0 Overcoming weed control problems

Broad spectrum herbicides offer effective chemical control of weeds in turf, but despite users applying the same product for a number of years, poor weed control can occur.

Herbicides work best when there is good strong growth enabling complete control. However, this year we have had unusual weather conditions, sometimes cold and wet, other times nice and sunny but with late frosts.

Mark De Ath of Headland Amenity explores the problem.

You would normally expect late April and early May to be one of best times of the year to achieve good control. However, we were made aware of an instance where the correct herbicide had been applied, but poor results were achieved.

When we looked at the weather statistics through our Headland Weathercheck service, it showed that whilst the days had been reasonably warm, the nights had been below or close to freezing and there had been little, if any, rain prior to the application period.

This sort of weather is not conducive to good growth and therefore, good weed control.

Rather than slavishly adhere to the calendar, because that is the time when you would normally spray, one should ideally plan a weed control application with one eye on the prevailing weather and the other on the subsequent weed growth.

Important aspects such as ensuring the correct water spray volume is used can avoid poor weed control. For example a low water volume may not only be illegal, but will give inadequate spray coverage of the target weeds.

Conversely spraying with a high water volume could lead to spray run-off and patchy weed control. Use the herbicide at the correct rate of application shown on the product label and if the herbicide does not control a particular weed, speak to your advisor about tank mixing with another to get that complete kill.

Another factor that could cause poor weed control is hard water. Hard water has high levels of calcium, magnesium and bicarbonate ions with high pH.

Bicarbonate ions are known to react in the spray tank solution with many herbicides making them less available to the plant and therefore you can get a reduction in weed control.

Quite a large area of the UK has hard water - if your kettle furs up you can be sure you're in a hard water area.

It doesn't have to just be the water out of the tap to consider. Recently we received an analysis of a bore hole water sample which we tested to understand why products were not working as well.

The analysis showed very high pH with a reading greater than 8 which, in our experience, is probably about as high as it can get. The sample also contained high levels of bicarbonate ions.

So if you are starting with some of the herbicide locked up and the weather is not playing ball, or you have difficult weeds like Speedwell to control, then your herbicide application could do with a helping hand.

You want to ensure that every drop of herbicide you apply reaches the weed. This helping hand can come in the form of water conditioners such Headland Transport Ultra that adds very little to the overall cost, particularly if retreatment costs are factored in.

Water conditioners lock up the bicarbonate, magnesium and calcium ions preventing them reacting with the chemical in your spray tank. In order to prevent this reaction, the water conditioner should be added to the spray tank first and then the chemical afterwards.

Broad spectrum herbicides offer effective chemical control of weeds in turf, but despite users applying the same product for a number of years, poor weed control can occur. Herbicides work best when there is good strong growth enabling complete control.

However, this year we have had unusual weather conditions, sometimes cold and wet, other times nice and sunny but with late frosts. Mark De Ath of Headland Amenity explores the problem.

You would normally expect late April and early May to be one of best times of the year to achieve good control. However, we were made aware of an instance where the correct herbicide had been applied, but poor results were achieved.

When we looked at the weather statistics through our Headland Weathercheck service, it showed that whilst the days had been reasonably warm, the nights had been below or close to freezing and there had been little, if any, rain prior to the application period.

This sort of weather is not conducive to good growth and therefore, good weed control.

Rather than slavishly adhere to the calendar, because that is the time when you would normally spray, one should ideally plan a weed control application with one eye on the prevailing weather and the other on the subsequent weed growth.

Important aspects such as ensuring the correct water spray volume is used can avoid poor weed control. For example a low water volume may not only be illegal, but will give inadequate spray coverage of the target weeds. Conversely spraying with a high water volume could lead to spray run-off and patchy weed control.

Use the herbicide at the correct rate of application shown on the product label and if the herbicide does not control a particular weed, speak to your advisor about tank mixing with another to get that complete kill.

Another factor that could cause poor weed control is hard water. Hard water has high levels of calcium, magnesium and bicarbonate ions with high pH.

Bicarbonate ions are known to react in the spray tank solution with many herbicides making them less available to the plant and therefore you can get a reduction in weed control.

Quite a large area of the UK has hard water - if your kettle furs up you can be sure you're in a hard water area.

It doesn't have to just be the water out of the tap to consider. Recently we received an analysis of a bore hole water sample which we tested to understand why products were not working as well.

The analysis showed very high pH with a reading greater than 8 which, in our experience, is probably about as high as it can get. The sample also contained high levels of bicarbonate ions.

So if you are starting with some of the herbicide locked up and the weather is not playing ball, or you have difficult weeds like Speedwell to control, then your herbicide application could do with a helping hand.

You want to ensure that every drop of herbicide you apply reaches the weed.

This helping hand can come in the form of water conditioners such Headland Transport Ultra that adds very little to the overall cost, particularly if retreatment costs are factored in.

Water conditioners lock up the bicarbonate, magnesium and calcium ions preventing them reacting with the chemical in your spray tank. In order to prevent this reaction, the water conditioner should be added to the spray tank first and then the chemical afterwards.

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