I used Resolva lawn weedkiller already made up on my lawn a few weeks ago. To my horror I now have at least twenty large dead grass patches in my lawn. I have tried to reseed but none of the seed has germinated. Can you help? For about ten days after I applied the weedkiller the patches kept getting bigger and in fact some of them have merged. I have used weed and feed every year for probably about twenty years and have never had this problem.