This last year was brutal on evergreens with a very wet spring that launched a fungal attack that took a great toll on our spruce trees. We saw very high levels of needlecast disease spreading all over the county.
What is Evergreen Needlecast?
As the name implies, affected evergreens cast or lose their needles and look sickly, very thin and browned out.
If you take a closer look, the individual needles will have brown bands or blotches up and down the needle that can be black, red or brown. This is caused by several different fungi bodies attacking the needle and then killing it so it falls off.
We typically see the emergence of needlecast and visible signs of the fungal fruiting bodies in spring to early summer.
Now with spring finally here, we will start the wet season where needlecast will bloom again. We usually see it in evergreens that are planted in rows and rather close together or in shaded areas. When there is rain it takes a long time for the needles to dry from sun and wind – and we all know that fungi love dark, moist areas!
Treatment for Needlecast
If we spray a fungicide on the trees we can prevent any new growth from getting needlecast fungi and restore a green healthy looking tree.
When to Treat
These treatments usually start in the beginning of May and continue every two weeks until we start to dry out going into summer.
Length of Treatment
Because of the needlecast life cycle, it is usually most effective to continue treatments for two years.
Tips to Prevent Needlecast
Do not prune evergreens during the wet spring timeframe since you will spread the fungal spores between cuts.
If it is necessary to prune, be sure to prune in the afternoon during sunny days. Start with healthy trees then move on to the diseased trees.
Also be sure to sterilize cutting tools with denatured alcohol or a 10% bleach mixture between cuts – and sterilize them carefully after you’ve finished pruning.
If you have an irrigation system, make sure it is adjusted so it does not spray on the foliage of your evergreens since this will create the perfect environment for fungal out break.