Cold Weather and Corn
Corn planting
was completed very rapidly this spring and for the most part the crop is off
to a good start. Generally corn plants are ahead of normal in terms of growth
and development. This fact may cause corn producers some anxious nights if weather
patterns produce the risk of frost. There is very little that can be done to
minimize the potential problem but here are some management factors that do
increase the risk of frost damage to corn should temperatures fall:
1. Inter-row cultivation
2. Side dressing nitrogen (where soil is disturbed)
3. Herbicide applications
4. Presence of weeds
5. High levels of previous crop residue
If the forecast calls for a risk of frost farmers may elect to delay inter-row
cultivation, nitrogen Side dressing or herbicide applications until warmer temperatures
return. If corn does receive frost damage it will generally have very little
effect on the crop providing the growing point of the corn plant is still below
the soil surface. This is the case until the young plant reaches roughly the
6th leaf stage. On more advanced plants/and or where damage is more severe stalks
will need to be split to see if the growing point has been damaged. However,
this procedure will require some patience! It probably takes 3-5 days following
a frost to accurately determine the degree of damage, to verify the presence
of healthy growing points (yellowish-white in colour and firm) or to see new
leaf growth.
In some cases frozen leaf tissue, which bleaches to a straw colour several days
after freezing, also develops a "knot" which may restrict expansion
of the undamaged tissue lower in the whorl. Often it appears that clipping these
knots by mowing the field aids in the plants recovery. Tests conducted on frosted
corn fields over the years have arrived at the conclusion that clipping appeared
to help the fields "green-up" but that unclipped sections of the same
fields often recovered as quickly and yielded as much or more than the clipped
sections.
Decisions regarding the severity of frost damage, the need to replant, or the
advantages to mowing the damaged corn should not be done in haste or without
due regard for the young corn plants ability to recover.