Date Available


Year of Publication


Degree Name

Master of Science (MS)

Document Type

Master's Thesis


Agriculture, Food and Environment


Plant and Soil Sciences

First Advisor

Dr. Travis Legleiter


Herbicide resistance is not a new problem for farmers in Kentucky, although the identification of herbicide resistant weed species continues to increase. Italian ryegrass (Lolium perenne ssp. multiflorum) is a problematic weed in Kentucky’s soft red winter wheat that has historically been documented as herbicide resistant in isolated locations. A greenhouse herbicide screen was conducted to further understand the level of glyphosate, pinoxaden, and pinoxaden plus fenoxaprop resistance in Kentucky Italian ryegrass populations. The preliminary screen and dose responses indicate there is one Italian ryegrass population resistant to glyphosate and two populations resistant to pinoxaden along with pinoxaden plus fenoxaprop. Harvest weed seed control is a potential option being evaluated in Kentucky to control herbicide resistant Italian ryegrass in soft red winter wheat. One specific method of harvest weed seed control is the use of cage mills to destroy Italian ryegrass seed found within the fine chaff exiting the combine at harvest. This can only be an efficient and viable option of control if Italian ryegrass seed is retained on the seed head up to the time of harvest and is able to enter the combines chaff flow. Seed retention and dispersal of Italian ryegrass was evaluated prior to and at wheat harvest in 2020 and 2021 in Kentucky. Within one week of harvest, both the Italian ryegrass seed heads and the top layer of soil debris were collected from within a m-2 area for approximately each 0.2 ha of Italian ryegrass infestation in eight Kentucky wheat fields. For the preharvest and harvest samples, 11,000 of the Italian ryegrass seeds remained on the seed head up to wheat harvest and 85% of the seeds retained did enter the combine which makes mechanical harvest weed seed control a potential viable option of for Italian ryegrass control in Kentucky wheat.

Digital Object Identifier (DOI)

Funding Information

This study was supported by the Kentucky Small Grain Growers Association and Siemer Milling Company in 2020 and 2021.

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