East: Blackgrass growing out of autumn Atlantis

They say when March comes in like a lamb it goes out like a lion and that is exactly what has happened, The middle of March saw air and soil temperatures move into double figures during the day to which winter crops responded to early applied nitrogen by greening up.

Rape crops which had lost their outer leaves now looking respectable. The spring vigour of hybrids varieties is really noticeable as they have flower buds showing above the canopy. Thumbnail image for P1000232.JPGThese will be treated with a fungicide with a growth regulatory effects , plus a trace element mix containing boron. At present there is little evidence of light leaf spot. My airing cupboard is resembling a growth cabinet , with many samples of oilseed rape plants in plastic bags  in order to try and incubate the disease, at present no symptoms have been exhibited. Grassweed control has proved to be very effective, especially with the later applications of propyzamide and carbetamide. Unfortunately I will have to eat my words as I thought that the autumn applied Atlantis had worked well, however blackgrass plants that looked totally dead six  weeks ago, are beginning to show signs of recovery as small new roots are appearing and new leaves are just emerging.

The sites on which this is occurring is where the blackgrass is known to be resistant to Atlantis, and also following a robust pre/peri-emegence treatment.  I have a feeling that the residuals may have not been as effective due to the following factors:

1 High soil temperatures and high rainfall in November causing hydrolysis and degradation thus reducing efficacy.

2 High KD factor of soil locking up residual

3 Movement of residuals down soil profile away from rooting zone of the blackgrass,

This all reduces the efficacy of the residual herbicide on blackgrass, thus putting more pressure on Atlantis.

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