It was great to see mixed variety plots at the Drummonds open day recently.

A five-way mix of winter wheat and six-way mix of winter barley were displayed at the company’s site in Termonfeckin, Co Louth.

As the amount of chemistry available to control plant diseases declines and as disease resistance to chemistry increases, it is essential to try to protect this chemistry, while also finding ways to reduce its use.

Mixing varieties can help with this, as different varieties carry different disease resistance levels and so disease pressure can be reduced.

Reduced levels

Some farmers across the country have already been trying this on their farms and it is clear to see when you walk these crops how disease levels reduce as you can see an infected plant and a clean plant standing side by side.

Conros, Spearhead, Costello, Graham and Torp were in the winter wheat mix on display and all of these varieties have different disease resistance profiles.

In the Department of Agriculture’s winter wheat recommended list, Graham and Torp rate at six for resistance to septoria, while Spearhead is rated at five and Conros and Costello are rated at four.

Conros and Costello are both rated at eight for resistance to yellow rust. Graham and Spearhead are rated at seven, while Torp is rated at four.


The difference in these profiles may help to reduce or slow down the spread of disease in a field of winter wheat.

However, it is important to consider growth rates of crops and ripening times.

When varieties are mixed together, growth rates will vary within the one field and this will affect spray timings. Some varieties will not be sprayed at the optimum timings.

For example, Graham has a score of seven for earliness of ripening, while the remainder of the varieties have scores of five and six.