I see some of this Mary in my garden but it usually follows injury of some kind to the fruit.

Fungus infections (Pythium, Phytophtora, Rhizoctonia, and Alternaria) settle into the injury and result in conditions similar to your photo. In my case the injury is usually from the cage wire or other support after high winds or storm. But there are other possible causes of it even with out injury happening first. All that is required is a thin skin variety and the right environmental conditions for fungi for it to develop.

There is a condition called Cotton Leak (aka Pythium rot) and another called Sour Rot that are both caused by the same range of fungi plus others. Both are encouraged by overhead watering and/or frequent rains.

All the fungi can be soil-borne so avoiding sprawl and heavily mulching and use of fungicides can help.

snuff-out-sour-rot-of-tomato

Dave

I don't know what it could be, other than maybe a bug getting in and spoiling it? Is that from one of your Korol Sibiri plants? Or just an unripe red variety?

I've noticed that a few of my plants are getting some black spots on the leaves, so I've been doing some spraying. Our weather the last 2-3 weeks has been very warm and humid here with occasional downpours, so I'm not surprised. Just want to limit the damage as the plants are starting to produce little green fruit. Some of the largest ones are getting about the size of golf balls.

Thank you, Digdirt and Subdood,

I looked into internet images and did not find anything similar. I do shake tomatoes once a day for pollination. It is possible that the fruits bumped into each other without any obvious damage to the skin. I did not spray this year much because I did not see a lot of leaf problems, the weather was hot and dry until the recent rains. It is time to start it again.

Some varieties has it worse than the others. Last year it was Malachite box which was mostly damaged but only in the autumn time. It has really thin skin, that is true.

This year it is unripe Mashenka , red tomato, first time growing it. I liked it very much until now. It has a good set of large good looking tomatoes which are close to round shape, but slightly wider on the bottom part. They actually started to ripen, but so far each of them has the same problem.

Does it ever happen at the same time as BER? Because that looks like it could be internal BER. Also, you mention the weather has been hot and dry until recently.

Have you looked for worms or maggots? I have gotten those.

So other than the fruit the plants themselves are fine? Good color and healthy leaves? If so and only the fruit are affected then gorbelly has a good point about internal BER as a real possibility.

Gray Wall is another possibility. Check out this link for more details.

http://vegetablemdonline.ppath.cornell.edu/NewsArticles/Tom_ComDis.htm

Dave

There was no insect damage. No any other blemish on the surface. Today I tossed another big tomato of the same variety (Mashenka) with the same symptoms. Did not even cut and looked inside.

This type of fruit damage usually happens to me in autumn, when the days become cooler and we have morning dew. And it happens more often on certain varieties, with thin skin and soft flesh, such as Malachite box from the last year.

I never had BER on my tomatoes.

The leaves by now started to show the moderate signs of septoria and I started to spray them regularly.

I was thinking that it might be Gray mold, but was not sure enough because it did not look exactly as on the pictures. And it never had any gray fuzz on the surface.

It seems that the decay starts inside and it works its way outside appearing as rotten wet spots, which leak liquid excessively and probably spread the infection.

So right now I think that it is some kind of fungus and I will spray accordingly.

Maria.

Cooler temperatures can cause BER, so the fact that you usually have problems around autumn doesn't rule it out.

But I think spraying is a good approach. If it is internal BER, there isn't much you can do about it anyway, so might as well try to protect against the other possibilities it could be.

I get Gray Mold later the season when it gets cooler, more rain, more humidity..

You won't see fuzzy stuff on the plant and fruits unless it fully develops where it stays wet / damp and there is no air flow.

On Gray Mold Chlorine spray works best. It actually kills the bacteria.

I think you add 7oz of regular Clorox to a gallon of water. JMO

Sey

UPDATE , CONFIRMATION:

yes , 7 to 8 oz of regular strength Clorox per gallon of water is how it should be mixed/sprayed. According to some very experience gardeners ( in another site) bleach spray works best on the foliage fungi , bacteria that is already there , to combat the disease.

A LITTLE MORE ...

Regular strength Clorox has about 6% Sodium Hypochloride. With thay you mix 7 to 8oz per gallon of water.

Then there is some kind of higher strength (ultra ? ) that has 8.25% SH. with this one you would mix 5oz per gallon.