Fusiform Rust Incidence in Loblolly and Slash Pine Plantations in East Texas

A method to predict the incidence of fusiform rust (Cronartium quercuum [Berk.] Miyabe ex Shirai f. sp. fusiforme) in unthinned loblolly (Pinus taeda L.) and slash pine (Pinus elliotti Englem.) plantations located on non-oldfields in East Texas is presented. In addition, procedures are described to estimate changes in rust incidence over time as: 1. A rust-free tree remains rust free, develops stem or branch galls, or dies. 2. A tree with branch galls remains with branch galls only, develops stem galls, or dies. 3. A tree with stem galls remains with stem galls, or dies. Multinomial logistic regression models utilizing basic plantation parameters as predictors were fit to estimate current rust incidence and, then, the change in rust condition over time. South. J. Appl. For. 15(2):79-84

Characterizing Fusiform Rust Incidence and Distribution in East Texas

Three measurement cycles were completed on an extensive network of loblolly( Pinus taeda L.) pine and slash (Pinus elliottii Engelm.) pine plots in industrial plantations throughout East Texas in 1984, 1987, and 1990.Because the incidence of fusiform rust caused by Cronartium quercuum [Berk.] Miyabe ex Shirai f. sp. fusiforme had been recorded at each measurement, it is possible to characterize the temporal and geographic distribution of fusiform rust among these industrial pine plantations in East Texas. Average rust incidence for each species by two year age classes is presented. For loblolly pine, there is no apparent change in overall average incidence between 1987 and 1990, whereas for slash pine, there is an apparent overall average decline of about 7-8 percentage points. For some slash pine age classes, the incidence decline is 20-30 percentage points. Loblolly and slash pine rust incidence maps depict the geographic distribution of rust infection by plantation age groups in East Texas. South. J. Appl. For. 18(1):29-3

Constraining the Littlest Higgs

Little Higgs models offer a new way to address the hierarchy problem, and give rise to a weakly-coupled Higgs sector. These theories predict the existence of new states which are necessary to cancel the quadratic divergences of the Standard Model. The simplest version of these models, the Littlest Higgs, is based on an $SU(5)/SO(5)$ non-linear sigma model and predicts that four new gauge bosons, a weak isosinglet quark, $t'$, with $Q=2/3$, as well as an isotriplet scalar field exist at the TeV scale. We consider the contributions of these new states to precision electroweak observables, and examine their production at the Tevatron. We thoroughly explore the parameter space of this model and find that small regions are allowed by the precision data where the model parameters take on their natural values. These regions are, however, excluded by the Tevatron data. Combined, the direct and indirect effects of these new states constrain the `decay constant' f\gsim 3.5 TeV and m_{t'}\gsim 7 TeV. These bounds imply that significant fine-tuning be present in order for this model to resolve the hierarchy problem.Comment: 31 pgs, 26 figures; bound on t' mass fixed to mt'>2f, conclusions unchange