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Ø Common Causes of Corn Ear Drop

Ø Acceptable Harvest Loss in Corn

Ø Green Stem in Soybeans



As we continue with harvest, keep in mind how far ahead we are ahead in heat unit accumulation.  The following table shows GDUs from May 15 planting date to date for 3 locations in northern Ohio.  This explain why we are observing crops much further along than normal for early-mid October.





GDU   Avg.


















Common Causes of Corn Ear Drop

Ear drop is usually caused by the interaction of numerous factors, rather than a single factor. Factors that contribute to ear drop are described below:

European Corn Borer

Second generation European corn borer causes dropped ears by tunneling in the shank and weakening attachment to the stalk. Dropped ears resulting from corn borer usually have husks still attached.

European corn borer 1European corn borer 2


Stalk Rots…..may lead to deteriorated ear shank

Droughty conditions, especially during grain fill, can predispose corn to a number of stalk rots. Fusarium stalk rot (whitish pink color) can infect the ear shank, causing deterioration of the tissues and dropped ears. Fusarium and Diplodia stalk and ear rots can lead to pithy, deteriorated, hollowed-out ear shanks.

Stalk Rots

Pinched Shank”

A “pinched shank” or constriction on one side of the shank can occur. This is usually associated with missing or unpollinated kernels at the base of the ear on the same side as the pinch.

Pinched shank


Moisture Stress

Severe moisture stress late in growth stages can cause abnormalities in corn plant growth and development. Critical moisture stress during shank development can cause irregular cell development in the shank resulting in more ear drop.


Rapid Dry Down

Harvest seasons where fast dry down occurs can have more ear drop compared to normal or slow dry down environments. The exact physiological cause of this is not known but it is probably related to unusually dry and brittle tissue at the point of ear attachment during these conditions.


Genetic Component

Certain hybrids are more prone to dropped ears because of susceptibility to European corn borer or having a small diameter shank attachment to the ear.


Acceptable Harvest Loss in Corn

Yield losses from machine harvest are unavoidable but minimizing these losses are every growers goal.

1-2% harvest loss is achievable at 20+% moisture but often climbs to 3-5% at <17%


·        2 kernels of corn/ft2 is approximately 1 bu/acre of grain left in the field.

·        Harvest losses were lowest when kernel moisture was between 19 and 23%

·        Header loss from ear shelling increased dramatically at moistures below 17-18%

·         Each lost ear in 100 plants represents about 1% yield loss.

·        Harvest Loss Goal = 1.8% = 1% ear loss + 0.3% threshing loss + 0.5% loose kernel loss

o   200 bu/acre = 3.6 bu/acre loss = 2 bu ear + 0.6 bu threshing + 1 bu loose kernel

Green Stems in soybeans

This year soybean stems (and in some cases leaves) are remaining greener even as pods reach harvest drydown. Why is this? As a whole, the industry has selected high yielding soybean varieties that produce & store photosynthates in plant vegetation until pods develop and remobilize the sugars, starch, and nitrogen from stems/leaves. In pockets of the field where greater stress was encountered (or in some whole fields), the plant likely aborted flowers & pods thus reducing yield opportunity. This seed reduction left reserves of water and nutrients in plant tissue with nowhere to go.  

Additionally, green stems have been associated with both insect feeding and soybean seed diseases. Both of which have been identified in the field this season.

green stem in soybeans



Agronomy information provided by:

Kyle Poling

Chasitie Euler