According to James Boswell, Hutchinsons agronomist in Kent, most winter oilseed rape in the region is looking very good.
Flea beetle levels have been higher this year but not terrible, on inspection fewer larvae in petioles. Many fields had previous crop straw removed before drilling, which helped rapid establishment, and most fields had a GAI around 1.5 in February.
As weather turns colder, pigeon damage is increasing. Disease levels have been low, with Phoma present in the autumn in areas with 12 inches of rain during November/ December. Astrokerb (propyzamide and aminopyralid) is working well on black-grass, with swollen stems already obvious. Some people have not needed to apply fungicide this autumn, due to low disease levels. Autumn PGR’s have been successful; Caryx (metconazole and mepiquat chloride) was used at 0.75l/ha on the strongest crops.
As data builds over the years, it is clearer that basing N requirement on GAI alone is fraught with inconsistencies and canopy weight is far more accurate measurement. Nitrogen slots should be driven by the target GAI required at mid flower (3.5-4) with the remainder timed as late as possible to feed pod fill and oil production. Sulphur should be applied at early stem extension as base sulphate around 85kg/ha SO³.
Light Leaf Spot is the target spring disease and fungicides can be applied from mid-February or when infections are seen. Fungicide should also have effects on Phoma, so prothioconazole based products are preferred.
Magnesium and Boron will be needed in most crops and growers should test for this. Magnesium deficiency symptoms can be confused with more serious TuYV infections and, as peach potato aphid catches were 'off the scale' last autumn, virus infections are potentially high.
James stresses that spring PGR’s in rape is about managing the flowering canopy to maximise light interception, and not trying to shorten the stem. For large crops Caryx at early green bud and Circle (trinexapac) at late green bud. For average crops, Circle only at late green bud.
He has seen a significant increase in Clearfield crops this year. Agronomically they are treated the same as non-Clearfield ones in the spring.