Battling Tomato Wilt

Gardeners have often heard the importance of rotating vegetable crops during seasons. Rotate your crops! Your plants will drain the soil of needed nutrients otherwise! Rotate your crops! Your plants will become more vulnerable to disease otherwise! I have gardened with this maxim in the back of my head, but often have found the tasty homegrown tomato bounties’ siren songs too difficult to resist. And so, bucking common wisdom, I grew tomatoes in the same spot as tomatoes years past. Until this year, all was well. Tomato plants flourished in the same locations year after year.

Well, the time has come to atone for my gardening sins. How I rue my confidence now, thinking that a major disease could never strike my plants. Well, fusarium wilt, or verticillium wilt, came this year with a vengeance. I guess I was due for my lesson from Mother Nature.

What bucking common wisdom will get you.

Both fusarium and verticillium wilt share many characteristics, making it difficult for a gardener to distinguish between the two. Both are soil-borne fungi, so the disease travels from the roots of the plant through the stem. [1] , [2]  Both brown the vascular tissue of the tomato plant, and choking the leaves off from nutrients from the soil. These leaves yellow, then brown, and then die. Individual plants are affected, with symptoms appearing when the plant begins to set fruit.

Fusarium and veticillium are distinguished from each other based on their ranges and based on how quickly the plant succumbs to the fungus. Fusarium wilt is much more common in the southern range of the United States. Veticillum wilt is common in the north, so much more than Fusarium wilt that the University of Illinois Extension office only has a website on the former. [3] The streaking that accompanies verticillium wilt is lighter than that of fusarium wilt and typically does not extend all the way up the stem. Veticilum wilt also proceeds more slowly.

Dark vascular streaking on Yellow Pear stem.)

There is no easy solution for either fungus. Instead, crop rotation and disease management is the only way to control the spread. This year, I have pruned the first foot of each tomato plant of foliage and have cut back watering to every other day. Without those lower leaves, the tomatoes have more airflow close to the ground.  Also, the drier soil prevents the fungus from spreading. Finally, in desperation, I have also treated each tomato with powdered copper fungicide below the fruiting level. This is risky because the plant is also in danger of being damaged by the fungicide and the copper never leaves the soil (it is a heavy metal after all). [4] I have also pruned all diseased leaves from affected plants on a weekly basis.

Pruning foliage has the added benefit of giant tomatoes!

 

My efforts seem to have stymied the spread of the disease in all of the tomato plants but the Yellow Pears. Yellow Pears are my mother’s favorite variety of homegrown tomato, and so she has been particularly disappointed with this year’s crop. I have grown the variety for her before and never had any problems with them.  Foolhardily, I only planted one Yellow Pear this year. Well, Mother Nature, I have learned my lesson.  Next year I will take heed of old gardening wisdom and rotate my tomato crop!