Both Riverside and Brookfield are experiencing severe outbreaks of Dutch elm disease this summer, according to their village foresters.

Scott DeRoss, the Brookfield village forester, said the Department of Public Works has cut down 11 (5.5 percent) out of the 200 remaining elm trees in the village. In normal years, he said, the village only cuts down one or two trees because of Dutch elm disease.

In Riverside, Village Forester Michael Collins said they’ve removed 33 elm trees from private property and 46 from public property. Although Collins did not know the total population of elm trees in the village, he said on public property alone there are about 600. The trees removed from public property amount to nearly 8 percent of the total elm population.

This is the second straight year Riverside has had a problem with Dutch elm disease. Last year, Collins said, there was more rain than usual, which meant there were also more elm bark beetles, the insect that spreads the disease, than in previous years. In 2004, by September, Riverside crews had cut down 60 trees due to Dutch elm.

This year the problem is the exact opposite. Both DeRoss and Collins said the drought in the Chicago area has put additional stress on trees and made them more susceptible to disease. Collins said many towns in the area have seen an increase in Dutch elm disease.

“I think everyone’s having a problem with it this year,” he said.

Collins said the disease is spread in two ways. The first is through the elm bark beetle, which carries the fungus that causes disease. The second is through root grafting between neighboring elm trees. If one tree is infected, it will spread the disease to its neighbor through its roots.

As for spotting diseased trees, DeRoss said residents should look for dead leaves on their lawn and “flagging” in the tree, which can be observed by a branch or section of a tree being completely bare of leaves. He said the disease is treatable with a certain fungicide, but it would have to be caught very early on.

“By the time you see signs of it, it’s usually too late,” DeRoss said.

Residents who lose their trees to Dutch elm disease do have the option of receiving a replacement tree from their village. Both Brookfield and Riverside have 50/50 tree buying programs, where residents pay half the cost of a new tree. DeRoss said the price varies from year to year, depending on how many new trees the village orders, but the average price is about $110.

Collins said he hopes residents choose to replace their trees, especially given the reputation and history of Riverside’s landscape.

“Ultimately the solution is the tree cooperative planting program,” he said, “and I hope residents participate to keep Riverside’s urban forest sustainable.”