Farm Progress

Stop peanut fungicide applications too early and yield and quality suffer. If yield and quality are not in jeopardy, though, save money and skip the unneeded expense.

Brad Haire, Executive Editor

September 5, 2016

2 Min Read

As peanut harvest approaches, one of the toughest decisions a peanut grower makes is whether to terminate the fungicide program. Stop peanut fungicide applications too early and yield and quality suffer. If yield and quality are not in jeopardy, though, save money and skip the unneeded expense.

Bob Kemerait, University of Georgia Extension plant pathologist, considers a peanut crop safe when any additional disease is unlikely to affect yield.  Under “normal” circumstances, growers should protect a peanut crop from leaf spot diseases to within two or three weeks of anticipated harvest.

"If a peanut grower is three weeks away from anticipated harvest and leaf spot disease is hard to find, a final fungicide application can likely be dropped without loss of yield," said Kemerait. "This is especially true if weather conditions are unfavorable for disease.  However, if disease is present and the grower is struggling to maintain control, or if conditions favor disease and threaten the harvest date, then it is important to stick to a full-season program.”

Once a plant is attacked by a disease-causing organism, however, a period of time must pass before infection, development of symptoms and further disease spread can occur.

"Where a disease like white mold/stem rot is active in a field and weather conditions favor continued development, I recommend careful consideration for extending a fungicide program beyond the norm.  Protecting the crop later in the season becomes increasingly important, especially when there is the possibility that harvest may be delayed by a tropical storm or other unexpected events," Kemerait said.

Remember, the use of propiconazole and products containing propiconazole, including Tilt/Bravo, Echo-PropiMax, Stratego and Artisan, isn’t advised because policymakers in the European Union decided earlier this year the methodology used years ago to determine maximum residue limits, or MRL, for propiconazole is inappropriate today, therefore those levels are no longer valid.

Most commonly, propiconazole has been mixed with chlorothalonil for a fungicide combination that offers protectant and curative properties. Several premix fungicides have been available, including Tilt/Bravo and Echo/PropiMax. Propiconazole has also been paired with trifloxystrobin to produce Stratego and is a component of Artisan (propiconazole + flutolanil), he said.

Kemerait gives alternatives for Tilt/Bravo:

  • Growers can replace Tilt/Bravo with Bravo (1 pt/A) + Alto (5.5 fl oz/A). The active ingredient in Alto is cyproconazole.

  • Growers can replace Tilt/Bravo with chlorothalonil (1 pt/A) and Eminent (7.2 fl oz/A).  The active ingredient in Eminent is tetraconazole; tetraconazole, unlike tebuconazole, is not active against soilborne diseases.

  •  Growers can replace Tilt/Bravo with chlorothalonil (1 pt/A) and Topsin-M (5-10 fl oz/A).  Note: a tank-mix of chlorothalonil + Topsin-M should not be used more than twice per season.

  •  Growers can replace Tilt/Bravo with chlorothalonil (1 pt/A) and Topguard (7-14 fl oz/A).  The active ingredient in Topguard is flutriafol.

  •  Growers can replace two early-season applications of Tilt/Bravo with a single application of Priaxor (6 fl oz/A) at approximately 40 days after planting.

  • Growers can cautiously replace Tilt/Bravo with Absolute (3.5 fl oz/A).  Absolute is a premix of trifloxystrobin and tebuconazole.

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