The weather is warming up and Barry County residents continue to delight in the beautiful buds, fragrant flowers, and lush leaves that spring brings to our forests. That extra time spent outdoors admiring nature may also lead you to discover some worrisome changes in your trees. If you notice your spruce trees exhibiting purple or brown needles, your trees may be infected with Rhizosphaera Needlecast, a fungus that affects many varieties of spruce.
The fungus is spread by water and is most commonly noticed in spring, although it is present -year-round and can become active at any time. It begins affecting the lowest and innermost needles first and eventually spreads to the rest of the tree if left untreated. The fungus is also identifiable by tiny dark specks on the infected needles. Normal needle die-off and some environmental problems can be confused with Needlecast, so it is important to contact a professional, such as Barry Conservation District Forester Shawn Kelly.
There is no way to cure old growth that is already infected by the fungus. However, you can protect new growth by applying a fungicide containing chlorothalonil to half-grown (about 1-1½ inch) needles and then reapplying the fungicide after 3-4 weeks. Follow the fungicide instructions carefully. Even with regular fungicide applications and pruning, it could take two or more years to control the fungus. In cases of severe infection in an area with many spruce close together, it might be more effective to remove infected trees.
There are many other ways to prevent future fungal infection. Selecting more resistant varieties like Norway spruce over susceptible varieties like Colorado blue spruce can help. Inspect any new trees before buying in order to avoid infected trees. Space trees properly to allow air flow and prune trees only when dry to help prevent the spread of fungus. After pruning infected trees, soak tools in denatured alcohol for a few minutes to sterilize them.
If you suspect that your trees might be infected with Needlecast or another disease or pest, please contact the Barry Conservation District (269-948-8056 x114), as early detection is the key to effective management of these problems.