Lodging in Soybean

One aspect of the plant population debate that is sometimes overlooked is the higher propensity of soybean plants to lodge at increased populations. Lodging has been shown to reduce yields by as much as 22%, not including the inherent harvesting problems that come with lodged plants (Noor and Caviness, 1980) Higher plant populations generally lead to taller plants with thinner stems than would be found at reduced populations in the same environment. Plants that are taller and which have thinner stems are more likely to lodge than shorter, thicker-stemmed plants (Cooper, 1981; Mancuso and Caviness, 1991).

This year, heavy rains throughout the season have lead to crops with a high yield potential, but this heavy rain combined with strong winds can lead to lodging in tall soybean plants (Board, 2001).

Lodged plants in Farmer Practice side of SoyMVP Field, August 5, 2009.

Lodged plants in Farmer Practice side of SoyMVP Field, August 5, 2009.

Lodged plants in Farmer Practice side of SoyMVP Field, August 5, 2009.

Dectes stem borer (Dectes texanus texanus) may also be to blame when lodged plants are found. Larvae overwinter in stems and adults emerge in June. Adults lay eggs throughout July and August. Larvae tunnel through stems in August and September. Larvae girdle the interior stem surface, making the plant weak at the point, where they can break off. A great deal of information about the Dectes Stem Borer can be found here. Images of Dectes Stem Borer can be found here.

References

-Board, J. 2001. Reduced lodging for soybean in low plant population is related to light quality. Crop Sci. 41:379-384
-Cooper, R.L. 1981. Development of short-statured soybean cultivars. Crop Sci. 21:127–131.
-Mancuso, N., and C.E. Caviness. 1991. Association of selected plant traits with lodging of four determinate soybean cultivars. Crop Sci. 31:911–914.
-Noor, R.B.M., and C.E. Caviness. 1980. Influence of induced lodging on pod distribution and seed yield in soybeans. Agron. J. 72:904–906.