Fusarium crown rot strikes at the root and wreaks havoc on the entire root system. It is extremely widespread in places with sandy, acidic soil. Southern Florida, for example, is much more likely to experience it than Colorado.
Causes and Symptoms
Caused by the fungus fusarium pseduograminearum, tomato fusarium crown rot is so prevalent because the fungus is easily picked up by weak or young plants. It can also be carried over to new soil from infected plants, thereby leaving both soil and plants extremely susceptible to plague.
There is distinctive brown discoloration beginning from the base of the stem and traveling upwards throughout the plant. Brown discoloration, especially in the veins of the plants, occurs. Older leaves will begin to yellow, and then they will eventually turn brown and black. The leaves will wilt and fall off. Defined lesions indicate that the plant is near death.
Treatments and Control
This tomato disease is easier dealt with using preventative measures. The fungus can remain in soil for up to two years after an initial infection. Use pre-plant fungus fumigants in the soil two weeks prior to planting. Cover the bed with plastic after fumigation. Avoid excess soluble salts, and maintain the soil’s pH at 6-7. After the tomato crop has been harvested, use tomato crop rotation and replant the area with something new.
Do not plant any tomatoes (or plant varieties that are also susceptible, such as wheat or asparagus) in an area that has been a known carrier of the fungus. Choose a disease resistant tomato variety that has the letter “F” printed on the label. These farmed tomato seedlings have been treated and raised to be resistant to the fungus. While these varieties are not completely immune, they do stand a greater chance of resistance. Combine them with pre-planting fungal treatments and then fungicides for tomato plants to achieve best results.
If the symptoms of the fungus do occur on existing plants, begin by checking watering practices. Over or under watering often mimics the symptoms of the disease, especially with the yellowing leaves. However, if the plants are indeed afflicted, it is almost impossible to cure.