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Proline challenges CBR

The promise of Proline fungicide seen in small-plot research trials testing its efficacy against CBR in peanuts played out in large-plot, on-farm trials in 2009.

Effective management of cylindrocladium black rot, also known simply as CBR, is a challenge for many peanut growers in the southeastern U.S.

Once CBR is established in a field, it is virtually impossible to eliminate. The fungus can survive for years in the form of resistant structures patiently awaiting the return of its favorite host crops: peanuts and soybeans. This disease, also called red crown rot in soybeans, can cause tremendous yield losses in either crop by killing the root systems. It also rots the peanut pods.

Peanut growers in North Carolina and Virginia fight CBR on a regular basis and routinely fumigate the soil with metam sodium prior to planting. Soil fumigation has been much less readily adopted by growers in the Deep South.

Proline offers another alternative.

In 2009, Bayer CropScience received a label from the EPA for the in-furrow use of Proline fungicide (prothioconazole) on peanuts for the management of CBR. In pre-label studies, University of Georgia plant pathologist Tim Brenneman found Proline in-furrow to be a promising tool for the management of CBR in his small-plot research trials. Large-plot, on-farm, replicated trials in 2009 confirmed Brenneman’s data.

One trial was conducted by county agent Bill Tyson in a commercial field widely infested with CBR in Effingham County. His treatments compared plots:

• with only an in-furrow application of Proline at 5.7 fluid ounces per acre split under peanuts planted to twin rows

• that did not receive Proline

• that received both Proline in-furrow at planting at 5.7 fluid ounces per acre split under twin rows and an at-cracking Proline application at 5.7 fluid ounces per acre 14 days after planting

The three treatments were integrated into larger plots that were sprayed during the season with either Provost fungicide at 10.7 fluid ounces per acre, or Artisan at 16 fluid ounces per acre plus Initiate at 1 pint per acre. Plots receiving Proline in-furrow outyielded plots without the in-furrow application by 442 and 526 pounds per acre for Artisan plus Initiate and Provost, respectively. Plots treated with both the in-furrow and at-cracking applications of Proline out-yielded the Artisan-Initiate program by 1,095 pounds per acre and the Provost program by 624 pounds per acre.

Although Proline did not eliminate damage from CBR, it did demonstrate that this fungicide is an effective tool for peanut farmers battling CBR. New recommendations for management of CBR in Georgia peanut fields include:

• extended rotation away from peanuts or soybeans

• more-resistant varieties such as Georgia-02C and Georgia Greener

• Proline fungicide as an in-furrow and perhaps at-cracking application

Kemerait is an Extension plant pathologist for the University of Georgia.

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Source: University of Georgia

This article published in the April, 2010 edition of SOUTHERN FARMER.

All rights reserved. Copyright Farm Progress Cos. 2010.