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Be on lookout for Dutch elm symptoms

BROOKINGS -- Dutch elm disease has begun to show up in trees across the state.

The symptoms to be on a lookout for include; wilting and browning leaves, often throughout the canopy but sometimes restricted to the length of an individual branch or limb, said John Ball, SDSU Extension forestry specialist.

"The trees expressing symptoms now were probably infected last year or even several years ago, sometimes by root grafts with nearby DED-infested trees that were not promptly removed," Ball said.

He added that these early expression of symptoms are not usually due to new infections carried in by beetles.

"The symptoms of new infections started by beetle-carried spores generally occur in July and are often limited, at least initially, to the leaves at the tips of branches turning yellow and wilting.," he said.

Bark beetles and root grafts are the primary means by which the fungus spreads from host to host. Ball said the most effective community-wide effort is to quickly identify and remove DED-infested trees.

"The sooner infested trees are removed, the less likely the surrounding healthy elms will become infected. Individual, healthy trees can be protected from the disease by root-flare injections of either Arbortect or Alamo fungicides though these must be repeated every two to three years," he said.

To learn more, visit iGrow.org.

-Source: iGrow press release

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