TITLE:
Extending the Shelf-Life of Myrothecium verrucaria, a Bioherbicide
AUTHORS:
Robert E. Hoagland, C. D. Boyette, K. C. Stetina
KEYWORDS:
Bioherbicide, Plant Pathogen, Weed Control, Lyophilization, Freeze-Drying, Mycelium, Mycoherbicide, Myrothecium verrucaria
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.8 No.12,
November
29,
2017
ABSTRACT: The shelf-life of a bioherbicide product
is an important factor with regard to its commercial potential. The
bioherbicidal efficacy of freshly fermented Myrothecium
verrucaria (strain IMI 368023) (MV)
mycelia formulations and MV
mycelia preparations that had been freeze-dried and then stored at -20°C for 8 years was compared. Two concentrations
of each formulation (1.0x and 0.5x) were tested, utilizing bioassays on
seedlings of the weed, hemp sesbania (Sesbania
exaltata) 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, i.e., ~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 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.