Agronomy Talk


Purple Corn Syndrome

Published on Wednesday, June 7, 2017

It’s not uncommon for me this time of year to receive calls regarding corn plants turning purple. While it’s not unusual, it is important to understand the underlying cause and, more importantly, that in most cases this condition is temporary and cosmetic, and will not impact yield.

There are several factors that can contribute to early-season purple coloration, but the major causes are likely to be induced by early-season stress and restricted root growth. Corn leaves produce sugars through photosynthesis. These sugars are typically metabolized to generate energy to promote further shoot and root development. However, when growth slows down or we experience cool nighttime temperatures around 40°F, these sugars accumulate in the leaf. This triggers anthocyanin pigment formation and causes purple discoloration. Most hybrids contain five of the eight genes required to express this purpling. The other three genes are only present in certain hybrids and are cold temperature sensitive, which is why purple corn syndrome is typically very hybrid dependent.

The good news is that these temperature sensitive genes are only expressed in corn up to the V6 growth stage so the corn plant will typically outgrow this condition by the time it’s 12 to 16 in. tall. Below is a photo of XL® 5828AM™* with purple corn syndrome near Wapak, Ohio.

While often times the source of this condition can be traced back to genetics, there are several other potential causes for this purpling. Inhibited root growth due to shallow planting, compacted soils, sidewall compaction or low levels of Phosphorous in the soil can also cause purpling of corn. Often times, if one of these situations exist, the condition will not be uniform throughout the field and will be more visible on end rows and high-traffic areas such as grain cart paths.

Research conducted to better understand purple corn has shown that the anthocyanin pigment is produced only on the surface layer of cells and does not affect the overall chlorophyll content of the leaf. Testing of corn plants exhibiting purpling at the seedling stage has found no evidence to support that it adversely affects metabolism or negatively impacts yield.

If you have further questions regarding purple corn syndrome or other conditions in your fields, please do not hesitate to contact myself or your local Beck’s representative.

®XL, Optimum, and AcreMax are registered trademarks of Pionner. XL® brand seed is distributed by Beck's Superior Hybrids, Inc.


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Luke Schulte

Luke Schulte

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