Growers of late drilled winter rape and of spring rape are being advised not to close the gate on Sclerotinia control just yet as these crops will still benefit from effective disease control, according to Mark Hemmant, Technical Manager for Agrovista.
"The recent warmer, wetter weather pattern means a higher disease risk in both winter and spring rape and, although sclerotia germination hasn’t been as high as last year in some areas, petal tests have indicted high levels of infection are likely from air-borne spores. Last year we had a slow start to germination and then a sudden increase towards the end of May and into June as temperatures and soil moisture levels increased," warns Mark.
"Later drilled winter rape crops, those held back by pigeon, rabbit or pest damage or those further North are still flowering and are still at risk. A second fungicide spray 3 weeks after the initial treatment will prolong protection and keep the canopy green for longer. Oilseed rape, unlike wheat, continues building yield well into pod set and so requires long-lasting protection against yield-eroding diseases such as Sclerotinia and Alternaria" advises Mark.
He also points out that there is lot more spring rape in the ground this year, as a consequence of the poor establishment of winter rape. "This crop can also suffer from Sclerotinia and this year with high spore production and flowering likely to coincide the risk is a lot higher. A single treatment of an effective fungicide such as Compass (thiophanate-methyl and iprodione) at mid-flowering stage will be needed. Currently most spring crops are between 6 to 8 leaves but some are moving towards green bud."
Mark Hemmant points out that Compass and Filan have label recommendations for use in both winter and spring oilseed rape. "They have been the top performing fungicides in HGCA trials. Compass also provides good control of Alternaria and Botrytis, particular problem diseases late on in the season and in wet weather."
ADAS and BASF are continuing their Sclerotinia monitoring service and the latest reports can be found at www.totaloilseedcare.co.uk by clicking on the Sclerotinia Monitoring button on the home page. The latest bulletin headline highlights that Sclerotinia stem rot symptoms are now developing and that late infection could still occur whilst the weather is unsettled. Most crops have now finished flowering but there is still some flowering in some late crops and in pigeon damaged areas. Consider spray decisions in spring oilseed rape.
For further information, please contact:
1)Mark Hemmant, Agrovista on 07909 997580
2)BASF Technical Services Hotline 0845 6022553
