The Q&A Archives: Tomatoes rotting on top

Question: This is our first year gardening, and we were totally amazed at how well our 6 Early Girl, 6 Heinz and 6 Sweet 100 tomato plants were doing till now. The Heinz and Early girls ripened at the same pace, and all the plants are loaded with fruit. However, almost ? of the Early Girls are rotting at the top of the fruit. This happens to some, but not as many of the Heinz also. They all seem to get very red on the bottom 2/3 of the fruit with the tops staying yellow. I'm learning that if I don't pick them at this stage and allow them to ripen on my windowsill, they will get black rotted areas near the top. I've heard of several people with tomato rotting problems at the blossom end, but not at the top. What could be causing this? This was a new bed, and we did not amend the soil. However, we know it is very nitrogen rich as my husband had been dumping woodstove ashes there from 1990 to 1997. We have watered daily during our unusually dry summer season, and I did use Miracle Grow prior to the flowers blooming, but not since.

Also, the sweet 100s are producing like crazy, but the vines are yellow and dying off.

These 18 plants are next to each other (1 row of 6 Heinz with a row of 6 Early Girls on one side and 6 Sweet 100s on the other.

I'd really like to avoid this problem next year, as gardening is becoming my newlyl discovered source of peace and tranquility, as well as a classroom for our 2? year old.

Thank you, in advance, for your advice.

Kathie Deaver
Lakeport (Canastota), NY

Answer: The rotting problem at the tops sounds like it may be caused indirectly by sunscald which is then followed by a fungal infection. There is no particular cure for this except to make sure that your plants are healthy so they have the maximum amount of foliage to shade the developing fruits. (It is not related to Blossom end rot.)

Blossom end rot is ultimately caused by a calcium deficiency in the soil but often only affects the tomatoes when the soil moisture level is allowed to fluctuate. In a dry year many gardeners will have trouble with that because their watering is not keeping the soil evenly moist.

With regard to fertilizing and improving your soil, the best way to keep it healthy is to run some basic soil tests and see what (if any) specific nutrients or amendments are needed. Your County Extension (684-3001) can help you with the tests and interpreting the results. I would caution you about adding wood ashes particularly during the growing season as they may have some drastic (but short lived) effects on the soil which could adversely affect your crop.

In general it is important to clean up, remove and destroy any fallen leaves or vines during the season and in the fall to try to avoid carrying any problems over in to the following year. You will also want to rotate your plantings so that you do not plant tomatoes or their relatives in the same spot for several years. Your County Extension may also be able to diagnose the problem with your Sweet 100's tomatoes and possibly suggest additional control measures.

Enjoy your garden!

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