If you are asking if it will cause brown spots in your lawn, it will only harm your lawn if you mis-use it and cause burn by over applying or not following label instructions. If you are asking if it will cause brown patch disease in your lawn, no it will not and if your lawn has a tendency of having brown patch you need to start doing a preventative fungicide application before the signs start appearing.
Yes, Ferti-Lome Lawn Food Plus Iron 24-0-4 can be used on all types of grasses, and can be used in the fall as well. Please be sure that temperatures are below the 80 degree mark for you ground temperature when using this product to get the best results, and to prevent burning on your lawn. We always recommend doing a soil test to be sure exactly what your lawn needs before applying any fertilizers.
Please keep children and pets off Ferti-Lome Lawn Food Plus Iron 24-0-4 treated area until treated area has dried. This will be about 2 hours.