Field Notes from Kip Cullers

Question: Our corn was off to the best start in years but the rains have stopped. It seemed to pollinate good, but the plant's curled-up like onions as soon as there is the slightest heat. What kind of yield possibilities are we looking at?

Kip: Since it pollinated, you have avoided a major risk where yield reductions can be quite drastic. Moisture stress during grain fill is more chronic in nature and what you are seeing with the curled leaves is the plant defending itself from water loss through evapotranspiration. This reduces exposure to sun and reduces lost water from the plant--but would also have the downside of reducing photosynthetic area.

Bottom line is that its difficult to tell how much yield loss will result. Corn has an amazing ability to come back with high yields despite what appears to be severe stress. It's possible that the stress you are seeing is isolated to lower moisture holding soils (sandy) of the field and this could serve to further minimize loss.

Under extreme stress, I have seen 180 bu yield potential drop below 80 bushel, but my guess is that you still have +140 potential in your area. It all depends on how long the stress lasts during grain fill.

Question: How tall are your beans when you put on your Roundup®? I have some weeds coming back this year. Soybeans are now a foot tall. Should I come back and respray and kill beans where I drive with tractor?

Kip: My background in vegetables makes me want to control weeds early even though that might require a second shot of glyphosate later in the season. If weeds are only coming in around the edges of a field, I might not spray the whole field to avoid the wheel tracks and crop damage you mention. If you used a planter instead of a drill, I would also suggest spraying across the rows instead of with the rows to minimize stand damage. Almost everything else I do to manage the crop will hasten growth and make the soybeans more competitive with any weeds.

Question: Foliar feeding fertilizer. Pros and Cons?

Kip: I use foliar feeding of various primary and micro-nutrients throughout the growing season. These are typically N and S plus Mn, Mo, Cu, Zn and B. My reason for applying these to my contest fields is simple. I want to maintain a high yield potential and I apply these nutrients to supplement the supply coming from the soil via root uptake. I don't put any P and K on with foliar applications but rely on soil applications of poultry litter to supply those critical nutrients. The only time I don't like to apply much of any foliar sprays is during pollination. At that time, all I apply is irrigation water as needed to eliminate drought stress.

Question: I have a couple of questions on corn roots. The woody triangle of stalk at the first four nodes of the plant root becomes brown, hard and looks dead. I'm wondering how any moisture or nutrients can get through that? Is it suppose to get that way? Are the nodle or "Brace roots" above the first four nodes bringing in all the nutrients? And finally do you cover your brace roots by cultivation or ridging?

Kip: The area that you refer to as the woody triangle is normal. Nearly, if not all of the water and nutrient flow occurs in the outermost ring of tissue on a corn plant. Just like a tree, if you girdle a stalk of corn it will die due to the stoppage of water and nutrient flow within the plant. Any part of the root mass of a corn plant that is still white and healthy is bringing in water and nutrients, however, the vast majority of uptake occurs with the younger nodal roots. If you dig a soil pit and take a look at the roots of a corn plant, it is quite obvious where most of the water and nutrients come from. No, I do not cover my brace roots with cultivation or ridging. By maintaining adequate soil moisture during nodal root development, we have no issues with nodal root penetration into the soil.

Question: Do you water during pollination?

Kip: Yes, we irrigate during pollination (if rainfall is insufficient) because this is the phase of crop growth where water is needed in the largest amounts and it is also when a deficit has the greatest negative impact on yield. But this is about all we do to the crop during pollination. We suspend fertilizer applications until well after pollination. We simply don't want to shock the crop in any way while the fertilization and ovule development process is underway.