Diseases and weeds strike again and sweet corn yields are taking a beating. A recent University of Illinois study found that maize dwarf mosaic (MDM) and wild-proso millet have teamed up, and the pair are leading to to less than desirable results.

Marty Williams, associate professor of crop sciences and USDA-ARS ecologist, said the study aimed to identify how MDM incidence and weed interference influences sweet corn growth, phenological development and yield. MDM is the most prevalent viral disease of sweet corn in the United States, and wild-proso millet is one of the most problematic weeds. Although MDM and weed interference are two commonly occurring stresses in sweet corn, little was known about the combination of these stresses and their effect on sweet corn until now.

Williams said resistance genes for MDM have been incorporated into some sweet corn lines, but most commercial hybrids have little or no resistance to the disease. Researchers conducted tests in two MDM-susceptible hybrids that differed in weed tolerance.

The combinations of these stresses, even at low levels, are particularly problematic, Williams said. MDM stunts crop growth and impedes sweet corn’s ability to capture limited resources such as light. Weeds intercept the extra resources. The crop, in turn, has a more difficult time competing for light as well as water and nutrients.

Researchers found incidence of MDM also delayed development as much as five days.

“Five days is huge because sweet corn has a narrow window for producing a marketable product,” Williams said. “Delays in silk emergence influence maturity, which is a big problem for producers and processors in terms of harvest timing and yield.”

Williams said this study gives the sweet corn industry and research community a better understanding of the individual and combined effects these two stresses have on crop growth and yield. The work provides strong incentive for developing hybrids with higher levels of MDM resistance and improved competitive ability with weeds.

This study, “Interactions between maize dwarf mosaic and weed interference on sweet corn” was published in Field Crops Research. Researchers include Marty Williams and Jerald (Snook) Pataky of the University of Illinois.