|Abstract or Summary
- The primary purposes of these studies were to investigate: (1)
the effects of air temperature, soil moisture, and supplemental light
on sprouting ability of quackgrass (Agropyron repens L. (Beauv. ))
rhizome buds; (2) the influence of 2-chloroethylphosphonic acid
(Ethrel) on growth, morphology, and regenerative capacity of quackgrass
and field bindweed (Convolvulus arvensis L.); and (3) the efficacy
of Ethrel in enhancing the phytotoxicity of a mixture of 3-aminos-
triazole and ammonium thiocyanate (amitrol-T) and 2, 2 -dichloro
propionic acid (dalapon) on the regenerative capacity of quackgrass
rhizomes. The studies were carried out in a greenhouse or growth
The percent sprouting of the single-node quackgrass rhizome
buds was decreased if the plants were subjected to 70°F day and 60°F
night air temperatures, a reduced level of light intensity, or
severe soil moisture stress.
Ethrel applied to mature quackgrass plants effectively induced
the rhizome buds to grow and develop into either rhizome branches
or into leafless, rhizome-like aerial shoots. The aerial shoots did
not develop normal leaves for two to four weeks. Later, as the effect
of Ethrel diminished, normal leaves developed on the upper parts of
the new shoots. Higher rates of Ethrel (4 to 6 lb/A) were more effective
in evoking growth of the rhizome buds than the lower rates, but
the resulting shoots remained leafless for a longer time.
A high level of soil-applied nutrients also induced growth of
quackgrass rhizome buds. In this regard, the effect of Ethrel and
high soil nutrient level was simply additive not synergistic.
Ethrel applied to intact quackgrass plants or to its excised rhizome
buds did not increase or decrease the percent sprouting of the
single-node rhizome buds. But the excised rhizome buds from quackgrass
plants growing at a high level of soil nutrients had a higher percent
Over a six-week period, Ethrel (6 lb/A) application doubled the
fresh and the dry weight of the leaves plus the newly formed shoots,
moderately reduced the dry weight but not the fresh weight of the rhizomes,
and inhibited root growth of the treated quackgrass plants in comparison to the untreated plants.
Pre-treating quackgrass plants with Ethrel did not enhance the
effectiveness of amitrol-T, applied subsequently, as measured by the
average weight of regrowth produced by the replanted rhizome segments.
But Ethrel in combination with amitrol-T completely inhibited
the rhizome segments of 60% to 80% of the plants from producing any
regrowth. When amitrol-T alone was used, the rhizome segments of
30% to 50% of the plants failed to have any regrowth.
The rhizome pieces from quackgrass plants treated with Ethrel
and dalapon produced more regrowth dry weight than the rhizome segments
obtained from similar plants treated with dalapon alone. The
reason for this antagonistic relation between Ethrel and dalapon was
Mature field bindweed plants sprayed with Ethrel sustained
severe to complete defoliation. Many of the existing stems also died.
The rootstocks of these plants, especially those treated with 1.0 lb
Ethrel/A, were stimulated to initiate numerous visible shoot-buds.
The initiated buds close to the soil surface emerged and developed
into aerial shoots with minute leaves and short internodes.
The rootstocks of field bindweed plants were segmented and replanted
to measure their regrowth potential. The segmented rootstocks
from Ethrel (1.0 lb/A) treated plants produced three times as
many shoots and five times as much regrowth dry weight than the
The effects of low rates of Ethrel (1/4 to 1.0 lb/A) on shoot and
root growth of young field bindweed were similar to those of mechanical
defoliation or mowing.