Farm Progress

Follow checklist to protect wheat from powdery mildew, tan spot, leaf rust and other early-season diseases.

March 23, 2017

3 Min Read
WHEAT PLAN: Scouting is the cornerstone of a good plan to protect wheat from leaf diseases.Syngenta

By Nathan Popiel

Rust, powdery mildew, tan spot and Septoria can cause yield reductions of more than 40%. These early-season diseases create some of the worst damage when you aren’t prepared for outbreaks. Even though these diseases are different in nature, their damage can be reduced by implementing proactive management strategies.


STRIKES EARLY: Leaf rust is one of the main early-season diseases to prevent. (Photo: Syngenta)

Track diseases
A good indicator that wheat may need extra protection is the level of disease present in states located to the south. Many diseases can spread through windblown spores, so being aware of conditions farther south can inform growers if and when to take preventive action.

Scout early and often
When scouting for disease, pay close attention to the top and bottom of the leaves of the wheat plant. Powdery mildew infections will produce small, irregular or circular gray-white spots on leaves at flowering. Signs of stripe rust include small, yellow or orange blister-like lesions, also known as pustules. Leaf rust infections will take the shape of small, round or oval raised orange-red pustules on leaf surfaces.


MILDEW THREAT: Powdery mildew grows on wheat leaves. (Photo: Syngenta)

After initial product applications, scout two to three weeks later to ensure good pest control. Maintain consistent scouting practices throughout the season and increase scouting frequency as needed during times of high pest pressure. It’s much easier to prevent diseases than to try to control them once they are already present in the field.

Make proactive product applications
Think of fungicides like a shield, holding off pests before they arrive and helping to maintain — and improve — crops’ performance. Many wheat growers are using herbicide-fungicide product combinations to offer the benefit of multiple products in one application, and ensure maximum grain fill and return on investment. Find what works best within the growing area, and stay ahead of disease and weed pressure.

Keep a sharp eye out for resistance
After repeated use of the same fungicide and mode of action, disease-causing pathogens can develop resistance to fungicides. This reduces the ability to control damaging disease outbreaks in crops. Once present in a field, resistance can last for a very long time.

To help manage the threat of fungicide resistance, be sure to implement sound chemical practices such as:

• scouting to identify diseases early, before pathogen populations become too large to manage

• limiting the number of applications of a specific fungicide mode of action and allowing adequate time between applications

• rotating fungicides with different modes of action and chemical classes from season to season

• following label directions and applying fungicides at the recommended label rates

• using a fungicide product that incorporates multiple modes of action to help ensure resistance management while providing premium disease protection

Cultural practices
There are several cultural practices that can reduce the risk of fungicide resistance. These include:

• spreading risk by planting multiple disease-resistant seed varieties

• rotating crops to prevent diseases from infecting the next crop via the “green bridge” effect

• cleaning tillage, seeding and harvest equipment when leaving fields with fungicide-resistant diseases

• scouting fields regularly for signs of fungicide resistance

Popiel is the Syngenta agronomic service representative in North Dakota. For wheat agronomy tips, email [email protected].

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