North: Tricky timings for blackgrass control in OSR

Crop establishment so far has been excellent with good seed-beds and temperatures above average.  Many have commented how wet land is underneath when the plough has got stuck in, but careful preparation has resulted in the right result.

Oilseed rape was slow to get going, but now we have had rain crops are really growing well. Thankfully flea beetle issues have been relatively minor compared to the horror stories of crops disappearing in more southern parts of the country. Phoma has just started appearing, but has not yet reached treatment threshold levels.

Timing of herbicides for blackgrass control in oilseed rape has been difficult as there has been an early flush which emerged with the crop followed by a second large flush since the recent rains. With active ingredients such as clethodim only having contact action it has been a fine line between waiting for more blackgrass to emerge without the earlier blackgrass becoming too big. Residual herbicides such as propyzamide will feature later to provide another line of attack against blackgrass.

Early sown wheats are already tillering and had high levels of gout fly eggs laid on the leaves. Insecticides have been applied to control gout fly where egg laying was high, but to also control the aphids that have been easy to find. Slugs so far have not been too severe with September being so dry, but now that soils are wet and more recent seed-beds not so good then they could become more of an issue.

Pre-emergence herbicides have been applied to control grassweeds, with blackgrass the main target. Various herbicide stacks have been used depending on the severity of the blackgrass. Like last year it is the early sown crops likely to suffer with poorer herbicide control due to soil conditions being so dry for so long. Thankfully most growers are adopting more cultural control methods to control blackgrass rather than relying on the sprays to control it all.

Winter barley crops have established really well so far and with limited herbicide options, most were drilled in or around moisture to get the best out of the pre-emergence herbicides. A further residual herbicide will be applied post-emergence of the crop and after that it will be a case of relying on good crop competition to limit the blackgrass.

Winter beans are beginning to be planted. Drilling the correct seed rate iscrucial to avoid crops becoming too thick. At 6’ 5” tall I rarely get lost in a crop, but a thick stand of winter beans is about the only situation where I might need a compass to find my way out. Therefore, establishing a plant population of 18-20 plants/sq m is the target. Thicker crops more prone to lodging and higher disease levels. The pre-emergence herbicide is a key timing, particularly for broad-leaved weeds, as there are limited options post-emergence.

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