What did county crop tour tell us?

Tony Nye - OSU Extension

It is hard to believe it is June already. It won’t be long before we are talking about fair week around here. Memorial Day weekend allowed many producers to get back into the fields. For some that was short lived as showers fell upon much of the county Sunday night and it came in buckets for some areas as reports of as much as three inches fell in the Lees Creek area.

As a result, Dale Hurtlein form the Farm Service Agency and myself took a drive through much of the county to assess not only the after math of the heavy rains Sunday but to really assess the planting progress in the county. The Tuesday drive revealed that we still had about thirty percent of the county to plant – either to corn or soybeans.

As one would expect, the majority of the county needing to get planted is south of State Route 28. My best guess is that 80 to 85 percent of the corn acres have been planted with limited remaining corn acres to get planted yet. Some producers are reporting they will switch corn acres to soybeans. Others are tied to inputs already applied for corn that will not allow them to switch.

Ironically, with all the rain delays, there is a small portion of the county on into Greene County that could use a nice rain.

In taking time to be on our weekly CORN conference call this week to discuss crop conditions around Ohio it clear that we are in a minority with crop planting progress. Only counties south of us are farther behind.

In terms of assessment of the growing crop that is out there, I can say there are many good fields of corn out there considering the kind of weather we have had up to this point. It is not without saying that there are some fields that suffered from poor emergence due to the early cold, damp soil conditions.

Some of these fields have been replanted or spotted in. The same can be true with soybeans. Many fields are looking good but there will be consequences to deal with especially in fields just planted right before the pounding Sunday evening rains fell upon us. So I expect some replanting to occur.

There have already been some early soybean fields needing some replant attention due to poor emergence, frost and insect issues.

If producers have not assessed all their fields now may be a good time to get out and really walk your fields. Based on some field observations on Thursday, there may be a need to estimating yield losses in corn due to poor emergence, hail, frost, and other types of plant injury.

Peter Thomison, Ohio State corn specialists notes it’s essential to establish the stage of plant growth at the time damage occurred (something many may not have taken time to do due to more field work needing to get finished). It’s also important to know corn stage of development in order to apply post-emergence chemicals effectively with minimum crop damage.

Counting leaf collars to determine the vegetative stage is feasible until the lower leaves can no longer be identified. At about the V6 stage, increasing stalk and nodal growth combine to tear the smallest lower leaves from the plant. This results in degeneration and eventual loss of lower leaves which makes it difficult to locate the lower leaves (especially the first rounded leaf).

When identification of specific leaf collars on plants is not possible how can the leaf stage of development of a field be estimated?

Thomison notes that given an understanding of corn leaf stage development and heat unit (growing degree day, GDD) calculation, a grower can estimate what leaf stage of development a particular field is at given its planting date and temperatures since planting.

Corn leaf developmental rates may be characterized by two phases. Purdue University research indicates that from VE to V10 (10 leaf collars), leaf emergence occurs approximately every 82 GDDs accumulated (Nielsen, 2014). From V10 to tasseling (VT) leaf collar emergence occurs more quickly at approximately one leaf every 50 GDDs accumulated. Iowa State University findings (Abendroth et al., 2011) relating leaf appearance to GDD accumulation are similar – from VE to V10 a new collared leaf appears every 84 GDDs accumulated and from V11 to VT, each leaf appears at approximately every 56 GDD accumulated.

Here is an example that Thomison has provided: (from Nielsen, 2014): “A field was planted on April 28, but you do not know exactly when it emerged. Since planting, approximately 785 GDDs have accumulated. If you assume that the crop emerged in about 120 GDDs, then the estimated leaf stage for the crop would be about V8. This estimate is calculated by first subtracting 120 from 785 to account for the estimated thermal time to emergence, then dividing the result (665) by 82 (equal to V8.1).”

Growth-limiting stresses and conditions (soil moisture deficits, nutrient deficiencies, compaction, etc.) affect the accuracy of these predictions. Nevertheless, this method may be useful in timing when plants will reach an approximate stage of growth.

Tony Nye is the state coordinator for the Ohio State University Extension Small Farm Program and has been an OSU Extension Educator for agriculture and natural resources for 28 years, currently serving Clinton County and the Miami Valley EERA.


Tony Nye

OSU Extension