|ACHARYA, JYOTSNA - Iowa State University|
|LENSSEN, ANDREW - Iowa State University|
|ROBERTSON, ALISON - Iowa State University|
Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/31/2016
Publication Date: 4/1/2017
Citation: Acharya, J., Bakker, M.G., Moorman, T.B., Kaspar, T.C., Lenssen, A.W., Robertson, A.E. 2017. Time interval between cover crop termination and planting influences corn seedling disease, plant growth, and yield. Plant Disease. 101(4):591-600. doi: 10.1094/PDIS-07-16-0975-RE.
Interpretive Summary: Cover crops provide important water and soil quality benefits, but also require farmers to make additional management decisions. One of the choices that farmers have to make when using cover crops is when to kill the cover crop relative to the expected date of planting their next grain crop. The length of this interval between cover crop termination and planting of the next crop may influence how much the cover crop grows, as well as how the subsequent grain crop performs. We performed experiments to test the effects of various time intervals between cereal rye cover crop termination and corn planting on corn seedling disease, corn growth, and grain yield. Shorter intervals increased seedling disease, and reduced corn emergence, shoot growth, and grain yield of corn following the cover crop compared with corn planted 10 or more days after rye termination or without the cover crop. The proportion of roots infected with Pythium spp. increased with shorter intervals. We also measured the proportion of roots infected by Fusarium spp., but the results were less consistent than for Pythium spp. A 10 to 14 day interval between rye termination and corn planting should be followed to realize the benefits of rye cover crops while protecting corn yield. The impact of this research is that farmers, extension personnel, crop advisors, and NRCS conservationists will be able to use and manage cover crops more effectively, which will lead to more cover crop adoption, less risk to corn yield, and more environmental benefits.
Technical Abstract: Experiments were established in controlled and field environment to evaluate the effect of time intervals between cereal rye cover crop termination and corn planting on corn seedling disease, corn growth, and grain yield in 2014 and 2015. Rye termination dates ranged from 25 days before planting (DBP) to 2 days after planting (DAP) corn in field and from 21 DBP to 1 DAP in controlled studies. Data were similar in both environments. Shorter intervals increased seedling disease, and reduced corn emergence, shoot growth, and grain yield of corn following the cover crop compared with corn planted 10 or more days after rye termination or without the cover crop. Incidence of Pythium spp. increased with shorter intervals (less than 8 DBP); incidence of Fusarium spp. was not consistent between runs and the experiments. In 2014, in 1 DAP treatment, number of ears and grain yield was reduced (P = 0.05 and P = 0.02, respectively). In 2015, all termination intervals reduced plant population, number of ears, and yield (P = 0.01) with the 2 DBP causing the biggest decrease. A 10 to 14 day interval between rye termination and corn planting should be followed to maximize the use of rye cover crop to benefit soil health, and maximize crop yield.