Weed Management in Spring Barley – June 2020

Spring barley has been growing rapidly and is mostly beyond the stage where it can be sprayed for weeds. The dry weather doesn’t favour weeds like chickweed and annual meadow-grass that are shallow rooting, they tend to die back in very dry weather. Crops have largely grown away from any weed problems.

The cut-off for many herbicides is GS 30, and the latest spring barley can be treated is GS 45, so for most crops, it is too late to do anything. For broad-leaved weeds in less advanced crops, ALS herbicides can mostly be applied up to GS39 or later.

To avoid resistance in weeds such as chickweed and mayweeds it makes sense to use both ALS and synthetic auxin-type herbicides, but this may well restrict how late they can be applied.

The use of an adjuvant helps ALS herbicides on larger weeds. However, the addition of an adjuvant will not reduce the chances of resistance development if the herbicide is used alone. Check the label.  Remember to follow washout procedures after treating spring barley with herbicide. There is a particular risk of herbicide damage where the sprayer is subsequently used to treat a broad-leaved crop.