Application Advice

In the battle against blackgrass Avadex is playing an increasingly important role, with analysis of trials showing its inclusion increases the percentage control by 16.8% across a wide range of programmes.

“For optimum results, however, Avadex 15G granules must be are applied evenly and accurately,” stresses Kuldip Mudhar, from Gowan Crop Protection. It’s also important remember all operators applying the granular pesticide hold a PA1 as well as the relevant PA4 G (safe use of granules) modules.

Do…

• Wear appropriate PPE
• Consider a patternation test when carrying out the pre-season calibration process
• Regularly check applicators’ pipework and deflector plates and keep deflector plates clean and at the correct angle
• Apply pre-emergence to well-prepared moist seedbeds
• Observe an aquatic 10m buffer zone if applicable
• In very dry conditions delay application until there is more moisture in the soil
• Make sure drilling depth is correct (4cm for wheat)
• Consolidate loose fluffy seedbeds before drilling
• Travel at appropriate speeds as defined by individual machinery manufacturers – high speeds will disrupt the spread pattern.

Do not…

• Apply to very cloddy seedbeds or shallow drilled crops
• Apply when top of soil is bone dry in the top 5-8cm depth
• Apply to soils with more than 10% organic matter
• Allow granules from application equipment to fall within in a distance of 10m of the top of a bank of a static or flowing water body or within 1m of the top of a ditch which is dry at the time of application
• Apply in strong winds as this will disrupt the spread pattern – if it’s too windy to spray then it’s too windy to apply Avadex
• Use spinning disc applicator
• Undersow grass species in crops to be treated with Avadex. It is safe to undersow clover and legumes.
• Sow oats or grass crops within one year of applying Avadex

For a full guide to using Avadex go to: https://eioperator.com/pro-operator-article/getting-the-most-out-of-avadex-new/

In the second exclusive EIO application advice video, Syngenta application specialist Scott Cockburn, explains the best techniques to employ when applying pre-emergence herbicides.

With increased resistance to post emergence herbicides, there’s never been a more important time to ensure you get your pre-emergence application correct.

Before starting any spray regime, it’s a good idea to make a plan, says Scott Cockburn. This should include:

• Stale seedbeds
• Delayed drilling
• Crop rotation
• Seedbed preparation
• Application timing

“Residual herbicides work best when applied to a firm, fine seedbed,” he says. “This will maximise coverage on the soil surface.”

Right on time

When it comes to timing, it’s really important to get the application on as quickly as possible – ideally within 48hrs after drilling, adds Scott. “This ensures it will kill the weeds when they are at their most vulnerable stage.”

Hit the target

For pre-em residual herbicides the target is the soil. It’s easier to miss than some may think, so a good set-up and technique will make a big difference to the application, says Scott.

As usual, boom height, forward speed, water volumes and nozzle selection will all help improve the efficacy.

Working together

Boom height and forward speed are closely linked. “We need to maintain 50cm above the soil surface and, ideally, at a speed of less than 12km/hr to protect boom stability. This will also have a significant effect on reducing spray drift.

“Less drift puts more product on the surface, which provides better control when the weeds do eventually emerge.

Volume is crucial

The aim of the pre-em application is to cover the whole surface – creating a ‘cling-film’ effect across the top of the soil – through which the weeds have to emerge. “This means the right water volume can help improve coverage,” he adds. Research shows 200 litre/ha proves the most effective with all nozzle combinations – typically achieving double the control of a 50 litre/ha application and a 30% better result than 100 litre/ha.

Nozzle choice to cut drift

With no crop to catch drift, correct nozzle choice is essential, explains Scott. “We have found 90% drift reduction nozzle such as the Teejet TTI can work very effectively – and in less than ideal conditions.

“In cloddy seedbeds, angled nozzles will reduce the shadowing effects of the clods and improve coverage,” he says.

Follow best practice

• Apply to a find firm seedbed
• Keep forward speed to less than 12km/hr
• Maintain 50cm boom height above the target
• Water volume of 200 litres/ha
• 90% drift reduction nozzles

Leading spray application specialist, Tom Robinson, combines his own expert advice with guidance from BASF, Bayer, Monsanto and Syngenta to discover how to fine-tune autumn applications to get the best control from their herbicides.

Grass weed control in the autumn has become increasingly difficult in recent years, due in no small part to increased herbicide resistance, particularly post emergence selective products.

The challenge for the operator is to get the best out of each herbicide application, through a combination of sprayer set up, timing and application technique. Representatives from BASF, Bayer, Monsanto and Syngenta all agree fine tuning applications will help achieve the best autumn grassweed control and get the best from the products.

Pre-drilling sprays

Glyphosate is the active ingredient of choice for pre-drilling (stale seed bed) applications.

Spray off blackgrass with Roundup, once the largest plants have two leaves. Germination should take place in about ten days, provided there is enough moisture – 540g a.i./ha is sufficient for good control.

Modern Roundup sprays work best at reduced volumes 80-100 litres/ha. They are sensitive to cation lock up in hard water, so may need a water conditioner. Lower water volumes also reduce the chance of cation lock up.

Monsanto’s technical development manager, Barrie Hunt, recommends two or three sprays where possible. More blackgrass will be successfully removed by spraying each flush of weeds at the two-three leaf stage, than waiting for a single spray just before drilling. Ensure you cultivate between sprays to tackle any survivors.

Barrie also explains as Roundup is compatible with most pre-emergent herbicides, it can be usefully tank mixed as a post drilling pre-emergence spray combined with other pre-emergence products.

Monsanto recommends traditional fan jets at 1.5-2.5 bar pressure, and also supports the use of angled 3D nozzles. Monsanto emphasises the need to use the recommended dose for all herbicide applications, to reduce the onset of herbicide resistance.

Pre-emergence sprays

Shadows behind clods, where no spray lands, can be caused both by the prevailing wind, or the speed of the vehicle imparting a horizontal trajectory to the spray.

Improving coverage in three dimensions requires a spray that has a backward trajectory greater than the forward speed of the machine, as well as downwards and forwards. The nozzle developed specifically for this job in 2009 was the Defy nozzle from Syngenta.

The latest 3D nozzle gives even better three-dimensional coverage, and is Tom Robinson’s nozzle of choice for autumn applications. It also achieves 1 and 2 star LERAP status. The nozzles are alternated forward and backward along the boom, to achieve the 3D spray effect.

Timing is key

Bayer CropScience emphasises the ideal timing of a pre-emergence application of Liberator (diflufenican+flufenacet) is within 48 hours of drilling. Later applications require pre-emergence herbicides to penetrate deeper into the soil profile to get within the rooting zone of the blackgrass.

Bayer recommends fan jets delivering a medium spray quality, and spray volumes of 100-200 litres/ha. It particularly emphasises the benefits of a smooth seed bed to ensure even soil coverage and to avoid the issue of clods causing shading or subsequent emergence as they break down.

BASF offers similar advice for its range of herbicides, stressing the need for a fine firm seed bed. BASF recommends spray volumes down to 100 litres/ha and forward speeds of 10-12km/hr. The preferred nozzle type is a traditional fan jet producing a fine spray for good soil coverage.

Latest thinking

The most up-to-date autumn herbicide application research work, in the past 2 years, has been carried out by James Thomas of Syngenta.

James has found with traditional fan jet sprays, that 50 litres/ha, 300 litres/ha and 400 litres/ha worked less well than 100 and 200 litres/ha. The 3D forward and backward at 100 litres/ha and 200 litres/ha outperformed all the fan jet treatments at the same water volumes.

Last season Syngenta trialled 90% drift reduction nozzles and achieved good results with these at the higher water volume of 200 litres/ha. The Syngenta recommendation is 12km/hr, 200 litres/ha using 3D nozzles forward and back when weather conditions are favourable, and 200 litres/ha using 90% drift reduction fan jets when conditions are unfavourable.

Post-emergence foliar sprays

Winter wheat

The most widely used product is probably Atlantis WG (iodosulfuron+mesosulfuron). Bayer’s recommendations include: Water volume – 200 litres/ha down to 100 litres/ha. Timing – GS 11-13 (1 -3 leaves).

Avoid application if rain is forecast. Traditional fan jets are preferred but angled nozzles may do a good job too. Maximum speed 12km/hr. The adjuvant Biopower is a key component to the product’s performance.

Winter barley

The most widely used product is probably Axial (pinoxaden). Syngenta’s recommendations include: Water volume 100-200 litres/ha. Timing – GS 11-12 (1-2 leaves). Speed up to 12km/hr. The adjuvant Adigor should be added to the spray mix at a rate of 1%, at volumes less than 200 litres/ha – i.e. 1 litre in 100 litres/ha. Preferred nozzle is the 3D.

If access to the weeds is good, pointing the nozzles all forwards will apply the most product to the weed leaves. This can more than double the spray on the leaf compared with a fan jet. However if the weed leaves are likely to be shaded by clods, then it makes sense to alternate the nozzles forward and backward.

In the first of a series of exclusive EIO application advice videos Syngenta application specialist, Scott Cockburn, explains how to get the most effective weed control when spraying off stale seedbeds prior to drilling.

In the face of increasing resistance to selective products, making the best use of stale seedbeds to control weeds with glyphosate provides the best start for the weed control regime.

Start by making a stale seedbed, advises Scott: “This takes time and patience. Aim to leave the field as long as possible, to achieve maximum germination of weeds and volunteers before spraying.”

Use shallow cultivations to disturb the surface, kill small weed plants and encourage a second flush to germinate. “Again, leave the field for as long as possible before spraying off with an application of glyphosate. This process should be repeated as many times as possible, to fit in with other cultural controls such as delayed drilling,” he says.

Key application areas

“Glyphosate’s systemic action means it takes only one drop to kill the target plant. But to get the most out of every application, pay close attention to some key areas,” he advises.

• Boom height – 50cm above the target.

This provides the best coverage with the nozzles and reduces the risk of drift and ensures the maximum amount hits the target.

• Forward speed – less than 12km/hr.

This maintains boom stability, ensuring it stays at 50cm.

• Nozzle selection – Grassweeds present a small target and angled nozzles provide better deposition on the plant.

In ideal spray conditions a nozzle such as the 3D, alternated forwards and backwards, will deliver optimum efficacy.

In compromised conditions 90% drift reduction nozzles are proven to work very effectively, and there is now a wide choice on the market. These nozzles produce a much coarser droplet and help to reduce the risk of drift.

Top tips for stale seedbed spraying

1. Employ cultural control methods
2. Be patient and create the best stale seedbeds
3. Use the best application techniques:

•    Maintain a 50cm boom height
•    12km/hr forward speed or less
•    Nozzle choice – select the best nozzle for conditions
•    Water volumes of 100-125 litres/ha