Download Bouquet Ears in Corn

Bouquet Ears in Corn
Bouquet ears in corn is generally an uncommon occurrence. Some territories are finding more
bouquet ears than normal. There are several theories about factors that may potentially increase the
risk for bouquet ears, but a definite cause is not known.
What is a Bouquet Ear?
Most field corn grown in the Midwest produces one ear per stalk.
When there is more than one ear per stalk, different terms are used to
describe where and how the multiple ears develop (Figure 1):
Prolific hybrids are more apt to produce two ears per stalk. Generally
the two ears express themselves at lower populations or on field edges,
and develop at different nodes on the stalk.
Twin ears are two ears at the same node, that may or may not develop
from the same shank. The primary ear is often larger.
Bouquet ears have three or more ears are at the same node, and
may or may not develop from the same shank. The middle photo in
Figure 1 shows multiple shanks at the same node. If kernel set is
poor on the primary and tertiary ears, potential yield loss may be
substantial. In 2006, fields in Iowa were reported to have yields of 50
bushels per acre with poor kernel set on bouquet ears. More
frequently, the ear development is relatively normal for the primary
ear and potential yield loss is minimal.
Basics of Ear and Shank Formation
The number of potential ear shoots is determined around V5. Apical
dominance, a strong characteristic in corn, is driven by plant
hormones and causes the plant to allocate resources to a primary
ear. Hence, even though several potential ear shoots may have
developed at V5, only one often produces a harvestable ear.
Bouquet ears are often at the node below where the primary ear
would be. This indicates that stress at V6 or V7 likely stopped normal
development of the primary ear, thereby breaking apical dominance.
That disruption of the hormone balance which causes the plant to
allocate resources to the secondary ear shoot, may contribute to
multiple ears developing at the secondary node.
Shanks are similar to stalks. Husks are attached at a node on the
shank, as leaf sheaths are attached at a node on the stalk. Ears may
develop at various nodes on the stalk, and in some cases, ears may
develop at nodes on the shank. It is difficult to determine why twin and
bouquet ears can develop from the same shank, or from separate
shanks at the same node, as information on the timing of shank
development relative to growth stage is limited.
Factors Contributing to Bouquet Ears
Field histories from fields with prevalent bouquet ears have not
revealed any strong common threads. Differences have been seen
among hybrids, and different hybrids might have different triggers.
Figure 1. Bouquet ears
can result in relatively
normal primary ear
formation (center) or
poor kernel set on the
primary and tertiary ears
(left).
The photo to the right shows a prolific hybrid
(produced two ears at different nodes) as well
as twin ears at the primary ear shoot node.
Growth chamber studies indicated the following are some of the
factors that may increase the risk of bouquet ears1:
• Longer photoperiods - Corn exposed to 16 hours of light versus 12
hours of light in early vegetative stages
• Cool Temperatures - 50º F or lower for 3 to 7 days around V6
• Water - Flooding during cold temperatures
Management Options
Management options are normal practices that help minimize the risk
of conditions that can result from the interaction between genetics
and environment:
• Planting a package of hybrids with different relative maturities and
diverse genetic backgrounds
• Minimizing stress (compaction, nutrient deficiencies, etc) to help
the corn crop be better able to cope with adverse conditions.
Sources: 1Elmore, R.W. and L.J. Abendroth. November 2006. Multiple Ears Per Node:
Iowa 2006 Situation & Hypothesis. Iowa State University, Extension Corn Production.
http://www.agronext.iastate.edu/ (verified 8/11/2010).
2Nielsen, R.L. 2006. A Problem with “Bouquets”. Purdue University Extension. http://
www.agry.purdue.edu/ (verified 8/11/2010).
Individual results may vary, and performance may vary from location to location and from year to year. This result may not be an indicator of results you may obtain as local growing, soil and weather
conditions may vary. Growers should evaluate data from multiple locations and years whenever possible. ALWAYS READ AND FOLLOW PESTICIDE LABEL DIRECTIONS. Technology Development by
Monsanto and Design(SM) is a servicemark of Monsanto Technology LLC. ©2010 Monsanto Company. 08162010EJP
1 / 1
Monsanto Technology Development