Is rootworm making my corn lodge?

root lodgeThis week I scouted a corn test plot that had a mixture of NK and competitive products. It was evident that some root lodging and “goose-necking” was taking place to varying degrees amongst the different hybrids. What was causing this? The field in question was third year corn ground. Could it be simply corn rootworm (CRW) feeding? Some hybrids had the Agrisure RW trait for protection against this pest. Other hybrids had a competitive CRW trait, and those without a Bt gene for CRW were treated with Force insecticide at planting. Upon further inspection (e.g. root digs), it became apparent that there was actually very little CRW feeding on the roots. All forms of protection were doing a pretty good job. A week ago this plot received 100 km/hr winds as a passing storm made its way through the area. The grower indicated that the field signs were tilted on a 45 degree angle the next morning. Since then, the signs had obviously been straightened again. Yes, high winds may contribute to root lodging. The field was also saturated from recent rains. Poor drainage, compaction, or a wet growing season can cause shallow rooted corn. This may also lead to root lodging problems. As NK employee Matt Tyhurst said, “Ask a farmer to wear a shirt that’s two sizes too small, and then try to work … this is how the roots feel in a compacted, saturated soil with poor structure”. In this particular field I determined from the length of a random sample of mesocotyls that the corn was also planted less than 1.5”. The planting depth varied from 1-1.25”. This too played a part in the observed root lodging. Finally, some hybrids naturally have a stronger, bigger root mass than other hybrids. All of these factors can contribute to root lodging problems. Check your fields for compaction and dig up some roots to see how your corn will stand through a windy wet fall.


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