
450-709
Plectosporium blight (formerly called Microdochium blight) is a disease of pumpkins and squash that was first reported in Tennessee in 1993. It is caused by the fungus Plectosporium tabacinum (formerly Microdochium tabacinum). In 1994 the disease appeared in Virginia in both pumpkins and zucchini, causing severe blighting of the vines before fruit maturity. The reason for the sudden appearance of this disease is unknown, but Plectosporium blight has been present in Virginia every year since 1994.
Fig. 1. White, diamond-shaped lesions of Plectosporium blight on pumpkin stem.
Fig. 2. Lesions coalescing on main veins on underside of pumpkin leaf. |
On fruit the white lesions are more circular and less diamond-shaped. Spots on the flesh remain small and scattered; however the ³handle² or stem stub on the pumpkin may be completely white at harvest (Fig. 3).
Fig. 3. Lesions on pumpkin stem and fruit. |
Fig. 4. Death of pumpkin vines due to Plectosporium blight. |
| Refer to the current Virginia Pest Management Guide for Home Grounds and Animals (VCE Publication 456-018), http://www.ext.vt.edu/pubs/pmg/, for details on the proper use of pesticides. |
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Issued in furtherance of Cooperative Extension work, Virginia Polytechnic Institute and State University, Virginia State University, and the U.S. Department of Agriculture cooperating. Rick D. Rudd, Interim Director, Virginia Cooperative Extension, Virginia Tech, Blacksburg; Wondi Mersie, Interim Administrator, 1890 Extension Program, Virginia State, Petersburg.
May 1, 2009