Wednesday, March 12, 2008

Bunnies! Bunnies! It must be bunnies!

Pop quiz! Three problems I kinda have guesses about, but would like confirmation on, are below. Remember to show your work.

Problem #1 of 3: Pelargonium

At work, we got many, many geranium (Pelargonium spp.) plugs in a couple weeks ago. We potted them up, set them on the tables, and then found them, not too much later, developing weird patterns of spots, sending everybody momentarily into panic mode, and leading to a scene something like this:

(watch fast -- I don't expect Youtube to leave this up long.)

Like this, of course, only in a very loose fashion, obviously.

Anyway. Leaves were collected and sent to Iowa State for pathology testing, but it may take a while before we hear anything, so I'm hoping to scoop Iowa State and get an answer first by harnessing the power of Teh Mighty Internets. So here, then, is what the leaves look like:

(Click on images to embiggen.)

The spots don't appear to be spreading, and don't seem to be on new growth.

The leading theories are, or have been:

1) Virus!
2) Chemical damage, from using pesticides in the greenhouse too soon after a traumatic shipping and repotting experience.
3) Cold temperatures and/or water droplets standing on leaves for too long.
4) Bacterial disease!
5) Bunnies.

We're open to other possibilities, of course. Anybody who's seen this before, please say something in the comments.

Problem #2 of 3: Begonia

We had a bunch of Begonia rex-cultorum all go nuts at once, too. I concede that they hadn't been getting treated all that well, because of the rearrangement of the greenhouse for the annuals and vegetables. We had them in a spot that could have been too hot and dry, though they'd been okay there for a few weeks before this happened. They were getting watered from overhead, but then, they always were. They might have been getting too much water, but it's hard to tell. This particular leaf is the clearest example I could find of the problem, but they all look more or less like this:

What does this look like to you?

Problem #3 of 3: Hedera canariensis

We got in either six or twelve hanging baskets of non-variegated Hedera canariensis in December, and they all did fine for a long time. This is the only plant left, and it's suddenly gotten really weird. In some places, the leaves have turned reddish between the veins --

and in other places, the leaves have gotten crispy edges --

Searches for spider mites were negative. We have other plants of the same species in the greenhouse, quite a few of them, and this is the only one that's doing this. I have a definite guess here, but I'm looking for confirmation.

Comments are set so that you can leave answers anonymously, or under a name of your choosing. I appreciate anybody who's stopped by to read this, whether you have any guesses or not.


Mr. Green Genes said...

Problem 1- I believe the correct answer is 3). I seem to remember this from way back. I used to grow Pelargonia, but many many years ago.

Problem 2- no idea. Never had a Begonia in my life, alas.

Problem 3- I think maybe the plant got a "heat/cold stroke". I remember (some 20 years ago!) the reddish coloring and the wilting being caused on a plant I had first a) misted and b) put in the scorching sun.

Hope I haven't done too bad, my average is low this semester...

Anonymous said...

I think I agree w/Mr. GreenGenes - key words stated were that you got them a couple of weeks ago - wasn't it *really cold* in IA a couple of weeks ago?
It was in my neighboring state! (Brrr chilly nippy freezin' chilly!)

The begonias I'm thinking are sun-scorched from being watered overhead. Did I read correctly that they were recently moved?
If so, I think it's the fact that spring is on it's way and the sun is brighter recently. The water droplets from overhead watering combined with the sun caused scorching. Just MHO.

Good luck

Karen715 said...

I have minimal experience with Hederas and Pelargoniums, so I can't help there.

But Begonias are susceptible to mildew, and I suspect that is the problem there. I've had rexes, semperflorens and cane begonias develop spots from powdery mildew seemingly overnight. I don't see the powdery substance in your shots, but the spots look like those left after that has been cleaned. Maybe another mildew or fungus?

mr_subjunctive said...

For the geraniums: the leading theory at work has been (after a brief period of virus! hysteria) chemical burn + shipping, which agrees with the observation that it doesn't seem to be spreading to other plants or new leaves. I haven't liked that theory, mostly because the pattern of affected plants doesn't match, and because if that's what it was, then at the very least you'd think that whole plants would be spotting, and instead it's almost always just one or two leaves. Even allowing for the fact that some of the affected leaves got picked off, that's still a weird distribution.

I initially favored bacteria, but then when it wasn't spreading I shifted to cold, because the plants closest to the (uninsulated) outer walls seem to have more of it than others. That doesn't seem quite right, either, though, because the affected leaves have definite "shadows" -- the zones affected are right next to zones that aren't, and if it was just temperature, you'd think that it'd be entire leaves or no leaves, none of this partial-leaf stuff. Also we've had a few leaves go bright, bright reddish-orange, which everybody seems to agree is a more definite sign of cold damage, and the red-orange thing has only happened on some of the plants that have the spots.

On the Begonia, my guess was water spots sitting on leaves in the sun. They were recently moved, but only after they did this, mostly because I didn't want the customers looking at them and wondering WTF. It's still a little weird: we've always watered from overhead (I know it's wrong, but there aren't many better choices), so it's interesting of them to pick now to react, but then, I suppose we've also been less consistent with the watering, both in terms of who's doing it and when it's being done. So I'll call this one solved, unless someone has a problem with the water-droplets-plus-sunlight theory.

On the Hedera, WCW thought that it was probably either too much sun or too much cold. Heat wasn't a theory I'd considered, but it could work: the spot it's in is fairly exposed right now because there used to be a lot of hanging plants over there, and most of them got moved away for one reason or another. That spot does get cooler than most of the greenhouse, because it's up near the ceiling vent, and it also gets hotter, when the vent's not open, so it could be either problem.

Still not sure on that one. I'm not ruling out bunnies.

Anna said...

The geranium looks like the ph is off. You will have to purchase a test kit and test the soil. They are so ph sensitive.

The begonia looks too wet and may not be in the correct soil mixture for the roots to grow.

The ivy looks like it may have gotten too much fertilizer and light. If it's hanging too close to the top of the greenhouse, it may be burned.

Anonymous said...

I know this is one year later and all, but that is definitely leaf spot or rust. I lost half my begonias to it. As far as I can make out overhead watering aggravates it and causes it to spread. The only answer is to just keep cutting off any diseased leaves. You can't be stingy here; if not you'll lose the whole plant. Better late than never I hope.

It also spreads from plant to plant so QUARANTINE. This is something I didn't do (and I lost many plants to it) until much later. I think high humidity is one of the reasons for the disease to spread. It came to my plants from a new plant I had just bought.

I have no idea whether its bacterial or a virus.

Erin said...

Your title is awesome, by the way. Perhaps one of my favorite episodes.