In every disease programme, one important target is to get the crop to a good finish, with a high level of disease control to enable it to realise its full yield potential. That said, crop yield is also greatly determined by weather and the level of sunshine, temperature averages and moisture availability.

2018 – unique weather

In 2018 we had unusually high sunshine levels, but we also had crop stress related to high temperature spikes and moisture stress. Both had a very dramatic effect on crops, reducing grain-fill duration and grain yield by 10-30% depending on the crop, sowing date and location. In the exceptional weather of summer 2018, the final spray on crops was therefore not very important, and had little consequence on cereal yield. So it was a rational cost saving to use less fungicide in the year that it was.

2019 – how to target wheat

For winter and spring wheat there are two key targets with late-season disease control – septoria and ear blight. The fungicide products used at these timings are good dual-purpose options, but higher rates of key triazole-based products, like Prosaro, are more likely to be needed to ensure a good level of ear disease control. The septoria control from well-timed T1 and T2 treatments should be good this year, as weather is favourable for good disease control. So one might expect that a contact fungicide like chlorothalonil (CTL) would only be needed at T3, if there is disease clearly in the upper crop canopy.

The triazole should give an adequate level of mildew control if it is showing in the crop, but extra spend on extra control of this disease is rarely cost-effective. So, target your spend on the wet-weather diseases, as they would be the yield robber if the summer turns wet and challenging. A good triazole rate will also do very well on rust diseases, should they occur.

Spring barley – delivering yield and quality

The 2018 experience with spring barley was a reminder of the benefits of a cool, moist climate for this crop. The crop only reached 50% of its potential on many farms, due to weather-related stress. Last year reminded us that this crop has high yield potential in Ireland, and a good basic disease control programme can ensure that this is realised.

Current chemistry options remain excellent on barley diseases. A straightforward and well-timed programme can give the crop good insurance at a modest cost. There are many fungicide options which range from very good- to -excellent for T2 on spring barley.

Is prothioconazole needed at T2? If there is lively rhyncho in a crop, then it should go in. If it was used at T1 and worked well, then it is likely to be less critical to include it at T2. But a triazole should be used at T2, so a reduced-rate prothioconazole is still the best option, unless disease pressure is very low.

Is Bravo/CTL needed? A definite yes. It is excellent on ramularia leaf blotch and at 1.0 l/ha, it is the most cost effective insurance spray in crop protection currently. It is also important to plan for when chlorothalonil is no longer available, so use folpet (Phoenix) on some of your crop to get a feel for how it works as an alternative. It is good on leaf blotch control but only expect 65-80% control compared to 80-90% with Bravo.

Should SDHI be used? SDHI fungicides are good on barley and have good spectrum, but the loss of ramularia control is a real blow which makes their automatic inclusion questionable. However, they are good at modest rates and it is better to use them at reduced rates of 50-60% than to leave them out, as they will deliver good yield and quality in a demanding summer.

Is there a role for strobilurin at T2? That’s a more difficult question. The practical reality is that it probably depends on product options, as it is likely to be a fourth mode of action if it goes in. Strobilurins are effective and useful on barley, especially on rusts and net blotch. It is usually not a significant extra cost, but one should still have a technical basis to justify its inclusion.

Oats – keep it simple

It is very important to finish oats well and fungicides remain very effective. The key products available are superb on rust and good for grain colour and quality delivery. So get the basics right and don’t short change the crop.

A modest spend can give a good outcome. Just get the timing and details right and don’t do any silly rate reductions, which will take out colour benefits in a wet harvest period.

Barra is a unique variety and may need extra attention, but it is grown by experienced growers who know its unique requirements. It should be treated properly, be that for extra mildew or rust control.

In summary

Dry, early seasons and low disease pressure can prove tempting to save on finishing fungicide sprays, especially on spring cereals. This can easily prove to be false economy when the summer turns wet and there are many cost-effective options that growers can consider.

While final spray timings and products will differ with the different crops, protection to the end is an integral part of potential yield delivery.