Plant Disease Clinic

Verticillium Wilt

This is a culture of a species of Verticillium isolated from wood chips of an infected Magnolia tree. Verticillium can be a serious problem that causes wilting and dying of susceptible plants. Culturing from wood chips also tests for Oak Wilt and Dutch Elm Disease.

Pine Wilt Disease

The pine wood nematode (Bursaphelenchus xylophilus) was extracted from the wood of this Scotch Pine. Nematodes are microscopic worms. Some nematodes are plant pathogens. The blue stain in this wood is caused by a fungus. Pine wood nematodes can feed on the blue stain fungus as well as the resin ducts and epithelial cells of certain trees. Nonnative pines are susceptible to Pine Wilt Disease.

Tobacco Rattle Virus (TRV)

TRV is the cause of the dramatic symptoms on this native woodland perennial, Phryma leptostachya L. (American Lopseed). This virus can be transmitted mechanically, by seed, and by nematodes of the family Trichoridae when they feed on roots of susceptible plants. Many plants are susceptible to TRV. Virus particles can be seen using Transmission electron microscopy (TEM).

Rhodococcus faciens

This is a pure culture of bacteria isolated from a leafy gall of an ornamental plant. DNA sequencing identified the bacteria as Rhodococcus faciens. This disease can infect many plants and there is no cure.

Goss’s Bacterial Wilt and Leaf Blight

This photo, taken thorough a microscope, shows bacterial streaming from a corn leaf that tested positive for Goss’s Wilt. Goss’s wilt is caused by Clavibacter michiganensis subspecies nebraskensis. Together, bacterial streaming, a serological test for Clavibacter, and visual symptoms on leaves are used to confirm Goss’s Bacterial Wilt and Leaf Blight.

Stakman Hall

The University of Minnesota Plant Disease Clinic is a multi-disciplinary diagnostic laboratory that provides testing for: fungal, bacterial, viral, and other plant health conditions for commercial growers and the general public. The goal of the Plant Disease Clinic is to provide our clients with an accurate, unbiased diagnosis.

Oak Wilt spores under the microscope

Oak Wilt

For more information about Oak Wilt, see My Minnesota Woods.

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