Over the last couple of days I've notice some leafs on my reaper plant turning a bit brown. Any ideas what could cause something like this? my guesses are either fertilizer, water, or fungus.... Maybe it's nothing to even worry about

They're in a 5-1-1 mix in mid 80 degree weather for past couple weeks. Fertilized with foliage pro at 1tsp per gallon per week for three weeks then a 20-20-20 tomato fert (recommended dosage) on the fourth week. Haven't been watering much between weekly feedings as soil has remained moist and leafs have not wilted.

the only other addition to ferts is two weeks ago I added Epsom salts with feed and last weekend I added dolomitic lime (at recommended mix for 5-1-1) because I had not added to original mix.

thoughts?