There are many reasons a weed may become hard to kill, this could from herbicide resistance or they may just be naturally to kill like Windmill grass or Feathertop Rhodes. However while they are difficult to kill there is two main reasons why they should be killed wherever possible as if they aren’t they’ll rob the crop of moisture and set seed spreading the problem.
Often weeds will only be resistant to a particular herbicide and their are generally other herbicide options or strategies available to a grower to control a weed problem. This can include changing up chemistry and double knocking to ensure a good kill. While this may seem costly it is cheaper than the potential yield loss that could occur from the moisture lost due to not controlling them. On top of that the weeds will set seed and the problem will grow the following year.
One option that can be looked at to reduce cost is the use of camera sprayer that only sprays herbicide when it identifies a weed in the paddock. Even if you don’t own a camera sprayer most districts have few getting around available for hire or contract spraying and while it may be hard to hire a camera sprayer when you already own a boom spray but generally the money saved on Chem makes it worth while.
Controlling problem and hard to kill weeds is essential, if you don’t control them you will lose yield and they will spread growing the problem. Therefore it is essential to do what you can to get rid of them even if it is more costly than a normal fallow spray and requires the hiring of equipment.