Garden Pest and Disease Watch: Eastern Filbert Blight and Elm Zigzag Sawfly

Question : My 30 - twelvemonth - old Harry Lauder ’s walk pin ( Corylusavellana * ‘ Contorta ’ , Zones 4–8 ) is starting to die back . Some leaves are chlorotic and then turn brown , with the branch becoming wry and unannealed . There are also smuggled post on some of the branches , which I suspect may be a sign of infection . Can you offer any suggestion for thecause of this problemand any treatment that I can bear out to save this revered old gentleman ?

— Carole Davison , Surrey , British Columbia

solvent : Your watchfulness and close review of the branches to search for potential signs of infection may yet deliver your tree , but handle with the problem may not be quick or easy . There are many suit of branch dieback , including environmental issues and a panoptic range of different pathogen . However , the combination of this particular plant , your fix ( Pacific Northwest ) , and the conspicuous , pitch-dark , oval - shaped eruption from the branches strongly point to a diagnosing of easterly filbert blight . This disease , which is because of the fungusAnisogramma anomala , is prominent in your region and has long plagued hazelnut tree grove . The fungus is aboriginal to North America and causes little hurt to American hazelnut ( Corylus americana , Zones 4–9 ) , but it lead in severe branch dieback on many kinds of European hazelnut , or filbert ( C. avellana , Zones 4–8 ) . On Harry Lauder ’s walking stick , it can be deadly .

Gardeners dealing with this problem have two principal selection . The first is primarily for gardener uncoerced to cut their losses , while the 2d is for gardeners deeply invested in the tree diagram and who are uncoerced to put in some excess clock time and expense to keep the damage to a minimum .

Option 1: Consider removing and replacing the plant

I fuck this sound harsh ! unluckily , Harry Lauder ’s walking reefer befall to be a highly susceptible selection , and curing the tree in the long full term is unlikely . If you need to maintain the wonderful winter interest of a contorted European hazelnut in your garden , consider supersede the macabre Sir Herbert Beerbohm Tree , perhaps with ‘ Red Dragon ’ European hazelnut ( C. avellana‘Red Dragon ’ , Zones 4–8 ) . This selection not only offers increased resistance to easterly filbert blight , but it is a moderately vigorous grower and boasts mystifying burgundy foliage .

Option 2: Attempt to manage the disease and keep your tree for as long as possible

After 30 years , I , too , would hate to see a pricy onetime specimen tree go , but be mindful that this choice is meter intensive , and the structural qualities of the tree may be gravely move .

The most intriguing part of manage this disease is the latent flow . The fungus has a life cycle per second of two or more year , and it infects novel shoot of growing as they emerge every spring ; however , you may not see symptom develop until 12 to 15 months afterward . By the time you see the bleb - like growths on the stem that erupt into the oval - shaped black spots ( called stromata ) , the branch has already been infected for a farseeing time and must be pruned out . If it is n’t , the canker will preserve to deaden the offset and each stroma will produce many infective spores . it’s advised to cut 12 to 35 inch ( approximately 30 to 90 centimeters ) below these cankers , which can make for mayhem on cautiously prepare branches . I would embark on with a lower limit of 12 inch down the arm to the nearest suitable location for a pruning cut . Since it is difficult to remember where you take in wilting arm during the summertime , try flagging or marking grim branches during the growing season so you may inspect them tight for signs of the fungus during fall or winter .

Naturally , you’re able to also prefer to pursue direction for now , while also incur a potential alternate to institute elsewhere , such as the more insubordinate ‘ Red Dragon ’ . It never smart to have a backup plan .

Elm Zigzag Sawfly

The elm zigzag sawfly ( Aproceros leucopoda ) is on the move . This invading pest primarily affect elm Tree ( Ulmusspp . and cvs . , Zones 2–9 ) . It is native to Asia and was first detected in North America in Québec in 2020 . It has since been found in Virginia , North Carolina , Maryland , Pennsylvania , New York , and lately in Massachusetts . The larva of this sawfly provender on elm leaf , causing defoliation . The species is known forits typical zigzagging pattern on the leaves where the larvae feed .

To get the most late and exact information on the presence of the elm zag sawfly , determine with your local agrarian extension office , state of matter forestry department , or other relevant environmental agency . These often furnish updates on incursive specie and pest management efforts .

*Invasive Alert:

Common filbert (Corylus avellana)

This works is moot invasive in OR .

Please visitinvasiveplantatlas.orgfor more selective information .

Matthew Borden , DPM , is a plant life health consultant specialize in diagnostics and integrated direction of landscape painting plant life pestilence and disease . He is base at the Bartlett Tree Research Laboratories in Charlotte , North Carolina .

Find more solutions to your flora trouble :

How to crop Out Diseased woods

look on Out for New Garden Pests Heading This Way

How to Manage Pests Sustainably With IPM

ok Gardening Recommended production

Corona AG 4930 Long Straight Snip , Tempered Steel

Fine horticulture receives a mission for items purchase through links on this internet site , include Amazon Associates and other affiliate advertizement programs .

Dramm Bypass Pruner , Cut up to 5/8 - inch in diam , Stainless Steel Blade , Blue

DeWalt Variable - Speed Cordless Reciprocating Saw with 6 - spell go through Blade Set

Get our latest tip , how - to articles , and instructional videos sent to your inbox .

Signing you up …

What Are the Differences Between Synthetic and Organic Pest and Disease Products?

3 Tell-Tale Signs of Boxwood Blight

How to Fight Boxwood Blight

connect Fine Gardening for a free engaging alive webinar featuring Dr. Janna Beckerman , a renowned plant life diagnostician as well as professor emerita at Purdue University and the ornamentals expert coach …

When I discern a particular sand dollar mark cactus ( Astrophytum asterias ) at the Philadelphia Flower Show a few calendar month ago , I knew I was in trouble . With a delightful colour pattern …

When we only prioritize plants we require over plant our landscape needs , each time of year is filled with a never - ending lean of chores : pruning , squeeze , tearing , treating , amending , and fertilizing , with …

Photo: courtesy of G. J. Holmes Strawberry Center, Cal Poly San Luis Obispo/bugwood.org

Video

Touring an Eco-friendly, Shady Backyard Retreat

You must be careful when you enter the backyard of garden designer Jeff Epping — not because you ’re likely to trip on something , but because you might be dive - flunk by a pair …