New growth on tomato plant is turning black

by Maggie Ashmore
(Blesoe, KY)

Q. One of my tomato plants is turning black on the top three leaves. The new growth that will soon emerge also looks black. The bottom leaves of the plant are nice and green. The tomato plants are about 12 inches tall and have been transplanted into the ground for about 2 weeks. The plants are in a small raised bed. All of the other plans look great and healthy. Since the tomatoes have been planted we have had one wet week and one dry week.

A. Darkening or purpling of tomato leaves can indicate a phosphorus deficiency. In severe cases the whole plant may take on a dark or purple hue. An affected plant may also exhibit stunted growth, thin stalks, and delayed blossoming or fruiting.

A phosphorus deficiency can indicate a low level of phosphorus in the soil, but sometimes the soil is OK but cool. Lower temperatures inhibit phosphorus uptake.

In the short term, apply a water-soluble, high phosphorus fertilizer to move the nutrient into the plant's system as soon as possible. Long-term, apply a balanced fertilizer (like Miracle Gro Tomatoes or Tomato Tone) throughout the season. Make sure to test your soil at the start of each season and amend accordingly. Working compost into the soil is always a good idea!

Good luck and happy gardening!
Your friends at Tomato Dirt