After very little rain in April, weather stations at NIAB Morley recorded 60mm of rain in May as we entered the last week of the month. That does vary across the region with some people recording up to 130mm, so we’ve had significant rainfall.
While that will have driven disease in wheat, the contrary is the case for temperature – it’s not been overly warm with only 6 days registering 15C or above.
That could be why up until the third week of May disease levels both visible and latent as tested by our rapid disease detection test have remained low – in fact we only had the first positive test for Septoria in that week on leaf five of late October drilled Graham.
Where spring barley crops were drilled into moisture and come through and picked up with the recent rain it is looking like quite a decent crop. Disease pressure so far has remained low, but it’s likely to pick up as temperatures warm up.
Flowering has been prolonged in oilseed rape. The frosts in April bent over some of the top racemes, but they looked to have recovered with hopefully no impact on yield.
The low amounts of disease in April and the cool temperatures through May has slowed the spread of disease, but the rain will have increased disease inoculum and will need to be addressed at T2 in wheats. The good news is we’re looking like we are in a protectant situation rather than curative at T2.
Some flag leaf sprays will likely already have been applied in the last week of May if conditions allowed, but many applications will be going on in early June this year.
In most crops Ascra (bixafen + fluopyram + prothioconazole) at 1.2 L/ha will be a good choice. If weather has prevented an application at the perfect GS39 (full flag leaf emergence) timing, and there is visible disease in the crop, especially on upper leaves, then a higher dose of 1.5 L/ha would be appropriate.
While the gap between T2 and T3 may well be even shorter than usual this season, it is still important to apply ear sprays at early to mid-flowering, even if that is only 7-10 days after T2 was applied.
That’s especially true if you’re targeting Fusarium and Microdochium, as if you leave it too late you won’t get optimum control.
If you didn’t spray a SDHI-containing fungicide at T1, then using Aviator (bixafen + prothioconazole) could be a good option at T3. It will bring added persistency especially to green leaf area retention, which is helpful for increasing yields pre-senescence, as well as good control of Fusarium and Microdochium, and topping up foliar disease control.
Where two SDHI fungicides have already been used, 0.55 L/ha of Proline (prothioconazole) will keep on top of ear diseases.
The awns emerging timing is the more critical one in spring barley for disease control. The recent rain will have increased disease pressure in spring crops.
With the changes in resistance status of some diseases including net blotch and Ramularia it is important to keep up doses of the prothioconazole component in Siltra (prothioconazole + bixafen) or Fandango (fluoxastrobin + prothioconazole). We’d advise 0.4-0.6 L/ha of Siltra or 0.75-1.0 L/ha of Fandango. Both are approved to be used on malting crops.
Ramularia could be a threat with the more stress-conducive conditions in May, so adding some folpet may provide some additional support.
As we approach harvest in July timing Roundup (glyphosate) desiccation sprays in oilseed rape correctly is important. Go too early and oil content will be compromised, maturity hindered, resulting in more red seed.
Take a representative sample of 20 pods from where most yield is being carried in the canopy, and typically when most of the seeds have changed from green to brown the crop has reached the spray threshold of 30% moisture.
Potato crops have been slow to emerge, but will rapidly grow as weather warms. With two aggressive strains of late blight dominating – 36 _A2 and 37_A2, and a lack of options for controlling tuber blight later in the season, planning blight programmes carefully is essential.
Infinito (fluopicolide + propamocarb) is a very good option for controlling these aggressive strains and can be used throughout the programme. But it is one of few options for tuber blight control so plan your four applications to take this into account.
Bayer also has a new, much needed option for early blight (Alternaria solani and Alternaria alternata) in Caligula (fluopyram + prothioconazole) as other options have been lost. Alternaria is increasing with larger areas of susceptible varieties, such as Markies, being grown, while hot and dry weather with extended periods of leaf wetness favour its development.
Caligula sets a new standard for control using a maximum dose of 0.5 L/ha, and can be used three times in the programme from tuber initiation, with a maximum of two sprays consecutively. It doesn’t have any late blight activity so it will need to be tank-mixed with one of a wide-range of late blight fungicides where both diseases threaten.
Sugar beet has also been slow to get going with the dry and cold spring, and herbicide programmes have been extended. With the rainfall we’re seeing late flushes of weeds, especially Polygonum species.
Finish off programmes with conventional herbicides, such as Betanal Tandem (phenmedipham + ethofumesate) to take care of these late germinating weeds.
In July attention will turn to disease control, with Cercospora likely to be a concern after last season’s very conducive conditions (warmth and humidity – particularly above 25°C). But don’t take your eye off the usual key diseases of rust and mildew. Timing for control with Escolta (cyproconazole + trifloxystrobin) is at the onset of disease.
Despite resistance issues with Cercospora against strobilurins and some insensitivity against azoles, BBRO trials last season highlighted Escolta did have decent activity against Cercospora when timed correctly, so some careful decisions will need to be made this season and a shorter interval between applications required if risk is high.
We’re looking forward to welcoming visitors again to our Field Days demonstration site near Long Sutton on 1 July. It’s been a long time since the last Field Day in 2019, so we hope to see you again then, for a look around wheat variety plots, cereal fungicide trials, sugar beet herbicide trials and FieldView demonstrations and the obligatory burger or hot dog.
Visit the home of East West region advice & expertise Hosted by your local Bayer technical managers who are on hand to offer advice and expertise on crop growing strategies.
As part of Bayer’s Rapid Disease Detection project in 2021, our technical managers have partnered with local farmers to track disease progression in commercial wheat fields across the UK and Ireland. Click to read weekly updates and results.
Our Bayer Field Days are back this year, visit our events page to find out your nearest site. Get a unique look into the latest trials, share insights with like-minded growers and get expert advice from your local technical manager. We look forward to seeing you there!