Counting the days to start a disease management program may give the disease a good head start.
Climate and past history are two factors producers can use to help predict potential disease problems for the coming season. While the spring climate is still coming into view, field history is something producers know at the end of the last crop.
As stated in the University of Georgia’s 2014 Peanut Update, “The history of disease in a field can be an important hint at the possibility of disease in the future…. Fields where growers have had difficulty managing disease in the past, despite the implementation of a good fungicide program, are more likely to have disease problems in the future than are fields with less histories of disease.”
No. 1 Foe
According to Bob Kemerait, University of Georgia Extension plant pathologist, the No. 1 disease in peanuts continues to be white mold. “Over the years, producers have spent millions of dollars to manage it, but lose millions to it,” he says. In regards to field history, where white mold has been a problem in the past, it can be expected to be again in the future. Additionally, without effective crop rotation, outbreaks of white mold can be expected to become increasingly severe each season. Kemerait says the basic foundation for managing white mold has not changed.
“Growers are still urged to rotate, plant resistant varieties and use Peanut Rx as a tool to see how all of the production components would affect white mold management,” he says. However, two new recommendations in the past few years have shown improved control over traditional programs.
It’s In The Timing
The first recommendation change was to spray at night or in the early morning hours before dawn. The purpose of this timing was to get the fungicide to the target area and not deposit it all over the foliage. Because peanut leaves fold up when it is dark, the crown area, which is where white mold attacks the plant, is more directly exposed and reachable by fungicides applied at that time. “The difference in day and night sprays can be as much as 1,000 pounds,” Kemerait says.
Last year, UGA plant pathologists began talking about banded sprays applied early emergence. Tim Brenneman, University of Georgia research plant pathologist, says white mold has been increasing much earlier in the season. “Normally, we think of it in the middle part of the season, but we are seeing white mold on young peanuts several weeks old. You may not see it above ground, but if you dig up the young plants, you can see the hyphae in there getting started on the young plant. At times, we have seen the young plants being killed.”
With this in mind, the recommendation was made for a banded spray of Proline early emergence. “When applied to the peanut crop after emergence at a broadcast rate banded at the full rate over the young peanuts, Proline can provide season-long benefits to the ma
nagement of white mold,” Kemerait says. While this early application will help producers get a jump on white mold, it is not all the control that will be needed and producers should follow with a standard soilborne fungicide program.
Watch The Weather
Besides using field history to gauge potential disease problems in the field, producers should know that weather patterns also offer a big clue. Very warm, even hot, soil temperatures early in the season can lead to aggressive development of white mold disease when the crop was still young. In fact, the hotter it becomes earlier in the season, the more likely it will be that white mold expresses itself earlier.
“Temperature drives white mold,” Kemerait says. However, even if temperatures are not achieved that would warrant early white mold expression, at some point in the season, it will. “We will always have conditions sometime during the year that are favorable to white mold outbreaks,” Kemerait says. “It’s not a matter of ‘if,’ but ‘when.'” The key is if conditions favor white mold earlier, then producers need to be ready to start their fungicide programs earlier and not wait until a certain number of days after planting