Thoroughly examine elms for DED symptoms from May through September. Immediately evaluate infected elms for therapy.
Reserve therapy for high value elms with 10% or less wilt. Poor risk trees, those with greater than 10% wilt, and older trees with deteriorating crowns and generally poor vigor, should be removed immediately. Poorly shaped specimens, trees aesthetically unacceptable after radical pruning, or trees located in insignificant locations, should be removed and treatment reserved for more valuable specimens. Therapy should not be performed when vascular discoloration extends into the main trunk. Small “windows” cut in the bark of the limb and in the trunk below the wilted segment help determine the extent of sapwood discoloration.
Immediately provide therapy to selected elms.
Inject fungicide into the trunk and the infected limb. Prune the infected limb 1-3 days after injection.
(1) There should be at least 5’ and preferably 10’ between the last visible sapwood discoloration and the pruning cut. (2) If discoloration extends into the main trunk, the tree should be removed.
Closely examine treated elms for symptom recurrence. Elms with recurring infections should be evaluated for further treatment or removed. Maintain complete records on each therapy case. Records should include: Tree location, dbh, percent and location of symptoms, date of treatment, amount of fungicide injected, and time required for treatment. A photographic record for each tree can be very useful.
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