Fungus eats away at blue spruce trees

Blue Spruce trees in the county are under attack from a nasty fungus. Several spruce trees in Sunset Park are dying as a result. Spruce tree owners in Washington have cut down their infected trees that are too sick to recover.

Washington Parks Director Tim Widmer said that perhaps as many as 10 trees are infected on city property alone. The city is treating the infected spruce with a fungicide if it shows symptoms of the fungus. However, Widmer said that at least four trees will almost surely die and two more may also die. His department will soon begin cutting down the dead spruce trees in the parks.

?We should have been out there spraying two years ago, but no one knew how serious it was going to be,? said Widmer.

The fungus that is attacking the spruce is known as Rhizosphaera Needle Cast. According to Iowa State University Extension, the disease first becomes noticeable on the tree?s lower branches. The second-year needles turn a purple or brown color and eventually fall off. After a few years of needle loss, whole branches may die. Typically, trees die from the bottom up. The fungus shows up on the discolored needles in the form of small black dots. These dots are the fruiting structures of the fungus.

Rhizosphaera survives the winter in needles on trees or in needles on the ground. The fungus is spread by splashing and dripping water. Emerging needles can become infected during a wet spring.

The blue spruce is most commonly planted in Iowa as a windbreak. It has been planted here for the past 50 to 70 years although it is not native to the state. It is native to the Rocky Mountains, where it learned to survive in coarse, nutrient-starved soil.

Local landscaper Mike Tadlock said the blue spruce does well in Iowa, and is the most commonly planted windbreak tree in the Midwest. However, he said that non-native species tend to cycle through these kinds of problems.

?I saw Needle Cast 20 or 25 years ago when I was in Iowa City,? said Tadlock.

Rhizosphaera is back, and is back with a vengeance.

?The damage it has done is major,? said Tadlock. ?In my 35 years in the nursery industry, I?ve never seen anything quite like it.  I think I?ve sold more fungicide this year than I did in all previous years combined.?

ISU Extension recommends spraying diseased trees with a fungicide in the last two weeks of May and again four to six weeks later. Tadlock said it?s getting late in the year for the fungicide to do any good.

?It will probably keep it at bay but it?s not going to cure the tree,? he said.

Tadlock saw signs that Rhizosphaera was making a come back three years ago. Some of his customers reported they were losing their windbreaks. He said conifers, such as the spruce, hide their infections well for long periods of time.

?When you start to see the damage, it probably began three to five months earlier,? he said.

Rhizosphaera has spread so much over the past few years because of the large amount of rain in the spring and early summer and because of the humid nights. The fungus thrives in that environment. Tadlock commented that many spruce trees are being lost to wet ground because they suffocate.

To prevent against further devastation from the fungus, Tadlock suggests spraying for the fungus as soon as possible next year.

?If we have another wet year next year, this isn?t going to stop,? he said.