Recent crop monitoring has warned growers of the need to spray oilseed rape for protection against yield-damaging diseases and pests at flowering, but timing of these sprays can be critical.
"Flowering is a critical time for protecting yields in oilseed rape. This is when Sclerotinia increases, a disease that causes premature ripening, pod shatter and yield losses of up to 1.0 t/ha. Alternaria can also be a problem with losses of between 0.2 to 0.4 t/ha. This year Botrytis is also common across the UK. The recent increase in temperature has led to a 'flush' of pollen beetles. However, seed weevil and pod midge could be more damaging, responsible for yield losses of up to 0.5 t/ha. If you have already spent time and effort getting the plant root and canopy structure right for maximum yields, this is not the time to take your foot off the pedal," advises Diane Heath, Oilseed Rape Product Manager for BASF.
Travelling through the rape crop at flowering needs justifying and this starts with high levels of disease control. "Filan (boscalid) gives excellent control of all three flowering diseases - Sclerotinia, Alternaria and Botrytis. Most importantly this year, its valuable persistent control and flexibility of application from late yellow bud/early flowering onwards helps growers to manage their crops. Early flowering applications cause less damage than later applications (about 1% at early flowering, 3% at late flowering)," reminds Diane.
In BASF trials, Filan gave a consistent 97% control of Sclerotinia at both early flowering and at full flower, whereas Amistar (azoxystrobin) gave only 73% control at the earlier timing and 84% at the later timing.
"The performance was reflected in yields with Filan producing a 5.1 tonne per hectare crop at the earlier window and 4.6 t/ha at the later window, compared with 4.5 t/ha at both timings for the strobilurin. This shows the superior persistence and performance of Filan during the flowering period and offers growers that bit more flexibility. The spray window for this protectant fungicide is from early flowering (GS 63) to the later timing of 50% pods at final size (GS 75)," explains Diane.
Filan is also bee-safe when mixing with most pyrethroids, unlike triazole based fungicides such as Proline (prothioconazole) and Priori Xtra (azoxystrobin + cyproconazole). With pollen beetle, seed weevil and pod midge all potential problems this year in rape, the timing of fungicide and insecticide may coincide and if it does, Filan can be mixed safely without any reduction in bee safety. However, in line with good practice, growers should inform bee-keepers of their intention to spray the crop in flower.
According to Ms Heath, the use of Filan (boscalid) also leads to increased yield potential due to its proven physiological effects. "In presence of disease, Filan produces an average of 0.5 t/ha extra yield but in absence of disease it produces 0.3 t/ha extra yield compared to untreated crops. This yield boost has been shown to be due to Filan's ability to reduce of ethylene production and keep chlorophyll levels high through the critical pod fill stage. Ethylene is produced during periods of stress such as drought and can initiate early senescence and premature ripening. Reducing ethylene production increases photosynthesis and prolongs seed fill which results in a yield boost."
"So Filan keeps the canopy green for longer through effective disease control and by reducing premature senescence and pod shatter. It also builds the yields by its proven physiological effects through the critical pod fill stages. In addition it has a flexible spray window, one hour rainfastness and can be mixed with most pyrethroids for combined disease and pest control," concludes Diane.
