2.3. Pesticide application
Treatment applications at the V3 soybean growth stage were
made when weeds were 10–15 cm in height while R1 applications
were made when weeds were 25–36 cm in height. Typically,
soybean at the V3 growth stage are 18–23 cm tall and leaflets on
the first (unifoliolate) through the fourth node leaf are unrolled and
typically occur 30–35 days after planting. At the R1 growth stage,
soybean plants are typically 38–46 cm tall and are vegetatively in
the V7–V10 stage (7–10 nodes are fully developed). Flowering
begins on the third to sixth node of the main stem, depending on
the vegetative stage at the time of flowering, and progress upward
and downward from there. Usually this stage begins about 45–50
days after planting (Ritchie and Benson, 1994).
Glyphosate alone or in combination with various fungicides
were applied in water with a CO2 backpack sprayer using Teejet
11002 flat fan nozzles (Spraying Systems Co., North Avenue and
Schmale Road, Wheaton, IL 60188) which delivered a spray volume
of 140–190 L/ha at 180–315 kPa. Soybeans were harvested at Yoakum but not at Tifton. Harvesting was accomplished with a small
plot combine and yields adjusted to 12% moisture.