Optimizing Weed Management via Microwave Irradiation

dc.contributor.authorRana, Amanen
dc.contributor.committeechairDerr, Jeffrey F.en
dc.contributor.committeememberHagood, Edward S.en
dc.contributor.committeememberGrisso, Robert D.en
dc.contributor.committeememberAskew, Shawn D.en
dc.contributor.committeememberMallikarjunan, Parameswaran Kumaren
dc.contributor.departmentPlant Pathology, Physiology, and Weed Scienceen
dc.description.abstractOne potential alternative to chemical weed control is the use of microwave radiation, a particular form of indirect thermal weeding. Absorption of microwave radiation causes water molecules within the tissue to oscillate, thereby converting electromagnetic energy into heat. This technique is rapid, versatile and effective, as the electromagnetic waves heat the plant tissue and destroy cellular integrity. The objective of this research was to evaluate the potential use of dielectric heating for weed management. Ten weed species representing monocots and dicots were selected for this study: southern crabgrass, dallisgrass, yellow nutsedge, fragrant flatsedge, false green kyllinga, common ragweed, field bindweed, henbit, white clover, and pitted morningglory. There was a lag or warm up period between energizing the magnetron and actual microwave radiation production. To eliminate the gap between electric power supplied to magnetron and actual microwave radiation produced, a conveyer was used. Overall injury to grasses, sedges and broadleaf weeds was higher at each dose when weeds were treated by microwave radiation while moving on a conveyer in comparison to being stationary. Grasses showed slightly more tolerance to microwave treatments in comparison to broadleaf weeds. Older weeds (8 to 10 weeks old) showed more tolerance to microwave treatments in comparison to younger weed plants (4 to 6 weeks old). Microwave radiation was able to control a range of weed species, although larger weeds were more likely to regrow after treatment. Ambient temperature had a significant effect on injuries caused by microwave radiation to target weeds, with control increasing as the air temperature increased. Weed control using microwave radiation required more energy when weeds were treated at 13 C compared to 35 C. More energy was needed at lower air temperatures to raise the plant canopy temperature from ambient levels to beyond the biological limit. Microwave radiation at lower doses caused greater injury to common chickweed and yellow woodsorrel than bermudagrass, suggesting the potential for selective weed control in certain situations. A custom built microwave applicator provided similar control of emerged weeds as the contact herbicides diquat and acetic acid.en
dc.description.degreePh. D.en
dc.publisherVirginia Techen
dc.rightsIn Copyrighten
dc.subjectmicrowave radiationen
dc.subjectnonchemical weed controlen
dc.subjectthermal weed controlen
dc.subjectambient temperatureen
dc.subjectplant ageen
dc.titleOptimizing Weed Management via Microwave Irradiationen
thesis.degree.disciplinePlant Pathology, Physiology, and Weed Scienceen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.namePh. D.en
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