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Pisum Genetics
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2007—Volume 39
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Brief Communications
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The following five papers are summaries of North American Pulse Improvement
Association presentations, November 1 and 2, 2007 Field evaluation of biological control and fungicide seed
treatments for pre-emergence damping off of chickpeas
Leisso, R.S. and Burrows, M.E. Dept. of Plant Sci. and Plant Path.
Montana State Univ., Bozeman, MT, U.S.A.
Pre-emergence damping off of chickpeas is a disease caused by a complex of soil-borne pathogens (1). In
Montana, an increasing number of growers are interested in growing chickpeas organically, especially the kabuli varieties. Montana has the greatest number of acres devoted to organic wheat production in the United States (2), and organic chickpeas have the potential to be a profitable rotation crop. A number of fungicide seed treatments for pre-emergence damping off are available (3-5), but growers cultivating chickpeas organically can not use fungicide seed treatments. Organic growers could use biologically based seed treatments, but little data exists regarding the efficacy of biocontrol seed treatments for chickpeas in Montana. However, tests of the biological seed treatment Kodiak (Bacillus subtilis GB03) in Colorado indicated success for this seed treatment (6). Beyond the use of biological seed treatments in organic systems, they could also be used by conventional growers for chickpeas as part of an integrated strategy for disease control. |
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Pisum Genetics
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2007—Volume 39
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Brief Communications
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The objective of this research was to determine which biological and conventional seed treatments would be
the most useful for both conventional and organic chickpea growers. Biocontrol seed treatments were tested alone and in combination with conventional seed treatments to determine if commercially available biological control seed treatments would be effective for managing pre-emergence damping off. Furthermore, this research sought to determine if biologically based seed treatments, whether used alone, or in combination with standard fungicide seed treatments, would affect other measures of plant health, ultimately leading to increased yield over untreated seeds and seeds treated solely with standard fungicides. Seed treatments were tested on both kabuli and desi varieties. Winter greenhouse results indicated that desi
varieties were less susceptible to pre-emergence damping off than kabuli varieties. Five replicates of twelve seeds each of a desi variety (CDC-Anna) and a kabuli variety (Dylan) were planted in sterile and non-sterile field soil obtained from a chickpea field in Big Sandy, Montana. Germination of the desi and kabuli seeds in sterile field soil were 84% and 70% respectively, whereas germination of desi and kabuli seeds in non-sterile field soil were 80% and 0% respectively. Results were averaged over two repetitions of the experiment. In collusion with these results, the desi variety (CDC-Anna) was also less susceptible to pre-emergence damping off than the kabuli (Sierra) variety in field trials. The biological seed treatments Actinovate SP (Streptomyces lydicus WYEC108), Kodiak (Bacillus subtilus
GB03), Mycostop (Streptomyces griseoviridis K61), Subtilex (Bacillus subtilus MB1600), T-22 (Trichoderma harzanium Rifai strain KLR AG-13), and Yield Shield (Bacillus pumilus GB34), as well as the fungicide seed treatments Apron XL LS (metalaxyl/mefanoxam) and Maxim (fluidoxonoil) were tested in greenhouse experiments to determine which were most effective for managing pre-emergence damping off cause by Pythium ultimum. Kodiak, T-22, and Yield Shield were the most effective biological seed treatments for reducing pre- emergence damping off and increasing stand counts over the untreated control. Apron XL LS was the most effective fungicide treatment and the most effective seed treatment overall for reducing pre-emergence damping off caused by Pythium ultimum in the greenhouse. Seed treatments were tested at three field sites near Bozeman, Huntley, and Sidney, Montana in the summer
of 2007. Each biological and conventional seed treatment was tested alone, as well as in combination with one another to determine if biological and conventional seed treatments would provide additive benefits. Treatments tested were as follows: Kodiak, T-22, Yield Shield, Apron, Maxim, Apron+Kodiak, Apron+T-22, Apron+Yield Shield, Maxim+Kodiak, Maxim+T-22, and Maxim+Yield Shield. All seed treatments were applied at the manufacturer's highest recommended rates two days prior to planting. |
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Table 1. Seed treatments tested for management of pre-emergence damping off of chickpeas
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Stand counts of chickpea seedlings were obtained at each of the field sites approximately three weeks after
planting. Desi variety CDC-Anna had low incidence of pre-emergence damping off and few significant differences in stand count between the control and seed treatments at all three sites. For the kabuli variety Sierra, seed treatments containing Apron were most effective for reducing pre-emergence damping-off and increasing stand count. On average, at Bozeman, seed treatments containing Apron increased Sierra stand counts by 60%, at Huntley 38%, and at Sidney, where the germination period was cool and wet and disease pressure severe, 900%. Stand count for seeds treated with biological controls generally did not differ significantly from the untreated control. |
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2007—Volume 39
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Brief Communications
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Ascochyta blight was rated in plots to determine if biological controls would have any plant health effects
including induced systemic resistance (7). Plots were monitored and rated for Ascochyta blight using a 1-9 scale (8) before foliar fungicide applications (Proline 480 and Quadris Opti SC) to control Ascochyta blight. Prior to applications of fungicides, disease ratings did not differ significantly from the untreated control plot at any of the locations. Ratings were taken every 7-10 days following the first fungicide application, and the overall AUDPC (area under the disease progress curve) calculated (9). Seed treatments did not consistently lower the severity of Ascochyta blight at any of the three locations. Other measures of plant health such as plant height, plant weight, seed size and yield indicated no differences between seed treatment plots and untreated control plots. Although significant differences in stand counts for seed treatments were observed, there were few consistent
significant yield differences for the desi or kabuli varieties. At Sidney, no yield data was collected for the kabuli variety Sierra, due to extremely low initial stands. Biocontrol seed treatments were ineffective for managing pre-emergence damping-off of kabuli chickpeas in
Montana. Desi chickpeas incurred low incidence of pre-emergence damping off and few significant differences in stand count were observed at any of the three locations in this study. Seed treatments containing the fungicide Apron XL LS were most effective for increasing stand count. Despite differences in stand count, there were few significant differences in seed quality or yield. 1 Trapero-Casas, A., Kaiser, W.J. and Ingram, D.M. 1990. Plant Disease, 74: 563-569.
2. United States Department of Agriculture, Economic Reporting Service. 2005. Montana Organic Production.
3. Chen, W., Paulitz, T.C., Mcphee, K.E. and Muehlbauer, F.J. 2004. Fungicide and Nematicide Tests 59
(ST017).
4. Lauver, M. and S. Guy. 2005. Fungicide and Nematicide Tests, 61 (ST003).
5. Smiley, R.J., Gourlie, J., Whittaker, R, Easley, S., Rhinhart, K., Jacobsen, E., Burnett, A., Jackson, J.,
Kellogg, D. and Zeckman, T. 2001. Oregon Ag. Expt. Sta. Annual Report, Special Report 1054, p. 120-127. 6. Hammon, R. and Berrada, A. 2001. Evaluation of Kodiak (R) Biological Seed Treatment to Control Seedling
Diseases of Chickpea, C.S.U.C. Extension, Editor. 7. Kloepper, J.W., Ryu, C.-M. and Zhang, S. 2004. Phytopath. 94: 1259-1266.
8. Singh, K.B., Malhotra, R.S. and Witcombe, J.R. 1981. Plant Disease 65: 586-587.
9. Campell, C.L. and Madden, L.V. 1990. Introduction to Plant Disease Epidemiology. John Wiley & Sons, Inc.
New York, p. 532.
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