Author：Dong-Hong Wu ^{1, 4}, David Gealy ², Yi-Chien Wu ³, Melissa Jia ², Jeremy D. Edwards ², Ming-Hsin Lai ¹, and Anna McClung ²

¹ Crop Science Division, Taiwan Agricultural Research Institute, Council of Agriculture (COA), Taiwan, ROC
² Dale Bumpers National Rice Research Center, US Department of Agriculture - Agricultural Research Service, Stuttgart, Arkansas, USA
³ Taichung District Agricultural Research and Extension Station, COA, Taiwan, ROC
⁴ Corresponding author, e-mail: dhwu@tari.gov.tw

ABSTRACT

    Weedy red rice (WRR) possesses traits, including seed dormancy and shattering, that facilitate its infestation in rice paddies from one crop season to the next. These plants are not only the potential source of pollen-mediated gene flow and hosts for diseases or other pests, but also are competitors for fertilizer due to their vigorous growth. In addition to increased production costs to control this weed, the red pericarp and undesirable eating qualities of WRR lead to reduced product value, consequently putting production constraints on the global rice industry. In rice cultivation regions world-wide, the rice industry is in search of effective ways to control WRR. The rice production system in Taiwan relies on transplanting which is recommended for effective control of weeds in rice fields during the seedling stage. However, the infestation of WRR in rice paddies has become increasingly severe in the past few years in Taiwan. Although WRR occurs at a rate of only 0.5 to 1% in contaminated paddies, it can be spread easily through use of shared field equipment among rice fields. Ratoon cropping or tillage immediately after harvest increases the population densities of WRR, resulting in future yield losses. Effective control strategies for WRR should meet the balance between economic benefit, efficiency, and feasibility. The recommended WRR control measures under a transplanting system begin with irrigating the paddy field after harvest to induce the sprouting of shattered seed, followed by plowing the WRR seedlings into the land. Herbicide is then applied three times in succession every seven days to kill emerging WRR and to field infestations. The final step is the manual removal of the remaining off-type plants of WRR.

Keywords: weedy red rice, seed shattering, seed dormancy, transplanting system, control strategy

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