Bioherbicides are microbes and/or microbial phytotoxins used to control weeds. This approach to weed control, has continued, with world-wide efforts as evidenced in several books and reviews – dedicated to bioherbicides. In order for bioherbicide usage to become more predictable, effective and acceptable, it is necessary to maximize the ability of a bioherbicide to infect, kill and/or reduce the competitiveness of weed hosts. Previous research in our laboratory and elsewhere has shown that certain formulations, such as invert emulsions and various vegetable oil-in-water emulsions can retard evaporation and trap water in bioherbicide spray mixtures, thereby decreasing the amount of additional free-moisture required to initiate spore germination and infection.For example,greenhouse and field results indicated that >95% control of sickle pod could be achieved with little or no dew using an invert formulation of the fungus Alternaria cassiae Jurair& Khan .The fungus Colletotrichum truncatum Andrus & W.D. Moore has shown bioherbicidal potential to control hemp sesbania.
Asout lined above, spores of this fungus require certain periods of sustained free-moisture in order to germinate, establish infection, and cause disease. However, hemp sesbania was effectively controlled in soybean by CT spores formulated in a water-in-oil invert emulsion, applied using specialized spraying equipment. Even though the invert formulation provided excellent hemp sesbania control , the difficulty in applying this viscous mixture precluded its practical usage. In other experiments,oil-in-water emulsions of unrefined corn oil and CT spore suspensions reduced the dew period requirements for maximum weed infection and mortality of hemp sesbania from 12 h to 2 h, and delayed the need for free-moisture for greater than 72 h . Unrefined corn oil also stimulated CT spore germination. A surfactant ncorporated in an unrefined corn oil emulsion also promoted germination and infectivity of Alternaria helianthi Tubaki& Nishihara spores on common cocklebur .Because hot water and steam can denature plant proteins, and alter plant epicuticular waxes, we hypothesized that hot water treatment,followed by a bioherbicide application might promote the efficacy a given pathogen for control of certain weeds.
Therefore, we chose to examine the effects of hot water applications and CT under greenhouse and field conditions for the control of hemp sesbania, an important weed in row crops in the southern U.S. that has also been reported to have tolerance to glyphosate.In all greenhouse experiments, treatments were arranged in a randomized blockde sign with four replicates and the experiments were repeated over time. In the field experiments, all treatments were replicated 4times and the experiment was repeated in successive years. Data were averaged over the 2-year testing period, after subjecting to Bartlett’s test for homogeneity of variance .In both the greenhouse and field experiments, the mean percentages of plantmortalities and biomass reductions were calculated for each treatment, and subjected to Arcsin transformation.The transformed data were statistically compared using analysis of variance. Results were back-transformed to the original measurements for presentation. Data were analyzedvia the PROC MIXED function of SAS v9.3 using a least significant difference of 0.05. Best-fit regression analysis was utilizedin all greenhouse and field experiments. Hemp sesbania plants were controlled 75% – 85% under field conditions following pre-treatment with hot water 12 – 15 DAT, with concomitant dry weight reductions.
No re-generative growth occurred in plants that were inoculated with CT following hot water pre-treatments at temperatures ≥45˚C .Although decent weed control was achieved in these experiments,application of hot water coupled with CT at an earlier stage of weed development when plants are more sensitive, would likely result in higher efficacy.Formulations of this bioherbicide have previously been shown to provide excellent control of seedling hemp sesbania seedlings . In those experiments, SW was used in combinations with an invert emulsion. Although excellent weed control was achieved with this combination, a formulation of SW + CT failed to provide acceptable hemp sesbania control. It is a four-carbon dicarboxylic acid that can be utilized as a key building block for a broad range of products: biodegradable plastics, cosmetics,food ingredients and pharmaceutical products.
The petrochemical synthesis of succinic acid involves hydrogenation of 1,4-dicarboxylic unsaturated C4acids or anhydrides, oxidation of 1,4-butanediol, hydrogenation of maleic anhydride to succinic anhydride and then hydration of succinic anhydride to succinicacid . Alternatively, bioprodution of succinic acid from renewable feedstocks is possible through fermentation of glucose using an engineered form of either Anaerobiospirillum succinici producens or Eschericia coli has been reported .Recent research has found that high yields and productivities of succinic acidbio-manufacturing can be achieved using Actinobacillus succinogenes 130 Z in acustom, and continuous fermentation step, which makes bio-succinic acid apromising value-added chemical in integrated biorefineries.