Autecology and population biology of dyers woad (Isatis tinctoria)

Abstract

Dyers woad (Isatis tinctoria L. # ISATI) has greatly expanded on rangelands in the Intermountain region. Herbicidal and tillage controls are not feasible on rangelands. Better knowledge of the biology of this species could help in the development of biological controls. We examined characteristics that could assist in this effort. Seed viability remained high and relatively stable, but germination decreased over a 10-month period. The seed dispersal pattern of dyers woad was best described by a negative exponential model (log₁₀y=1.92-0.02x; r²=0.60), where y equals seeds/m² and x = distance from mother plant (cm). The root system of dyers woad is dominated by a taproot with some laterals in the upper 30 cm of the soil profile. Survivorship of experimentally established populations monitored over 2 yr showed constriction at two stages: 1) germination and establishment, and 2) young rosette. The latter stage should be targeted for biological control