11.2 Introduction

Before examining the details of mechanical weed control options, there are a few important points to highlight in regards to weed science research findings:

• Different tillage practices have different effects on the weed populations. Remember that the weed population is always adapting and that is true in mechanical systems, as well as herbicide programs.
• As for effects on weed seed banks, there is a bit of both good news and bad news. On one hand, tillage will increase seed germination, bringing the seeds up to the soil surface which helps them to germinate. If those seedlings are controlled when they grow, then over time tillage will help reduce seed bank reserves. At the same time, tillage can also bury weed seeds and thereby increase the seed bank.  In this case, weed seeds stay dormant longer and increase their longevity or their viability.
• Research is also showing in a no-till system, some weeds are capable of increasing seed production. Examples of this are redroot pigweed and large crabgrass.

The key is to remember fields are a dynamic environment, always in flux.  As such, it is crucial to stay current with new findings being made by extension specialists and weed researchers.

This chapter consists primarily of three short guest lecture videos provided by Dr. Kent Harrison in the Horticulture and Crop Sciences Department of OSU-CFAES.  He teaches a graduate level Principles of Weed Ecology and Management course.  In these clips Dr. Harrison provides a quality introductory discussion on the key aspects of mechanical weed control.