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Saturday 29 April 2017

Tillage: April's bitter weather did us a favour by putting a halt to the gallop of disease

EU Agriculture Commissioner Phil Hogan with Abbey Machinery's managing director Clodagh Cavanagh, former managing director Charles Cavanagh and director Owen Cavanagh at the official opening of the new Abbey Machinery factory in Toomevara. Photo: Alf harvey/HRPhoto.ie
EU Agriculture Commissioner Phil Hogan with Abbey Machinery's managing director Clodagh Cavanagh, former managing director Charles Cavanagh and director Owen Cavanagh at the official opening of the new Abbey Machinery factory in Toomevara. Photo: Alf harvey/HRPhoto.ie

Richard Hackett

The inclement April weather, from very wet to very cold and anything in between, slowed down progress on all tillage fronts, but all that's in danger is not lost.

It's early in the season and there is no evidence that permanent damage has occurred, and in some instances the inclement weather could actually have improved crop prospects.

Winter wheat sown last autumn into excellent conditions basked over a very mild winter and bounced in to the early spring far too strong for comfort.

Indeed in my article in mid-February, I talked about the 'rude health' of crops and that the threat from septoria proliferation was real. The Irish climate soon saw to that and crops became very open and thin and sat suspended in development for nearly six weeks.

Now that growth has again commenced, winter wheat crops are thin and development stages are still stacking up. However, these thin crops could well be a blessing. Thin crops are not ideal environments for disease spread.

Cold weather over the last month has also helped put a halt to the unbridled gallop of septoria spread, so while there is plenty of disease present which remains a threat to the emerging second and flag leaves, the balance of power is more in favour of good disease control than it appeared two months ago.

While it can be argued that thin crops may not have the number of heads per unit area necessary for maximum yield, wheat has a huge ability to compensate over the course of a season.

A deficiency in the numbers of heads can be made up for in the number of viable grains and the weight of these grains produced in these heads, so it's back to the grain fill period in mid to late June/early July to decide whether the yields of the last two years can be equalled, or even bettered in 2016.

The thickness of winter barley crops seems to be maintained over the cold spell and many crops retained a good colour over the period.

Rhynchosporium is an issue in some crops, even where treated, but again, the improvement in weather came just in time and the net effect of the cold spell may well be thicker more sturdy crops less likely to lodge, but time will tell.

Barley has much less capacity to compensate for poor numbers of heads per unit area and if the crop had to jettison tillers in order to keep the main tillers alive during times of stress, yield effects will accrue.

Some winter oat crops looked alarming earlier in the spring, as they turned completely yellow and looked like they were finished. Questions were asked. Diaries, recommendations and empty cans were anxiously checked to ensure nothing untoward was applied.

It might have been as a result of sodden roots, temperature fluctuations, frost damage on soft growth, or a combination of many factors, but most have thrown out new leaves of reassuring rich dark green colour and it remains to be seen whether any long term damage has occurred.

As of now, however, yield potential appears to have been restored.

I don't think the same can be said for some winter oilseed rape crops however. Normally oilseed rape can grow quite well in cold conditions, but many crops this year appeared to struggle.

The main culprit appears to be pigeon grazing and some fields were grazed in very unusual patterns. In some cases there were very distinct parallel lines in the field, where regular sized widths were grazed to the clay, while adjacent bouts were allowed to continue growing quite well.

Sometimes these bout widths matched the direction of planting and tramlines, sometimes not. Sometimes they even matched planting directions of previous year's crops. Pigeons like to graze in bare or weaker areas where it easier to keep a look out and also easier to land and take off from, so they always tend to stay in grazed areas and decimate that area before being forced to move on to 'more lush' areas.

That doesn't explain why they initially selected areas in parallel bouts across a field. Perhaps there is a fertility issue and some areas were growing more rapid than others from the get-go of the crop.

Alternatively, there may have been an uneven application of fertiliser or lime previously that now puts a taste in the crop that they select for or select against.

Either way, uneven crops can be very difficult to manage and its difficult to see that as we approach mid-May, where these crops haven't evened up, that there is not some long term yield effect.

Dr Richard Hackett is an agronomist based in north County Dublin and is a member of the ITCA and ACA.

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