STEM BORING OF SOYBEAN BY DECTES TEXANUS (COLEOPTERA: CERAMBYCIDAE) AND THE NATURE OF ITS IMPACT ON YIELD - Soybean and Wheat Crops: Growth, Fertilization, and Yield - page 120

and Williams (1988). In contrast, the latter authors observed markedly disparate distributions
of stem diameter for infested and uninfested plants in Mississippi in both 1984 and 1985, with
plant populations of 236,822 and 146,175 plants per hectare, respectively.
Although large sunflower stalks may attain a girth that is well beyond the girdling radius
of D. texanus larvae, the same is not true for soybean stalks that, regardless of size, are often
visibly cut through to the outside leaving 'sawdust' visible on the soil surface. Thus, although
irrigation and reduced planting density will increase plant size, neither are viable cultural
approaches to reducing lodging losses to this pest in soybean as they are in sunflower. Given
tendencies for larger soybean plants to have higher rates of infestation, increasing plant
density to produce a larger number of smaller plants may actually reduce the proportion
infested by reducing their average suitability to the pest, and by diluting the impact at field
level.
Figure 1. Frequency distributions of soybean plant stem diameters infested and uninfested by larvae of
Dectes texanus sampled in two fields in central Kansas.