Farm Ireland

Wednesday 22 November 2017

Weather gods have smiled on winter cereals but spring crops have had a torrid time

The new Leeb GS6 Horsch sprayer which is pictured working a 125ac field of spring malting barley in Wicklow. Photo: Roger Jones.
The new Leeb GS6 Horsch sprayer which is pictured working a 125ac field of spring malting barley in Wicklow. Photo: Roger Jones.
Winter barley has thrived

Richard Hackett

It looks like the weather gods have been consulting 'the ideal weather patterns for winter cereal production' since the crops have been put in the ground. If a certain beer company did weather patterns they would have delivered what we have experienced in the last few months.

Winter barley, in particular, has thrived and the majority of crops look luxuriant, clean and just about the right height.

As the final fungicide is applied and the gate is closed until harvest, it has been a very easy season in which to grow barley.

Winter wheat is also making the most of the good weather, and with the critical fungicide application timing upon us, again crops show great promise.

Irish weather being what it is, there is plenty of time for the wheels to come off the wagon, but as we enter the winter cereal grain fill stages, the most critical stage of yield formation, crops certainly show plenty of promise.

The same however can't really be said for spring crops. While winter cereals have plenty of ground cover and established root systems to mine and make most efficient use of moisture and therefore nutrients, spring sown crops have had a torrid time emerging and establishing in the dry conditions.

Many crops of spring cereals battled hard, especially where seedbed conditions were not ideal.

Some of these crops will bear the scars of these battles to harvest, with large bare patches and uneven areas evident even after rain.

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Problems have been exacerbated with crops that have only residual pre-emergence herbicides available to them for weed control.

Residual herbicides require a film of moisture to create the necessary seal to prevent weed seeds from germinating and establishing.

When this moisture is not available, season long weed control or even control until the crop establishes is often very difficult and can be impossible to achieve.

Some vegetable crops in particular will suffer greatly as the season progresses if weeds start coming through.

Many crop types have few if any post emergence options for herbicides available to them and the ones that are available are often very specific in the range of weed they control and are often extremely phytotoxic to the crops themselves.

So the impact of the dry spell early in the season may be felt throughout the season.

Another impact the unseasonable weather has had is on pest development.


Aphids in particular have been very evident since very early in the year and at times populations have been startling.

The available armoury of pesticides to control aphids is not nearly adequate enough.

The cheap and cheerful options are not effective enough and losing efficacy at an alarming rate.

They also have very questionable impacts on non-target organisms.

More effective and environmentally benign aphicides are too expensive for broad acre use. We are approaching a point where other options need to be looked at.

When looking at the area of aphids in cereals and the spread of barley yellow dwarf virus (BYDV), there are many fundamental questions that remain unanswered:

What is the actual impact of BYDV on modern crop production?

What varieties are most prone to BYDV?

What aspects of production can be manipulated to overcome the impact of BYDV such as enhanced tillering, an improved ability to 'crowd out' affected plants etc?

What is the ability to predict BYDV levels and not just aphid levels in a season?

What are the main beneficial organisms that attack BYDV bearing aphids and how can they be manipulated at wide scale level?

Unfortunately, most of the perceived facts and assumptions we have on BYDV control are based on research carried out decades ago.

They are also predicated on the basis that effective control of the vectors of the disease was and is available for €2/acre, obviating any need to look for answers to some fairly fundamental questions.

Of all the pesticides that we apply to our crops, insecticides are by far the most troublesome in terms of effect on non-target organisms, including ourselves.

Fungicides, herbicides and plant growth regulators can attack and manipulate biochemical systems that just don't occur in bees, birds and Jimmy in the sprayer.

However trying to kill 'little animals' while keeping the 'bigger animals' standing on the sidelines in full health is a complicated business and one that costs hundreds of millions of euro in product development.

We are approaching a point where the full cost of applying insecticides will have to be paid and in this context asking some basic questions of how we control and why we control diseases such as BVDV, need to be asked.

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

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