see a flicker of iridescent blues accented with splashes of red; the calling card of a red-spotted purple butterfly (Limenitis arthemis astyanax).  The red-spotted purple is so named because of its overall purple hue and for the red to orangish-red spots on the underside of the wings.
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Joe Boggs

Wee Beasties

  During the course of this summer a number of beasts of various sizes have passed by my lens. These often turn into bygl-alerts, for example 17-year cicadas and monarch butterflies. A few have not qualified – until now. Here are just a few beauties of the summer bestiary.
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Jim Chatfield

Tar Spots of Maple

  Tar spots of maple, caused by species of the Rhytisma fungus, are prominent now, although mostly not as severe as in wetter summers. There are two different tar spot diseases of maple, one affecting silver and red maples, caused by Rhytisma acerinum, resulting in dense, tarry spots that truly reflect the “tar” spot name (first picture below).
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Jim Chatfield