NPZ UK breeder’s trials show up the effect of a tough season on winter oilseed varieties that rely solely on Rlm7 in contrast to the latest hybrid varieties with RlmS and Rlm12 resistance. 

“A review of the oilseed rape trials plots at our site in Cambridge shows up the pressure on some varieties in what we all know has been a tough, dry season,” comments Michael Shuldham of breeders NPZ UK.

“We have a lot of Verticillium pressure in our oilseed rape trial, and where we see a combination of Phoma and Verticillium, the results can be devastating.

“Take this widely grown variety as an example. It has Rlm7 and Pod shatter, but the stems and whole plant are dead as the plant has senesced far too early, no longer able to take up nutrients or to support itself.  

“To explain, Rlm7 is a cotelydon resistance – it acts to stop a Phoma lesion forming on the leaf, but when it’s overcome it has no effect against Stem Canker.

“We have seen a big breakdown of Rlm7 in recent years, and it is clear that on its own it is no longer enough to protect our rape crops. 

“It underlines that RlmS, Rlm12 and Verticillium tolerance are the real keys to holding onto yield all the way to harvest. 

“RlmS and Rlm12 work to stop the infection travelling down the petiole into the stem, stopping Stem Canker forming. 

“Growers need to focus very strongly on RlmS or Rlm12 backed hybrid varieties for their oilseed rape this Autumn.  it’s the best way to keep their crops as clean as possible and reduce their risk of losing out before harvest even arrives.”

“In our trials, Maverick with RlmS plus Rlm7, and our other oilseed rape varieties, such as our candidate Karat with RlmS plus Rlm12, are showing the benefits of strong stem health from these genetics,’ Mr Shuldham adds.