Pythium Blight

Pythium (Pythium spp.) can cause a myriad of diseases such as blight, root rot, and root dysfunction on turfgrasses. This article will be examining Pythium blight induced by the causal agent P. aphanidermatum.

Pythium Blight Induced by P. aphanidermatum

Pythium blight is seen on any species of cool-season turf as well as some warm-season grasses like Bermudagrass. In the summer months when humidity is prolonged, temperatures are 65oF or greater, and air is stagnant, large patches of bronze matted turf begin to make an appearance. Upon closer examination, one may see either a dark, wet spot similar to a grease or oil stain, or possibly even white mycelium in the midst of these matted circles, which are all clear symptoms of a Pythium infection. Under the most favorable conditions for this disease, damage can be irreparable after just two days, therefore action should be taken to alleviate excessive moisture and heat stress.



The simplest factor to manipulate is moisture. Frequent aerification will reduce soil compaction and keep water and moisture away from the turf. In certain landscapes, air flow may be affected by tree placement or land topography, therefore turfgrass managers may find a high-powered fan useful for moving air into these areas. Soil fertility also plays a key role in Pythium occurrence. Typically soil high in nitrogen will be more likely to develop this pathogen. Lastly, if Pythium blight is a common occurrence on your turfgrass, it is best to remove your clippings when mowing and to not mow when humidity and temperatures are high. Employing these practices can decrease the likelihood of the spread of this pathogen.


Anderson, Z. R. and Fermanian, T. W. (2009). Early Detection of Pythium Blight and Brown Patch through Multispectral Imaging of Creeping Bentgrass Foliage. International Turfgrass Society Research Journal, 11: 137-149.


Kerns, J. A. and Tredway, L. P. (2013). Advances in Turfgrass Pathology since 1990. ASA-CSSA-SSSA Turfgrass Monograph, 742-743.