Does This (Corn Plant) Look Infected?

July 16, 2013 07:37 AM
Does This (Corn Plant) Look Infected?

Five tips to make better in-season crop disease diagnostics.

To the untrained eye, many corn and soybean diseases look very similar. Some can even be easily mistaken for various nutrient deficiencies or herbicide injuries. But it’s still important to learn to make correct disease diagnoses in your field, says Farm Journal field agronomist Ken Ferrie.

"It’s amazing how you can cripple some of these hybrids by not managing for their weaknesses," he says.

Ferrie, Bill Bauer of B&M Crop Consulting, Inc., and others led 2013 Farm Journal Corn College attendees through interactive disease diagnostic workshops to explore some of the visual nuances of some common corn and soybean diseases. There are five tips in particular to keep in mind when developing a disease management plan.

1. Know what you are comparing. For example, some companies list disease ratings from 1-10 (with 1 being the best) and others from 10-1 (with 1 being the worst). If a corn hybrid scores an 8 against gray leaf spot, for example, management style could differ significantly based on which way the scale tilts. And beware the lack of industry standardization, Ferrie says. "A 5 rating in one company is not the same as a 5 in another company," he says. "There’s no standardization in place."

2. Know your hybrid. Know the strengths and weaknesses of the hybrids and varieties you select, Bauer says – and don’t discount a hybrid you like just because it is susceptible to a particular disease. "If it’s a high yielder, keep it in your lineup if you know how to manage around it," he says.

bill instruction
Bill Bauer, B&M Crop Consultanting, Inc., leads a group of retailers and consultants through a disease diagnostic exercise at the 2013 Farm Journal Corn College.


3. Understand that weather is only one factor. You also have to consider many other aspects, including crop rotation, tillage system, drainage, current stress level of the crop and more, Bauer says.

4. Scout, scout, scout. "Make a plan and execute it in a timely fashion," Bauer says. Also keep in mind that disease presence and persistence in your area will change over time, so stay on your toes, he says.

5. Keep a systems approach in mind at all times. "Changing one thing may cause a chain reaction throughout your system," Bauer says.

Ready to hit your fields? Consider these seven must-have scouting tools before you go.

1. Safety glasses
2. Scouting manuals or scouting apps
3. Camera
4. Hand lenses
5. Dissecting scope
6. Laptop microscope
7. Insect repellent/sunscreen

Thank you to the 2013 Corn College sponsors:

AgriGold, BASF, Chevrolet, ESN/Agrium, Great Plains, Honeywell, Koch, Novozymes, Precision Planting, SFP, Top Third Marketing

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