Last week saw the start of the Teagasc spring crop walks across the country.

The Irish Farmers Journal travelled to Teagasc Oak Park on Wednesday 8 May where there were a host of crops to see.

The farm is the home to crops research and tests the newest technologies, but the weather has hit all farms this year and Oak Park was no different.

Timings of fungicides and herbicides were all hard to get right, but they did manage to get barley planted in March on some drier ground.

Spring barley

Barley sown in March at Oak Park was very advanced. However, it was not hitting targets.

A plant count in the field showed 250 plants/m2, where the target is 300 plants/m2.

Teagasc’s Shay Phelan commented that it was too late to roll the crop to promote tillering.

Plant growth regulator was the other option and would need to be applied as soon as possible to increase tillering. CeCeCe is the best option here.

Crops should grow quickly this season, as they are planted later and temperatures are increasing so there will be a lot of things to control and try to prevent in a short space of time. In order to reduce stress big tank mixes could be avoided.

The aphicide could be applied on its own or along with a plant growth regulator or possibly a wild oat spray, but you would need to be confident that the wild oats are up.

The annual meadow grass was controlled two weeks after herbicide application.

Canary grass

If canary grass is an issue on the farm then this timing is probably too early for applying Axial Pro to control wild oats and canary grass, as canary grass takes longer to emerge.

Barley yellow dwarf virus

The majority of crops are at high risk of barley yellow dwarf virus (BYDV) infection this year as they were sown in April and May. Crops planted in March are at low risk and do not require an aphicide.

New research into BYDV and aphids is ongoing at Teagasc, but there is not enough data gathered to change any advice being given at present.

Therefore, the research being used dates back to 2008.

At the walk, Teagasc showed figures from this research explaining that the best timing for aphicide application is the four-leaf stage using a full rate of insecticide.

Table 1 shows that when crops were sprayed when they have four leaves it was the most economical.

The percentage of BYDV infection was 8.6% and the yield was 5.6t/ha when treated at four leaves.

There was no advantage to yield with two applications and two applications can also contribute to the buildup of resistance to pyrethroid sprays in aphid populations.

In fact, there was no advantage to yield where four sprays were applied.


Where crops were untreated in this trial, the percentage infected was 36.4% and yield was 1.3t/ha lower than at the optimum spray timing of four leaves.

It was suggested to monitor how the aphicide worked in the week after application. That is, check if dead aphids are present.

A lot of crops will now be at the three- to four-leaf stage or coming near it. Some earlier-sown crops may be passed it so watch the timing of this spray.

At this stage, you could also add in nutrition for known deficiencies such as magnesium and manganese.

Weed control: key steps

  • Weed control should consist of a sulphonyl urea and a mix partner like fluroxypyr (Starane, Binder) which should be used on resistant chickweed or an arylex based product like Pixarro.
  • Galaxy which contains fluroxypr, clopyralid and florasulam will control corn marigold and thistles.
  • If mixing in Axial Pro for wild oats then increase the rate to 0.6l/ha.
  • A rate of 0.4l/ha can be used before GS29 where the product is applied on its own, but the higher rate is needed for canary grass.
  • Winter barley

    Winter barley is at its final spray timing across the country. Awns are emerging and in some of the earlier varieties like KWS Joyau the head is fully emerged.

    Many final sprays have been applied in the passed few days. At last week’s crop walk, Teagasc noted that the key timing for this fungicide is when the crop is at the paintbrush stage.

    Awns emerging on winter barley in Teagasc Oak Park, Co Carlow on 8 May 2024. \ Claire Nash

    The awns are emerging. Shay explained that this timing is important to prevent Ramularia in the crop, so you will not know the impact a late application will have until it is too late as when Ramularia appears it is too late to control.

    Folpet at 1.5l/ha plays a key role in Ramularia prevention, as well as helping to protect chemistry from resistance. It should be applied with an azole, along with an SDHI or a strobilurin.

    Chemistry should always be mixed and alternated as much as possible. There are numerous options to choose from.

    Where does barley yield come from?

    The green leaf area allows the plant to photosynthesise, feed itself and therefore create yield.

    At the crop walk, Shay explained that 78% of barley yield comes from the bottom leaves and the stem.

    So this is very different to wheat where the focus is on protecting mainly the top leaves of the plant.

    Approximately 36% of yield comes from the stem, 16% from leaf five, approximately 26% from leaves three and four and about 7% from leaf two, less than 5% from leaf one (the flag leaf) and approximately 12% from the ear (Figure 1).

    Winter wheat

    The crop of winter wheat we looked at was Graham, which was planted in October. It received its weed spray two weeks ago and the annual meadow grass was dying.

    Winter wheat in Teagasc Oak Park where the T1 was delayed.

    It had been due its T1 the previous week, but rain delayed application. It was due to be applied on 8 or 9 May last week.

    The flag leaf was beginning to peep on some of the crop and would most likely be fully out around 20 May.

    Shay said that the flag leaf spray should be applied then, even though the sprays will be less than two weeks apart. He added that product rates should not be compromised in the shorter window.

    The flag leaf was starting to emerge on the winter wheat crop, but will not be likely to be fully out until around 20 May.

    Both the T1 and T2 sprays should contain folpet at 1.5l/ha along with an azole and an SDHI. There are many different options.

    Different chemistry should be used on both sprays to prevent resistance buildup.

    Spring beans

    There was bad bean weevil infestation in the spring beans in Oak Park which were planted a month ago. The only option here was to spray.

    Spraying should take place when notching is visible. However, it should be noted that often times bean weevil infestation may not be very bad with notches here and there but, in this case, as can be seen in the picture the infestation was all around the leaf.

    Bean weevil damage on the leaves.

    A pre-emergence herbicide had taken care of broadleaved weeds. Any grass weed control will need to be completed before flowering and fungicide should be applied at the start of flowering.

    Advice is going to differ greatly this year from farm to farm and within farms. No doubt people are thinking of reducing spend on crops, as yields may be impacted by late sowing, but some things should not be cut back.

    Take spring barley, for example. Nitrogen can probably be cut a little bit where the yield is expected to be lower than usual, but if your field has a manganese deficiency this cannot be ignored and should be treated early with the aphicide spray and again possibly at the weed spray or wild oat spray, if it is carried out separately.

    Teagasc advice is to apply the T1 fungicide from mid-tillering and this is based on years of research. However, we also need to consider the year and the farm situation.

    Some fungicide with the weed spray, particularly where the herbicide is being delayed to wait for later germinating weeds, may be a good idea to keep tillers clean.

    Crops are likely to grow very fast this season and if showery weather arrives, it is better to have crops protected, particularly given how much the lower leaves of barley contribute to yield.

    You can hear more from the crop walk on the Irish Farmers Journal Tillage Podcast here.