III. Uptake and distribution of radioactive 2,4-D by brush species

Further evidence of the correlation between 2,4-D movement and food movement in plants was provided by tracer studies in seven species of woody plants common to California: coyote brush, arroyo willow, wedge-leaf ceanothus, manzanita, toyon, blue oak, and live oak. In addition to detailed analyses of the tracer studies in these species, the following general conclusions are presented: Contact injury is a major hindrance to the uptake and transport of 2,4-D. Soil moisture and root growth are important to 2,4-D transport and response. In evergreen species the chemical may move throughout the plant for many months, whereas in deciduous species it may move only for relatively short periods. Different species require different treatments; a single application cannot be expected to control mixed brush populations under California conditions.