Garden Detective

Garden Detective: Wilt put a halt to tomato season

Q: My tomato plants started getting tomatoes and looked good, but the bottom leaves turned yellow. Then, the stems turned yellow and the flowers dropped off. I didn’t get any more tomatoes. This was on the Early Girl and Big Boy. I got quite a few Husky Cherry Reds but the flowers on them started to drop off, too. What can I do to prevent the flowers from dropping off so I can get tomatoes?

Freda Andem, Elk Grove

A: Although there are several reasons why tomato leaves would turn yellow, your description sounds similar to the symptoms for either fusarium wilt or verticillium wilt, according to UC master gardener Vickie-Marie Ward. Both wilts are caused by a fungus in the soil.

A solution to either of these problems is to not grow tomatoes in the same location as the previous year. Tomatoes, potatoes, peppers, eggplant and most cucurbits (cucumbers, melons and squashes) – even if resistant to the fungi that cause the problems – will still fail to thrive and may pick up the symptoms you described and others from the soil where carrier plants grew in the past seasons.

To avoid these problems in the future, it is recommended that none of the above-mentioned plants be planted in the same soil in which any of these plants have been planted in the past two years.

In other words, crop rotation over a four-year period is recommended.

If planting in containers, the soil can be removed and new soil used. If planting in the ground or in raised beds, then it is best to rotate.

Other crops such as corn, beans or carrots can be planted instead.

After soil removal and/or crop rotation, select tomato plants that are resistant to verticillium, fusarium and nematodes. The plant label will say “VFN Resistant.”

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