The Effect of Microwave Treatment on Ryegrass and Wild Radish Plants and Seeds

Abstract

Annual ryegrass (Lolium rigidum) and wild radish (Raphanus raphanistrum) are significant weeds in Australian winter cropping systems. These species have developed significant herbicide resistance and new control strategies need to be developed. Microwave energy has been considered for weed control for some time. The research considered the effect of varying amounts of microwave energy on plants and their seeds for each species. Several experiments explored the interaction between microwave energy and seed depth in the soil. Plant responses to microwave energy were also determined for each species. Seed treatment requires higher energy applications than plant treatment and is conceptually similar to soil fumigation treatments. Soil treatment may have application in some high value horticultural crops, which already use soil fumigation. Microwave treatment of plants requires less energy, with wild radish requiring about 60 Jcm^-2 to achieve 100% mortality, while ryegrass plants require about 370 Jcm^-2 to achieve 100% mortality. Microwave treatment of growing plants can be compared to the application of herbicide. Therefore control of growing plants should be the focus of developing a commercially viable microwave weed control device for cropping systems.