Desiccation of OSR will be the preferred pre-harvest management option in most cases (swathing is perhaps more appropriate on exposed sites). Glyphosate is the cheapest option for desiccation but remember that it cannot be used on seed crops (or crops saved for seed). Glyphosate is not recommended if stems are heavily diseased or stems are broken or chinked; or where there is secondary regrowth of the crop. In these cases, or where crops are ripening unevenly, diquat is the preferred option.
For both products follow label guidance on timings and water volumes and observe harvest intervals. While diquat is best applied at dusk (to allow it to be distributed throughout the plant prior to being activated by light), glyphosate is best applied in the morning as efficacy can be impaired if applied at dusk.
Efficacy of both products can be enhanced by adding Companion Gold, which has full label approval for use as an adjuvant with glyphosate and diquat for oilseed rape desiccation and offers growers the unique combination of improved desiccant efficacy, yield improvement (by reducing pod shatter) and drift reduction. The reduction of spray drift in OSR is particularly important, given the height of the spray boom when
desiccating OSR, and the potential damage to other crops and non-target areas (eg field margins) caused by spray drift.
Early maturing rape varieties give a distinct advantage to farmers, allowing them to finish their rape harvest before the wheat harvest starts and giving more time for stale seedbeds for weed control and optimising drilling dates of following crops, says Mike Mann of breeders DSV. “Primus, Climber and Record are designed to appeal to a wide range of farmers, being short and stiff strawed, but without being semi dwarf and sacrificing yield. They all deliver high gross output and are early flowering and early maturing – as early as Excalibur, but with more seed and oil yield!” Mike continues. “None of these three made it into Recommended List trials as very early maturity means they are disadvantaged when trials are all cut at the same time. On farm this isn’t an issue, as growers cut when the crop is ready. We have a few hundred hectares of Primus in the ground now and Climber and Record are in several private trials, as well as being available in limited quantities to a few farmers last year. Growers have already noted all the positive attributes of this type of variety.”