Might be a "leaf curl virus", but it is more than likely due to mites that have fed on the underside of the leaves and stems to cause them to grow distorted. This should not affect the flowering, only make them unsightly.

Ian

I surely agree. I think it's a physiological problem, not a disease of any sort It's common in greenhouses and can be due to any number of things affecting the tissue when it's differentiating before it expands and grows. Mites, water stress, mechanical injury, latex crud. I especially see it on standard zinnias, because they flag out so easily when they go short on water once or twice and the foliage shows the aftereffects. Subsequent foliage usually looks fine.

I thought no one was going to answer my question, and then I get two posts in the same hour :)

I waited a few days to see if the condition of the apices improved, but they still remained chlorotic and stunted. So I lopped them off to promote some sidegrowth. However, even the new shoots seemed quite sickly. Thinking it might be a mite infestation, I sprayed some insecticidal soap yesterday. Then again, is it possible for mites to *not* affect the other plants only inches away?

We have been getting sufficient rain here, so I don't think it's water stress (too much water, perhaps?). As for mechanical injury, I was quite careful during transplanting and staking so it's probably not that either. Will observe them closely over the next few days and keep you posted.

You should never spray any insecticide on a plant unless you have seen and identified the pest involved. the steps in Integrated Pest Management are
1) Identify the problem
2) determine if the problem needs intervention
3) apply the least toxic solution to solve the problem
4) determine if that solved the problem
5) return to step one.

@kimmsr

You are right. But I waited a few days with no response from the forum, so I just did what I could out of desperation. I figured that if it *is* a mite problem, I had better act fast before it spreads to the other healthy plants. And if it isn't, I suppose insecticidal soap is pretty harmless since there weren't any other bugs in the vicinity. Guess I skipped 1) and went straight to 2), 3) and 4).

What would you suggest I do, since removing the deformed portions did not help?

Spraying a bit of insecticidal soap is no big deal....even applying a fungicide may result in an improvement.
If you were using diazinon or other toxic chemicals, then I could see where there may be a concern.

Anyway, It may be something in the soil or possibly other physiological aspects of those 2 plants that made them grow that way.

Ian

OK, so I have more or less given up on those two poor plants since they seem to have stopped growing completely :(

However, the others are nice and fat, and I was quite relieved to see buds forming on all the main terminals. But this morning when I woke up to find the first one on the verge of blooming, I noticed that the petals were very sparse and pale. In fact, it looked less full than a single flowered variety, and mine are supposed to be *semi doubled*!

Does this usually point to a phosphorus deficiency, or are there many other factors to consider? I fertilize with a combination of Peters (20-20-20) and Schultz (10-15-10) liquid fertilizers. Could nitrogen excess suppress flowering? This might explain why the leaves seem kinda big (then again, this is my first time, so I'm not exactly sure what size they're supposed to be).

Will post some pictures later today.

Hi, Mak. ;o) Don't beat yourself up over applying a little Safer's Soap as a shotgun approach. It's of little consequence and breaks down harmlessly. Washing your car is far more environmentally unfriendly.

Let's play detective and see if we can figure anything out. Since you found no insects, let's take a closer look at the probability of a nutrient disorder (already eliminated mechanical injury too, hmm?). Because it is located in the top of the plant and in new growth, we can eliminate herbicide injury and all the mobile nutrients as a probable cause. This reduces the probability to either the secondary macronutrient Ca, or any of the micronutrients. All of these and Ca are immobile for all intents & purposes in your situation.
Though 2 or 3 micronutrients can affect leaf shape, Ca deficiency is almost always manifest in symptoms at the top of the plant. I was fairly sure what the deficiency was, but consulted the text "Water, Media, and Nutrition for Greenhouse Crops" for an exact quote/description of symptoms. It reads "Calcium Deficiency: Symptoms are expressed at the top of the plant on new growth. Young leaves may develop variable patterns of chlorosis and distortion, such as dwarfing, straplike shape, or crinkling. Shoots stop growing, petals or flower stems may collapse. Roots are short, thickened, and branched."

So ... if you concur that it is likely a deficiency, we next determine what could cause it. If you don't concur, stop here. ;o)

It could be caused by an actual deficiency of Ca in the soil, or very low soil pH, but the latter is not very likely. Waterlogged or poorly oxygenated soils can block the uptake of Ca and would be a distinct possibility. I know you've been lurking on the Container Forum, so you should be able to determine if this condition is likely. Anything that slows transpiration, like high humidity is another possibility as a Ca uptake blocker, especially for your area. Finally, an excess of Mg (have you been using Epsom salts in your fertilizer program that could cause this?) in soils could cause Ca to be unavailable.

Anything sound familiar - like we're getting close?

Al

Say I am having the same Ca symptoms. What would you recommend for a fert that can be found generally at a garden center? I have been using 20-10-20 at 125 ppm every week for the last 3 weeks. They are 6 weeks old and spindly because I screwed them up as seedlings alternating 15-30-15 and 20-10-20 at 50 ppm. They are now showing signs on the new leaves where the base towards the tip is yellow and curled with a nice green tip.