Harvest 2013 is likely to be late and the pressure will be on to get next season’s crop back in leaving a narrow window of opportunity to prepare for the following crop.

After such a challenging year it has been necessary for many growers to adapt rotation plans. In order return to the original plan, Brian Ross, an agronomist with Frontier, cautions growers to take into account herbicide history and the possible impact of the previous season’s herbicides on the following crop.

Brian explains: “The crop that is most likely to be affected is oilseed rape particularly as the preferred method of establishment is using non-inversion techniques. Where tank mixing or sequencing issues arise, the label will dictate how a following crop should be established and often that brings a requirement to cultivate to a depth of at least 15cm. Many herbicide products will have been applied much later than is usual in spring 2013, making following label instructions is vital this year.”

Which products and crops are affected?

Late applications of iodo/mesosulfuron products, such as Atlantis or Pacifica, in a dry summer can adversely affect the following rape crop if the soil is not disturbed to a depth of at least 15cm, as advised on the label instructions.

Any use of products containing DFF brings a requirement to plough down to a depth of 15cm. DFF contained in Othello (iodo/mesosulfuron/DFF) has potential to cause bleaching of the cotyledon if soil is not sufficiently distributed. Although this bleaching will normally be outgrown in an ‘average’ year, late crops this season may mean this is not the case highlighting the importance of following label advice carefully.

“Some growers may have managed to avoid any crop damage where DFF has been applied in the past but this will usually have been where application took place earlier than this year,” says Brian.

Where other SU weed killers have been tank mixed or sequenced there is no evidence to show problems will arise.

Where straight SUs only have been used, such as Biplay or Ally, there are no establishment issue for following rape or beans. A dry, late spring/summer could cause issues to arise with following crops where growers have applied Lexus in autumn 2012 and sequenced with another SU. Again, this will all be ameliorated by soil disturbance.

Unite, Broadway Star and Sunrise do not have any special cultivation requirements if used alone. However, when applied in sequence with a straight metsulfuron based product the label states a requirement to plough to 15cm, whereas non SU sequences have no following crop restrictions.

Where Galaxy has been applied in spring 2013, pulses should not be drilled in the autumn. However, there are no cultivation restrictions for cereals or rape following Galaxy.

With the emergence of the anaerobic digestor market, maize is rising in popularity and is generally followed by cereals. Though an unlikely choice, where rape is selected to follow and Callisto/Calaris/Peak was used on the previous maize crop, ploughing will be required. Where Samson has been applied, oilseed rape should not be considered as the following crop.

Where Cadou Star has been used on maize, surface cultivation or ploughing will be required for wheat and ploughing for oats and barley. Rape should not follow use of this product.

Where Linseed has been grown and metsulfuron applied, only cereals should follow and this remains the case for 16 months from the date of application.

In cases of pea and bean crops that have been treated with Nirvana, rape must not be drilled as a following crop. Again, only cereals should be drilled with soil disturbance to 15cm.

Linzone and Cirrus treated crops carry a requirement to cultivate to 15cm before the following crop, especially in the event of a dry late spring/summer.

“In essence, check with your agronomist and read the labels carefully before drilling crops such as rape or beans. In my opinion the more cultivations, the safer the outcome – especially this season,” cautions Brian.