Welcome to the October edition of the Life Scientific Newsletter.
October is always a busy month for us with our range of oilseed rape fungicides (AURELIA, DIFENOSTAR, ESKER, ORASO PRO, and ZONOR), cereal herbicides (FIRESTARTER and NIANTIC), and our insecticide (LAMBDASTAR) for use against BYDV and Cabbage Stem Flea Beetle.
Last month we focused on oilseed rape disease control and the benefits of using FIRESTARTER early in your cereal grass weed control programme.
In this edition, we will look at BYDV and the use of an autumn ALS-inhibitor product, NIANTIC, for weed control in winter wheat.
Barley Yellow Dwarf Virus
Weather conditions this autumn have meant that aphids can be found in a range of crops now, so the risk from Barley Yellow Dwarf Virus (BYDV) must be considered.
BYDV is transmitted by cereal aphids, the principal species being Grain Aphid, the most important vector in the midlands and north, and Bird Cherry-Oat aphid which is most important in the south.
According to AHDB, the virus can cause yield losses of up to 60% in winter wheat and 50% in winter barley. An aphid will carry the disease for its entire life once acquired. The virus is not passed to the aphid’s offspring so has to be ingested by feeding on infected plants. Warm dry conditions encourage aphid reproduction and movement in the crop, increasing the risk of greater infection. Crops are infected in the autumn, although symptoms do not appear until the spring, at which point it is too late for control. Significant infection occurs when the second generation aphids move out from the initial infection point. Infected plants grow slowly and the youngest leaves will discolour. Later in the season plants are stunted and yellow patches appear throughout the field.
AHDB provides information on their website from regional monitoring sites in York, Hereford, Broom’s Barn and Starcross of the proportion of aphids carrying virus.
Chemical control options are limited, so targeting the second generation aphids at the correct time is important. These aphids are predicted to be present when accumulated temperature above 3 degrees C reaches T-Sum 170 from the day of crop emergence or after an application of a pyrethroid insecticide. Agronomists and growers should check the crop carefully and use a monitoring tool which uses temperature to predict when the second generation will occur such as AHDB’s BYDV management tool, which can be found on their website at https://ahdb.org.uk/bydv.
This shows predicted T-Sum figures for sites across the country and resets once T-Sum 170 is reached. The date that T-Sum 170 is reached for your crop will depend on when your crop emerges or when you applied a pyrethroid.
Life Scientific’s pyrethroid product LAMBDASTAR, containing 100g/L lambda-cyhalothrin, is approved for the control of aphid vectors of BYDV in winter wheat, winter barley, winter oats and durum wheat. It should be used at the full rate of 50ml/Ha.
See the approved LAMBDASTAR label for detailed use instructions and restrictions.
NIANTIC – an autumn herbicide for use in wheat
NIANTIC, containing 30 g/kg mesosulfuron-methyl + 6 g/kg iodosulfuron-methyl-sodium, is a reverse-engineered herbicide formulation based on the reference product, Atlantis WG, and is approved for use in winter wheat in the autumn.
NIANTIC, plus authorised adjuvants PROBE or Biopower, will control the following important weeds in winter wheat. The active ingredients are ALS-inhibitors which affect cell division so the product is most effective when weeds are small and actively growing.
One application of 0.4 kg/Ha NIANTIC + 1.0 L/Ha PROBE should be applied to small, actively-growing weeds, ideally between 1 and 3 leaves, and when the majority of the weed population has emerged. It can be applied from autumn until early spring when the wheat has two leaves (GS12) up until flag leaf ligule just visible (GS39).
Populations of black-grass and Italian rye-grass with varying levels of resistance to ALS herbicides are widespread in the UK. NIANTIC must therefore always be used as part of an integrated approach to weed control involving rotation, cultivations, stale seedbeds and delayed drilling. NIANTIC + PROBE should be mixed with an effective residual tank-mix partner and sequenced with alternative modes of action such as the pre or early post-emergence herbicide, FIRESTARTER which contains flufenacet and diflufenican.
See the approved NIANTIC and FIRESTARTER labels for all detailed use instructions and restrictions.
NIANTIC – control of wild oats
In our August Newsletter we reported the findings from a NIAB survey sponsored by Life Scientific which looked at wild oat resistance in Avena fatua (spring wild oat), which tends to germinate in spring, and Avena sterilisludoviciana (winter wild oat) which tends to germinate more in autumn.
Source: NIAB
If you have wild oats on your farm, hopefully seed has been collected and tested, as knowing the species present can help target the best approach to control the weed in your fields.
Whilst winter wild oat showed higher levels of resistance than spring wild oat in the NIAB work, most populations still showed good susceptibility to herbicides containing mesosulfuron-methyl and iodosulfuron-methyl-sodium such as NIANTIC.
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: NIAB
As with all ALS-inhibitor herbicides, remember that sprayers must be thoroughly cleaned after use of NIANTIC using an appropriate tank cleaner, and that ALS-inhibitor herbicides used on cereals can only be used in tank-mixture or sequence with another ALS-inhibitor if a specific joint application is approved on label.
See the approved NIANTIC label for all detailed use instructions and restrictions.
