Aminocyclopyrachlor was developed for invasive weed control in non-cropland. Weed control, soil dissipation, and seedling grass tolerance with aminocyclopyrachlor were evaluated in field and greenhouse trials. Weed control was evaluated with aminocyclopyrachlor applied at 70 to 210 g ha-1. Absinth wormwood was controlled when treated during vegetative growth, but yellow toadflax was only controlled at flowering. Aminocyclopyrachlor alone did not control houndstongue. Aminocyclopyrachlor dissipation generally increased as either soil moisture or temperature increased. The DT50 values ranged from 3 to > 112 d. Aminocyclopyrachlor applied to cool season grasses at 91 to 112 g ha-1 provided adequate weed control and was safe for use on intermediate wheatgrass, but injured western wheatgrass. Efficacy to green needlegrass could not be determined. Big bluestem, sideoats grama, and switchgrass were difficult to evaluate due to poor grass establishment, but minimal injury was observed when aminocyclopyrachlor was applied at 91 to 168 g ha-1.

Thesis (PhD)--Montana State University--Bozeman, 2008. / Typescript. Chairperson, Graduate Committee: Lisa J. Rew. Includes bibliographical references (leaves 198-217).

There has been little documentation of the success of introduced agents for classical weed biological control. Field evaluation of an insect's establishment, spread and early host impact within its new environment must be performed before agent success can either be doucmented or predicted. Population attributes of the ednophagous biological control agent, Mecinus janthinus Germar (Coleoptera: Curculionidae), and interactions with its target weed, Dalmation toadflax, (Linaria dalmatica (L.) Mill.) (Scrophulariaceae), were explored across variable levels of resource availability and insect abundance. Patterns of population growth and impact of this biocontrol agent were very consistent throughout this study. Within four years of release, populations of M. janthinus achieved outbreak population levels and virtually eliminated the seed producing shoots from toadflax stands. There is a tight but flexible relationship between oviposition site selection and offspring performance in this endophagous herbivore, maximizing offspring survival even under moderate to high M. janthinus densities. These attributes allow M.janthinus to be an effective biocontrol agent under changing levels of resource availability. / ix, 134 leaves : ill. ; 28 cm.

A key question in biology is how changes in gene function or regulation produce new morphologies during evolution. The nectar spur is an evolutionarily labile structure known to influence speciation in a broad range of angiosperm taxa. Here, the genetic basis of nectar spur development, and the evolution of differences in nectar spur morphology, is investigated in Linaria vulgaris and two closely related species of orchid, the primitively longer-spurred Dactylorhiza fuchsii, and more derived short-spurred D. viridis (Orchidinae, Orchidaceae). Despite considerable morphological and phylogenetic differences, nectar spur ontogeny is fundamentally similar in each of the study species, proceeding from an abaxial bulge formed on the ventral petal relatively late in petal morphogenesis. However, spur development is progenetically curtailed in the short-spurred orchid D. viridis. In each case spur development involves class 1 KNOTTED1-like homeobox (KNOX) proteins. KNOX gene expression is not restricted to the spur-bearing petal, indicating that additional components are required to define nectar spur position, e.g. canonical ABC genes, determinants of floral zygomorphy, and additional (currently unknown) factors. However, constitutive expression of class 1 KNOX proteins in transgenic tobacco produces flowers with ectopic outgrowths on the petals, indicating that KNOX proteins alone are, to some degree, capable of inducing structures similar to nectar spurs in a heterologous host. Interestingly, KNOX gene expression is high in the ovary of all study taxa, suggesting that KNOX proteins may also have been involved in the evolution of this key angiosperm feature. Although principally involved in maintaining indeterminacy in the shoot apical meristem (SAM), members of the KNOX gene family have been co-opted in the evolution and development of compound leaves where they suppress differentiation and extend the morphogenetic potential of the leaf. A similar model is presented here to explain the role of KNOX proteins in nectar spur development. Co-option of KNOX gene expression to the maturing perianth delays cellular differentiation, facilitating the development of the nectar spur but requiring additional, unknown factors, to determine nectar spur fate. As facilitators of nectar spur development, changes in the spatio-temporal patterns of KNOX gene expression may alter the potential for nectar spur development and explain the critical length differences observed between the orchids D. fuchsii and D. viridis (and among other angiosperm taxa). Taken together, the available data indicate that KNOX genes confer a meristematic state upon plant tissues in a variety of morphogenetic contexts, making the gene family a potentially versatile tool to mediate a wide variety of evolutionary transformations.

Yellow toadflax, Linaria vulgaris (L.) Mill. (Plantaginaceae), is a non-native invasive plant. Rhinusa pilosa Germar (Coleoptera: Curculionidae) is a proposed biocontrol agent. Gall development by R. pilosa was described using histological methods and compared between plant populations from native and introduced ranges. Key stages of oviposition were isolated histologically to determine their importance in gall induction. Rhinusa pilosa galled and developed on four geographically distinct Canadian populations in a pre-release quarantine study. Low agent densities only negatively affected one population. High densities of R. pilosa reduced potential reproductive output and plant biomass. Conducting detailed investigations into the biology, impact, and development of R. pilosa on populations from invasive and native ranges may help predict the efficacy of R. pilosa in the field if approved for release and.goes beyond current pre-release testing requirements. / ix, 168 leaves : ill. (chiefly col.) ; 29 cm