While large acreages of cotton and milo have seed germinating on the stalk, much of the Delta’s 2001 soybean crop has deteriorated to the point that it isn’t able to germinate, according to Alan Blaine, Extension soybean specialist at Mississippi State University in Starkville, Miss.
For example, Blaine says 60 percent of the state’s soybean crop was planted to maturity group 4 varieties and 50 percent of the group 4 acreage has experienced seed rot, physiological seed deterioration or overall deterioration. The soybean crop is most heavily damaged, he says, south of Highway 82, which runs east and west through the Mississippi cities of Greenville, Greenwood and Starkville.
Growers are also reporting soybean quality losses north of that area between Highway 82 and Highway 6, which runs through Tupelo, Oxford and Clarksdale, Miss.
“This is a weather phenomenon, not a maturity group 4 phenomenon,” says Blaine. “What we’re dealing with is a hurricane without any wind, which caused a large portion of the Delta to remain cloudy, overcast and very humid during the same period of time that much of the state’s soybean crop was approaching maturity.”
Other variables also determined a grower’s odds of experiencing soybean quality losses this year, including insect population levels, disease pressure and drainage.
“Soybean fields with poor drainage may yield better in dry years, but in 2001 the incidences of seed rot is a lot worse in those areas,” Blaine says. “We’re also seeing a lot of seed rot simply caused by physiological deterioration of soybeans that remained in the field after reaching maturity. Those growers who don’t have the combine capacity to harvest as efficiently and timely as possible may have to rethink their decision to plant maturity group 4 varieties.”
Some of the soybean seed rot being documented throughout the central and southern Delta is believed to be caused by the disease, Phomopsis longicula. This disease, according to Blaine, causes very fast, progressive seed rot.
“I do feel that stinkbugs were a major factor this year because the damage caused by stinkbugs allowed that disease pathogen to get into the soybean plants a lot faster,” he says. “That concerns me because we are often dealing with high population numbers of this pest. Farmers need to key in on stinkbugs in the future and pay closer attention to the control of stinkbugs in soybeans.”
In addition, he says, there may have been some varietal differences playing a part in the quality of the Delta’s 2001 soybean crop.
Blaine says two soybean varieties are receiving the most attention, but it may simply be because these two varieties, Delta King 4868 and Asgrow 4702, were the most heavily planted varieties in this region. “We did receive reports from farmers that the gray-podded soybeans appeared to get hit first, but after the inclement weather continued for another 10 days or so, the brown-podded beans ended up in basically the same shape.”
In what he calls “sheer luck,” Blaine had initiated soybean fungicide trials in 2001. The studies consisted of three different fungicide treatments applied at the R3 to R4 soybean growth stage. “None of the various rates of the fungicides we tested had any influence over this late season seed quality problem, which may be attributed to the early application of the fungicides.”
However, he says, “an on-farm test in Vaiden, Miss., yielded quite different results. Blaine says the fungicides in this test were applied later in the season when the soybeans reached the R6 stage, or at beginning seed development. “We noted obvious differences in seed appearance at maturity between the different treatments.”
Included in the on-farm fungicide trial was a per-acre tank-mix treatment of 6 ounces of Quadris and 2 ounces of Dimilin, a treatment of Dimilin alone at the 2-ounce per acre rate and an untreated check. The combination treatment yielded 66 bushels of soybeans per acre. The Dimilin treatment cut 58 bushels and the untreated area yielded 55 bushels per acre.
Blaine cautions that all of the data is preliminary but says, “What gave us the most benefit on this disease-related problem was the Quadris and a yield difference of 1.5 bushels per acre will pay for the Quadris application.”
What researchers have also discovered in this one-year test is that the Dimilin treatment is apparently controlling frog-eye leaf spot disease in soybeans. And, at an estimated cost of $2 per acre, Blaine suggests the treatment is a very economical option for growers.
Another bit of good news, Blaine says, is the quality losses experienced by many Delta growers who planted early maturing varieties shouldn’t carry over to later-maturing soybeans. The reason, he says, are the recent weather changes, including drops in temperatures and humidity.
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