DiseaseHigh Severity

Ceratocystis Ulmi (Dutch Elm Disease)

Ophiostoma ulmi (formerly Ceratocystis ulmi)

Dutch Elm Disease is one of the most devastating tree diseases in North America, caused by the fungus Ophiostoma ulmi and spread by elm bark beetles. This vascular wilt disease has killed millions of elm trees and continues to threaten remaining elm populations.

Peak Season: Primary transmission: Late spring during beetle emergenceSymptom appearance: Late spring through summerSecondary spread: Throughout growing season via root graftsOverwintering: In infected woody materialCritical period: Spring when new generation of beetles emerges
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Dutch Elm Disease symptoms

Identification & Symptoms

What to Look For

Yellowing and wilting of terminal leaves in late spring
Premature browning and leaf drop
Twigs turning inward creating 'shepherd's crook' appearance
Twig crotches notched by beetle entry holes
Sparse, chlorotic foliage in subsequent seasons
Brown streaking in sapwood of infected branches
Beetle galleries under bark of dying trees

Potential Damage

Rapid tree mortality, often within one growing season
Vascular system disruption preventing water transport
Branch-by-branch progression of symptoms
Root graft transmission causing uniform crown wilting
Complete landscape-level elm mortality in susceptible areas

Lifecycle

Fungus overwinters in infected trees, logs, and stumps. Elm bark beetles carry spores from infected material to healthy trees during egg-laying activities. Larvae develop in beetle galleries, emerging as adults coated with sticky spores. The disease also spreads through natural root grafts between adjacent trees.

Professional Treatment Approach

1

Fungisol treatments for high-value trees as preventive measure

2

Immediate removal and destruction of infected trees

3

Sever root grafts between healthy and infected trees

4

Avoid pruning during beetle flight periods

5

Professional diagnosis essential for proper management

Recommended Mauget Products

Fungisol

Professional-grade treatment specifically effective against ceratocystis ulmi (dutch elm disease).

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