Crops have come through the winter with excellent potential, but carrying high levels of foliar disease. We asked four consultants how they will protect and maintain yield in the UK’s three most important crops this season.

See also: New OSR flowering spray boosts yields by 0.23t/ha

Wage war on septoria in the South West

As with most years in Devon, last season was a challenging one from a septoria point of view.

Historically, our response to fungicides is in the region of five times more than in the drier East.

The best trial result I have ever seen was a response to fungicide in Riband that gave a 4,800% yield response over untreated.

My starting point for septoria control is variety choice – one with a Recommended List resistance score of at least 6, preferably 7. Next, matching the plant population and drilling dates is crucial to avoid crops that are too thick.

Disease control starts with a robust T0 application, which will be a multisite and a more active septoria azole such as epoxiconazole or prothioconazole.

A standard T1 application will now be a robust dose of triazole and SDHI, applied at GS32 and three weeks after the T0.

Arguably there is now a case to apply a T1.5 midway between T1 and T2, given the declining performance of the triazoles. This application would probably be a multisite, such as chlorothalonil.

The T2 flag-leaf applications will happen at GS37 to 39 and will again be an azole/SDHI combination, possibly in mix with another multisite active, depending on disease pressure.

A T3 spray in the South West is as much about septoria control as ear disease management.

If there is significant rain in the flowering period a fusarium active triazole will be used; if there is no rain then septoria remains the main focus of the application.

In some respects we are lucky in the South West. There are no judgement calls to be made; we just wage war on septoria.

Score a disease double at OSR stem extension

The season of 2013-14 gave us unprecedented levels of light leaf spot in the south of England.

It has traditionally been associated with the North or Scotland, but we have always had small pockets of it along the South Coast.

With this winter setting off on a similar pattern to last, we all anticipated a similar seasonal outbreak.

Where phoma sprays were used, products that also had some effect on light leaf spot were always preferred.

Difenoconazole, relatively cheap and good on phoma, does diddly-squat on established light leaf spot and so was restricted to situations where phoma came in early.

Prothioconazole, having good effect on both phoma and light leaf spot, was probably the product of choice later in the season.

However, with rape prices where they are at the moment, restricting the cost of inputs has been as big a focus as the disease itself.

Unlike last year, this winter we have had a significant cold spell. The light leaf spot does not appear to have exploded quite as dramatically as before but there is still a risk.

Consequently my strategy will be to start sclerotinia protection with products that will still help against light leaf spot.

An obvious candidate will be prochloraz, which is available on its own. It is better still when pre-formulated in a mixture with tebuconazole.

The two together at stem extension – with tebuconazole rates adjusted according to how much plant growth regulation effect we want – will be a firm foundation on which to build our sclerotinia and alternaria protection.

We can no longer think about MBC fungicide carbendazim in our strategies. We do, however, have thiophanate-methyl.

Unfortunately, its ridiculous cost means that, if I use it, I will be saving it for the mid-flowering spray, probably in mixture with good old tebuconazole.

As with most arable inputs, timing is more important than product, and prevention is better than cure.

Key oilseed rape disease risk periods
Disease	Risk period
Phoma	October to November
Light leaf spot	November to March
Sclerotinia	March to late April
Alternaria	May to June

Septoria and yellow rust present in eastern wheats

Present disease levels remain much as they did before Christmas. Within the base of the canopy, many wheats are exhibiting high levels of septoria and yellow rust – my two main targets at T0.

For its protectant qualities, chlorothalonil will be the core T0 application.

For yellow rust, azoles all fit, but I’m a fan of the strobilurins at T0 – they easily dry out yellow rust and give a physiological boost, encouraging rooting and nitrogen scavenging – crucial for bringing a struggling crop out of the winter.

Septoria is my main target at T1, but yellow rust, fusarium and eyespot all pose a huge threat once again in 2015. Minimum 85% doses of high-end triazoles such as epoxiconazole or prothioconazole are therefore my preferred choice, alongside SDHIs.

As eyespot is a threat, it will either be 1.5 litres/ha Tracker (boscalid + epoxiconazole) or a minimum of 0.6 litres/ha prothioconazole plus SDHI. Eyespot cannot be ignored and these are the only two real options.

Some manufacturers say there’s no hierarchy among SDHIs on septoria – but some are more equal than others.

HGCA data places fluxapyroxad and bixafen at the top, with prothioconazole and epoxiconazole being the two best azoles on septoria, so combinations of these are my base – plus chlorothalonil, particularly if the season is wet at GS31.

At T2, 85% minimum doses of prothioconazole or epoxiconazole again form the core of my flag-leaf programme, with fluxapyroxad or bixafen.

Bayer does not back the inclusion of chlorothalonil with Aviator (prothioconazole + bixafen) and, as chlorothalonil can slow triazoles in an eradication scenario, it’s probably better to go with higher doses of septoria-active triazoles such as prothioconazole or epoxiconazole if high disease pressure prevails.

For 2015, choice will come down to price if there is nothing between them in terms of yield and disease control. The inclusion of a strobilurin will help greening and rust control.

Timing is everything for a T3 ear spray and fusarium is my target at T3, therefore if wet at GS61-63, go for a 75% dose of prothioconazole, metconazole, or tebuconazole.

All are equal to each other according to HGCA, so price dictates choice. Subsequent applications of fungicides for fusarium are futile and not in my plan.

Potential worth protecting in winter barley

Crops are coming out of the winter in good shape in the North and this is true for winter barley in most situations.

There is some mildew present and low levels of net blotch, but the cool and dry weather throughout February – apart from one balmy day when 16C was recorded – has kept a lid on diseases.

Since January land has dried up considerably, enabling growers to get some early nutrition on to the most forward crops. So the potential is there for crops to yield well and close attention to fungicide timings over the next few months will help to deliver.

All the data from trials last season showed responses to fungicides of up to 1.6 t/ha. So despite current price pressures, it makes sense for growers to protect their investments with a good programme.

The backbone of winter barley programmes for the past few years has been prothiconcazole and this will continue.

T0 plans will involve Ennobe (epoxiconazole + prochloraz) or Fielder (chlorothalonil + proquinazid), depending on the disease spectrum and if the weather continues to co-operate the timing may not be that far away.

T1 sprays will be centred on Jaunt (prothiconazole, fluoxystrobin and trifloxystrobin) and it will also feature at T2. Ramularia is always a risk up here and chlorothalonil will again be used at T2.

Spring barley crops were excellent last year and this has had a knock-on effect, making contracts for this year’s crop hard to come by.

Spring barleys that received a good fungicide program in 2014 gave a 1t/ha response and this year it will be important to look after a crop well and make sure the quality is up to standard.

Programmes will again be based around Jaunt with chlorothalonil added at T2.