Terrible blossom drop syndrome.

pitcom(7a)June 29, 2012

I was hoping someone would have some suggestions as I cannot figure out what exactly is going on, although I have an idea.

I have 32 tomato plants,both my neighbor and a friend both have 4 which i started for him. Of those 32 I have 8 cherry tomato varieties. Each of those plants is setting fruit at near 100% compared to how many flowers develop. This includes my San Marzano tomatoes.

However, all of my other varieties, such as Kellogg's Breakfast, Potano Romanesco, Brandywine, Beefsteak, Cherokee, Red Calabash, Caspian, Green Zebra ect, all have severe blossom drop issues. My plants average about 6 foot tall, and I have at most 4 tomatoes on each plant, (some only have 1 or 2). No flowers since the first set of flowers has produced any fruit. I have hundreds of flowers on all of my plants, and they are all turning yellow and falling off.

I went to my neighbors and checked, and all 4 of his plants are experiencing the same exact problem. I checked with my friend, 2 of his plants were cherries and they have fantastic fruit set, yet the Kelloggs and Cherokee I gave him have blossom drop syndrome.

Does anyone have any insight to why this happening? I have so many flowers and so little fruit. I do not believe I have over-fertilized at all. At the beginning of the season I added lobster compost to the tomato beds, and since then I have only gave the plants a small feeding of fish emulsion twice in 2 months. My neighbor planted his in leaf compost which our township gives out for free and has not fertilized.

The only thing I can think of is pollination problems. Our area is eerily devoid of bees this year and I have been having some problems with my squash being sufficiently pollinated. But if it was a pollination issue, why are all of the cherry varieties setting fruit near 100%?

Any help would be appreciated, thanks.

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dickiefickle(5B Dousman,Wi.)

Toms are self pollinating,no bees needed. If you google , high temps and humidity are to blame . You can help a bit by shaking branches or rub your hand across blossoms.

    Bookmark   June 29, 2012 at 9:29PM
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Tomatoes need a low temp of 65-70 at night in order to set fruit. I am a zone north of you, and it is just as bad for me. It was 107 here today, and the low will be around 80.

I need a giant air-conditioned tent that I can set up every night over my plants...

    Bookmark   June 29, 2012 at 10:06PM
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missingtheobvious(Blue Ridge 7a)

Tomatoes need a low temp of 65-70 at night in order to set fruit

The general rule is that if the daytime high is above 90-95, and the overnight temps are either above 75 or below 55, fruitset will not occur. See the FAQ Why are the blossoms on my tomato plant dying and falling off?

Your cherries are still setting because they can handle more severe temperatures than most non-cherries. Some varieties of non-cherries are slightly more tolerant of bad temps than others -- and others demand even milder temperatures than the general rule.

But even if the temperatures don't present a problem, high humidity can also cause blossom drop.

And if the air is too still (whether because of lack of wind or for tomatoes in a greenhouse without a strong fan), fruitset may not occur. A breeze, buzzing insects landing on a blossom (even if they can't reach the pollen inside the flower), or a person shaking the stem or tomato cage can help pollination to occur.

    Bookmark   June 30, 2012 at 1:05AM
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Thanks for the input. I read all about the temperature ranges on various sites. From may 13th to June 20th we had fantastic weather every single day ranging in temps from average lows of 63 and highs around around 80. On June 6th it got down to 53 degrees and on June 20th it got to 97 degrees. So you are telling me that 1 night of 53 degree weather has killed hundreds of flowers? To me it looks like it should have been excellent growing conditions.

All of the fruit is at the very bottom branches of each plant, where the first flowers came. I've never had a problem like this with my tomatoes. Last year was way hotter than this and my plants were loaded to the gills with fruit.

    Bookmark   June 30, 2012 at 9:34AM
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missingtheobvious(Blue Ridge 7a)

No, I'm not telling you that anytime the temperature falls below 55, all pollination will fail.

If daytime temps are below 90-95, tomatoes can set fruit during the day regardless of what happens at night (I'm sure there's a minimum daytime temperature -- perhaps 55? -- but no one cites that).

Also, regardless how hot it is during the day, tomatoes can set fruit at night as long as overnight temps fall below 75 but not 55.

So if it's too hot during the day, you might be able to have fruitset at night, and if it's too hot (or cold) at night, you might still have fruitset during the day.

And of course it gets more complicated because of microclimates (your brick house may give off extra heat, so tomatoes planted against it might not be able to set fruit at night despite temperatures that should be favorable; etc.). And each variety has its own particular temperature limits.

And temps might be fine but the humidity too high.

jrslick uses misters in his high tunnels to lower daytime temperatures. Some people use misters outdoors around the patio or deck to make that area more comfortable. I've read of SW desert people using misters and/or shadecloth to cool their tomato plants; you could try that and see what happens (and what the cost is). jrslick mentioned his misters on this thread:

I think he is also active on the Vegetables and Market Gardening forums.

    Bookmark   June 30, 2012 at 10:27AM
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digdirt2(6b-7a No.Cent. AR HZ8 Sun-35)

So you are telling me that 1 night of 53 degree weather has killed hundreds of flowers?

No. But seriously, in zone 7 you have only had one day above 90 and no nights above 75? I wanna move where you live!

I haven't had a day below 95 in weeks nor seen a night below 75 for at least 2 weeks. It was 95 here at 11 pm last might. At least the humidity has been low but that only means dry, hot winds which is just as bad.

1) you can't compare Blossom Drop on regular fruit varieties to small fruit and cherry types. Cherry types are much less affected by the causes of b. drop.

2) as explained in the FAQ linked above there are other causes of b. drop than temps. Excess N and poor timing of feeding are the biggest. 6' tall plants with few fruits is a classic sign of excess feeding and/or poor timing of feeding that kept the plant in growth mode and out of fruit-set mode.


    Bookmark   June 30, 2012 at 11:24AM
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Bets(z6A S ID)


Quoting from the FAQ: "If the night temps fall below 55 or rise above 75 or if the day temps are above 90, the pollen becomes tacky and non-viable. Pollination cannot occur. If the bloom isn't pollinated, the bloom dies and falls off."

The conditions are listed with the word "OR" not "and", so either condition can trigger blossom drop, it does not have to be a combination of conditions. Once pollen is denatured by any of the variables, temps goig back into the optimal zones will not make it viable. That is why if you get a heat wave that stops pollenization, even if the temperatures moderate, it may be 3 weeks before you get any blossoms that set.

I once asked how old the blossoms had to be for the pollen to be affected, no one knew and I have not been able to find out since.

I do know that the higher the temperature, the shorter the time it takes for the pollen to denature. I read a study that was done in a desert clime, and if I recall correctly, as little as 2 hours at 105 degrees can do it, while it takes something like 8-10 hours at 90-95 degrees. Sorry, I don't have the article handy, and I don't have time to look now, I have somewhere I have to be and must leave shortly. I'll try to locate it later, it was a good article.


    Bookmark   June 30, 2012 at 11:38AM
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"regardless how hot it is during the day, tomatoes can set fruit at night as long as overnight temps fall below 75"

I hope you're right, but I don't see it happening. I think the pollen is cooking in the heat. It's 105 with 20% humidity and a breeze. It feels like a convection oven outside. My whitefly infestation probably isn't helping, either, but the only green plants around are my tomatoes and the whiteflies can't stay away.

There has been a lot of research regarding corn pollen and high temperatures. Basically, it's bad :(

    Bookmark   June 30, 2012 at 12:31PM
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I've been growing tomatoes for more than a few years now and I am having the same situation you are. I am about 10 miles south of Pittsburgh, PA. Mine is weather related. I have 4 cherry/grape types that are thriving with fruits ready to pick for the 4th. Of the other varieties I planted this year only Goose Creek is setting fruit as usual. 4 other varieties are 5 to 6 feet tall and have few if any fruit set yet. Blossoms just drop. Not to over simplify it but I think 90% of my success or failure is weather related. We had early warm temps this spring and since then wide temp fluctuations with some cold nights and some hot. Now we are into a heat wave. I had the happen several years ago and still got plenty of tomatoes. They just came later in the season than usual. Time will tell for this year.

    Bookmark   July 1, 2012 at 12:52AM
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