Extending the Shelf-Life of Myrothecium verrucaria, a Bioherbicide

摘要

The shelf-life of a style="font-family:Verdana;">bioherbicide product is an important factor with regard to its commercial potential. The bioherbicidal efficacy of freshly fermented style="font-family:Verdana;">Myrothecium verrucaria style="font-family:""> style="font-family:Verdana;">(strain IMI 368023) (MV) mycelia formulations style="font-family:""> style="font-family:Verdana;">and MV mycelia preparations that had been freeze-dried and then stored at style="font-family:Verdana;">-20°C for 8 years style="font-family:Verdana;">was style="font-family:""> style="font-family:Verdana;"> compared. Two concentrations of each formulation (1.0x and 0.5x) were tested, utilizing bioassays on seedlings of the weed, hemp sesbania ( style="font-family:Verdana;">Sesbania exaltata style="font-family:Verdana;">) under greenhouse conditions or in darkness utilizing hydroponically grown seedlings. Freeze drying of freshly prepared MV mycelium produced a light, brownish-colored powder. Efficacy tests of this reconstituted 8-year-old dried material showed that some bioherbicidal activity was lost during long-term storage, style="font-family:Verdana;"> i.e style="font-family:Verdana;">., ~20% and ~60% seedling dry weight reduction at the 1.0x and 0.5x rate, respectively. Although plant mortality was greater in the fresh mycelial preparations treatments versus the freeze-dried and stored samples at all time points in the time-course, the stored material still caused >80% mortality, 15 days after treatment. Comparative disease progression ratings also showed a similar trend. Overall results show that freeze-drying MV is a useful method to reduce the bulk and cumbersomeness of storing heavy liquid fermentation product, while retaining bioherbicidal activity. These findings style="font-family:""> style="font-family:Verdana;">increase the utility of this bioherbicide and offer the potential to use the dried material in soil treatments or in a more concentrated form than attainable via the fermented product.