Cover Crop Management Effects on Weed Communities in a Planting Green System

Open Access
- Author:
- Ficks, Teala
- Graduate Program:
- Agronomy
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- November 05, 2021
- Committee Members:
- Erin Connolly, Program Head/Chair
John M Wallace, Thesis Advisor/Co-Advisor
Carolyn Lowry, Committee Member
Heather D Karsten, Committee Member
Allyson Muth, Committee Member - Keywords:
- Cover crop
no-till
resource partitioning
seedling ecology
weed ecology
cover crop
no-till
resource partitioning
seedling ecology
weed ecology - Abstract:
- Integrated weed management (IWM) is essential for managing herbicide resistant weeds in no-till cropping systems. The use of cover crops as an integrated weed management tactic provides an opportunity to reduce herbicide selection pressure and increase control of herbicide resistant species. Cover crop management decisions made by growers depend on agronomic tradeoffs and input costs associated with cover cropping tactics. Planting green is a cover crop management tactic where cover crop termination is delayed until cash crop planting. In Pennsylvania, there has been increased interest in planting green. We investigated the effects of cereal rye seeding rates on weed suppression when using planting green tactics at two locations in Pennsylvania and one location in Delaware. Weed population responses were evaluated across four cereal rye seeding rate treatments: 0, 51, 101, 135 kg ha-1. Our results found that the presence of cereal rye improved weed suppression compared to the control treatment. Weed suppression was similar across cereal rye seeding rates 51 – 135 kg ha-1. An additional field experiment evaluated the effects of cover crop termination timing and reduced herbicide inputs on weed suppression. This study was conducted at Rock Springs, PA across three growing seasons and included two cover crop termination treatments: planting green with reduced herbicide use and standard cover crop termination with standard herbicide use. Our results found that planting green provided similar summer annual weed suppression compared to standard cover crop termination. However, standard cover crop termination improved horseweed control compared to the planting green treatment. A third experiment investigated the effects cover crop surface mulch could have on weed community composition in a greenhouse experiment. Seedling establishment and resource allocation of ten weed and two crop species was evaluated across a seed mass gradient and cereal rye surface mulch levels, including 0, 3,360, 6,720, and 10,080 kg ha-1. Our results demonstrated that seed mass was positively correlated with seedling establishment rates under increasing cereal rye mulch levels. In response to increasing cereal rye surface mulch, resource allocation in broad-leaved species were diverted to aboveground biomass, particularly hypocotyl elongation, but surface mulch levels had no significant effect on monocotyledon species.