Mendel

Mendel is a hybrid variety bred by LS Plant Breeding

With more oilseed rape being grown in closer rotation, club root is becoming a major limiting factor to UK crop productivity.

 

What is Club Root?

Occurring in brassica species, including turnips, kale, cabbage, cauliflower, broccoli and sprouts as well as oilseed rape, club root can also be hosted by Cruciferous weeds.

The causal microbe Plasmodiophora brassicae infects plant roots, causing irregular swellings - 'clubs' - on the roots. These reduce a crop's ability to take up water and nutrients cutting rape crop yields by 30-40% and in severe cases, causing complete plant failure.

Brassicas grown in close rotation are most at risk and greatest yield loss occurs when wet soil conditions encourage the microbe to move through the soil and invade the roots, which then dry out, putting the host under stress.

Unfortunately, the microbe can persist in the soil for 20 years or more and will reappear in any brassica crop.

Experts confirm that it can take just three years for a field with low level 1% club root expression to go to 100% infection, so growers need to be vigilant and adopt sensible agronomic practices to minimise risks.

 

Minimising Club Root

If you don't have club root, then take care to minimise any build up of the pathogen in your soils:

Reduce the number of rape crops in rotation - 1 in 5 is best - 1 in 3 is just about acceptable.

Delay sowing - but be careful not to compromise establishment prior to winter, and take steps to control Phoma.

Maintain a neutral soil pH by bringing lime back into your farming practices.

Consider mixing any lime into the topsoil by ploughing prior to drilling wheat.

Drop stubble turnips and sheep from your farm.

 

Managing Club Root

If you do have patches of club root on your farm then:

Adopt practices that won't spread spores around the farm.

Widen your rotation, so that rape only features every fourth or fifth year.

Lime fields, where possible, differentially liming patches within fields to raise pH to a standard of 6.5-7.2.

If necessary, improve field drainage.

Improve calcium and boron nutrition.

Grow Mendel.

 

What is Mendel?

Mendel is the most widely grown oilseed rape variety with proven resistance to common strains of club root.

HGCA data shows that on club root infected land, where 30-40% of plants from nonresistant varieties suffered from the disease, Mendel increased crop yields by 1.5t/ha.

Mendel offers growers a stable yield on club root infected ground and agronomically, Mendel is stiff strawed with an 8 for resistance to lodging and a 9 for stem stiffness, with good disease resistance ratings.

As a hybrid, Mendel produces vigorous early growth and strong establishment - even where club root is an issue.

However, Mendel is no substitute for poor agronomy. Always adopt practices that minimise club root build up and lessen its voracity.

"In order to maintain varietal performance and prevent the selection of resistant strains only grow club root resistant varieties where you know you have a club root problem. Ensure you get the rotation and soil pH right first," says SAC's Elaine Booth.

 

Agronomic Characteristics

Data source: HGCA Recommended List 2010/11, for Oilseed Rape North Region

	Mendel
Resistance to lodging	8
Stem stiffness	9
Earliness of flowering	6
Earliness of maturity	6
Light leaf spot	5
Stem canker	5

Widespread growing of resistant varieties where club root is not an issue could encourage the build up of resistant populations of Plasmodiophora brassicae and should be avoided.

Mendel as with any other potentially resistant variety should only be grown where there is a known club root problem.

Mendel's resistance to club root is not complete and it never has been. As a result, even in soils where club root is not a major problem, you can expect to see some symptoms, but these are usually limited to a very minor swelling of the roots and don't lead to significant yield loss.

KWS UK would like to thank the following organisations for the advice provided in this leaflet: SAC, NIAB, ADAS and also Prof Geoff Dixon, Chairman of the International Club Root Working Group.