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Agronomy Updates

Fresh is Best; time to give agchem stocks a second look

Here’s a quick challenge when you next have a few spare minutes. It’s super easy, and it’s good for both you and your customers.

All you have to do is cast your eyes over your agchem stock and stores, and see how many grey containers are on the shelf or in the warehouse.

Why? Because almost certainly they contain product that was manufactured by Dow AgroSciences before it became Corteva Agriscience.

Corteva has now been in existence for three years. With the change of name came a change in pack colour, from the distinctive grey Dow used for many years to the white that virtually dominates the market.

“It’s a very easy way to spot older product,” says national sales manager Richard Brenton-Rule. “Those grey drums in particular tend to stand out.”

He knows, because he and his field team have been seeing a few too many of them in retail stores and farm chemical sheds, along with old Dow AgroSciences branding.

In one notable case, the date of manufacture (DOM) for the product in question was 2014; in others, DOMs have stretched back to 2017.

The concern with these older packs is not cosmetic, but rather product integrity and stewardship.

“We really can’t guarantee their performance, particularly if drum or packet has been opened,” he explains. “Once opened, there’s a greater risk of degradation and or contamination.”

By law, all crop protection products sold in the New Zealand market must carry a DOM. If they are highly perishable, some will also carry a use-by or shelf life date.

If there is no shelf life or use by date on the label, for regulatory purposes products are assumed to be stable for at least two years from the DOM, under normal storage conditions.

(That means they’re stored unopened, away from direct sun, and at a stable temperature.)

In other words, going back to the 2014 drum Brenton-Rule found in a store recently, even if it had been stored impeccably, it was still five years past the time it should have been used.

That was an extreme example, but ‘younger’ older packs are equally concerning, he says.

“We can’t recommend they be used, particularly in a high risk scenario.”

Corteva’s general guidance on any products leaving its warehouse is that they should be used in the current season, or the following one.

That’s why this autumn and winter are the perfect time to check your greys, because all current (white) Corteva containers are within two years of manufacture.

They should be rotated per their DOM, as per normal practice, but apart from that, they’re good to go.

Brenton-Rule agrees it can be easy to get caught out with inventory, and end up carrying a bit of stock over. 

“In those situations the best thing to do is call your local Corteva territory sales manager with the batch number or DOM, and the name of the product – they’ll be able to give you some advice.”

The same goes for the grey containers or anything with old branding.

He also understands why holding onto older product that hasn’t sold is more commercially palatable than writing it off.

The fact remains, however, that the longer it sits around after its DOM is two years old, the less use it is.

“As a general rule, we recommend purchasing pack sizes appropriate for the job. Larger drums or packs can be more attractive because the product price per litre or kilogram is lower. But buying packs suitable for the job at hand or season ahead is better.

“It reduces the risk of products sitting in the shed well past the time when they should be there, and for farmers and contractors, minimizes chemical inventory.”

Written by Kathy Davis.

Published in Issue 151  March/April Agribusiness magazine.

How Kiwi Farmers are looking after their friends

New Zealand farmers grasp the concept of 'mateship' better than most. In a business that can be unforgiving, having friends you can count on can make all the difference. Of course, that's about more than just being part of a tight-knit rural community.

It's also about your connection to the environment and your relationship with your allies – the beneficial insects which make their homes amongst your crop. As natural enemies to key pests, these friendly insects can have a huge impact on the health of your crop, and looking after them is paramount.

This is a vital part of a strong Integrated Pest Management (IPM) program – an approach which utilises biological (e.g. natural predators and parasitoids), chemical (e.g. selective insecticides) and cultural controls in an effective and sustainable way. Creating a successful IPM program starts with a regular walk through your crop, taking the time to identify and monitor any pests which are present (as well as their natural enemies), gauging the degree of crop damage against the balance between pests and beneficials before determining the need to spray.

Then it's about selecting the right product(s) for the job. For many Kiwi farmers, the cornerstone of their IPM strategy comes in the form of Sparta and Transform, two powerful new generation insecticides from Corteva Agriscience.

Creating a successful IPM program starts with a regular walk through your crop, taking the time to identify and monitor any pests which are present, gauging the degree of crop damage against the balance between pests and beneficials before determining the need to spray.


Creating a successful IPM program starts with a regular walk through your crop, taking the time to identify and monitor any pests which are present, gauging the degree of crop damage against the balance between pests and beneficials before determining the need to spray.

Perfectly suited to New Zealand conditions, Sparta is a unique insecticide providing best-in-class control of an array of pests. Safer for both the applicator and the environment, it acts quickly, causing caterpillars and other chewing insects to cease feeding just minutes after ingesting it.

The naturally-derived formulation, which has a novel mode of action and no record of resistance, is highly-effective against some of the country's most invasive pests, including diamondback moth, white butterfly and leaf miner.

Transform is a systemic insecticide providing 'best-in-class' aphid control. Offering rapid knock-down and longer residual control, it stops sap-sucking insects from feeding, halts the spread of disease, and creates a barrier which prevents new populations from entering the crop.

Together, these two products provide a rock-solid foundation for a successful Integrated Pest Management programme.

Find out more about our IPM friendly products here.

Keep those brassicas in good shape over summer

What difference does a month make?

Quite a lot, when it comes to forage brassicas.

If your farmers are among the many who have moved towards sowing forage brassicas later in summer – or maybe even planting in autumn – it’s time now to make sure they have adjusted their crop protection input decisions accordingly.

That’s the advice from Corteva Agriscience national sales manager Richard Brenton-Rule, who says selecting the right post-emergence herbicides in particular assumes new importance in such situations.

That’s because residues and plantback intervals of some products can become limiting for the next crop in the rotation.

Going by product orders, he believes the peak sowing season for spring forage brassicas has moved up to a month later over the past 10 years.

At the same time there has been increase in autumn sowing of crops like forage rape and turnips for winter grazing, especially in the North Island.

“Seasonal conditions have pushed some of those spring plantings later than what we would have traditionally expected,” he says.

“And we’re also seeing more crops like forage rape and turnips sown in February and March for winter grazing, as farmers reach autumn after a dry summer and realise they need feed for winter. It just gives them a bit more flexibility.”

Regardless of the cause, the upshot is a narrower interval between forage brassica herbicide application, for example, and the following crop.

It’s a scenario where using Korvetto for post-emergence weed control can make a valuable difference, he says.

“Korvetto’s short plantback is a standout feature, no matter when crops are sown. But in these situations, where planting dates are significantly later, it really comes into its own.

“It’s the most flexible post-emergence option available, with a three month plantback for clover and a six month plantback for fodder beet.

“Some other herbicide options have plantbacks of 9-24 months, which can be quite limiting.”

Korvetto plantback periods for maize, cereal, ryegrass and forage brassicas are nil; vegetables and legumes other than clover are six months.

As well as controlling key forage brassica weeds like fathen, nightshades and Californian thistles, at 1 litre per ha Korvetto provides best-in-class control of shepherd’s purse and fumitory, Brenton-Rule points out.  

Crop safety is excellent for leafy and bulb turnips, kale, forage rape and swedes.

“Another important benefit is that it is registered for aerial application which means customers are not solely reliant on ground-spray. That’s good to know when conditions are such that site access is an issue.”

Sowing forage brassica crops later in spring, or in autumn, also has implications for insect pest monitoring and control, he says.

“In the warmer conditions of summer, pest numbers can increase rapidly, raising the risk of the crop being severely impacted. It’s important to keep a really close eye on those crops to make sure pest populations are dealt with before they explode.

Brenton-Rule says where required, IPM-compatible Transform and Sparta offer farmers a welcome alternative to older chemistry such as synthetic pyrethroids (SPs) and organophosphates (OPs), which are very harmful to beneficial insects.

“It’s time to move on from using OP or SP chemistry for springtail, leaf miner, caterpillars and aphids in forage brassicas, and utilise the more sustainable and IPM friendly options available.”

Transform contains the novel active Isoclast (Group 4C) for excellent aphid control, with a different mode of action to other commonly used aphicides, high end user safety and low environmental risk.

Isoclast belongs to a unique insecticide group known as the sulfoximines which do not have cross resistance to any other insecticide group, making Transform an ideal rotation partner for insecticides with alternate modes of action in resistance management programmes.

Key points of difference include Transform’s ability to provide longer residual control than some of the alternatives, Brenton-Rule says.

Sparta Jemvelva® active (spinetoram) controls diamond back moth and white butterfly caterpillars, looper caterpillars, leaf miner and springtails in forage brassicas.

Its unique chemistry provides powerful control of diamondback moth and white butterfly that out performs current market standards.  

It is also very effective at controlling other pests such as leaf miner.

Users appreciate its speed and efficacy of kill, lack of smell, low tox profile and low application rates.

In addition, Sparta’s unique mode of action means OP and SP resistant insects will be effectively controlled, plus it provides an ideal option for resistance management as a rotation partner to other IPM compatible chemistry such as the Group 28’s.

For more detail talk to your local Corteva Agriscience territory manager. 

Californian Thistle control requires a 3-shot spray programme approach

In the battle against one of New Zealand’s most unwanted pasture weeds, Californian thistle is winning more than it should. One of the reasons is that effective Californian thistle control requires a well-timed, 3-shot programme approach. Key sprays often get missed, or not applied at the correct growth stages, thereby getting poor control.

Ian Kirkland, upper North Island territory sales manager for Corteva Agriscience, says it’s no wonder farmers get disheartened when their efforts to control Californian thistle don’t seem to work.

One herbicide application over 12 months is simply not enough to get control of Californian thistle.  It is important to have a 3-shot spray programme with well-timed applications, otherwise this persistent species continues to grow and spread, and the infestation is likely to end up back where it started.

The first herbicide application to Californian thistles should be when they have reached the hardball stage, just before the flowers open.  This growth stage is usually around November/December and application timing is important as:

1.       Most of the shoots have emerged, so you are less likely to miss spraying any dormant shoots.

2.       There is sufficient leaf area on the thistle to absorb herbicide into the plant.  

3.       Spraying at the hardball stage, prior to flowering means the photosynthates (sugars) are being translocated down into the roots which also aids the translocation of chemical into the root system.  Spraying at flowering or after flowering means that a lot of the photosynthates (sugars) stay near the top of the plant for flower and seed development and so the chemical is not translocated to the roots where it is most effective.

The shoot growth of Californian thistles sprayed at hardball stage will die off at the top, however the massive underground root system supporting each plant will respond by sending up fresh new shoots. It is these new shoots that need to be hit hard a second time, several weeks after the first initial herbicide. This is normally around February/March, ideally when the thistles get to knee high and there is plenty of green leaf to absorb the herbicide to allow it to be carried down to the roots.  Spraying too early means that not enough of the seedlings have emerged and that the leaf area does not allow enough absorption of the herbicide.

Some of the plants not controlled by the first two herbicide applications may still regrow. While some of these may be controlled by the winter frosts, the remaining plants require a third spot spray application in the following November/December.

Ian Kirkland has seen enough paddocks to notice the impact of farmers skipping the second and third sprays, which he describes as the missing link in effective control programmes.

He puts the proliferation of Californian thistles down to a lack of understanding about the plant in general, as well as a plethora of information (and misinformation), opinion and theory about how to control it. “It’s easy for farmers to get confused, and then discouraged.  But it’s also easy for reps to start setting them straight with sound advice and the right herbicide”.

“Tordon Pasture Boss is the best herbicide to control Californian thistles, but it’s still not a one-shot application. They can’t just spray and walk away, wave goodbye from the gate.”

The withholding periods of Tordon PastureBoss are relatively short (three days for milk; seven days for meat).  Although Tordon PastureBoss will damage clover, pasture production and grazing are already greatly reduced where Californian thistle populations are high, and that productive ground will be re-gained the following season, and the clover will eventually return.

What’s more important than any herbicide is often a change in mindset.

“Farmers get overloaded with information, the message is diluted, and in some cases they end up not even starting a control programme.

“They need confidence in the fact that they can get things turned around, with the right advice and the right approach. And reps are the people best placed to help them achieve this.”

For more detail contact your Corteva Agriscience territory sales manager or click through to our Tordon PastureBoss page below.


Gallant Ultra - new registration

Corteva Agriscience, has announced the successful registration and launch of the selective

post-emergence grassweed herbicide Gallant Ultra™ in time for the upcoming forage brassica and fodder beet season.


Trusted for generations and extensively evaluated for weed control efficacy and crop safety in local product development trials, Gallant Ultra is a selective, post-emergence grassweed herbicide that can now be used in fodder beet, kale and late maturing rape.


There are several attributes of Gallant Ultra that benefit forage brassica and fodder beet growers. These include the ability to control some of the most invasive grassweeds in crop, including summer grass, perennial ryegrass, and bristle grass. In addition to grassweeds Gallant Ultra is also one of the most effective herbicides for controlling Storksbill which is common in parts of New Zealand and loves dry, bare open soil, often competing to get established at the same time as crops in summer. The ability to provide control on some of the toughest grassweeds and storksbill means Gallant Ultra is the perfect companion product for post emergence broadleaf herbicides sprays such as Korvetto™ or Milestone™, ensuring a clean seed bed and less competition for forage brassica to get established.


Prior to planting implementation of a robust spray out program is important to reduce the weed burden in crop, then with all post-emergence herbicides, timely application to young weed seedlings and the encouragement of a strong crop canopy is important to maximise weed control. One new feature with Gallant Ultra is the ability to reduce the rate for perennial ryegrass control to 125ml/ha from 250ml/ha if applications are made before the 3 tiller stage.


The high strength formulation of Gallant Ultra means less product to transport and handle, as well as minimizing the

environmental impact by reducing packaging requirements. Gallant Ultra should always be applied in a mixture with Uptake™ spraying oil at 1L/ha and if required it is also compatible with most commonly used broadleaf herbicides and insecticides.


Gallant Ultra has extensive withholding periods in forage brassica and fodder beet so understanding the impact of these before use and implementing appropriate grazing plans is important to ensure meat and milk tolerances are not exceeded.


Gallant Ultra


A selective, post-emergence, grass weed herbicide for use in Kale, late maturing rape and fodder beets


•       Broad-spectrum grassweed control

•       including annual and perennial ryegrass, cultivated couch and summer grass

•       Outstanding control of storksbill

•       Highly selective (“safe”) to forage brassica and fodder beet crops

•       High strength formulation

•       low use rates

•       reduced packaging and handling requirements

For further information contact your Territory Manager or click through to our Gallant Ultra page below.

Watch for pest outbreaks in forage brassica

Insect pests cause damage which may significantly reduce the potential of your forage brassica crop. These pests can impact yield by reducing plant population or damaging leaf tissue and growing points, which restricts plant development and provides infection sites for disease or transmission of virus. Forage quality and palatability may also be impacted. Forage brassicas, like most crops, are most vulnerable during the establishment phase, but continue to be at risk from key insect pests throughout the growing season.

Crops should be walked regularly during the establishment phase to ensure any issues are identified as soon as possible. Start walking each crop perhaps every three days from planting then push out to weekly from canopy closure. Be aware that pest populations and subsequent damage can develop rapidly in forage brassicas and in some unfortunate cases the decline from having a great crop to needing to replant can be just 3-4 days.

Key things to observe in your brassica crop during establishment include damage to seedlings and the presence of both insect pests and their natural enemies, including beneficial predators and parasitoids.

The key insect pests of brassicas in New Zealand are springtail, diamondback moth, white butterfly and aphids1. Other notables include leaf miner, Nysius and cutworm. The AgPest website ( is a great resource for familiarizing yourself with these pests and their impact on the crop.

Ideally your crop will host a population of natural enemies of key insect pests such as ladybirds, hoverfly, lacewings and parasitic wasps. These are worth protecting by adopting an integrated pest management (IPM) approach and using insecticides with minimal impact on beneficial insects such as SpartaTM and TransformTM from Corteva Agriscience.

SpartaTM and TransformTM from Corteva Agriscience are ideal tools for control of key insect pests in forage brassicas. Both products have excellent environmental and toxicology profiles, providing a high level of safety for both ground and aerial based applicators. Only minimal protective equipment is required when using Sparta or Transform – specifically overalls, water-resistant work boots and a washable hat. Use of a face shield or goggles is recommended when measuring and mixing. The use of a respirator is not required.

Sparta works by contact and ingestion to control key pests such as springtail or leaf miner and provides ‘best in class’ control of diamondback moth, white butterfly and looper caterpillars. Translaminar activity ensures good control of insects feeding on the underside of leaves.

Transform is a systemic insecticide that provides fast knockdown and residual control of both green peach aphid and cabbage grey aphid. As aphids build up to levels requiring treatment, Transform can be included as a tank partner with Sparta if leaf miner and caterpillar pests are also present, or applied as a standalone product if aphids are the only pest needing treatment.

Always read the product label before using agricultural chemicals to ensure suitability for your situation and understand directions for use. For more guidance talk to your Territory manager or click through to our Forage Brassica page below.

1De Ruiter, J et al. 2009. Management practices for forage brassicas. Forage Brassica Development Group. Pp44-45.

T-Max registered for forage plantain crops

The increased relevance and demand for forage plantain in both dairy and dry-stock systems encourages investment in technologies to improve performance.

This includes developments such as new and improved cultivars and also the registration of herbicide options for use on the crop.

T-MAX is a post-emergence herbicide that has been used extensively for the control of a wide range of broadleaf weeds in pastures and forage brassicas, and as a partner for glyphosate at spray-out. It is particularly effective against docks, giant buttercup, black nightshade, willow weed, fathen, ragwort and thistles, including Californian thistle.

Farmers have been waiting for registered herbicides to use on plantain and will welcome the addition of T-MAX to their arsenal in the fight against weeds in this crop.

Recommended forage plantain crops where T-MAX can be used:

>    Newly sown and established pure swards of plantain.

>    Mixes of plantain and grasses or forage brassicas, for example Italian ryegrass or forage rape.

>    As a selective treatment for plantain mixes with clover and/or other herbs that have become overwhelmed by thistles and other broadleaf weeds. The clover and other broadleaf species will be removed, but plantain is retained and can be undersown with grasses.

Richard Brenton-Rule, Territory Manager for Corteva Agriscience explains, “There are many pure-sward summer or perennial crops of plantain where T-MAX will be a welcome tool for weed control. There are also a number of situations where perennial mixed swards containing plantain are overcome by high weed numbers, but there is a sufficient population of plantain worth retaining. The plantain can be retained using T-MAX to cleanup the sward before undersowing or oversowing with a suitable partner like Italian or short-rotation ryegrass to get another season or two from the block".

Corteva Agriscience conducted extensive trials throughout New Zealand evaluating T-MAX over plantain for crop safety and grazing interactions to establish reliable guidelines for use. Trials1 showed T-MAX is best applied to young, actively growing weeds in established plantain, that is after grazing. Allow a few days following grazing for weeds to freshen up, then spray. Applying T-MAX after a grazing ensures good coverage of target weeds and minimises the impact of the spray on the plantain crop.

While some short term reduction in growth can occur from application of T-MAX, this is minimised by spraying after grazing and trials1 showed that growth recovers fully within a few weeks and long term yield or plant numbers are not reduced.

For more information on the use of T-MAX in plantain, consult your Territory Manager and always read the updated version of the T-MAX product label for further guidelines on timing and use in plantain.