Managing a Few Diseases on Ornamentals

image0001image0002  Remember all that Fireblight (1st photo) and Apple scab (2nd photo) we had the last couple of years on apple, crabapple and pear?  Now is the time to start fighting back.


Bacterial ooze of Fireblight on canker in spring (Photo: Ontario Ministry of Agriculture, Food and Rural Affairs)

Bacterial ooze of Fireblight canker on Malus (Photo: Extension, Utah State University)

Pruning out “cankers” and dead looking branches on apple and crabapple is still a good idea where trees are dormant (buds still enclosed in brown bud scales).  The overwintering bacteria of Fireblight (Erwinia amylovora) hide out in these cankers and start to ooze (photo above) as buds swell and leaf tips start to poke out from bud caps.  This bacterial ooze will increase and spread to newly emerging foliage and flowers in the coming weeks.   Collect and destroy pruned material immediately to prevent disease spread.

Silver tip in Jonathon apples.

Silver tip on Malus (Photo: Mark Longstroth, Michigan State University Extension)

Where apple and crabapple are showing silver tips on their leaf buds, apply copper with good coverage to buds to help protect emerging tissues from Fireblight bacteria.  It is important to note that besides apple, crabapple and pear trees, hawthorn, mountain ash, cotoneaster and quince are also susceptible to Fireblight and should be scouted and managed for this devastating disease.  Young nursery stock is more susceptible since Fireblight is lethal once it gets into the main stem.  Young trees with cankered stems (trunks) should be removed and destroyed immediately.

Honeycrisp apple - green tip

Green tip on Malus (Photo: FruitAdvisor.Info)

Honeycrisp apple-green tip ++

GreenTipPlus on Malus (Photo: FruitAdvisor.Info)


Where apple and crabapple are showing green tips, a copper application is a good idea to protect leaf tips for both Fireblight bacteria and the fungal spores of Apple Scab (Venturia innaequalis).  Again, good coverage to buds is essential for managing the disease at this stage.

OMAFRA maintains Fireblight prediction models for Ontario producers and can be found by clicking HERE.

Some of you may be wondering about copper spray after green tip?  Copper can be damaging on developing fruit and is therefore not recommended in fruit producing trees (e.g. orchards) past green tip of the leaf bud.  However, for ornamental or juvenile nursery stock, fruit is not usually a concern and many growers elect to use copper for its disease fighting benefits in their management program.

Save Apple Scab-specific fungicides for the leaf emergence period.


Cankers of Filbert Blight on Dormant stem of Corylus spp. (

Eastern filbert blight (Anisogramma anomala ) on common filbert (Corylus avellana ) - 5475181

Overwintering cankers of Filbert blight (Forestry Images: Stephanie M. Adams, The Morton Arboretum,



And while you’re out there looking for overwintering eggs masses, scale nymphs and cankers….take a look at Corkscrew Hazel (Corylus avellana ‘Contorta’) for overwintering cankers of Filbert Blight (Anisogramma anomala).  Prune out cankered stems and destroy immediately.   If you can complete pruning before budbreak, you can significantly reduce innoculum and disease spread to healthy stems….and other Corylus in the area.

Are you hearing snoring coming from ponds, and other wet areas?  It’s likely the call of the Northern Leopard frog.  These are a very common species in southern Ontario lakes and ponds.  Another species you’ll hear is the Wood Frog, these guys are really noisy and one of the first species to be heard in our area.  And one of my personal favorites, the Spring Peeper.  Check out the amazing video link for the spring peeper.  How can so much noise be coming from such a small little creature?

About Jen Llewellyn

OMAFRA Nursery and Landscape Specialist @onnurserycrops
This entry was posted in Diseases, IPM, Nursery Production and tagged , , , , , . Bookmark the permalink.

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