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Curled leaves on Petunias

Posted by blueflint z6a OH (My Page) on
Sun, Feb 14, 10 at 16:03

I have a few hundred petunia seedlings in the nursery currently. The oldest ones are probably 7 weeks old now. In one batch (one color only) I have a few seedlings that have heavily curled leaves and a few of these have their newest leaves slightly thickened. Any idea what is going on here? A virus?

Thanks,
Blueflint


Follow-Up Postings:

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RE: Curled leaves on Petunias

improper heating through the night???

how do you filter light so you know they arent being zapped in full sun????

seems like there are a lot of cultural questions to address, before we jump to disease questions ... though it might not hurt to tent them for isolation ...

more facts please.. and a pic sure might help

ken


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RE: Curled leaves on Petunias

Pick up those leaves and look very closely on the undersides and also the stems for evidence of aphids. There are many issues to cause curling leaves, but aphids are right up there as the first thing to suspect.


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RE: Curled leaves on Petunias

No aphids. These plants until last week have been under fluorescent shop lights, next to the other colors, about 2"-3" away from the bulbs. This week they have been on the bench in direct light...well if the sun would ever shine again :) Lots of snow here! I have been fertilizing with a liquid at recommended rate, once a week. Otherwise they look good, dark color, growing well. It has been a little cool at nights in the nursery (50's) so root development is not as good as I would like but overall they look good except for the curled leaves!

Blueflint


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RE: Curled leaves on Petunias

so can you rule out a cold draft on that group of plants????

ken


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RE: Curled leaves on Petunias

This can also be caused in petunias by high media pH, viruses, boron deficiency (and that can be caused by too much of another micronutrient)


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RE: Curled leaves on Petunias

  • Posted by antm0 USDA 9 (My Page) on
    Tue, Feb 16, 10 at 20:53

Or those few seed just happened to be a genetic whoopsie?
Calliope's suggestion is sound

do these particular ones hold moisture longer then the others?


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RE: Curled leaves on Petunias

Well, if there is only a few I would certainly move them away from the others just in case. Better safe than sorry!


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RE: Curled leaves on Petunias

No cold drafts I'm sure. I was wondering about the PH, I use Metro Mix 360 to start these. I know Petunias like a little lower ph. I did have an iron deficiency too at first, but these plants have since all darkened down in color. Also know iron problems can sometimes be from too high ph, plants can not absorb iron in higher ph so changed to a Miracid type fertilizer, trying to lower the ph or at least not make matters worse. In another batch (different color), no leaf curl problems but a few still have iron problems. All colors are growing well. temps are in the mid 50's to mid 60's at night, in the 70's to mid 80's in the day (mostly 70's).

Blueflint


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RE: Curled leaves on Petunias

I don't have hundreds, but do thousands of petunias each winter/spring. It's not unusual to have just one variety with problems like you are having, but not be exhibited in other petunias. I've found that when good growing weather hits, some of these pull out of it and as they continue to grow, all new foliage and stems revert to normalcy. I sometimes see stunting in the malformed seedlings and they never do diddly squat and play catch-up for the rest of their lives. I have tried pinching them back when they are more mature, and sometimes this helps and sometimes it doesn't.

I do some of my petunias from seed myself, and some from plugs shipped in from other wholesale growers and plug producers. It's on those runs where the malformed seedlings seem to be. In this case, I have often wondered if an over application of growth retardant or other chemical they used wasn't to blame or may have caused damage to the meristematic tissue and that will cause deformation from any leaf or flower growing at that point. That's why if they hang in there, they can sometimes appear normal and healthy again.

I always suspect viruses when I see shipments of seedlings like that because thrip control has been a major problem in the last few years in large operations. Thrips and other insects carry viruses from one plant to the next.

You sound pretty savy about the regime for a hobby gardener. Were these by chance from plugs you bought?


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RE: Curled leaves on Petunias

Blueflint,

"...changed to a Miracid type fertilizer, trying to lower the pH or at least not make matters worse."

Calliope's explanation could be the answer, but if you are using Miracle-Gro brand Miracid fertilizer, it contains both aluminum and urea, either of which, or both of which, can be toxic to plants.

Unlike animals, plants can't excrete urea, so urea waste accumulates to toxic levels if Nickel is insufficiently available to activate the Urease enzyme for the internal hydrolysis of urea to ammonia and carbon dioxide, even if you didn't supply urea in the nutrients. If you applied urea as a nutrient, that increases the likelihood of the problem. The trace element Nickel is the only known activator of Urease in plants.

The use of urea-containing nutrients in sterile growing media is not a good idea. Soil microbes break urea down into usable forms, but those microbes are absent in sterile growing media, so the urea is a potential problem.

Since aluminum can easily be phytotoxic to plants, the use of alum to lower pH is a very questionable practice. There are several ways to lower pH without using an aluminum compound.

ZM
(not associated with any product or vendor mentioned)


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RE: Curled leaves on Petunias

Hey Blueflint. I see you are from Adams County, Ohio. That was home to my Mama's Daddy. Cherry Fork to be exact. I'm in S.E. Ohio. I am also sighing with the lack of sunlight we have for winter crops. I have never seen a Winter in 23 years of growing with fewer days of sunlight.

I wouldn't be messing too much with trying to acidify the soil unless you have been tracking the pH and know what your baseline trends are and also have a handle on your water pH.


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RE: Curled leaves on Petunias

Thanks for the responses. Yes, we live 2 miles from Cherry Fork on 136 towards Rt 32. We have a small produce farm and also sell hanging baskets in the spring. All itmes are grown from seed. I grow mostly Easy Wave petunias plus some heirloom/open pollinated petunias which we produce our own seed for. We start probably 300 to 400 petunias each spring.

The petunias in question are growing great and I think they will "grow out of it"...at least I hope so. I will keep everyone posted.

Thanks,

Blueflint


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