With a focus on black-grass over recent years,wild oats have become the forgotten enemy,saysRuth Stanley, country manager foroff-patent manufacturer,Life Scientific.But itsactually ourmost competitivegrass-weed,on a potential yield loss/plant basis.

Just one wild oat plant/sq.mcan reduce yields by as much as 1t/ha in winter cereal crops, and0.6t/ha in spring cereals.Wild oats alsoact as hosts for pestsand diseases, such as barley yellow dwarf virus.

There are two species of wild oats that are weeds in the UK the common wild oat and the winter wild oat.

The common wild oat (Avenafatua) is an important weed in all parts of the UK and grows in most soil types, causing problems in winter and spring crops.A second species, the winter wild oat (Avenasterilisssp.ludoviciana)is becoming more widespread and increasing in number.Both species are capable of germinating in winter or spring.

This increase in wild oats comesas a result of several factors, she explains.Min tillage or direct drilling doesnt bury wild oat seed, burial increases dormancy so seeds left on the soil surface are more likely to germinate andthrive.

There hasalsobeen a reduction in the use of ALS chemistry traditionally used to control black-grass,but growers worried about reliance on this chemistry for black-grass controlhaveforgottenthat these herbicides areactuallyvery effective at wild oat control.

Last year Life Scientific and NIAB worked together toconduct aUK widewild-oat herbicide resistance survey- the first one in over twenty years.105 wild oat seed samplesweresent in bygrowersandwere screened for resistance to Axial Pro (pinoxaden) and Niantic (iodosulfuron+mesosulfuron) at field rates.

Theresultspointedto cases of resistance in both species to both Axial Pro and Niantic, with the study confirming that the occurrence of resistance is higher in the winter wild oat (Avenasterilisssp.ludoviciana).

For winter wild oat populations specifically,the resistance to ALS orACCasechemistry is the same,but in springwild-oat populations resistance toACCaseis double that of ALS chemistry.

These are important messages for the industry,shesays.Although were getting more and more reports of wild oats as a problem weed,weknow from these survey results and the resistance testing, that ALS chemistry such asinthe herbicides Nianticin the autumnandCintacin the spring, are still effective on wildoatsand have a valuable place in the herbicide programme to provide efficient control.

Thatsaid less than 20% were resistantto ALS chemistry,and these were from growers who thought they had resistance issues anyway,so the emphasisis stillto ensure correct product application to prevent decreased sensitivity in the fieldin orderto get the best performance from these herbicides.

However, where ALSchemistry is not being used, or ALSresistancemay be a concern,it is possible to useaherbicide such asKipota(240 g/lclodinafop+60 g/l cloquintocet)which is a reverse engineered version ofTopik.Kipotacan be used anytime from when the crop hasestablished upto growth stage 41.

In recent trialswork with NIAB, theactivityfrom Life ScientificsKipotaonsusceptibleoat populationswasshownto be comparable toTopik, which is the very premise of the concept of reverse engineering an off-patentproduct from itsoriginalreference product.

Key factors to consider for wild oat management

• Identifying and understanding more about the two differing wild oat species on their own farm.
• Making better use of existing products tomaximisetheir potential in-field getting the application timings right relative to growth stages and conditions.
• Herbicides and rotating active ingredients- there is relatively low-level of cross-resistance between herbicides in both species, so this approach will become increasingly important.

• Adopting some element of cultural control in order to supplement and sustain the control achieved by herbicides.

TABLE:Gettingthe best fromNiantic andCintacapplication

1. Timing

Weeds should be actively growing

Consider temperature and moisture

1-2 leaves

1. Dose

Use maximum rates (0.4kg/ha Niantic or 0.5kg/haCintac)

Addauthorisedadjuvant

1. Application

Match nozzle to the conditions

Keep boom height at 50cm above target

Forward speed of 12-14kph