By Blake Jackson
Last fall, some wheat fields in Pennsylvania experienced late emergence, and in some cases, wheat failed to emerge entirely. This issue stemmed from delayed planting and dry weather post-planting, which hindered germination.
Since fall tillers are vital for determining winter wheat yields, farmers are left with three key questions about how late emergence will affect crop productivity.
Can Late-Emerged Wheat Vernalize and Produce Productive Tillers?
Winter wheat requires a cold period, typically four to eight weeks below 48°F, to transition to the reproductive stages and form a grain head. This process, called vernalization, is essential for wheat growth.
Even if a plant has not emerged but the seed has germinated, it can still vernalize and produce productive tillers. Now is a good time to scout fields that haven’t emerged yet, digging into the seed furrow to check for germination.
Seeds that have germinated will show a radicle (seminal root), which indicates the plant is on track for vernalization.
Fields with germinated seeds should meet the cold requirements by February and March, allowing them to transition into reproductive stages by spring.
What Yield Potential Can We Expect from Late-Emerged Fields?
This is the challenging aspect. While plants that have germinated will produce at least one productive tiller, late emergence may not allow enough time for multiple tillers to form, reducing yield potential.
In Pennsylvania, satisfactory wheat yields typically require 50 to 70 heads per square foot, which are generally achieved with about 25 to 30 plants per square foot.
Fields with low plant stands due to dry or late seeding are likely to experience yield losses, especially if fewer than 50 plants per square foot are present.
Are There Management Practices to Improve Low Plant Stands?
Applying nitrogen fertilizer early, around Feekes 2-3 (beginning of tillering), can promote tillering in low stands. Studies show that early nitrogen application increases tiller density and yield.
However, careful management is necessary to avoid nutrient loss through runoff or leaching, especially in wet conditions. While local studies are limited, this strategy is generally accepted to support wheat growth.
Despite these concerns, USDA reports indicate that winter wheat emergence progressed as expected last fall, with significant emergence in early November. Scouting fields this winter remains essential due to varying conditions across fields.
Photo Credit: gettyimages-vadven
Categories: Pennsylvania, Crops, Wheat