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ARS Home » Southeast Area » Stoneville, Mississippi » Crop Genetics Research » Research » Publications at this Location » Publication #300771
Title: Tillage, Fungicide, and Cultivar Effects on Frogeye Leaf Spot Severity and Yield in Soybean

Author
item Mengistu, Alemu
item KELLY, HEATHER - University Of Tennessee
item Bellaloui, Nacer
item Arelli, Prakash
item Reddy, Krishna
item WRATHER, ALLEN - University Of Missouri

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/15/2014
Publication Date: 11/1/2014
Citation: Mengistu, A., Kelly, H.M., Bellaloui, N., Arelli, P.R., Reddy, K.N., Wrather, A.J. 2014. Tillage, Fungicide, and Cultivar Effects on Frogeye Leaf Spot Severity and Yield in Soybean. Plant Disease. 98(11):1476-1484.

Interpretive Summary: Frogeye leaf spot disease of soybean has been a problem in the southern USA for many years but has recently become an increasing problem causing significant yield losses in the northern USA. This increase in disease severity has been attributed to increased utilization of no-tilled planting and changes in climate. In a field study conducted at Milan, TN from 2007-2010 with three frogeye leaf spot susceptible cultivars in maturity groups III, IV and V to determine frogeye leaf spot severity in tilled and no-tilled plots treated with pyraclostrobin fungicide at beginning pod and beginning seed development stages, there was a significant reduction in disease severity in tilled compared with no-tilled plots. The reason for this is not clear. There was no significant difference in disease severity between tilled and no-tilled plots when plots were not treated with fungicide Across four years, disease severity for Progeny5115, a maturity group V cultivar was significantly greater than for NKS39K6 a maturity group MG III and Asgrow4403 a maturity group MG IV cultivar. Fungicide application consistently improved yield all four years. The yield gains ranged between 1 to 17 % with the highest yield gain in Asgrow4403. In no-tilled plots, only 50% had a yield increase from fungicide application. This research showed that no-tilled plots did not reduce or enhance the severity of FLS when no fungicide was applied but when fungicide was applied, disease severity was not reduced as in treated tilled plots suggesting that fungicide program under no-tillage system may require further study to minimize the risk of frogeye leaf spot severity.

Technical Abstract: Frogeye leaf spot (FLS) of soybean, caused by Cercospora sojina K. Hara, has been a problem in the southern USA for many years but has recently become an increasing problem causing significant yield losses in the northern USA. This increase in disease severity in the north USA has been attributed to increased utilization of no-till planting and changes in climate. A field study was conducted at the University of Tennessee, Milan Research and Education Center, Milan, TN from 2007-2010 to determine severity in tilled and no-tilled plots treated with or without fungicide at R3 and R5 growth stages. Three FLS susceptible cultivars, one each in Maturity Group III, IV and V, were treated with pyraclostrobin (Headline) fungicide. Analysis of variance using the area under the disease progress curve (AUDPC) indicated no significant difference (P=0.05) in disease severity between tilled and no-tilled plots without fungicide. This is the first study showing that no-tilled plots did not reduce or enhance the severity of FLS when no fungicide was applied. Fungicide application significantly reduced (P=0.05) disease severity in tilled plots, reduced AUDPC and increased yield. The yield gains in tilled plots ranged between 1 to 17 % with the highest yield gain for Asgrow4403. When fungicide was applied disease severity was not reduced in no-tilled as in treated tilled plots suggesting that fungicide program under no-tillage system may require further study to minimize the risk of frogeye leaf spot severity.