Fungus on Tomatoe plants

[rwodka21]

My father's crop of tomatoes has been plagued with what he thinks as early blight for the past 2 years. I was wondering if someone could shed some more light on the subject to what he can do to stop this from happening. Is their pesticides that can be bought at local stores that he could use. He really enjoys planting a garden each year but seems to lose a majority of his plants to this. Thank you for the suggestions ahead of time