Why Cereal Growth Stages Matter

Knowing the cereal growth stage is key to profitable grain production. Effective herbicide and fungicide applications are dependent on timing them at the correct growth stage of the crop. Spraying herbicides and fungicides at the wrong time can not only damage a crop but also reduce yield and profit potential through ineffective weed and disease control.

This guide is intended to help growers know when herbicides and fungicides should be applied. It uses the Zadoks1 scale, which follows plant development through 10 primary development stages (Figure 1).

Scale for plant development through ten primary development stages and flag leaf stages.
Figure 1. Zadoks1Scale for plant development through ten primary development stages.

General Recommendations

Herbicides:

Herbicides can be applied between 1st leaf and just before flag leaf emergence. Stem elongation is a critical growth stage for herbicide timing and for some herbicides, application prior to this stage can help provide a margin of safety from potential crop injury. Early herbicide application can be an effective management strategy for controlling weeds that can impact yield potential.

Table 1. Bayer herbicide products and growth stage application timings in cereal crops.

Herbicide

Crop

Timing of Application

Buctril® M Herbicide

Barley, Oats, Wheat (spring, durum, winter)

Barley, Oats, Wheat (spring & durum) – 2-leaf stage until the early flag leaf stage

 

Winter Wheat –2- to 4-leaf stage in the fall or from the time growth commences to the early flag leaf stage in the spring

Infinity® Herbicide

Barley, Triticale, Wheat (spring, durum, winter)

1-leaf stage until the flag leaf is just visible but still rolled

Infinity® FX Herbicide

Barley, Triticale, Wheat (spring, durum, winter)

2-leaf stage until the flag leaf is just visible but still rolled

Olympus® Herbicide

Wheat (spring, durum, winter)

One week prior to planting spring, durum, and winter wheat or immediately after planting but prior to crop emergence.

Pardner® Herbicide

Barley, Oats, Wheat (spring, durum, winter)

Barley, Oats, Wheat (spring, durum, winter)– 2-leaf until early flag leaf stage when applied alone

Puma® Advance Herbicide

Barley, Wheat (spring, durum)

Barley, Wheat (spring & durum) - 1 to 6 leaves on the main stem plus 3 tillers. Apply at the 3- to 4-leaf stage for maximum crop tolerance and weed control

Tundra® Herbicide

Barley, Wheat (spring, durum)

Barley, Wheat (spring & durum) - 1- to 6-leaf stage on the main stem plus 3 tillers.

Thumper® Herbicide

Barley, Wheat (spring, durum, winter

Barley, Wheat (spring, durum) – 4-leaf stage until the early flag leaf stage.

Varro® Herbicide

Wheat (spring, durum, winter)

1- to 6-leaf stage on the main stem up to emergence of the 3rd tiller, but prior to appearance of the first node (jointing).

Velocity™ m3 Herbicide

Wheat (spring, durum, winter)

Spring & Durum Wheat - 1-to 6-leaf stage, maximum 3 tillers, but prior to appearance of the first node (jointing)

 

Winter Wheat – Apply either in the fall or spring when the majority of plants have 1-leaf to full tillering, but prior to appearance of the first node (jointing)
Table 1 lists Bayer cereal herbicides registered in Canada. For products available in your geography please reach out to your local Bayer representative.

Fungicides:

Fungicides have three different application windows, each with a specific purpose.

  • T1 Application – occurs as early as the four-leaf stage. Fungicides applied at this time can help control early season diseases like powdery mildew (Figure 2). T1 fungicide application occurs at herbicide application timing, with both often tank-mixed together. Head size and yield potential are determined during wheat’s tillering stage, so it is important to protect against diseases like tan spot, Septoria leaf blotch and stripe rust at this time.
  • T2 Application – occurs when the flag leaf has fully emerged, but before the head emerges from the boot (Figure 2). Flag leaf is the most important stage for grain fill. Fungicides applied at this time can help protect the flag leaf from disease from below the canopy, such as Septoria or rust. This helps protect the main yield producing leaf.
  • T3 Application – occurs when the head is just fully emerged and begins to shed pollen (Figure 2). Fungicide applications at this time are centered around protecting the head, particularly from Fusarium head blight disease (head scab). Infection from Fusarium head blight at heading can cause substantial yield losses and quality reductions. Optimal timing of application is when 75 percent of heads across the entire field are emerged to when 50 percent of the heads are in flower.

Fungicide Application Priorities to Consider for Optimal Yields in Different Crops

  • Spring Wheat/Durum – priority should be given to the T3 application for both Fusarium head blight and leaf disease control.
  • Winter Wheat – priority should be given to a T1 application at herbicide timing followed by a T3 later in the season.
  • Barley – There are two options. The priority should be given to a T3 fungicide application where Fusarium pressure is high. However, in cases where head blight pressure is low and/or if Fusarium diseased kernels and DON levels are not a factor with your grain, then a T2 application may be a better option. The reason to consider a T2 application with barley is because the penultimate leaf and leaf sheaf contribute up to 65% to yield potential, whereas with wheat, the flag leaf contributes a greater percent to yield potential.
Stages in cereal crop development critical for herbicide and fungicide timing.
Figure 2. Stages in cereal crop development critical for herbicide and fungicide timing. Key stages for herbicide application include emergence, 2-leaf, 4-leaf, 6-leaf and when the flag leaf emerges. Key stages for fungicide applications include 4-leaf, flag leaf emergence, full heading and flowering.

Table 2. Bayer fungicide products and growth stage application timings in cereal crops.

 

Fungicide

Crop

Major Diseases Controlled/Suppressed

Timing of Application

Prosaro® XTR Fungicide

Barley, Oats, Wheat (spring, durum winter)

Tritical

Rusts (crown, leaf, stripe and stem), Powdery Mildew, Septoria Leaf and Glume Blotch, Fusarium Head Blight*

Barley - As a preventative spray when 70% to 100% of the barley main stem heads are fully emerged to 3 days after full head emergence.

 

Wheat – Apply as a preventative spray when at least 75% of the wheat heads on the main stem are fully emerged to when 50% of the heads on the main stem are in flower.

Prosaro® PRO Fungicide

Barley, Oats, Triticale, Wheat (spring, durum, winter)

Blotch (glume, leaf, net, spot), Powdery Mildew, Rusts (leaf, stem, stripe), Tan Spot, Ergot*, Fusarium Head Blight*

Barley - as a preventative spray from when 70% to 100% of the barley main stem heads are fully emerged to 3 days after full head emergence.

 

Wheat - as a preventative spray from when at least 75% of the wheat heads on the main stem are fully emerged to when 50% of the heads on the main stem are in flower.

 

Stratego® PRO Fungicide

Barley, Millet, Oats, Rye, Triticale, Wheat (spring, durum, winter)

Rusts (crown, leaf, stem, stripe), Powdery Mildew, Septoria Leaf Blotch, Scald, Tan Spot

Optimal timing is T1. Application can be made in conjunction with herbicide timing for early-season pest control.

Delaro® Fungicide

Barley, Oats, Triticale, Wheat (spring, durum & winter)

Rusts (crown, leaf, stem, stripe), Septoria Leaf Blotch, Powdery Mildew, Tan Spot, Scald, Net Blotch.

Winter Wheat: Applied as a preventative disease control measure or at the very early stages of disease development. This could occur anytime during tillering or stem elongation. Typically, one application from tillering up to the flag leaf emergence is required. A second application may be made if needed. Must be applied prior to head emergence.

Single Application: 4-leaf stage up to flag leaf.

Two Applications: First application: 4-leaf stage to flag leaf. Second application: not within 14 days of the first application and prior to head emergence.

 

Wheat (spring, durum), barley, oats, triticale - as a preventative disease control measure or at the very early stages of disease development, from tillering up to flag leaf emergence.

TilMOR™ Fungicide

Barley, Oats, Wheat (spring, durum, winter)

Blotch (glume, leaf, net, spot), Rusts (crown, leaf, stripe, stem), Tan Spot, Powdery Mildew, Fusarium Head Blight (Wheat)*

Leaf Disease – from late vegetative stage (flag leaf fully emerged to awn emergence) to the end of the flowering stage.

 

Fusarium Head Blight (Wheat) – when at least 75% of the wheat heads on the main stem are fully emerged to 50% of the heads on the main stem are in flower.

*Suppression only
Table 2 lists Bayer cereal fungicides registered in Canada. For products available in your geography please reach out to your local Bayer representative.

 

 

Sources

1Zadoks, J.C., Chang, T.T., and Konzak, C.F. 1974. A decimal code for the growth stages of cereals. Weed Research vol. 14:415-421.

Vermey, M. 2020. Timing is everything: Know your cereal growth stages. Ontario Grain Farmer.

https://ontariograinfarmer.ca/2020/04/03/timing-is-everything/

Dietz, J. 2015. Timing for winter wheat herbicides. Top Crop Manager.

https://www.topcropmanager.com/timing-for-winter-wheat-herbicides-17812/

 

Legal Statements

ALWAYS READ AND FOLLOW PESTICIDE LABEL DIRECTIONS. Performance may vary from location to location and from year to year, as local growing, soil and weather conditions may vary. Growers should evaluate data from multiple locations and years whenever possible and should consider the impacts of these conditions on the grower’s fields.

Tank mixtures: The applicable labeling for each product must be in the possession of the user at the time of application. Follow applicable use instructions, including application rates, precautions and restrictions of each product used in the tank mixture. Bayer has not tested all tank mix product formulations for compatibility or performance other than specifically listed by brand name. Always predetermine the compatibility of tank mixtures by mixing small proportional quantities in advance. Bayer, Bayer Cross, Buctril®, Delaro®, Folicur®, Infinity®, Olympus®, Pardner®, Prosaro®, Puma®, Stratego®, Thumper®, TilMOR™, Tundra® and Varro® are trademarks of Bayer Group. Used under license. Velocity™ is a trademark of Bayer Group or its licensor. Used Under license. Bayer CropScience Inc. is a member of CropLife Canada. ©2021 Bayer Group. All rights reserved. 1043_S1_CA