PPDL Picture of the Week for
December 10, 2012

Kernel Red Streak in Corn

RL (Bob) Nielsen, Purdue Agronomy

Kernel red streak, or KRS, is a phenomenon wherein streaks of red pigments radiate throughout the pericarp of an otherwise yellow kernel. The KRS symptom was apparently first documented in 1963 in fields throughout northeast Indiana, southern Michigan, and northwest Ohio and in Ontario in 1964. By 1966, researchers had begun to associate the KRS symptom with the concomitant presence of the wheat curl mite (Aceria tulipae K.; aka Aceria tosichella Keifer), a pest in wheat. Research suggests that the pigmentation results from "salivary phytotoxins" secreted by the mites as they feed on the pericarp of kernels. Growers often worry that the red streaks may signify the presence of ear molds or toxins, but there is no such documented relationship. The most frequent concern with KRS occurs with food grade corn grown under contract for snack food processors. While purely cosmetic, the red pigmentation in the pericarp can discolor the finished products (e.g., corn chips, tortilla chips, taco shells) and, apparently, deter some customers. This appears to be especially true for the wet milling industry wherein the pericarp is not always removed prior to the alkaline cooking process and the remaining pigmented pericarp pieces can turn black with the cooking. Thus, the snack food industry is not keen on purchasing corn grain with high levels of KRS.

For more information, see my lengthier newsletter article online at http://www.kingcorn.org/news/timeless/KernelRedStreak.html

Click image to enlarge

Kernel Red Streak on corn

Purdue Plant & Pest Diagnostic Lab Purdue Cooperative Extension Service