TITLE:
Hot Water Treatment Enhances the Bioherbicidal Efficacy of a Fungus
AUTHORS:
C. Douglas Boyette, Robert E. Hoagland, Kenneth C. Stetina
KEYWORDS:
Bioherbicide, Mycoherbicide, Hemp Sesbania, Sesbania exaltata, Colletotrichum truncatum, Hot Water Pre-Treatment, Improved Bioherbicide Efficacy, Weed Control
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.9 No.10,
September
28,
2018
ABSTRACT: Hemp sesbania (Sesbania exaltata)
plants (>30 cm tall) sprayed with hot water (45°C – 95°C),
followed by spray applications of fungal spores of Colletotrichum truncatum (CT)
at 1.0 × 107 spores/ml-1 and 22°C – 25°C,
suspended either in: 0.2% Silwet L-77 surfactant (SW); unrefined corn oil
(CO)/distilled water (1:1, v:v); or 0.2% SW in CO were controlled by 80% - 95%, 12 days after
treatment (DAT) under greenhouse conditions. These treatments also reduced dry
weight accumulation of this weed. Plants treated with hot water without CT were
also injured at temperatures ≥35°C (5% mortality), and 60% mortality at 95°C.
Artificial dew treatments (25°C, 12
h), imposed on plants after the treatment protocols above, had little or no
effect on weed mortality or dry weight reduction compared to treated plants
without dew. Under field conditions, 85% control of hemp sesbania was achieved
12 - 15 DAT when a
pre-treatment with hot water (65°C) was
followed immediately with a CT application at the spore concentration as
described above. Plants in field tests treated with CT without a hot water
treatment were visually unaffected, with no mortality or plant biomass
reductions recorded 15 DAT. These results suggest that use of hot water may be
an important tool for improving the infectivity and bioherbicidal potential of
some plant pathogens.