Disease Facts
- Physoderma stalk rot and the more commonly observed foliar symptoms known as physoderma brown spot are both caused by the fungal pathogen Physoderma maydis.
- This pathogen was first documented in India in 1910 and in the United States in 1911.
- Historically, physoderma stalk rot has generally been of little economic importance in the US, although instances of severe localized outbreaks have been reported.
- However, prevalence has increased in the U.S. Corn Belt within the last few years, possibly due to wetter conditions early in the growing season.
Disease Symptoms
- Symptoms of physoderma stalk rot includes blackening of lower stalk nodes and potentially some stalk rot of the pith, which can result in breakage at the node.
- Physoderma stalk rot can occur in fields in which foliar symptoms (physoderma brown spot) are not present.
- Plants in which physoderma stalk rot symptoms are observed are often otherwise healthy with large ears.
Physoderma stalk rot (Physoderma maydis) stalk breakage at lower node (Sept. 2014, Iowa).
Disease Cycle
- Overwintering fungal structures, sporangia, survive in infected corn tissue or soil.
- Sporangia germinate to produce infective zoospores under conditions of moisture and light.
- The biology of disease in corn caused by P. maydis is not well-understood.
Harvest Management
- Careful scouting and harvesting fields according to crop conditions can help prevent yield losses.
- Closely monitor stalk quality by looking for plants broken at the lower-most nodes and by pushing stalks to better understand stalk integrity.
- Check 20 plants in 5 areas of the field. If more than 10-15% of the stalks are rotted, that field should be scheduled for early harvest.
Stalk breakage and dark lesions on lower nodes of affected plants (Sept. 2014, Iowa).
Disease Management
- Tillage and crop rotation may be helpful in reducing disease inoculum, as the fungus survives in infected crop residue.
- Specific management for this disease is not typically required, as the occurrence is sporadic and the effect on yield should be minimal.
- Field observations suggest some variability among hybrid susceptibility to physoderma stalk rot; however, Pioneer® brand corn products are not currently rated for genetic resistance to this disease.
Authors: Jeff Mathesius, Mark Jeschke, and Jennifer Chaky
Photos courtesy of Nate LeVan, Pioneer Field Agronomist
PIONEER® brand products are provided subject to the terms and conditions of purchase which are part of the labeling and purchase documents.
The foregoing is provided for informational use only. Please contact your Pioneer sales professional for information and suggestions specific to your operation. Product performance is variable and depends on many factors such as moisture and heat stress, soil type, management practices and environmental stress as well as disease and pest pressures. Individual results may vary.