May 21, 2009
This has been a very difficult spring for Mississippi’s corn crop.
With all the rain “there have been extremely narrow planting windows with the exception of a few days in late April,” says Erick Larson, Mississippi Extension corn specialist.
“Most of the Delta corn was planted earlier than late April. However, there is some in the north Delta that was planted late along with a lot of the state’s dryland crop.”
The latest round of “wet/flooded/saturated conditions” started the first week of May. There were “several massive rains that flooded a lot of acreage. That’s prohibited producers from getting into the field for side-dressing nitrogen and post-emergence herbicide applications. The corn is just way behind.
“Thankfully, right now, the weather is sunny. It needs to remain that way for an extended period to allow the crop to get back on its feet. Root development is very important before the crop enters mid-season.”
Overall, Larson does expect productivity to be “inhibited or cut substantially” by the wet conditions. It’s hard to put a figure on what that will mean “because there’s so much variation between fields. Some fields are badly flooded and some are only affected on the bottom ends. Add in all the various management parameters and it’s even more variable.
“But it’s safe to say the crop will take a hit. Over the term of my career — from 1995 onward, anyway — this has been the most difficult spring for Mississippi’s corn.”
The state will lose some corn acres to flooding and soil saturation. Farmers are already considering planting other crops. A lot depends on whether they’ve already applied herbicides that will restrict replanting options.
“We have corn development all over the board. The late April/early May corn in the northern and northeast parts of the state is only 6 to 12 inches tall. Corn farther south is shoulder-high, or better.”
Another problem: much of the corn is now tall enough to prevent ground rigs from moving through fields. That is restricting needed fertilizer and herbicide applications and means more reliance on high-clearance equipment or aerial applications.
“One thing that may happen is instead of a single side-dress nitrogen application, we may have to apply nitrogen two or three times by airplane. That would be to keep from incurring leaf burn on the corn plants.”
Instead of putting out a large amount of granular fertilizer — which could burn leaves severely — Larson says it’s better to reduce the amount of fertilizer to a level that will only produce slight-to-moderate leaf burn. Spread the lower volume applications out and it’ll mean different leaves are exposed during each.
“By doing it that way, there’s less risk that certain leaves — those really important to the energy production for grain development — will be severely burned.
“The ear-leaves and those around the ear will be in the whorl when the corn is about 4 to 5 feet tall. The more granular fertilizer we put out at one time, the more granules end up in the whorl of the plant and the more severe the burn. You don’t want to kill a lot of tissue on the leaves around the ear because they supply a high percentage of energy to developing ears and grain.”
This spring’s wet weather has “certainly affected farmers’ pocketbooks by having to make more applications of fertilizer.” It has also meant herbicide issues.
Besides glyphosate, atrazine is the most common herbicide used in corn production. It can’t be applied over-the-top on corn plants over 12 inches tall. Furthermore, “there are very few herbicides that can be applied over-the-top on corn that’s taller than 30 inches. And much of our crop is close to, or has already exceeded, that height restriction.”
Because of that, growers are being forced to use alternative herbicides “and possibly applications methods. These are the cards they’ve been dealt. There are some herbicides labeled over-the-top for larger corn (although) some are not legal to apply by airplane. Before making any spraying decisions, I’d check the labels very carefully.”
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