Experiments were initiated to determine if the tropical soda apple (TSA) biological control agent, Tobacco mild green mosaic tobamo virus (TMGMV), could be mixed with synthetic herbicides to provide effective broad-spectrum weed control. When TMGMV was mixed with 2,4-D ester or amine, metsulfuron, or hexazinone, TSA control ranged between 80 and 100%. On average, TMGMV increased TSA control by 81% as compared to these herbicides applied alone. Treatment applications were made by rubbing only three leaves, not as a broadcast application. Although this is not the optimum method for herbicide application, it does indicate the level of control the herbicide alone potentially provided relative to the herbicide/TMGMV mixture. Results indicate that the majority of TSA control was due to virus and that the herbicides mixed with TMCMV did not interfere with the virus's ability to infect TSA. Additions of organosilicone adjuvants or low rates of crop oil or nonionic adjuvants to TMGMV solutions resulted in greater infection of TSA. The finding that TMGMV remains infective when mixed with herbicides will allow greater flexibility for landowners attempting to control TSA and other troublesome weeds.
Nomenclature: 2,4-D amine; 2,4-D ester; dicamba; hexazinone; metsulfuron; tropical soda apple; Solanum viarum Dunal SOLVI.