Tillage management: Herbicide options for winter crops

Poor ground conditions over the winter left many crops without a herbicide. Although farmers are eager to get out with sprayers, ground conditions are not suitable for work in many areas.

While ground conditions are poor, temperatures are also fluctuating. The average air temperature in Oak Park, Co. Carlow, for March – so far – stands at 4.4°. Soil temperatures are not available for March.

However, the average soil temperature for February stood at 2.5° and the average air temperature in February was 3.6°. Plants will react better to herbicide application when they are actively growing.

Herbicides can often be harsh on crops and set them back. It can be hard to get the balance right; while waiting for optimal application conditions, weeds may be getting stronger.

Winter wheat

Growers with an annual meadow grass problem in winter wheat have a few options. Monolith is a new product from Bayer with good annual meadow grass and sterile brome control at this time of the year.

It can be applied from February 1 up until GS32 (growth stage 32). Broadway Star remains a good option where sterile brome is an issue. This also has good control of many broad-leaved weeds.

Growers will need to mix products where cleavers are an issue. Zypar, a new product from Dow AgroSciences, gives good control of cleavers, volunteer beans and oilseed rape.

Image source: Shane Casey

Where a clean-up of broad-leaved weeds is needed, in crops which were sprayed in the autumn/winter, temperature will have a large effect on herbicide options. Many of the sulphonyl-urea products, such as Ally and Cameo, work best in warmer temperatures.

Weeds like cleavers are easier to control in warm conditions. They can be sprayed later in the season, where a herbicide has already been applied in the autumn.

Winter barley

Winter barley has fewer options for annual meadow grass control. However, Firebird can still be used up to March 31. A clean-up of the crop can be carried out with sulphonyl-urea based products. In instances where cleavers or chickweed are a problem, Zypar is an option.

Winter oats

Weeds in oats can be controlled with a sulphonyl urea like Ally Max. CMPP or a chloropyralid product should be applied with it.