Wednesday, April 4, 2012

Spruce Diagnostic Workshop

Thanks to the Illinois IPM Grant, I was able to develop a Spruce Diagnostic Workshop.  The first spruce diagnostic workshops were held at the Gardeners' Big Day at Dixon Mounds, Lewistown, Illinois.

The workshop was designed to bring awareness to home gardeners that over the last several years, we have been seeing many spruce issues in Illinois at the U of I Plant Clinic.  This is largely due to the fact that spruce are not a native to our area.  They prefer moist, well drained sites (sandy soils, hilly, or mountainous terrain) and NOT poorly drained or clay soils!  Spruces do not do well in hot and dry conditions.  Sometimes spruce problems do not start to develop until roots outgrow the area, grow into poor soil, or until weather stress aggravates the situation. Without adequate growing conditions or a proper site, spruce trees can become more susceptible to pests!  The Colorado Spruce (known to most as the "blue spruce") seems to have the most problems!

I also wanted to make participants aware that a single spruce tree could be diagnosed with many problems.

In my diagnostic workshop, everyone was given a factsheet with pictures and descriptions of the following spruce problems:  site issues, climate problems, herbicide injury, nutrient stress, Rhizosphaera needle cast, Stigmina needle blight, root and butt rot, Cytospora canker, SNEED (Sudden needle Drop), Spruce adelgid galls, Spruce spider mite, and Bagworms.

Next, I set up 8 spruce diagnostic stations with examples of Illinois spruce problems listed on the factsheet.

Each participant was given a spruce diagnostic activity sheet. By working in groups, they were told to visit each of the 8 spruce diagnostic stations and answer the questions on the spruce diagnostic activity sheet by using the spruce fact sheet as a guide.

This Diagnostic workshop help the participants to learn the following:
  • The diagnostic and management differences between Rhizosphaera needle cast and Stigmina needle blight
  • How to scout and identify spruce spider mites as well as identify the correct time to treat for these pests
  • The diagnostic signs of Cytospora canker and how to properly manage this disease
  • How to identify bagworms and adelgid galls as well as how to properly manage these pests
  • The symptoms and sources of spruce nutrient problems
  • How to properly check for spruce site problems
  • How to recognize SNEED symptoms as well as knowing that SNEED has not been proven to be a disease and it can only be diagnosed by a trained diagnostician by properly identifying their ascospores
  • How to recognize herbicide injury symptoms on spruce and to be very, careful when handling herbicide complaints.  We need to remember to rule out all other possible causes for similar symptoms as well as have the proper resources to help determine if herbicide is to blame.