CFS Growing Insights 5.08.2019

Weather Update
Warm weekend weather helped push soil temps up towards the 50-degree mark across the territory to allow for some fieldwork and planting ahead of Wednesday’s rain forecast. The first week of May finds us starting to track slightly behind normal GDU accumulation, but the forecast looks positive after cold rains move through the area midweek.

Cold Weather Concerns

With a few scattered acres of corn planted the last few weeks that endured various weather up’s and downs, the germination process can give insight into potential issues that may have occurred. Corn seeds have to imbibe (take up) water, then cell membranes stretch and cells expand. Agronomist’s often caution against planting directly in front of a cold rain forecast due to “imbibitional chilling.”

Continue reading to learn more about these effects...
 
"Imbibitional Chilling"
This occurs when corn plants imbibe cold water in the first 24-48 hours after planting (Interesting fact: water is at its densest at 39.2°F). When cold water is imbibed, it can result in membrane damage. If these ruptured membranes occur in the cell walls, it can “leak” out cell contents. This, of course, disrupts normal physiological processes in the young embryo, which interferes with future growth of the seedling. Research has not been able to pinpoint the exact temperature that is required with small differences of soil moisture, temperature, and time after planting can be the difference in seeing a problem or not.

Take a look at those swollen kernels after a few days’ pass (a healthy seed should look like Figure 1), and look for chilling injury symptoms. Swollen kernels that fail to germinate, aborted radicles, and delayed seedling growth all can be evidence of imbibitional chilling. Wide fluctuations in soil temperature, on the other hand, can cause cork-screwed mesocotyls’ and leafing out underground; which is something early planted corn definitely may fall victim to this year with temperature swings. This is where stresses compound on each other, and can cause complete failure or delayed emergence, and a higher susceptibility to diseases and pests.
Planting Depth
One very tempting thing always seems to occur when planting conditions get a little questionable; shallowing up planting depth.  It’s easy to want to do since conditions all the way down 2” just might not be perfect when we are anxious to get back in the field.  DO NOT shallow corn planting to less than 1.5” to try to get the corn to come out of the ground quicker!

When you plant too shallow, the risk of uneven emergence, varying growth stages, and root-lodging during late summer months’ increase dramatically. Remember, the nodal root system normally develops about ¾ of an inch beneath the soil surface. When you plant shallow, the nodal roots set up close to the soil line (lower-left image) and reduces stability for late-season winds.

Since planting is your only chance to get planting depth right, continue to check for seed depth throughout the day and varying soil conditions. Don’t shallow up planting for short-term gain! It might look like those plants are doing better initially when they come out of the ground fast, but it doesn’t take long for the proper-depth plants to out-grow the shallow planted corn. Keep the target planting depth at 1.75” at the minimum!
Corn Emergence Process
The complex process of getting a corn seed from being safely stored in a bag to germinating & emerging can be summarized in 5 steps: imbibition (taking in water), enzyme activation (turning the key on), initiation of embryo growth (utilizing energy), rupture of the seed coat and finally emergence.

It takes 100-120 GDD’s to get corn to emerge, and 3-4 days after that to have V1 corn with a fully-visible collar. 7-10 days after that, we will see V2 corn at about 200 GDD’s, and V3 will hit 10-20 days after emergence, or about 350 GDD’s.