With its crops and management approach, south Louisiana certainly adds diversity to Mid-South agriculture. So it isn’t unexpected that, nearing mid-May, the region had some unique issues to deal with.
“We range from Lafayette Parish in south-central Louisiana all the way through Terrebonne Parish to the southeast up north to Iberville Parish, which is about level with Baton Rouge,” said consultant Blaine Viator during the second week of May. “We’re true south Louisiana folks — farther south than New Orleans, if you can believe it.”
Growing sugarcane profitably requires a long commitment. Unfortunately, the usual cropping pattern has been thrown off in recent years by an abundance of hurricanes.
“We had a drought prior to (Hurricane) Gustav, last year. When he hit, it delayed a lot of cane planting. Growers had to dry out land to plant. Unfortunately, some let it dry out too much and then we hit an extended drought.”
At this point, the biggest impact of that on this year’s crop has been the plant cane crop. “The one we recently planted is very, very weak with the exception of some cane that was fortunate enough to be planted prior to Gustav.”
Many growers have had to plow out newly-planted cane because of stand failures. Taking that action “is probably the most expensive hit a grower can take in sugarcane production — that means four or five years of potential production lost.”
In the past 20 years, “we’ve had growers routinely plant soybeans in fallowed fields, kept idle for five or six months to control bermudagrass and johnsongrass. Typically, they’ll plant early-maturing soybeans — Group 3s and early 4s — harvest them and then plant cane.”
This growing season, because so much acreage has been plowed out due to sugarcane stand failures, “even more growers have gone ahead and planted soybeans to try and gain back some lost income.”
Viator is “most alarmed about sugarcane stands that, to me on the ground, look very good and adequate. But I was up in a helicopter taking photos of some field plots and, from the air, you could really pick out the newly-planted cane fields. They were very thin, somewhat gappy. Even the planted cane with a decent stand will have some yield losses.”
On the brighter side, the first/second/third stubble crop “is excellent. We had very little rutting during harvest last year. It was very dry. That has allowed the stubble to come back even more vigorous with less damage to the roots.”
Currently, Viator is watching the development of sugarcane brown rust.
“We’ve yet to find orange rust in Louisiana. But we expect to find it this year, like it was found in Florida. However, if that happens it’ll be late-season.”
Of more immediate concern is how the brown rust is interacting with newer sugarcane varieties. “We’re heavy into a variety called 540, which has replaced 384 and become dominant on a big chunk of acres. The last two years, we began seeing isolated areas — mostly in southern parishes — where brown rust was attacking 540.”
Susceptible cane varieties develop brown rust infections during the initial “grand growth” stage, which occurs from April through May. That’s when sugarcane is experiencing its most rapid growth and is most susceptible to brown rust.
In the past, 540 typically had enough vigor that it “pushed out of the susceptible growth stage rather quickly and begin to recover. And thus far we’ve had excellent yields with 540 even with the rust.”
In 2003, when growers were relying heavily on 384 (released in 1993), the variety experienced a steep decline in vigor. There were failed plant cane stands and yields dropped dramatically.
“We began noticing the rust on it in 1999 and 2000, when 384 still had a lot of vigor. It would turn very red from the rust and then grow out of susceptibility. We had some record yields in 1999 and 2000.”
Once the variety lost vigor, however, “it couldn’t push out and grow past the susceptible stage of brown rust.”
And that brings the focus back to 540 and worries that if it follows the same pattern as 384, vigor could soon collapse. “What’s different this year from the last two is the brown rust is much more widespread. We’re finding a lot more fields in different areas with brown rust.
“We’re not quite sure yet but the earliest developed cane we’ve seen brown rust on appears to be growing out of susceptibility. That’s after three weeks of infection. Hopefully, the other fields will experience the same.”
Another “alarming” thing this year involves another new sugarcane variety, 226, that looks poised to be dominant. Up until this year “we’ve seen no rust in it. Now, we’re finding fields with fairly heavy infestations. That’s a concern. Hopefully, since these varieties have just come out of the cooperative breeding program, they’ll have enough vigor to push out of the problem.”
There is a Section 18 label for Headline fungicide in sugarcane. Right now, it will take “a minimum of two applications to control brown rust. At the 9-ounce rate, along with application costs, growers are looking at over $30 per acre, per application. And we still don’t know if brown rust will cause any significant yield losses in the new varieties.
“Hopefully, after this year and all the research going on we’ll have some answers. You know, if we’re losing over two tons of sugarcane per acre to brown rust, growers can justify the cost of the fungicide. But if that isn’t the case, it doesn’t pay to put them out.”
During the early days of May, some areas Viator where consults caught 5.5 inches of rain within three or four hours. Other areas received “just a few tenths of an inch. Rainfall is all over the board.
“Our soybeans are planted on raised, 6-foot sugarcane beds. That helps in extremely wet situations. But we did have some acreage that went underwater for 24 to 36 hours. Those beans look a little weak, but I think they’ll make it. Any fields that were underwater a bit longer are in jeopardy, though.”
In the cane/soybeans rotation growers don’t usually have the opportunity to replant soybeans. In south Louisiana, soybeans are generally planted from April 20 through May 10. After May 10, “if we try to plant even the earliest-maturing varieties, the harvest window is pushed so far back that there isn’t time to plant cane behind them.”
Currently the region’s soybean planting is around 95 percent finished. “For the most part, where there’s no water, the stands look excellent.
“Some growers overseeded pretty heavily this year. They wanted a good stand and better yields. On some fields, upwards of 73 pounds of seed per acre were planted. That’s well over 200,000 seed per acre.
“We’ve always encouraged our growers to stay around 130,000 seed per acre. Depending on the seed size, that translates to 40 to 55 pounds per acre.”
Planting 73-plus pounds of seed per acre “is costing as much as $20 or $30 more for the seed. Also, when getting into high seeding rates on the sugarcane beds, it encourages lodging later in the season.”
In mid-May, isolated cases of fall armyworms developed in newly planted beans, resulting in damage similar to that caused by cutworms. Most of the cases were in stale seedbeds that had winter and early spring weeds and were subsequently burned down.
“The fall armyworms migrate from the weeds to the soybeans when the weeds die. Fortunately, no infestations have required treatment, as we still have well over six plants per drill foot throughout these fields, and only large, late instar larvae are remaining.”
More residual herbicides are being applied at planting, says Viator. “That’s because of the resistance management programs that companies are offering. Traditionally, we rarely put out a pre-emergence at planting.”
Unlike its Mid-South neighbors to the north, south Louisiana hasn’t had to worry about glyphosate-resistance. In sugarcane, “we can only use it once every four or five years when the cane is plowed out. That spares us the glyphosate after glyphosate after glyphosate situations that help develop resistance.
“We do have to be concerned, however, with growers looking north to buy used harvesting equipment for soybeans. Some of those combines are coming from Arkansas, Tennessee, the Carolinas and other places with (resistant weeds). I am a little concerned that resistant seed may reach us through those avenues.”
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