I recently had my garden landscaped (paving and gravel). When the landscaper came to price up the job last year he noticed that I had a problem with mares/horses tail in the area which was to be graveled. He explained that it was public enemy number 1 and he would have to use a different type of weed fabric in that area. The job was completed in march and looked good until about six weeks ago. Mares tail started appearing, so I treated it with Round up which had no effect what so ever. I phoned the landscaper he came out with some Deadfast(sodium chlorate) and treated the entire outbreak. He left me a 5kg tub and told me to treat it every time it appeared he also said it wont go away over night it will probably take 2, 3, maybe even 4 years to get rid of completely(he said he would supply me with as much Deadfast as needed). After about 2 days it all started to die however lots of new bits appeared, the only good news was it wasnt in the areas previously treated. Ive just noticed today I now have small black mountains of weed fabric coming through the gravel where the roots are running underneath.
Could he have done anything to prevent this outbreak?
Is everything he is saying right?