Fusarium Root and Crown Rot (Tomatoes) Description: Entire root system is affected. Brown discoloration is obvious at the base of the stem. Disease progresses slowly from bottom to top, sometimes causing wilting. Disease is widespread in tomato growing regions. Solution: Maintain soil pH at 6.5 to 7.0. Test soil pH; if it is too acid, use ground limestone to raise pH. Most garden centers and farm stores sell ground limestone. Sprinkle SoilGardTM Microbial Fungicide over seed at time of sowing, before covering seed with soil. When starting seed indoors, mix SoilGard with potting soil before seed is sown.