Between snow in February and lockdown it’s been difficult to get out too much to look at crops in fields. But as the days lengthen and warmer weather arrives, crops will start moving. Weed control will be a priority for cereal crops in March, especially where pre-emergence residual treatments were missed pre-Christmas and where the effects are wearing off.
Towards the end of the month susceptible wheat crops should be monitored for yellow rust especially with a view to treating with a T0 in early April if necessary.
Generally oilseed rape crops look in better shape than this time last season, with early establishment aided by more moisture availability at drilling. But at the time of writing it is unclear whether cabbage stem flea beetle larvae in the stems will effect spring growth in March. There are reasons to be cautiously optimistic but time will tell.
As spring arrives, and crop and weed growth resumes, it is a good time to walk both winter wheat and winter barley crops to assess the efficacy of any autumn residual herbicide programmes on grass weeds.
Map out areas that are needing further attention as active growth resumes. Weeds such as black-grass and rye-grass will be better controlled with contact herbicides while they are relatively small.
In wheat, Pacifica Plus (mesosulfuron + iodosulfuron + amidosulfuron) has good activity against a range of grass weeds and broadleaved weeds, including cleavers. Where brome species are the main grass weed target, Monolith (mesosulfuron + propoxycarbazone) may be a better option.
In barley options are much more limited for post-emergence control, and if black-grass has survived through to spring there is little that can be done, except considering whether to spray off with glyphosate and start again.
If you’re considering this, assess barley fields individually to assess weed burdens and how this might affect seedbank returns for following crops. It is usually better to call it a day earlier on barley crops heavily infested with black-grass and get a timely spring barley crop established that can yield, rather than wait until April when conditions may not suit germination.
If spring barley or spring wheat crops are planned then a timely and effective stubble or seedbed clean up spray before drilling is a good opportunity to remove troublesome weeds before the crop is planted.
A good quality Roundup (glyphosate) product will be a good choice as they are formulated to optimise performance in tough conditions, such as where there is slower weed growth or winter hardened weeds.
The wetters and surfactants in Roundup branded products are the keys to its better performance, as they help get the active ingredient into the weeds where it can do its work.
Applications of products, such as Roundup Flex and Roundup PowerMax are rainfast on annual weeds in one hour and four hours for perennials, while cultivations can begin 24 hours after application to annuals, and after five days for perennials. That flexibility may be useful in a busy spring season.
Our free Spotcheck service, where you can send away oilseed rape leaves to be assessed by ADAS plant pathologists for light leaf spot and other diseases, has so far shown a high percentage of crops carrying latent infections of light leaf spot even though visual symptoms have not yet appeared.
Assess crops using Spotcheck or by incubating leaves in a plastic bag in an airing cupboard for those with ancient hot water systems like me, and see what develops.
Those crops that didn’t receive an autumn fungicide are likely to be highest priority for treatment this spring. Products such as Proline (prothioconazole) or Prosaro (prothioconazole + tebuconazole) will give control of light leaf spot, as well as Phoma and mildew.
Depending on temperatures, weather and whether seed has arrived on farm, sugar beet drilling might start in March.
With desmedipham no longer approved, it means Betanal maxxPro (phenmedipham + desmedipham + ethofumesate + lenacil) is no longer available for weed control.
Its replacement is Betanal Tandem (phenmedipham + ethofumesate). One thing to note about its use is it should always be co-applied with either a 95% methylated rapeseed or vegetable adjuvant oil, unless temperatures dictate otherwise.
Visit this page for a full summary of recommendations and timings for Betanal Tandem.
A second method for applying Velum Prime (fluopyram) has been added to the label. In addition to in-furrow application at planting, there is also an option for overall application and incorporation before planting.
Both application methods have shown equivalent efficacy against potato cyst nematodes (PCN) in Bayer trials, so the choice of which method to use largely comes down to which best suits your system and what equipment is available.
With Vydate (oxamyl) approval not renewed, Velum Prime provides a low dose, cost effective way of reducing PCN damage and reducing multiplication in potato crops. In higher pressure situations the combination of a half rate dose of nemathorin plus full rate Velum Prime is a good option.
This season will be the last where Emesto Prime (penflufen) can be used as a seed treatment on potato seed for reducing black scurf caused by seed-borne Rhizoctonia.
The latest date for sale, storage and use is 31 June 2021, but importantly there has been no change to the Maximum Residue Level (MRL) for harvested tubers, so there will be no issues with storing and selling potatoes grown from Emesto Prime treated tubers this spring.
As growers look ahead to spring 2021, the picture is a lot better than many feared. In general, winter cereal crops were drilled in good time, and although it was wet in early October, most crops have got up and away and looking much better than they did in January 2020.
Find out more information on the key disease threats to your wheat crop. For each disease you will find out the importance of the disease in terms of potential yield penalty, how to identify the disease in its early stages and our advice on the best control strategies.
Bayer’s SpotCheck initiative, which helps oilseed rape growers identify light leaf spot (LLS) and other diseases in the crop, will re-open to receive leaf samples from October. The previous season saw epidemic-levels of disease so growers are advised to be alert to early signs of LLS and apply fungicides early.