It is seldom we see a product that has departed the market reappear years later. This is largely the situation with tri-allate. For those who have been in the business for years, that active was Avadex. It was never that popular at the time, mainly because of its formulation – it was a granule and had to be applied immediately post-planting. This was a very busy period during autumn planting and it also needed specialist application equipment.
Recent changes
Two things have changed since then. The first is that the application of pre-emergence herbicides has become more common, due to changes in product availability and a more complex set of target weeds. The second is that a liquid formulation of tri-allate called Avadex Factor is now available on the market.
There are two other reasons growers might have an interest in the return of this active. One is that it is one of the very few that has not been weakened by the growing number of types of resistance, which have either developed or been imported into the country.
While wild oats were its original target weed, it is also effective on ‘tame’ oats
The other reason for additional interest is its activity against oats. While wild oats were its original target weed, it is also effective on ‘tame’ oats. It has a 12-month gap requirement between its application and the planting of an oat or grass crop. So, this could be very useful in crops following oats which suffered head and seed loss in the various storms this year.
However, price may be a deterrent in some situations. At a cost of €21 -€22/ac (+ VAT ) it is most likely to be targeted at resistant blackgrass or for sterile brome control in winter barley, especially in min-till crops.
What is tri-allate
So, what is Avadex Factor and how does it work? It is a liquid formulation, a suspension concentrate containing 450g/l of tri-allate. It can be used on winter wheat and winter and spring barley, which can add to its appeal in certain situations.
It is a pre-emergence residual herbicide, which should ideally be applied within 48 hours of drilling. It should not be incorporated into the soil for winter crops, but can be for spring barley.
Where rolling is being done, it should be applied post-rolling, so that it can seal the surface against emerging seedlings
It is said to be less affected by dryness than other residual actives, but in situations where ground is very dry, it may be best to hold application until rain arrives. But it must be applied before the emergence of the weeds to be effective. Like any other residual, it will perform best in good, even seedbeds that have adequate soil moisture.
Where rolling is being done, it should be applied post-rolling, so that it can seal the surface against emerging seedlings. It needs to be applied in 200-300l/ha of water to help get it into the soil.
The application rate for Avadex Factor is 3.6l/ha and at 450g/l, that supplies 1,620g/ha of tri-allate. The supplier, Gowan, states that there is no rate flexibility, because this quantity is already only 72% of the rate of active that would be applied using granules.
Mode of action
Tri-allate is a thiocarbamate herbicide. It is taken up by the coleoptile during emergence and affects cell division and elongation in susceptible seedlings – they effectively fail to emerge and die. It is only active on emerging seedlings, so once they are emerged, they are not affected and there is little or no root activity.
However, the active also inhibits the synthesis of lipids, which make the wax on the leaf surface. So, susceptible seedlings that do emerge have poor wax and are more susceptible to other post-emergence herbicides. This can be very useful when dealing with problem weeds like blackgrass, as they can become more susceptible to herbicides, against which they may have developed some level of resistance.
After tri-allate is taken up by susceptible seedlings, it is oxidised into the sulfoxide form in the cells, and that is the substance that is the herbicide.
Take care with
Wheat seedlings are somewhat sensitive to the active. Therefore, this crop must be sown more than 4cm deep to protect seedlings from damage. Uneven planting depth can impact on establishment in a treated crop.
It is by far the most tolerant residual herbicide to seedbed dryness
Oats are highly sensitive and so cannot be treated – hardly surprising since it is a wild oat herbicide. It could also be very useful where a big volunteer oat problem is expected. There must be 12 months between application of Avadex Factor and the planting of oats, so a treated spring barley crop cannot be followed by winter oats. It is by far the most tolerant residual herbicide to seedbed dryness. Its effective activity can range from two to six months.
Avadex Factor should always be used as part of a programme and never entirely on its own. It can be tank mixed with other pre-emergence products.
Grass targets
In good working conditions, it can be very effective against all the brome grasses, Italian ryegrass seedlings, and blackgrass. However, tank mixes or sequences will be needed to ensure full control. It also impacts on the growth of many broadleaved weeds, with common field speedwell and red dead nettle being the most affected. But the impact on the wax of other species may increase their susceptibility to other actives.
The return of tri-allate provides another mode of action in the fight against herbicide resistance in grassweeds.Avadex Factor is a liquid formulation that must be sprayed on pre-emergence of the weeds.It is taken up from the soil through the emerging coleoptile and susceptible species fail to emerge.Wheat need to be planted at >4cm deep to avoid the risk of damage.It is effective against a range of troublesome grassweeds.
It is seldom we see a product that has departed the market reappear years later. This is largely the situation with tri-allate. For those who have been in the business for years, that active was Avadex. It was never that popular at the time, mainly because of its formulation – it was a granule and had to be applied immediately post-planting. This was a very busy period during autumn planting and it also needed specialist application equipment.
Recent changes
Two things have changed since then. The first is that the application of pre-emergence herbicides has become more common, due to changes in product availability and a more complex set of target weeds. The second is that a liquid formulation of tri-allate called Avadex Factor is now available on the market.
There are two other reasons growers might have an interest in the return of this active. One is that it is one of the very few that has not been weakened by the growing number of types of resistance, which have either developed or been imported into the country.
While wild oats were its original target weed, it is also effective on ‘tame’ oats
The other reason for additional interest is its activity against oats. While wild oats were its original target weed, it is also effective on ‘tame’ oats. It has a 12-month gap requirement between its application and the planting of an oat or grass crop. So, this could be very useful in crops following oats which suffered head and seed loss in the various storms this year.
However, price may be a deterrent in some situations. At a cost of €21 -€22/ac (+ VAT ) it is most likely to be targeted at resistant blackgrass or for sterile brome control in winter barley, especially in min-till crops.
What is tri-allate
So, what is Avadex Factor and how does it work? It is a liquid formulation, a suspension concentrate containing 450g/l of tri-allate. It can be used on winter wheat and winter and spring barley, which can add to its appeal in certain situations.
It is a pre-emergence residual herbicide, which should ideally be applied within 48 hours of drilling. It should not be incorporated into the soil for winter crops, but can be for spring barley.
Where rolling is being done, it should be applied post-rolling, so that it can seal the surface against emerging seedlings
It is said to be less affected by dryness than other residual actives, but in situations where ground is very dry, it may be best to hold application until rain arrives. But it must be applied before the emergence of the weeds to be effective. Like any other residual, it will perform best in good, even seedbeds that have adequate soil moisture.
Where rolling is being done, it should be applied post-rolling, so that it can seal the surface against emerging seedlings. It needs to be applied in 200-300l/ha of water to help get it into the soil.
The application rate for Avadex Factor is 3.6l/ha and at 450g/l, that supplies 1,620g/ha of tri-allate. The supplier, Gowan, states that there is no rate flexibility, because this quantity is already only 72% of the rate of active that would be applied using granules.
Mode of action
Tri-allate is a thiocarbamate herbicide. It is taken up by the coleoptile during emergence and affects cell division and elongation in susceptible seedlings – they effectively fail to emerge and die. It is only active on emerging seedlings, so once they are emerged, they are not affected and there is little or no root activity.
However, the active also inhibits the synthesis of lipids, which make the wax on the leaf surface. So, susceptible seedlings that do emerge have poor wax and are more susceptible to other post-emergence herbicides. This can be very useful when dealing with problem weeds like blackgrass, as they can become more susceptible to herbicides, against which they may have developed some level of resistance.
After tri-allate is taken up by susceptible seedlings, it is oxidised into the sulfoxide form in the cells, and that is the substance that is the herbicide.
Take care with
Wheat seedlings are somewhat sensitive to the active. Therefore, this crop must be sown more than 4cm deep to protect seedlings from damage. Uneven planting depth can impact on establishment in a treated crop.
It is by far the most tolerant residual herbicide to seedbed dryness
Oats are highly sensitive and so cannot be treated – hardly surprising since it is a wild oat herbicide. It could also be very useful where a big volunteer oat problem is expected. There must be 12 months between application of Avadex Factor and the planting of oats, so a treated spring barley crop cannot be followed by winter oats. It is by far the most tolerant residual herbicide to seedbed dryness. Its effective activity can range from two to six months.
Avadex Factor should always be used as part of a programme and never entirely on its own. It can be tank mixed with other pre-emergence products.
Grass targets
In good working conditions, it can be very effective against all the brome grasses, Italian ryegrass seedlings, and blackgrass. However, tank mixes or sequences will be needed to ensure full control. It also impacts on the growth of many broadleaved weeds, with common field speedwell and red dead nettle being the most affected. But the impact on the wax of other species may increase their susceptibility to other actives.
The return of tri-allate provides another mode of action in the fight against herbicide resistance in grassweeds.Avadex Factor is a liquid formulation that must be sprayed on pre-emergence of the weeds.It is taken up from the soil through the emerging coleoptile and susceptible species fail to emerge.Wheat need to be planted at >4cm deep to avoid the risk of damage.It is effective against a range of troublesome grassweeds. 
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