During the past few growing seasons, corn growers have been talking about the growing presence of northern corn leaf blight in their fields. In the past, resistant hybrids helped limit yield losses. However, the disease has increased in recent years.
In a 2015 study by the Ontario Ministry of Agriculture, Food and Rural Affairs, 97 percent of fields surveyed had detectable levels of northern corn leaf blight. Every field in Southern, Western and Central Ontario showed some level of infection, while only five fields in Eastern Ontario showed no detectable infection.
Albert Tenuta, a field pathologist with OMAFRA, highlights the role that genetics plays in staying ahead of disease. “One of the reasons we’re seeing an increase in northern corn leaf blight is because more races of the disease are developing, and they are able to bypass current resistant genes,” he said. “The most important decision growers can make is selecting the best genetics for your fields. Moving forward, growers will really need to think about their hybrids. On top of that, they’ll want to arm themselves with as many disease management tools as possible.”
Northern corn leaf blight can reduce yield potential. Research trials from the University of Guelph Ridgetown Campus show that even under good environmental conditions with moderate pressure, the disease can result in yield losses of 20 to 30 bushels per acre.
Growers should have an integrated disease management plan for protecting their crop from diseases including northern corn leaf blight, eye spot, and grey leaf spot. Scouting early, just prior to tassel emergence, helps determine the level of disease pressure in a field. “Being able to identify the disease, and getting out in the field early is important,” said Tenuta. “With northern corn leaf blight, significant yield loss is common even in good environmental conditions.” When scouting, growers should be vigilant for early northern corn leaf blight symptoms, including tan streaks or long, elliptical tan or greyish-green lesions.
Once a disease such as northern corn leaf blight is detected, growers should consider applying a fungicide with multiple modes of action. A fungicide such as Headline AMP, which has Group 3 and Group 11 active ingredients, protects plants by preventing the growth and germination of multiple fungi, including the fungus that causes northern corn leaf blight.
“Using multiple modes of action is particularly important for managing diseases like northern corn leaf blight,” said Ken Currah, a Business Representative with BASF. “The disease can overwinter on crop residues, and is easily spread through wind and rain. Using multiple chemistries helps manage resistance issues in that disease build-up. Headline AMP can be applied from pre-tassel through to the R1 stage. However, to maximize success, growers will want to use a preventative application prior to the onset of disease.”
In addition to applying a fungicide, rotating crops and managing residues can help growers control diseases such as northern corn leaf blight. Using multiple strategies helps manage disease and promote crop and field health, preserving yield potential and maximizing success both now and for future seasons.
Source : BASF