Oilseed rape crops are one month ahead according to Dr Caroline Young from ADAS, with some plants flowering super-early.

The advanced crop state is borne of the recent unseasonably warm weather, Dr Young suggests, and accompanying it is a significantly earlier Sclerotinia risk compared to spring 2013.

Dr Young says: "The map colours indicate how close we are to the expected appearance of the Sclerotinia fungal fruiting bodies (an apothecium).”

She recommends that growers in all areas need to review their crop risk and plan their fungicide strategies accordingly.

"Observations at BASF’s Sclerotinia monitoring sites shows that germination of apothecia has now started in all depots.”

Any crops at early or mid-flower, which are considered at risk from infection are likely to justify a foliar fungicide application now. Some crops will also be heading towards being at risk, so fungicide treatment now will also be beneficial, assuming a three week protection window for fungicides, under normal conditions.

“Crops at late flower may also benefit from fungicide treatment; they are still at risk, but late infection tends to affect more of the lateral branches and therefore not be so damaging to yield as infection that occurs early and affects the main stems."

She adds that if lodging occurs however, infection occurring at any flowering phase can then spread rapidly through a crop by plant to plant spread.

In terms of timing, Dr Young advises that the main difference for growers this year, compared with 2013, is the calendar dates for early flower fungicide applications - growers will need to be applying fungicides now, or have already applied them, rather than the more usual time of later in April or into May.

“The usual guidelines for fungicide timing according to susceptible crop stage (open flowers), inoculum risk (sclerotial germination observations and predictions, and/or petal tests) and weather conditions (warm, light rain) will still apply.“

“However 2014 conditions have seen fungicides being applied earlier, where, if no other guidelines are taken into account, oilseed rape flowering began early and continues to progress earlier than in most years. Flowering onset is variable from year to year, but, for example in most years, ADAS Herefordshire trial sites have reached yellow bud in early- to mid-April.“