abstract in order to determine efficacy of some registered graminicides in control of resistant and susceptible ryegrass biotypes, two greenhouse trials were conducted at weed research department of iranian plant protection research institute during 2007. experimental design was completely randomized design with eight replications. the susceptible and resistant biotypes were treated by 19 herbi...

A wild population of a plant species, especially a cross-pollinated species, can display considerable genetic variation. Genetic variability is evident in differential susceptibility to an herbicide because the population can show continuous phenotypic variation. Recent, recurrent selection studies have revealed that phenotypic variation in response to low herbicide rates is heritable and can r...

Herbicide rate cutting is an example of poor use of agrochemicals that can have potential adverse implications due to rapid herbicide resistance evolution. Recent laboratory-level studies have revealed that herbicides at lower-than-recommended rates can result in rapid herbicide resistance evolution in rigid ryegrass populations. However, crop-field-level studies have until now been lacking. In...

A general model of crop yield response to herbicide application is proposed. The model includes three components: the effect of herbicide dosage on weed density, the effect of surviving weed density on crop yield and the effect of herbicide directly on the crop. The model is used to estimate the response of wheat yield to application of diclofop-methyl to control ryegrass .(Lolium rigidum) in A...

A single herbicide (Trimec or Strike 3 ) application in early season (March or April) was made to marginal areas around Þelds in 23-km test sites of the Mississippi Delta in 1999, 2000, and 2001. The herbicide was used to kill broadleaf weeds in the marginal areas that served as hosts for tarnished plant bugs, Lygus lineolaris (Palisot de Beauvois). The herbicide treatment caused a signiÞcant r...

Bermudagrass is often overseeded with a cool-season grass species in the fall to provide a green surface during cool weather. Recently, two new turfgrass species, meadow fescue and tetraploid ryegrass, have shown promise for use in overseeding situations. The objective of this study was to determine the performance of herbicides commonly used to remove (transition) perennial ryegrass from an ov...

Herbicide resistance in annual ryegrass across southern Australia is currently a major issue for grain producers. Currently annual ryegrass (Lolium rigidum Gaudin) has evolved resistance to all post-emergent herbicides that can be used to control it in cereal crops and to the pre-emergent herbicide trifluralin. No new herbicide modes of action for the control of annual ryegrass have been market...

Results are presented from a three gene population genetics and dynamics model of herbicide resistance in annual ryegrass. The models predictions are compared with those of other one and two gene resistance models to validate the modelling approach which will ultimately be used to develop a five-gene herbicide resistance model. The importance of initial gene frequencies for resistance in unsele...