Warm Temperatures Accelerate Development & Wheat Fungicide at Bloom Timing

Written By: Matt Wehmeyer

Wheat fields across the Lower Midwest are advancing quickly due to recent warm temperatures. The crop is currently ahead of 2024, which was an early year for many. Depending on plant date and variety maturity, growth stages are commonly at early heading through early bloom.

One of the most critical passes of the season is a targeted fungicide at early bloom. This application’s main focus is to protect the plant from Fusarium Head Blight, as well as general plant health from other diseases. Farmers can uniquely experience a ROI from the following areas:

Improving yield.
Improving test weight.
Lowering DON levels (vomitoxin).

The 3 most recommended fungicide products to use are (in no particular order):

Miravis Ace (Syngenta).
Prosaro Pro (Bayer).
Sphaerex (BASF).

Optimum Timing, defining growth stages:

Although some labels suggest Feekes 10.3 is ok to spray, it is generally recommended to wait. Feekes 10.3 is when 50% of the heads are ½ emerged. Many of the tiller heads are still splitting the boot, which is not ideal.

Feekes 10.5 is when 50% of the heads are fully emerged. Waiting until this timeframe will allow more head emergence, including the tillers, thus improving fungicide performance vs 10.3.

Optimum timing is defined as Feekes 10.5.1, which is early flowering. The wheat heads will begin flowering in the middle of the head, identified by the yellow or purple anthers, and then move up and down the head. Once the anthers turn white, flowering is complete. You will notice at this stage, the heads have started extending above the flag leaf. This greatly enhances the coverage of the fungicide application on heads, while also allowing more time for tillers to be receptive.

See the below pictures of growth stages, courtesy of The University of Wisconsin.

How long do I have:

Heading and flowering is a relatively short window, generally lasting 10 days from the start of seeing heads to flowering. The pictures below were taken in 2024 in Southern IL and show the progression.

On 4/25, the crop was at Feekes 10.5. This is 3 days ahead of optimum, but would qualify for an early application. You can see ½ of the heads have emerged, but are somewhat hidden in the flag leaves.
On 4/28, the crop was at Feekes 10.5.1. This is optimum. You can see a few anthers and notice how the heads have extended over the flag leaves. Targeted coverage is greatly improved at this stage.
On 5/1, the crop was at Feekes 10.5.3. This is 3 days post optimum. You can see how the anthers have turned white and bloom is complete. Applying fungicide at this stage has still shown many positive benefits. In fact, research has shown that a later application typically is better than an early application.