Submitted to: Journal of Plant Pathology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/7/2007
Publication Date: 2/7/2008
Citation: Sanyal, D., Bhowmik, P.C., Abbas, H.K. Effect of surfactants on bioherbicidal activity of Alternaria helianthi on multiple-seeded cocklebur. Journal of Plant Pathology. (7)1:104-108. 2008. Interpretive Summary: Cocklebur is an important invasive weed in crops such as soybean, cotton, and corn. Cocklebur has become resistant to some conventional herbicides previously effective in controlling this weed, thus there is need for alternative control measures. The fungus Alternaria helianthi has been shown to control cocklebur however, delivery systems to enhance its control has not been optimized. This research has determined that application with an appropriate surfactant enhances the effectiveness in this fungus to infect and kill cocklebur, making it useful as a Biocontrol agent.
Technical Abstract: Greenhouse studies were conducted to investigate the bioherbicidal activity of Alternaria helianthi (Hansf.) Tubaki & Nishih. on multiple-seeded cocklebur as affefct by various rates of Tenkoz COC (crop oil concentrate), Activator 90 (non-ionic surfactant), BAS 9050 O S (methylated oil), Silwet L-77 (organosilicone surfactant), and Top film (natural based surfactant). Alternaria helianthi resulted in significant reduction in fresh weight, plant height and leaf number of multiple-seeded cocklebur as compared to the plants treated without the fungus. The bioherbicide activity of A. helianthia was always higher when exposed to a 12 h dew period as compared to a 6 h dew. Under 12 h of dew exposure, A. helianthi was more virulent even in the lowest rate of Tenkoz COC, Activator 90, and Silwet L-77 than the treatment without a surfactant. However, with 6 hr dew exposure higher rates of these surfactants were required to get a significant reduction in fresh weight, plant height and leaf number of multiple-seeded cocklebur as compared to the treatments without a surfactant. These data show that the duration of dew period requirement can be minimized with a higher rate of these surfactants. Whereas, at the lowest rates of BAS 9050 O S (0.25%) and Top film (0.06%). A helianthi was most virulent and the bioherbicidal activity was decreased with higher rates.