|Davis, Vince - PURDUE UNIV.|
|Phippen, Winthrop - WESTERN IL UNIV.|
Submitted to: Weed Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 25, 2005
Publication Date: December 1, 2005
Citation: Forcella, F., Amundson, G.B., Gesch, R.W., Papiernik, S.K., Davis, V.M., Phippen, W.B. 2005. Herbicides tolerated by cuphea (Cuphea viscosissima x lanceolata). Weed Technology. 19:861-865. Interpretive Summary: Cuphea is a potential new oilseed crop for the upper Midwest of the United States. However, it is very susceptible to competition from summer-growing weeds, and no previous research has been conducted on tolerance of this broadleaf plant to herbicides. For this reason we examined in a greenhouse a large number of preplant incorporated, preemergence, and postemergence herbicides for tolerance by cuphea. Promising herbicides then were tested in the field for two years. Only a few herbicides appeared suitable for cuphea production. There were two suitable preplant incorporated herbicides (ethalfluralin and trifluralin), one suitable preemergence herbicide (isoxaflutole) and one suitable postemergence herbicide (mesotrione). Finally, there were three suitable combinations of herbicides: ethalfluralin followed by mesotrione, isoxaflutole followed by imazethapyr, and isoxaflutole followed by mesotrione. Knowledge that these herbicides can be used in cuphea production will aid the domestication and acceptance of this new crop greatly by farmers, crop advisors, researchers and the oilseed industry.
Technical Abstract: A hybrid of two species of cuphea (Cuphea viscossima Jacq. x lanceolata f. silenoides W.T. Aiton; "PSR-23") is a potential new oilseed crop. Because of its slow growth during spring and early summer, cuphea is highly susceptible to interference by weeds. Although grass weeds can be controlled easily by graminicides that are tolerated well by cuphea, broadleaf weeds remain an appreciable problem. Consequently, several broadleaf herbicides were screened for tolerance by "PSR-23" cuphea. Broadleaf herbicides to which cuphea showed tolerance in a spray cabinet and a greenhouse were tested in a field setting for two years. Tolerance was considered as absence of negative impact (p > 0.05) both years to any of the four measured traits: overall vigor, dry weight, stand density and time to anthesis. Cuphea showed acceptable tolerance in the field to three soil-applied herbicides (ethalfluralin, isoxaflutole and trifluralin) and one postemergence herbicide (mesotrione). A few combinations of soil-applied and postemergence herbicides did not damage cuphea. These combinations were ethalfluralin followed by (fb) mesotrione, isoxaflutole fb imazethapyr and isoxaflutole fb mesotrione. Availability of these herbicides for use in cuphea production will aid the domestication and acceptance of this new crop.