ReachOut: Under Water

Mike Zwingman

Mike Zwingman

The rainfall events of this past weekend definitely fell into what my Grandfather used to call the “frog strangler” category.  These rains have caused flooding of low lying areas or ponding in poorly drained spots in fields throughout much of the Northern Region of UFC territory.  The rest of the fields, while not flooded from a technical perspective, will most likely remain to have saturated soils for a considerable amount of time.

So what are the chances that recently submerged cornfields or plants could endure and survive the days of saturated soils?  The answer that is most dismissive is that such plants or fields suffering this bleak fate will survive until they die.

Like I said it’s a dismissive answer.  What I should have said is that no, one person can tell you with any confidence a few days after the storm whether or not a ponded or flooded out spot will survive or what the damage to yield potential will be.  What we need is time, time for the water to leave, time for plants to start growing, and time to actually assess the situation for actual recovery of a crop stand.   What we can do is this; discuss the contributing factors that could increase or decrease the risks of severe damage or death to flooded and saturated soils.  That, my loyal readers, is what we are going to do today, and make a plan on how to go about making a replant decision if it comes to that.  Here is a brief explanation to what is going on.

Plants that are completely under water are at greater risk than those plants that are only partially submerged.  Those plants that are only partially submerged possibly could continue the process of photosynthesis but in a much limited capacity.  We aren’t sure about corn that hasn’t germinated yet, but if there are any differences at all it is attributed to the characteristics of the hybrids.ponded corn

Most of us agree, we want the water to come off our fields as quickly as possible, and that is because the longer the water is standing or the soil is completely saturated the higher risk the field is at.  If our ambient air temperatures are cooler, like mid 6o’s cooler, the plant could survive up to 4 days.  When the soil warms up to about 70 or higher that lessens to fewer days.  The trump card to all of this is the roots, because in a saturated soil all of the oxygen in soil is displaced by water.  If this condition remains for 48 hrs or more the plants cannot perform critical life sustaining functions, such as nutrient and water uptake.

Other mechanical issues like the deposition of mud and residue will have an effect on yield because of the decrease in photosynthesis.  Younger corn plants, smaller than V6, are at greater risk than plants that are bigger than V6 most likely because they are more easily submerged than a larger plant.  The growing point which is still below ground should be inspected by splitting the plant up with a knife 3-5 days after the water has receded and crop growth may have restarted.Header1

Corn that experiences ponding for an extended period of time is more than likely to have greater pressure from diseases like Pythium, crazy top and common smut.  They are also likely going to have some death of root tissue, and stunting of new root growth until the soil dries out to an acceptable level and the plant takes off in full blown growth again.