Welcome to the August edition of the Life Scientific Newsletter.
Firstly, we would like to wish all our customers a successful and safe harvest, following a very challenging year.
In the crop year of 2023/2024, we conducted more replicated fungicide and insecticide field trials than ever before with distributor customers, ADAS, PGRO and Warwick University, and investigated application and performance of a new development fungicide with Silsoe Spray Applications Unit.
This month, we would like to share results from work on wild oats conducted in partnership with NIAB. This interesting and useful work can help growers to keep on top of this increasingly important weed.
Wild oats
August is still an important time to monitor which weeds are present in crops, especially grass weeds which have appeared above the canopy.
Resistance is known to exist to some herbicides in our key weeds, black-grass, Italian rye-grass and wild oats, and there should still be time to collect seed for testing.
In the case of wild oats, collected seeds must be completely ripe. According to John Cussans of NIAB, the best way to collect seed is to run your hand along the plant and the seeds will shed out naturally. He states that about three coffee cups of seed are needed, compared with one cup for black-grass as the seeds are larger and have awns. Collected seed should be dried for a few days and packed in paper bags before being sent away for testing.
In 2020, we sponsored a NIAB survey and laboratory work to look at wild oat resistance in the two species that exist in the UK, Avena fatua (spring wild oat) which tends to germinate in spring, and Avena sterilis ludoviciana (winter wild oat) which tends to germinate more in autumn. 70% of samples collected contained spring wild oat and 30% contained winter wild oat.
Knowing what species you have on your farm is important to help you plan the most appropriate control strategy. It is also useful to understand the resistance status of the weed so that you can use the best herbicide strategy.
100 samples in the survey were tested for resistance to key active ingredients, cycloxydim, pinoxaden, fenoxaprop and iodosulfuron-methyl-sodium plus mesosulfuron-methyl (the active ingredients in NIANTIC).
Whilst winter wild oat showed higher levels of resistance than spring wild oat in the work, most populations still showed good susceptibility to herbicides such as NIANTIC (see the chart below).
RRR Resistance confirmed, highly
likely to reduce herbicide performance.
RR Resistance confirmed, probably reducing herbicide performance.
R? Early indications that resistance may be developing, possibly reducing herbicide performance.
S Susceptible.
Source: John Cussans,NIAB
NIANTIC can be used in the autumn and can control sensitive wild oats post-emergence up to GS 29 of the weed and must always be used in mixture with adjuvants PROBE or Biopower. Application is most effective when the weeds are small and actively growing.
See the approved NIANTIC label for detailed use instructions and restrictions.
Autumn weed control
As well as wild oats, black-grass is of course one of the most problematic weeds in winter cereals. Given that black-grass plants can produce as many as 1000 seeds per plant, populations can build rapidly. Add to this the fact that most UK black-grass populations show some level of resistance to ACCase and ALS herbicides, black-grass control remains the most challenging issue for cereal growers in many areas.
Control of the weed requires a whole rotation approach, utilising rotations, cultivations, and contact and residual chemistry from different chemical groups. 95-100% control of black-grass is required in the cereal crop to prevent the field population increasing.
Whilst there are a number of chemical tools available, resistance has made a programmed or stacked approach to herbicide choice vital.
FIRESTARTER contains flufenacet, one of the herbicide active ingredients currently least affected by resistance, and one that is critical to any black-grass programme. It also contains diflufenican, the combination giving useful annual meadow-grass and broad-leaved weed control. It is physically compatible with a range of herbicides including NIANTIC plus PROBE or Biopower.
See the approved FIRESTARTER label for detailed use instructions and restrictions.
LAMBDASTAR
In last month’s Newsletter we gave details of a cabbage stem flea beetle trial conducted in oilseed rape by Warwick University last autumn.
Results showed that two full rate applications of LAMBDASTAR reduced “shotholing” at the site.
The trial showed that the Warwick University population was not completely resistant to pyrethroids, but levels of resistance could be much higher on other sites and levels of control may not reach those seen in this trial.
If you consider the application of an insecticide appropriate, see the approved LAMBDASTAR label for detailed use instructions and restrictions.
