Rotten Tomatoes and Yellow Leaves.

by Rees on July 10, 2011 · 9 comments

in advice,Problems and Solutions,Veggies & Fruits

So why do my tomato leaves turn yellow and why are my tomatoes rotting before they are ripe?

Vegetable season is in high gear and fruit is beginning to ripen. This is the time when I start to get all the questions.  Why do my zucchini drop off? Why won’t my melon set fruit?  What are those worms on my peppers? I had been working on a post to address one of the most common ones on tomatoes, Tomato End Rot when I got the following question from a reader who purchased one of my Growing Juicy Delicious Tomatoes eBook from Rainforth Home and Garden.  First I’ll address his question and then finish up with my thoughts on the issue of rotting tomatoes.

Here is the question from Mr. B. Crowder

What causes the base of the leaves on my tomatoes to turn yellow? How can I save the plants?

Here are my thoughts on that Mr. Crowder. In most cases yellow leaves, which begin turning yellow at the base of the plant first are due to one of two causes. Not just with tomatoes but any plant. Usually, when the older/lower leaves turn yellow it is the result of too much water in the root zone. This could be from watering too frequently but most likely it is caused by a poorly draining soil. I won’t get into the details of the plant physiology but plants don’t like wet feet.  Monitor the soil moisture closer and things should improve. Tomatoes like about 1” (3cm for my UK readers) of water per week. I try to water mine once a week. Another possible cause is that as the plants get large the upper foliage begins to shade the lower leaves. This causes the lower leaves to turn yellow and drop off.  This is natural and not a problem. It might help to cultivate the soil near the plants to allow better air penetration into the root zone and your plants should recover. It’s a little tough to diagnose with a short description so I hope this helps Mr. Crowder.

Of course there are several other potential reasons for yellowing leaves, (fusaruim wilt, tobacco mosaic virus, alternaria leaf spot). If Mr. Crowder wants to send a more detailed description or even a photo I’d be happy to post my thoughts.

Now for a more common problem, TOMATO END ROT

Tomato End Rot

Yes, this even has happened to me.



Tomato end rot starts as a small brown spot on the bottom of the fruit and enlarges to cover the entire end of the tomato. Eventually the tomato just falls off. The root cause (pun intended) of brown rot on the end of tomatoes is low calcium levels in the plant.  The most common cause of irregular calcium uptake is an uneven watering schedule. If you are watering like I advise, consistently and evenly, 1”(3cm) per week you should be okay.  A good mulch layer will help even out the soil moisture levels; if you’re already using mulch, you may need a deeper layer but 4” deep maximum.

Take heart in the fact that tomato end rot will not spread from plant to plant and this problem is usually more prevalent on the first few tomatoes. As subsequent tomatoes grow they are less likely to have end rot.

Don’t think you can just spray a chemical and the problem will go away. Since low calcium is the culprit, the use of fungicides or insecticides won’t help.

You could apply a fertilizer that is high in phosphate and low in nitrogen. (3-12-3) That will help the calcium in the soil release better for uptake into the plant but chances are the plant will outgrow the problem. Next season add some well composted organic matter and some of the high phosphate fertilizer and you should be fine.

I hope this helps.

Here are a couple of other posts on tomato problems that you may find helpful too.

SPLITTING AND CRACKING TOMATOES?

BROWN SPOTS ON TOMATOES?

FYI these are all covered in my eBook Growing Juicy Delicious Tomatoes.

Rees

{ 9 comments… read them below or add one }

rachael July 30, 2011 at 7:55 pm

Wonderful site! Our tomatoes were cracking and found you through google. Keep up the posts!

Linda Sletten August 8, 2011 at 8:54 pm

Great information. I found my plants(in pots) to be drying out and I have been watering them almost every other day and now my tomatoes are almost all splitting. Am I to assume that if I water them once a week that is enough? Thank you

Rees August 9, 2011 at 6:16 am

Hi Linda, Thanks for the nice words. In answer to your question the point is to try to keep the water available to the roots steady and avoid extreme swings from dry to wet. Watering every day sounds like a lot but if the pot is small or an unglazed clay pot, which looses water rapidly, daily water may be needed. Just make sure it drains well.
Here is a link to my post on why tomatoes split HERE
Enjoy your harvest!
Rees

Nokie May 19, 2012 at 4:58 pm

Thanks for the help. I am trying a new method for me ,with my Cherokee purple tomatoes they are in a plastic tub with a system that allows them water at all times with an air gap in between and an overflow to keep from drowning the plant. I feed them through a tube that extends to the water reservoir .
Thanks again for the help.

Rees May 19, 2012 at 6:15 pm

Sounds Interesting Nokie,
Any method that gives constant moisture should help reduce several tomato problems. I’m playing around with a method myself. It’s simple and so far looks good. I’ll write a post on it if it is successful this year. FYI my first crop is in full bloom!. Looks to be a good year for tomatoes. Oh and I love the Cherokee’s, wish I had some seeds.
Thanks again for stopping by,
REES

audrey weaver September 2, 2012 at 8:40 pm

Hi

I would be pleased if you could till us why our tomatoes are dropping off the plants
they are rotting at the top of the tomatoe not the bottom
Thank you

Rees March 14, 2013 at 9:22 am

Hi Audry,
Rot on top can be from a couple of issues. The first that comes to mind is sunburn. If they’ve been shaded and are later exposed they can scald. Various bacterias and viruses could also be a probable cause. Can you send me some photos?
Rees

Scott A. Deaton April 19, 2013 at 2:51 pm

I tried a home remedy type experiment to help ward off blossom end rot that seems to work. I raise chickens as a hobby and one of their necessary food supplements is crushed oyster shell which helps promote good eggshell thickness. I broadcast several handfuls over my tomato patch and mix it in well while preparing the soil for planting. This extra calcium seems to help prevent blossom end rot from doeming.

Rees April 24, 2013 at 8:47 am

Hi Scott and thanks for stopping by.
I think your solution is a good one. Calcium is the answer. It would have to be mixed into the soil as you did. Just applying to the surface will take many years for it to leach into the root zone.
Raising chickens sounds like fun. It’s on my bucket list.
Thanks again for the idea,
Rees

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