Dutch elm disease, oak wilt, Verticillium wilt (vascular wilt) samples 
Collect three branch pieces, 1/2 to 2 inches in diameter, 6 to 8 inches long, from recently wilted branches. Pieces from branches that are partially alive and partially dead are best. * DO NOT * send branches that have dried out and have a brown layer directly under the bark.

Soil samples 
The PDDC does not routinely test soil for plant disease-causing organisms.  Typically, examining infected plant tissue is better way to provide an accurate diagnosis.  Soil can be tested for certain plant pathogenic organisms, however (e.g., nematodes).  The PDDC does not provide this nematode testing, but forwards soil samples requiring this testing to the UW Nematode Diagnostic Lab.

Tree and shrub root samples
Select three to four sites around the drip line (i.e., the edge of where the branches extend) of the tree or shrub. Dig down 3 to 6 inches at each location and look fibrous (small) roots from the tree or shrub.  Roots from all locations can be mixed together for shipment.  A handful of roots is needed for testing.

Turf samples
The PDDC does not diagnose turf diseases.  Turf samples submitted to the PDDC will be forwarded to the UW-Madison Turf Diagnostic Lab for analysis.