|Mint Root Borer|
|AN ABSTRACT OF THE THESIS
Michael Lee Talkington
for the degree of Master of Science in Entomology
presented on May 27 1983,
Oregon State University
Title: Effects of Tillage on Emergence of Mint Root Borer, Fumibotys fumalis Guenee, and on Other Agronomic Factors in Peppermint, Mentha piperita L.
Studies were conducted in the Willamette Valley of western Oregon to evaluate the effects of plowing (7.515 cm deep) and disking (510 cm deep) in peppermint, Mentha piperita L., on the following factors: 1) emergence of adult "mint root borer", Fumibotys fumalis Guenee; 2) suppression of common groundsel, Senecio vulgaris L.; 3) spread of Verticillium wilt, Verticillium dahliae Kleb.; 4) soil chemical factors such as pH and nutrient elements; and 5) peppermint growth, Yield, and oil quality and maturity.
Plowing and disking significantly reduced emergence of adult F. fumalis. In all treatments adult emergence peaked from early July to early August. Female emergence peaked about one week later than for males in two test plots. Populations of immature F. fumalis were
aggregated, and were not significantly correlated with populations of adults.
In one test plot, plowing significantly reduced the density, dry weight
biomass, and plant vigor of S. vulgaris. Even though plowing reduced the density
of S. vulgaris in other test plots, neither the dry weight biomass nor plant
vigor were reduced. Disking reduced stands of S. vulgaris to a limited extent.
Plowing significantly reduced false dandelion, Hypochaeris radicata L., by about
65 percent in one test plot.
Plowing resulted in a more uniform distribution of pH
and nutrients throughout the 0-15 cm soil layer. Plowed plots had higher levels of pH and
Ca in the surface 0-5 cm of soil, and higher levels of P and K in 5-15 cm of soil. In
disked plots, levels of pH, P, and K in 0-5 cm and 5-15 cm soil samples were intermediate
between plowed and untilled plots. Tillage treatments did not significantly affect levels
of Mg or B.