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2003 Evaluations of Fungicides for Control of Sclerotinia Stem Rot of Canola in North Dakota and MinnesotaCarl A. Bradley • Greg Endres • Bryan Hanson Paul Porter • David LeGare APRIL 2004 Canola grown in North Dakota and Minnesota is subject to attack by Sclerotinia sclerotiorum, the fungus that causes Sclerotinia stem rot (SSR). Because there are no resistant canola varieties available, the principal means of managing SSR is with fungicides. At the end of 2003, four fungicides were registered for use on canola grown in North Dakota and Minnesota for SSR management. These four fungicides consist of vinclozolin (Ronilan), thiophanate-methyl (Topsin M, T-methyl, and others), boscalid (Endura), and azoxystrobin (Quadris). The objective of this project was to evaluate the efficacy of several registered and experimental fungicides on SSR of canola at three locations in North Dakota and one location in Minnesota. A published report of canola fungicide trials conducted in 2001 is also available. Materials and MethodsField trials were conducted at North Dakota Research Extension Centers located at Carrington, Langdon, and Minot, N.D. The University of Minnesota trial was conducted at Red Lake Falls, Minn. See Table 1 for varieties, planting date, and plot size at each location. Nine different fungicides were evaluated at each location (Table 2). There were 21 to 22 treatments at each location including an untreated control. Fungicides were applied at 30 and/or 50 percent bloom stages. All plots were inoculated with S. sclerotiorum ascospores at approximately the 60 to 70 percent bloom stage after fungicide treatments were applied. Mist or sprinkler irrigation was used at each location to provide environmental conditions conducive for ascospore infection and disease development. Fifty plants within each plot were evaluated for disease incidence and severity just prior to swathing. A 0 to 5 disease severity scale was used in which 0 = no disease; 1 = superficial lesions or small branch infected; 2 = large branch dead; 3 = main stem at least 50 percent girdled; 4 = main stem girdled but plant produced good seed; and 5 = main stem girdled, much reduced yield. A 0 to 100 disease severity index (DSI) was calculated for data collected at Carrington, Langdon, and Minot, N.D., by: ((mean % incidence) x (mean severity))/5.
Results and Discussion� Carrington, N.D.Disease pressure at Carrington was moderate, with the untreated control having a DSI value of 32 (Table 3). Five treatments had a significantly lower DSI value than the untreated control, and were: Endura at 5.8 oz./A. applied at either 30 or 50 percent bloom; JAU6476 at 5 fl. oz./A. applied at 50 percent bloom; and JAU6476 at 5.7 fl. oz./A. applied at either 30 or 50 percent bloom. None of the fungicide treatments had a yield significantly greater than the untreated control.
� Langdon, N.D.Disease pressure at Langdon was very high, with the untreated control having a DSI value of 83 (Table 4). Six treatments had a significantly lower DSI value than the untreated control, and were: Endura at 5.8 oz./A. applied at either 30 or 50 percent bloom; JAU6476 at 5 fl. oz./A. at either 30 or 50 percent bloom; JAU6476 at 5.7 fl. oz./A. applied at 50 percent bloom; and Rovral at 14.4 fl. oz./A. applied at 50 percent bloom. Ten treatments had a significantly greater yield than the untreated control, and were: Ronilan at 12 oz./A. applied at 50 percent bloom; Endura at 5.8 oz./A. applied at either 30 or 50 percent bloom; JAU6476 at either 5 or 5.7 fl. oz./A. applied at either 30 or 50 percent bloom; Rovral at 14.4 fl. oz./A. applied at either 30 or 50 percent bloom; and V-10116 at 9.5 fl. oz./A. applied at 30 percent bloom.
� Minot, N.D.Disease pressure at Minot was low, with the untreated control having a DSI value of 5.8 (Table 5). All fungicide treatments except for Blocker alone applied at 3 pt./A. had a significantly lower DSI value than the untreated control. None of the fungicide treated plots had a significantly greater yield than the untreated control.
� Red Lake Falls, Minn.Disease pressure at Red Lake Falls was moderate, with the untreated control having an incidence of 23 percent and severity of 4.0 (Table 6). All fungicide treatments had significantly less DSI than the untreated control. None of the fungicide treatments had a yield significantly greater than the untreated control.
Overall, where disease pressure was high (Langdon, N.D.), yield was significantly increased with efficacious fungicides; however, yield was not significantly increased with fungicides at locations with moderate to low disease pressure. The newly registered fungicide Endura and unregistered products Rovral, JAU6476, and V-10116 show the potential for SSR control in canola. AcknowledgementsWe thank the USDA-CSREES North Central Canola Research Program for funding and AMVAC, BASF, Bayer, Cerexagri, and Valent for providing fungicides. Literature CitedLamey, A., Endres, G., Hanson, B., Henson, B., McKay, K.,
Halvorson, M., and LeGare, D. 2002. 2001 Canola and Crambe Fungicide Trials
in Minnesota and North Dakota. NDSU Extension Service Report no. 75. This publication may be copied for noncommercial, educational purposes in its entirety with no changes. Requests to use any portion of the document (including text, graphics or photos) should be sent to NDSU.permission@ndsu.edu. Include exactly what is requested for use and how it will be used. For more information on this and other topics, see: www.ag.ndsu.edu County Commissions, North Dakota State University and U.S. Department of Agriculture cooperating. Duane Hauck, Director, Fargo, North Dakota. Distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914. We offer our programs and facilities to all persons regardless of race, color, national origin, religion, gender, disability, age, veteran's status or sexual orientation; and are an equal opportunity institution. This publication will be made available in alternative formats for people with disabilities upon request, (701) 231-7881. |
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