Evaluating Disease Progression

2019 has been a tough year in some parts of the state, with many growers hesitant to invest any more in their crop. However protecting this year’s yield is still important, especially in fields that have experienced heavy rainfall. Late-planted corn can be susceptible to disease due to rapid growth.

Agronomists at Dekalb/Asgrow have had reports of Grey Leaf Spot across the state due to the weather. The presence of Grey Leaf can have a huge influence on yields already in a rough place.

Symptoms of Grey Leaf Spot begin as small, dark, t spots encircled by a thin, yellow radiance. The tissue within the “spot” begins to die as spot size increases into longer lesions. Initially brownish and yellow, the characteristic grey color that follows is due to the production of grey fungal spores (conidia) on the lesion surface. Mature corn grey leaf spot lesions have brown rectangular and vein limited shape.

There’s an easy process for monitoring Grey Leaf Spot and other disease progression, all it takes is a can of spray paint, the more eye catching the color the better, and a flag for marking.

Paint Marking Method

  • Be on the lookout for symptoms of Grey Leaf Spot when scouting fields.
  • When symptoms are sighted spray the infected area of the plant with spray paint.
  • Mark the crop row entrance with a flag.
  • Return to the marked spot within five days to check the progress of the disease. If the disease has spread past the painted area, note the duration of time passed and how far it has spread.

Contact your Co-Alliance Agronomy team member to discuss what steps you can take to prevent yield reduction to the disease.