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ARS Home » Midwest Area » Urbana, Illinois » Soybean/maize Germplasm, Pathology, and Genetics Research » Research » Publications at this Location » Publication #196563
Title: Irrigation and Inoculation Treatments that Increase the Severity of Soybean Sudden Death Syndrome in the Field

Author
item FARIAS NETO, A - Embrapa
item Hartman, Glen
item PEDERSEN, WAYNE - UNIVERSITY OF ILLINOIS
item Li, Shuxian
item BOLLERO, GERMAN - University Of Illinois
item DIERS, BRIAN - University Of Illinois

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/17/2006
Publication Date: 12/21/2006
Citation: Farias Neto, A.F., Hartman, G.L., Pedersen, W.L., Li, S., Bollero, G.A., Diers, B.W. 2006. Irrigation and Inoculation Treatments that Increase the Severity of Soybean Sudden Death Syndrome in the Field. Crop Science 46:2547-2554.

Interpretive Summary: Sudden death syndrome can result in severe seed yield losses to soybean. The fungus is soilborne and infects plants through the roots resulting in root necrosis and a reduction of root mass. The above ground symptoms include interveinal chlorosis and necrosis of leaves, premature defoliation, and pod abortion. The use of resistant cultivars is the most effective method for controlling SDS. The development of a reliable field inoculation method as well as greater knowledge about the effect of moisture and soil compaction on SDS symptom development is needed to help researchers identify genotypes with resistance to the disease. The objective of this study was to evaluate the effect of field inoculation treatments, soil compaction, and irrigation timing on the occurrence and development of SDS symptoms. Significant increases in foliar SDS severity were observed from inoculation and irrigation treatments, but not from compaction treatments. The inoculation treatments that placed the fungus close to the seed resulted in the greatest foliar severity. Irrigation treatments during mid to late reproductive growth stages resulted in significant increases in SDS foliar symptom development. These results increase our understanding of what environmental conditions increase SDS field symptoms and will be useful to researchers establishing SDS field nurseries.

Technical Abstract: The occurrence of sudden death syndrome (SDS), caused by the fungus Fusarium solani f. sp. glycines is unpredictable in soybean [Glycine max (L.) Merr.] field trials making it difficult to evaluate soybean for resistance to the pathogen. Our objective was to evaluate the effect of field inoculation, soil compaction, and irrigation on the occurrence and severity of SDS symptoms. Six inoculation treatments were tested which included applications of F. solani f. sp. glycines infested grain planted in the furrow with the soybean seed, broadcasted and incorporated into the soil prior to planting or placed below the soybean seed just prior to planting. Soil was compacted by driving a heavy farm truck across the field with wheels edge to edge, once in early spring. Irrigation treatments were applied with a trickle irrigation system and included rain and combinations of irrigation at V3, V7, R3, R4 and/or R5 growth stages. Significant increases in foliar SDS severity were observed from inoculation and irrigation treatments (P<0.05), but not from compaction treatments. The inoculation treatments that placed inoculum close to the seed resulted in the greatest foliar severity. Irrigation treatments during mid to late reproductive growth stages resulted in significant increases in SDS foliar symptom development. These results increase our understanding of what environmental conditions increase SDS field symptoms and will be useful to researchers establishing SDS field nurseries.