Q.Poisonous spray
I inadvertently sprayed my roses with Astix (isomer mecocrop-p the active ingredient). They have obviously died but my question is, will the earth be contaminated below the roses, and if so, how long before I can replant? I have learnt a salutary lesson.

I am sorry about your plants. The soil may still have remnants of the chemicals used for some time but after about a year or so without the use of any chemicals, it should be ok. You can try flushing the area periodically with water to help speed the process along but until then you can always put your plants in containers or a raised bed instead.