Vertical and horizontal spatial variability in the biodegradation of the herbicide bentazone was compared in sandy-loam soil from an agricultural field using sieved soil, which represents the method most widely used to investigate biodegradation rates, and intact soil cores. An initial experiment compared degradation at 5 depths between 0 and 80 cm using sieved soil. Degradation was shown to fo...

The recent development of genetically modified sugarcane, with the aim of commercial production, requires an understanding of the potential risks of increased weediness of sugarcane as a result of spread and persistence of volunteer sugarcane. As sugarcane is propagated vegetatively from pieces of stalk and the seed plays no part in the production cycle, the fate of seed in the environment is y...

Seeds beneath the soil sense the changing environment to time germination and seedling emergence with the optimum time of year for survival. Environmental signals first impact with the seed at the seed coat. To investigate whether seed coats have a role in environmental sensing we investigated their ultraweak photon emission (UPE) under the variable temperature, relative humidity and oxygen con...

Six species of insects and a rust fungus have been successfully established for biocontrol of the weed Parthenium hysterophorus L. in Queensland, Australia. Effectiveness of biocontrol insects was evaluated at two properties in Queensland during 1996-97 based on an exclusion experiment using insecticides. Parthenium-infested plots with and without biocontrol insects were sampled at monthly inte...

Soil seed banks are important for vegetation management because they contain propagules of species that may be considered desirable or undesirable for site colonization after management and disturbance events. Knowledge of seed bank size and composition before planning management activities facilitates proactive management by providing early alerts of exotic species presence and of abilities of...

We investigated the effects of organic and conventional pest and fertility management on weed cover and the seed bank community in an organic rotation. The study was conducted during the 4th and 5th years of an organic rotation on part of a long term organic-conventional comparison trial. Results showed that although crop type (potato vs. cabbage) in a single year significantly affected wee...

M. Brodahl U.S. Department of Agriculture, Agricultural Research Service, Water Management Research Unit, Fort Collins, CO 80526 Comparing distributions among fields, species, and management practices will help us understand the spatial dynamics of weed seed banks, but analyzing observational data requires nontraditional statistical methods. We used cluster analysis and classification and regre...

Seed banks are common characteristics to many plant species, which allow storage of genetic diversity in the soil as dormant seeds for various periods of time. We investigate an above-ground population following a Fisher-Wright model with selection coupled with a deterministic seed bank assuming the length of the seed bank is kept constant and the number of seeds is large. To assess the combine...

Ryegrass is the probably the most damaging weed to winter wheat over a large part of the high rainfall area in the central, north and east Texas. Economic losses in wheat occur through reduced grain yield, quality, foreign matter, and harvest efficiency. Yield loss can exceed 90% in heavy infestations. In addition to yield reduction, reduced harvest efficiency results in lower test weight, high...

Risk analysis can be used as a scientific tool for addressing the health of ecosystems. Here we describe a protocol for characterizing risks in the ecosystems of several polluted soil scenarios in the Madrid Community (Central Spain). Our starting hypothesis was that to recover the health of degraded ecosystems that could affect public health, an ecotoxicological diagnosis of each site is requi...