Treating Needlecast Diseases In Evergreens
Needle cast diseases occur when different fungi infect the new needles on pines, spruce, Douglas fir, and true fir. The needles become infected. The symptoms of needlecast disease are not always noticeable until the following winter or spring season. It is common to see yellowing or browning of the needles, with characteristic dark fungal fruiting structures. The infected interior needles are shed early leaving the tree with a sparse, thin appearance. The remaining needles are the current season’s new growth.
What Do I Need To Know About Needlecast Disease?
According to studies from Penn State University, “we have a lot to learn about when these fungi attack a tree”
- How long the fungus must be in the tree before needles are shed.
- When is the best time to apply a fungicide?
- Which chemicals provide the best protection.
Needlecast fungus form small structures on the infected needle forming thousands of spores. The “fruiting structures” can be black, orange-red, or tan, depending upon the fungus. Finding a fungal fruiting structure on a dead needle is not immediately proof that the tree has a needlecast disease. Contact a professional to inspect the tree to find out the severity of the diesease.
Managing Needlecast Diseases
To avoid this disease from harboring your trees and letting them die off, there are a couple of tactics you can utilize which include:
- Remove tall weeds that surround the tree to increase air movement to promote drying of the needles.
- Thin out or remove shrubs and trees that are blocking sunlight and air movement.
- Reduce disease pressure by removing and disposing of fallen (infected) needles.
- Avoid pruning trees when branches are wet.
- Reduce the spread of disease by sterilizing tools after pruning affected trees.
Evergreen Needle Cast Fungicides:
In addition to cultural practices, fungicides will prevent the spread of Needlecast Disease. Infections are going to be most efficiently managed when they are found and treated as early as possible, preferably before several years of defoliation have happened. Small trees can be sprayed with a product containing the active ingredient chlorothalonil. It is best applied when the fungus is most active during the springtime when needles are halfway elongated. Apply a second foliar application when needles are fully elongated, which would be 2 – 4 weeks later. It is recommended to apply the fungicide for two years for best results.
Trees that have a diameter of 2 inches or more should be treated with microinjection of Fungisol. Again, for best results the Fungisol should be injected in the early spring when there is evidence of new growth, indicating that the tree has emerged from winter dormancy. In this instance, it is also recommended two years of applications are performed for best results.
Professional Tree and Shrub Care
The good news is that there is progress being made in these areas. With the help of tree care specialists, like professionals at Green Machine Lawn Care, not all hope is lost. Our technicians have been providing services and treatment for Evergreen trees affected by the needlecast disease in the Northeastern PA area for over 37 years. There is a treatment to save the health of your trees and the privacy of your property.