Question 453732: Reply to Response by Expert

Asked May 16, 2018, 9:44 PM EDT

Does the University of Minnesota Extension have a service that would come to our yard to diagnose the possibility of Rhizophaera needle cast? Or do you know of a service that will diagnose and, if spraying is necessary, spray?

Anoka County Minnesota

1 Response

There is a service that can confirm rhizosphaera needle cast. See the second bullet below. It may be too late to begin spraying this year if the new needles on your spruce have grown longer than 1/2 the length of the old needles.

  • Chlorothalonil can be sprayed twice in the spring to protect new needles. The first spray should be applied when needles are half the length of the mature needles. A second spray should be applied 3-4 weeks later or as prescribed on the fungicide label. Read and follow all instructions on the label when applying a fungicide!
  • Before spraying fungicide, confirm that Rhizosphaera is the fungal pathogen causing damage by sending a lab sample to the University of Minnesota plant disease diagnostic clinic. Several other fungi result in symptoms very similar to Rhizosphaera.

Thank you for your question for eXtension.