A website from UGA Cooperative Extension

News, events, and happenings in Colquitt County agriculture.

Helminthosporium in Rye

Before Christmas Holidays, we looked at a couple of winter rye fields that were having problems with the lower leaves dying on the plants, and the younger leaves exemplifying numerous necrotic spots.  These symptoms were caused by a stressed derived pathogen called Helminthosporium.  This disease is the causal agent of the leaf spot/blotch that occurs on forages such as rye.   Since Helminthosporium is a stress related pathogen, anaerobic conditions such as standing water, lack of oxygen, or fertility issues are the primary cause of this disease.  Therefore, it is very important to practice good management practices such as:

  • Checking soil fertility to maintain the adequate levels of fertility needed
  • Checking pH because nutrient uptake is influenced by pH
  • Alleviating thatch build up and compaction.

Maintaining these practices will help control stressed derived pathogens like Helminthosporium.

As shown in the by the pictures below, in some areas of the field, the rye had almost completely died.  The lesions present on the leaves were small or large, ranged in shape from oval to elongated, and were yellowish-tan to reddish-brown in color.  When the intensity of the disease is high like in some areas of the fields we visited, the lesions on the leaves will merge forming large irregular areas of diseased tissue.  Helminthosporium will not only cause leaf symptoms, but also brown decay of the lower stems.   This disease can be a problem when the infection is severe because many leaves will die causing reduced yields and grain quality.

 

Helminthosporium in Rye 2Helminthosporium in Rye

 

 

Helminthosporium in Rye 3Helminthosporium in Rye 4

 

References:

 Dr. Alfredo Martinez-Espinoza, UGA Professor of Plant Pathology

https://ipm.illinois.edu/diseases/series300/rpd309/

https://www.clemson.edu/extension/rowcrops/small_grains/pdfs/diseases_small_grains.pdf