Spring is an important time to make key management decisions for winter wheat. Decisions should be made on wheat growth stage, not calendar date or crop height. Correct growth stage identification and knowledge of factors that affect grain yield can enhance management decisions, avoiding damage to the crop and unwarranted or ineffective applications. Several scales can be used to identify wheat growth stages, including the Feekes and Zadoks scale. Here we focus on the Feekes Growth Scale and key spring management practices.
Feekes 5 Growth Stage. At Feekes 5 growth stage, leaf sheaths are strongly erect. This is an ideal growth for spring topdress nitrogen application. Weed control efforts should be made prior to or during Feekes 5.0 with 2,4-D and other labeled herbicides. This is also a good stage to begin scouting for foliar diseases.
Feekes 6 Growth Stage. At Feekes 6 growth stage, the first node is visible above the soil surface and is commonly referred to as ‘jointing.’ Above this node is the head or spike, which is being pushed upwards. To identify Feekes 6 growth stage, you may need to remove the lower leaves and leaf sheath to see or feel the first node (Figure 1). A video demonstrating for identifying Feekes 6 growth stage can be found here: https://www.youtube.com/watch?v=D_f3VrqzV5c&list=PLYlh_BdeqniJ8oD8TnyGhQHRd96ptV0Yt&index=1
Most herbicide applications should be made by the time wheat enters the Feekes 6 growth stage. Herbicide options become increasingly limited as wheat enters Feekes 6 and progresses to the boot stage. Do not apply growth regulator herbicides such as 2,4-D, dicamba, or MCPA after Feekes 6 as these materials can be translocated into the developing head, causing sterility or distortion. Figure 1 in the Weed Control Guide provides growth stage cutoffs for the different herbicide options. Refer to the herbicide label for specific guidelines, as growth stage restrictions vary among different products. Sulfonylurea herbicides are safe at this growth stage, but for practical reasons, weed control should have been completed by now. Wheat can still show good response to nitrogen topdressing at this time.
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Figure 1. Wheat stem with leaves and sheath removed showing the first node above the soil surface, indicating Feekes 6 growth stage. |
Feekes 7 Growth Stage. At Feekes 7 growth stage, the second node is visible above the soil surface. These nodes are usually seen as clearly swollen areas of a distinctly different (darker) shade of green than the rest of the stem. Wheat will still respond to nitrogen fertilizer applied at Feekes 7 if weather prevented an earlier application; however, mechanical damage may occur from applicator equipment. A video demonstrating for identifying Feekes 7 and 8 growth stages can be found here: https://www.youtube.com/watch?v=bnV57AhUt-Y&list=PLYlh_BdeqniJ8oD8TnyGhQHRd96ptV0Yt&index=2
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Figure 2. Feekes 8 growth stage where the flag leaf is visible, but still rolled up. |
Feekes 8 Growth Stage. At Feekes 8 growth stage, the flag leaf is visible, but still rolled up (Figure 2). This stage is particularly significant because the flag leaf makes up approximately 75% of the effective leaf area that contributes to grain fill. It is therefore important to protect and maintain this leaf healthy (free of disease and insect damage) before and during grain development. To confirm that the leaf emerging is the flag leaf, split the leaf sheath above the highest node. If the head and no additional leaves are found inside, Feekes 8 growth stage is confirmed. At this stage, the grower should decide whether or not to use foliar fungicides to management early-season and overwintering foliar fungal diseases.
Feekes 9 Growth Stage. At Feekes 9 growth stage, the ligule of the of the flag leaf is visible. After the flag leaf emergence, army worms can seriously damage yield potential. A video demonstrating for identifying Feekes 9 and 10 growth stages can be found here: https://www.youtube.com/watch?v=K1UVNBR2jRk&list=PLYlh_BdeqniJ8oD8TnyGhQHRd96ptV0Yt&index=3
Feekes 10 Growth Stage. At Feekes 10 growth stage (‘boot stage’), the head is fully developed and can be easily seen in the swollen section of the leaf sheath below the flag leaf (Figure 3). This is another important growth stage for making fungicide applications for foliar disease management, particularly late-season diseases such as Stagonospora leaf and glume blotch and rusts.
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Figure 3. At Feekes 10 growth stage, the head is fully developed and can be easily seen in the swollen section of the leaf sheath below the flag leaf. |
For more information on wheat growth stages and management, please see our FactSheet- https://ohioline.osu.edu/factsheet/agf-126 and Ohio State Agronomy YouTube playlist- https://www.youtube.com/playlist?list=PLYlh_BdeqniJ8oD8TnyGhQHRd96ptV0Yt