Among fungal diseases that attack tomato crop wilts and root rots are found to be the most important diseases. The root rot caused by Fusarium sp., Pythium sp. or Rhizoctonia solani can be very devastating and destructive diseases of tomato. However it can be difficult to see difference between symptoms caused by Rhizoctonia solani, Pythium sp. and Fusarium sp. Symptoms for these pathogens can be wilting and a slow or rapid collapse of the plant. The roots can appear brown and water-soaked instead of white.
Rhizoctonia solani is the most important soilborne pathogen of tomato crop. In addition to root rot Rhizoctonia solani was also reported to cause stem canker (Wokoma, 2008) and damping off (Dutta and Dutta, 2007) and is considered to be the most important soilborne disease of tomato causing severe losses under favourable conditions at nursery beds and under greenhouse conditions. Roots affected by Fusarium sp. and Rhizoctonia solani gradually turn brown and die, and small dark spots appear on their surface. A water-soaked lesion can often appear at the base of the stem if plants are affected by Fusarium sp. but not if affected by Rhizoctonia solani (the base of the stem appear dry and brown). As the disease progresses, the plant's growth is inhibited.
In closed systems, with recirculation of nutrient solution and rock wool as a growing medium, Fusarium crown and root rot of tomato can cause serious problems. Cultural and biological control are the only tools in tomato crops to manage Fusarium sp. and Rhizoctonia solani disease. Biological control of Rhizoctonia solani with Trichoderma sp. is quite effective. Trichoderma based products are dog not very effective if Fusarium sp. is affecting plants.