Pro Ag Supply • 4750 East Hwy 12 • Aberdeen, SD 57401 • 605-225-9221

Late planted corn prone to stress, hormone imbalance, rapid growth syndrome.

June 3, 2019

Stoller Technical Research Agronomy Team - May 31, 2019

If you were one of the fortunate to get your crops planted or are still planting, there are several things to understand about late planted crops as it relates to how they grow and the challenges they face verses earlier planted crops.

We certainly recognize rapid growth syndrome in corn but rapid growth syndrome can affect any crop we grow. When cooler-than-normal temperatures exist followed by a fast transition to very warm temperatures, our plants begin growing more rapidly above ground than what they do below ground. This induces a hormonal imbalance, high auxin (produced above ground) and low cytokinin (produced in the roots) comparatively. When this happens the first signs we typically see are nutritional deficiencies. This occurs because the root system doesn't acquire needed nutrients fast enough to keep up with growth demands. As hormones remain unbalanced, we get an auxin overdose effect; first, rigid leaf margins, then twisting or puckering of the leaf area. In corn a twisted whorl is common, internodes can form crooked etc. Rapid growth syndrome looks very similar to 2,4-D or dicamba herbicide injury as these herbicides are both auxins as well. Late planted crops often face rapid temperature changes due to the time of season. Adding additional auxin herbicides to a spray program can make this condition even worse.

Rapid Growth Syndrome plant leaves fail to open, the whorl twists and wraps up, leaves appear rippled, and the plant leans over. This is a result of hormone imbalance.

Why does this all matter? Many grass crops such as corn and small grains set ear or head size very early, V3 through V6. When we have auxin overload this causes the abortion of potential rows and kernels, so rather than having ears with 16-20 rows, our ears will be more likely to set 12-14 rows. This significantly lowers the genetic yield potential. We have two approaches to dealing with this issue. First the preventative approach, Fortified Stimulate YE+ applied at V3-V4, because of its ability to increase root growth, increasing cytokinin, which has shown to virtually eliminate this problem. Second is a recovery approach, foliar applying X-Cyte™ and Bio-Forge® Advanced. X-Cyte will help bring the plant back into hormone balance, and Bio-Forge Advanced will reduce the abiotic stress, allowing these plants to return to normal function and preserve the yield potential it has. Both solutions work well, however the preventative is always the best choice. Late planted crops face many challenges due to the environmental conditions mother nature tosses at them, Stoller Technologies help you, as growers, battle these conditions and preserve the yield potential you paid for when you bought your seed.