Curling Leaves on Tomatoes

lilokiegardener(7)July 12, 2011

Ive noticed that some of my cherry tomato plants' leaves are beginning to curl under.. This is my first time trying to really grow tomatoes of any kind, but I looked under the leaves to see if I saw any bugs or disease, but I don't see anything that looks abnormal.

I have been watering them in the mornings before it gets really hot, and making sure the soil doesn't get too dry.

They have flowered some but not produced any fruit.

Any ideas or suggestions?


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Okiedawn OK Zone 7

Your plants likely are suffering from physiological leaf roll. At this time of year, the primary cause of physiological leaf roll is heat stress and/or moisture stress. Although it can be caused by soil that is too dry, it also can be caused by soil that is too moist. Just try to keep your soil evenly moist and hope and pray for better weather.

The poor fruit set is usually caused by the heat. Sometimes with bite-sized tomatoes, you'll continue to get fruitset even at very high temperatures, but other times you won't. In general, once daytime temps are exceeding 92-95 degrees (it differs from one variety to another) and nighttime lows are exceeding 72-85, fruit set on tomatoes ceases or is very sporadic. All you can do is try to keep the plants healthy and hope for a cool spell.

The droughe this year is really hard on everything, and hardest of all at this point on tomatoes.

    Bookmark   July 12, 2011 at 1:50PM
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Thanks for that info! I knew a little about the heat causing issues with not fruiting, but the rest was pretty new.

I did accidentally let the soil dry out once, but it wasn't as hot as it has been recently.. and I certainly try to make sure that the soil is moist, but not saturated. I think I water every other day because of the heat.

Will they produce when the weather cools down? Or will this heat keep them from fruiting at all at some point?

Thanks again!

    Bookmark   July 12, 2011 at 2:08PM
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Okiedawn OK Zone 7

You're welcome. I had a typo above, and it should read "72-75", not "72-85".

The plants should produce just fine once we have cooler weather as long as they are healthy and have adequate moisture.

Even if we get a spell of cooler weather that only lasts a few days, often you'll get fruitset during that time as long as your plants have blooms at that point in time.

One way to manipulate your plants into flowering when a cool spell is expected is to feed them a Bloom Booster type water-soluable plant food 5 to 7 days before you expect the cool temperatures. It won't guarantee fruit set, but it increases the odds. I have some plants blooming now, but the only ones setting new fruit are Ildi, SunGold, Matt's Wild Cherry, Tess's Land Race Currant, Husky Red Cherry, Black Cherry, Mountain Magic and Jaune Flammee'. Of those, only Jaune Flammee' is not a bite-sized tomato. Normally plants that produce bite-sized tomatoes are not as affected by the heat as plants that produce larger fruit. Once the high temps are over 100 though, even the bite-sized varieties slow down.

Heat affects tomato fruitset in different ways. One way is that it can make the pollen 'sticky' so that it doesn't move around easily inside the flower. (Tomatoes are perfect flowers, which means the flowers fertilize themselves, but for that to happen the pollen has to shed from the anthers, and sticky pollen doesn't shed well.) To help out that sticky pollen, thump each blossom or gently shake each plant daily, preferably early in the morning, to help the pollen move around inside the flower.

Another way the heat hurts is by denaturing the pollen which renders it sterile. The return of cooler temps puts an end to the denaturing of the pollen.

Flowers that don't set fruit within a few days wither and fall off the plant, and this is known as blossom drop. In this case, it is heat-related blossom drop.

Here in Oklahoma we are always in a mad rush to get our tomato plants into the ground (or containers) as early as reasonably possible without having them freeze in order to get the plants large enough to flower and set fruit well before the high temperatures arrive. In a more normal year, we might see the temps getting high enough to impede fruitset sometime between mid-June and mid-July. This year we started having those temperatures in mid-May in some areas. A lot of plants didn't get a chance to set much fruit because of that. It is a problem in many parts of the state this year, and in lots of other hot southern states as well.

Patience, patience, patience....and some better weather would be really helpful too. : )

    Bookmark   July 12, 2011 at 11:22PM
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I hope my vines are still healthy enough to produce when (or if) the weather cools. I put six cherry plants in the ground fairly late, 2 Sungold, 2 Yellow Jellybean, and 2 Black Cherry. Although they are out the top of the 5 foot cages, they are not thick with foliage. The Sungold has been producing for a couple of weeks but maybe just a half dozen a day. The Jellybean has had 2 fruits, and the Black Cherry hasn't produced at all. The vines look healthy and so do the four plants I put in the ground later than these. The earlier ones have suffered from the heat. Not every plant, but many of them. Tess's Land Race has tomatoes everyday, but the vine is not full like they usually are.

Our bridge was declared unsafe and has been closed so just to run to town is a round trip of 22 miles if I stay on paved roads, and the gravel roads are awful. I limit my trips and try to do more things in one trip and had run out of bacon, so I haven't even had my first BLT for the year. We went to Sam's in Joplin yesterday and I stocked up, so hopefully lunch tomorrow will be a BLT. It seems odd to be getting so few tomatoes.

    Bookmark   July 13, 2011 at 1:16AM
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I ate my first BT last night. It might be awhile before I eat anymore. The fruit that are ripening are small. I picked one more last night. But after these first ones finish there will be a lull. PH is the only smaller one I've seen one big enough to stand out. JD's Special C-Tex has at least one on one plant. I have seen these when looking for the Horn worms. Removed 6 more last night. I have now removed 3 from one plant. As if the plants don't have enough stress already. Overall knock on wood I'm very happy with the health of my plants. The one long range man keeps saying he feels a moderation could be coming. It looks like it will be at least another 7-8 days. Hope everyone's plants survive and produce well later. Jay

    Bookmark   July 13, 2011 at 5:13AM
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I have 4 plants, all the same variety (not sure which one right now) and only one of them has been doing a ferocious job of growing. Its outgrown its 4 foot cage and is in bloom all over the place.. but no fruit still.

The other 3 are smaller, still inside their cages, one reaching around the top, the other two aren't.

I can't really seem to figure out the difference on that one plant, but I might start gently shaking it in the mornings and see if anything happens.

I doubt it because of the heat, but maybe. Thanks again!

    Bookmark   July 15, 2011 at 4:47PM
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Jay, At least you got to eat that first sandwich. Maybe the next BPT will be soon. I am getting several tomatoes a day now and although we are eating them every day, I noticed that I have a bowl full of cherries in the kitchen. As many as we eat in the garden, or by the handful from the garden, I wonder how the bowl could be getting full.

I have an enormous number of pollinators hitting my garden right now. I always have bumble bees and wasps, but I have seen a lot more honey bees this year. I have noticed it for about 3 weeks now so I guess it is so hot that it has burned up a lot of the normal flowers and they are all searching for a food source. In addition, my air conditioner always creates a puddle on the ground, so there is fresh water for the butterflies and other insects so that may also bring them in.

I have been picking my large tomatoes earlier than normal. The small ones change color so quickly that they are usually ripe or close when I pick them, but I am not willing to share my big tomatoes with anything wild (well maybe Al). I picked the first Jet Star this morning and I have several other varieties that are close. I had about given up on Bush Goliath since it set a few fruit early and then just seemed to set there. I wondered if it was even worth the room to grow eventhough it is a small plant. The first fruit is now turning that whitest tint that you usually notice before blushing, and they are finally getting blooms again up near the top of the plant. Hopefully our nights in the 70's will help to set more fruit.

I just looked at Yahoo weather and it says we are at 99 degrees, but with a humidity of 42 percent, they say it feels like 108. To me it just feels like a sauna. They say it is cooling at night, but it must be the early morning because the nights feel hot to me also.

I actually thought of you this morning as I was picking Sungold. I have noticed that Sungold, more than any other tomato I have grown, will drop from the vine if not picked soon enough. It breaks off about 3 quarters of an inch above the fruit. It reminded me that you called those elbows, which was a terminology that I had never heard. So, as I was 'breaking elbows', I was thinking of you. LOL

    Bookmark   July 15, 2011 at 5:25PM
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Okiedawn OK Zone 7

Carol, They must be lying when they say it is cooling off at all night. I've been coming in from fires at various times during the night and will notice it is something like 92 degrees at 2 or 3 a.m. and is 88 degrees at 7 a.m. Then I look at our closest Mesonet station and it shows a low of 77 or 75 or whatever.....and I'm thinking "not at our house".

I just went out onto the porch and looked at our Min-Max thermometer's numbers for today and it shows 93 for our Min and 109 for our Max. No wonder the tomatoes are so unhappy.

    Bookmark   July 15, 2011 at 11:50PM
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