POP TIPS: emergency pruning of fire blight and black knot!

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Phil Forsyth

Aug 8, 2022, 5:38:00 PM8/8/22
to Philadelphia Orchard Group
Philly Orchardists,
This edition of POP TIPS highlights two common fruit tree diseases that require immediate pruning to prevent further spread and damage:  

1.  Fire Blight is a very common and serious bacterial disease that affects pome fruits (apple, pear, Asian pear, quince, medlar, hawthorn and serviceberry).  We've seen many trees with some fire blight this season- untreated, these infections can kill trees by the end of the year if not pruned out! 

fireblightfireblight fruit  
Typical fire blight damage appears as if the tips of branches have been singed by fire, often bending over to form a 'shepherd's crook'.  It can also affect fruit, which appear black and shriveled. 

If you identify Fire Blight in your orchard, please see our new video on treating Fire blight on POP's youtube channel and our newly updated blog post on Fire blight for more information. 

2. Black Knot is a fungal disease common on plums and cherries:   

Easily identifiable damage from black knot disease on cherries and plums!
Black knot will continue to spread and cause additional damage if not removed.  For more information on preventing and treating it, see our full blog post on Black Knot here.  

For both Fire Blight and Black Knot, the first course of action is pruning 6 to 12 inches below any sign of infection.  Always sterilize your tools with rubbing alcohol, hydrogen peroxide, or a 10% bleach solution after every cut to prevent spreading the disease further! 

Phil Forsyth, Co-Executive Director
Philadelphia Orchard Project
Pronouns: he/him

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