Easter weekend freeze damage continues to escalate Mid-South crops, especially in the northern regions. That means some critical decisions on replanting will be made this week.
“It's finally beginning to warm up,” says Angela Thompson, Tennessee Extension corn specialist. “The forecast is calling for temperatures in the 60s and 70s. But we had another round of temperatures in the mid-30s last weekend. That just slowed things down even more.”
Some Tennessee corn fields were so badly damaged during the Easter freeze that “farmers were already asking questions about replanting early last week. Before making a final decision, we're asking them to wait a few days, if possible, to see what kind of growth, if any, the current sunshine allows the crop to put on.”
Bob Scott has been fielding many replant questions — mostly on grain sorghum and corn.
“The first big decision, obviously, is whether to replant or not,” says the Arkansas Extension weed specialist. “If you do need to, usually some of the crop left in the field will survive. Those plants will become, essentially, a weed for the replanted crop.”
For those needing to replant a field of Roundup Ready corn, one possibility would be to use a Liberty-tolerant variety. Liberty would be able to take out any surviving Roundup Ready plants.
“To take out existing vegetation, there may be an opportunity to spray gramoxone. Also, for corn, we've got a 24-c for gramoxone plus Sencor.
“Regardless, for any crop you're replanting it's very important to control the old crop first. Whether that's through herbicides or tillage, it is imperative.”
Another big issue Mid-South growers are running into is an inability to gauge how damaged their crops truly are.
“There are a lot of sick crops with cold damage that aren't growing well in these cool temperatures,” says Scott. “It's tough to spray herbicides in those situations. Weeds are popping out all over. But with a sick crop, it's a tough call on whether to treat.”
Milo, for example, “isn't that tolerant of atrazine, especially when it's sick. Stressed milo isn't something I'd want to spray — that's a tough call. You could make a sick crop even sicker.”
Corn is in the same boat. “The crop is trying to recover from the freeze damage and it's shaky to load it up with (an atrazine product),” says Scott.
So it's best to wait a week on herbicides?
“Yes, wherever possible. Before herbicides are applied I'd like to see a new, healthy leaf emerge on whatever crop is being considered for treatment.”
But Scott adds a caveat.
“In the case of milo, if you've got small, one-leaf grass spiking, atrazine-plus-oil is your only opportunity to kill it. Not treating could mean you'll lose the crop to weeds. In those instances, the producers might as well spray.”
East and central Arkansas is where William Johnson has spent his time since Easter.
“From what I'm seeing,” says the Pioneer agronomist, “any corn planted after March 23-25 looks like it will be okay. The health of any corn planted before then largely depends on the topography and growth stage.
“A lot is ugly, though. I'm driving by a field right now that, several days ago, was fairly green. Now, it's as yellow as a gourd and is on its way out.”
If the corn was “juiced up” and growing rapidly prior to the freeze, “it's more likely to be wilted. And, today, we're finding growing points turning black. Most of that is four-collar corn.”
Some three-collar corn is also wilted, “but there's still about a 1.5-inch stub above the ground that's turning hunter green. It appears it's trying to break a leaf out. Any plants that look like that should be given a chance to rebound. If there are more than 22,000 plants per acre alive in those fields, we'll keep them.
“In much of the corn still standing erect, there's a new leaf coming out of the whorl. I'd leave those fields alone.”
Like the specialists interviewed, Johnson says it will be the weekend “before we can get a good plant stand count. It will be something to watch because I'm hearing northeast Arkansas producers may have to replant a large majority of their corn acres. In central and eastern Arkansas, the fields I've seen are either getting better or going south fast. In a couple more days, it'll be much easier to tell what to do.”
Like Scott, Johnson urges producers not to replant or apply herbicide too quickly. “For the part of the corn crop that's banged up but holding on, a contact herbicide could be the killing stroke. The plants are so weak they may not survive another stress.”
As for fertilizer concerns if growers must replant corn, Johnson suggests figuring in another 40 units of nitrogen.
“If you put out 100 units preplant, probably half of that is lost. I'd seriously consider putting out 40 units of nitrogen as a side-dress. If you're replanting a field, wait until the corn has two or three collars. Then, instead of putting out 90 units of nitrogen, put out about 135 units.”
If a producer is keeping a field, Johnson suggests he put out about 20 extra units of nitrogen.
Scott says he doesn't like to recommend replanting. “It's a last resort and there are a bunch of factors on the downside. Again, the old crop can act as a weed and the farmer has already been hit with the expense of planting.
“I'd give the crop enough time to ensure replanting is the best option. In cases of herbicide drift and other instances, I've normally seen better results just holding onto the original crop. That said, sometimes it's necessary to replant and, unfortunately, this may be one of those.”