Farm Ireland
Independent.ie

Thursday 29 June 2017

Cool, bright conditions are the ideal

Oilseed rape in full bloom.
Oilseed rape in full bloom.

Richard Hackett

IT APPEARS there are a few more twists and turns to the story of the 2015 cropping season.

We are approaching the grain fill periods for cereal crops and the weather that occurs over the next four or five weeks will have more bearing on the final outcome at harvest time than any weather that we have endured, or enjoyed, since these crops were last autumn or spring.

The perfect weather conditions to ensure maximum grain fill is a curious mix of cool, yet bright conditions. You would expect that bright sunny weather would help grain fill.

The more sun, the more the green chlorophyll contained in plant material can work its magic to convert a useless collection of elements and nutrients into useful products, whether that's grain starch, cabbage heads or timber.

Yet the reason cool weather maximises yield production is that temperate plants such as cereals can lose a lot of moisture in warm conditions.

When air temperature increases beyond a very modest level, the plant has to decide between high growth rates or high moisture loss.

It will err on the side of caution and once the plant temperature goes beyond its limit, it will shut down completely and wait for cooler conditions to prevail before setting off again. During the summer, temperate plants will only grow in the morning and evening.

During the day, when maximum sunlight is around that you would think maximum growth is occurring, the plant is in fact in 'siesta' mode. So wave the magic wand for bright, yet cool, weather over the next few weeks.

Winter barley and oilseed rape crops are currently running the grain fill gauntlet. Most winter barley crops appear thick enough, are remarkably clean and don't seem at risk of lodging.

While they might not look to have the potential of last year, so far the omens look alright. Rape also looks to be in prime condition for grain fill, with generally thick even crops low disease levels and strong green colour.

Oilseed rape has disappointed over the last few years as the 'critical temperature before shutdown' of rape set at a very low level.

In other words, during hot weather, the rape spends most of its time asleep in the corner rather than soaking up the rays. In the bad weather years such as 2008 or 2009, oilseed rape often performed better than expected but in the hot years of 2013 and 2014, proved very disappointing. Perhaps you can't have a bumper crop of rape and winter barley in the same year?

Fungicides

Winter wheat has yet to run the grain fill gauntlet. Final fungicides are in the process of being applied, but it will be another few weeks before the newly protected leaves will be pressed into serious action to fill the multitude of grain sites available.

Crop potential to date looks good, disease levels appear manageable so far and colour has improved remarkably over the last few weeks but there still is a way to go before any eggs can be counted.

Spring crops on the other hand look to have taken a beating this May and it is highly improbable, nearly impossible, to suggest that permanent damage has not been done to yield potential.

Cereal crops have improved in colour, but they have lost a months growth in what is a very short production cycle and it is inevitable that some effect will be endured.

Crops that were seriously affected by the cold May weather are vegetable crops.

Vegetable crops are mainly developed and designed for production in mainland Europe and in order meet the specific targets when grown on a rock in the middle of the north Atlantic, everything has to work in their favour.

Especially problematic are crops planted in a programme over the spring and summer, for summer/autumn harvest, such as broccoli, cabbage and lettuce.

The regime is to plant or sow so much a week, so that at the other end of a very specific growth period, say 90 days or 110 days, there is a constant supply of product to harvest every week.

That's fine until the temperature decides to disappear for the whole critical month of May.

What happens then is a 'melodeon' effect. All the plantings back up upon one another and go completely out of sync.

Crops that should be ready are not ready, so can't be sold. Then all of a sudden two or three batches will come in together, in volumes greater than what the market can handle, so product goes unsold or prices plummet in a flooded market.

This is part of normal production of such crops, and techniques and systems are developed to counteract this. However, what was unusual this year is the length of time that the cold spell lasted, and the amount that growth suffered for so long.

So much so that normal techniques, such as covering batches with fleece, or trying to encourage crops to grow with extra fertiliser or nutrients were completely ineffective.

In such circumstances, every day is a school day.

Dr Richard Hackett is an Agronomist based in North County Dublin and is a member of the ITCA and ACA

 rhackett@ independent.ie

Indo Farming