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Weed control

Weed control

The forecast for many areas over the coming week is for a period of dry weather, which may facilitate some of the delayed jobs that have had to be postponed due to the very wet period that we have had.

Weed control on various crops e.g. winter barley, wheat and oilseed rape are now important especially where grass weeds need to be controlled. Options on winter barley are limited with flufenacet, prosulfocarb, pendimethalin or chlotoluron only effective on small grass weeds once they begin to tiller then efficacy is reduced. Firebird Met has now passed its latest application date so options like Firebird, Tower, Stomp, Defy and Diflanil are the main options either as solo products or in mixes. Consult the weeds controlled by each product to see what are the best options for each field situation bearing in mind different products may be needed for different fields.

For oilseed rape crops, many of which may have only received a graminicide to control volunteer cereals, many growers have opted to use Astrokerb or Kerb to do the majority of the weed control. There will control problem grass weeds, while the aminopyralid in the Astro kerb will give more broad-spectrum weed control including, groundsel, poppy, bindweed and mayweed. But be aware that crops sprayed with Astrokerb, must have the straw incorporated and not baled, so these fields should be entered into the Straw Incorporation Measure (SIM) on the 2023 BPS application if you haven’t reached the limit with cereal crops. Both Kerb and Astrokerb work best when soil temperatures are below 8oC and are dropping so the coming week may be the ideal timing for the two products.

For winter wheat crops there are still plenty of options to control grass weeds in the spring such as Pacifica Plus, Broadway Star, Monolith or Alister Flex all will give good control of bromes etc. but Broadway Star for example will not control annual meadow grass. So again, choose products to control the different target weeds in different fields.

BYDV

Weed control and insecticide application often go hand in hand at this time of time of year but this year things may be different also. The recent wet weather normally would reduce aphid flight as is seen from some results at the aphid suction towers that Teagasc have placed in different parts of the country.

Effect of rainfall on aphid flight

Effect of rainfall on aphid flight

However, crops locally should be monitored to check for the presence for aphids. Teagasc currently have more than 20 crops in different location throughout the country using yellow traps to trap aphids so we can see what species are flying and also if they are carrying virus. To date numbers appear to be relatively low but there are some differences between locations.

A yellow trap in winter barley

A yellow trap in winter barley

Recent research has also backed up previous work that one application of an insecticide will give the same control as multiple applications especially in October sown crops therefore there is no need for multiple applications. The research has also shown that a pyrethroid e.g. Sumi Alpha is as effective as Transform which is the other option currently available, again be aware that this is the last year Transform can be used.
Video on insecticide applications for aphid control

Get more information and advice from the Teagasc Crops team here
Find your local Teagasc office here