GROWERS that have a problem with verticillium in their oilseed rape fields, have been reminded that there is 'n o cure.'

Neil Groom, technical director for Grainseed, added that there is no chemical that will control it and that this disease can remain in the soil for more than 10 years. The only thing you can do is to choose a variety which has proven resistance to this disease, he argued.

The AICC has done several independent trials looking at verticillium resistance this year. In this year’s trial in Sussex, the variety Mambo was one of only three varieties out of 35 tested to have zero infection. Twelve out of the 35 varieties suffered from this disease, with more than 10% infection rates. For instance, Quartz, which is known to have poor resistance to verticillium, had 25% of plants infected at 5% level.

Mambo also yielded 116% of the control and another variety, Keeper – bred by Mike Pickford – showed only 5% infection at 2.5% severity. It yielded 106% of controls.

In the Suffolk trial, severity of verticillium ranged from 4.2% to 60% and Mambo was deemed 'very good' at 15% on 13% of plants. It yielded 106% of control yield.

“Growers should be aiming to drill in the first three weeks of August into moist seedbeds. They should use an adequate seed rate (for conventionals around 100 seeds/m²) and double roll to improve seed to soil contact," said Mr Groom.

"Drilling 100 seeds m² of a vigorous conventional variety for less than £20/acre gives the best chance of establishment, whilst minimising upfront costs. If it works, you can continue on to a potential £600 plus per ha gross margin and have a proper first wheat entry.

"If the CSFB pressure is too great, you can rip it up and put in a different crop and your losses are under £20 / acre. The cultivation to establish the OSR is not wasted as it will contribute towards the seedbed for the new crop,” he argued.

“Mambo also has one of the highest disease resistance ratings for phoma stem canker (7.8 rating). It has a 6.4 for light leaf spot, which is also one of the higher ratings for this disease, too. Keeper has a 7 rating for phoma and a 6 for light leaf spot. Both varieties have a good combined disease tolerance and the resistance against phoma is multigene, so is unlikely to break down,” said Mr Groom.

Mambo and Keeper are both 'easy to manage'. “Keeper is a short variety with good stem stiffness of 7 and resistance to lodging of 8. Less lodging allows good air flow through the canopy meaning even ripening and quicker harvest," he pointed out.

"Mambo also has an even better standing power (a rating of 9 for resistance to lodging and an 8 for stem stiffness.) It has a height of 145 cm. Both varieties are low biomass varieties which helps speed up harvest, saving on time and costs.”