What is killing my Petunias?

10 years ago

Last year we grew petunias with phenomenal success. Using the old adage, 'If it ain't broke, don't fix it', we are growing them this year using the same methods and materials.

We start them from seed. We get our seed from a variety of wholesalers. The die-off is occurring in all of our plants, so I doubt it is the seed.

We start in 72-cell trays using ProMix PGX. They are then transplanted into 3 1/2" pots with Kellog Patio Plus soil:
http://www.homedepot.com/p/Kellogg-Patio-Plus-1-5-cu-ft-All-Natural-Outdoor-Potting-Soil-681/100160888

They also get a very small shot of Dr. Earth Life:
http://drearth.net/blog/products/organic-fertilizers/life-all-purpose-fertilizer

The only plants that are currently affected are those that in the 3 1/2 inch pots. We have a mixture of some old pots from last year and some brand new pots.

They are in the greenhouse with propane heat. We are not dropping dead when we walk in so I don't think there is an exhaust leak from the propane heater. We are in the Pacific Northwest and have had some fairly cold days. The effected trays were near the back of the greenhouse, furthest from the heater. Our coldest night dropped down to approx. 38F in the greenhouse.

We also have a large amount of pepper transplants that also seem to be dying in the same manner.

This is what they look like in the 72-cell trays. Everything seems to be going well:
http://imgur.com/WohJsa0

This is one of the transplant trays with the dying plants. They seem to get a whitish tinge on the edge of the leaves before they keel over:
http://imgur.com/wwGM7NP

This tray seems to look ok. There is a bit of death on the edges of the leaves, but they don't seem to be looking sad in the same way as the other ones. I don't recall exactly where in the greenhouse this tray was so I don't know if they were touched by cold air:
http://imgur.com/tZTFOUw

Any help in this matter would be greatly appreciated. Thank you for your time.

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Comments (7)

ken_adrian Adrian MI cold Z5
10 years ago
looks like cold damage to me ... keep clicking the image until you get a super close up ...

it appears .... that there was individual plant cell damage with near freezing temps ...

one might wonder how you established 38 degrees... was the thermometer at the warm end.. or the cold end ...

i think you already diagnosed your problem.. when you noted that the problem is at the end.. furthest from the heater ... its apparently much colder down there...

having never run a greenhouse.. if you cant increase heat.. can you increase air movement????

ken

{{gwi:2524}}
snarg
Original Author
10 years ago
Ken,

Thank you for your response. At this point I think that the best answer would be if it was, indeed, the cold. If it is my potting soil then, well, I have a problem. I have eight pallets of it sitting in my yard right now.

The thermometer was centrally located in the greenhouse on that very cold nigh. There is a good chance that that end of the greenhouse got colder.

I *can* increase the heat, I am just hoping that I don't need to. Propane is not cheap right now and that stupid money tree I bought off of eBay has yet to produce a yield. I may try putting a fan in there to increase circulation on the next cold night we have.

We are testing our soil and growing conditions right now and hoping to pin down the exact cause.

If anyone else has any other input, it would certainly be appreciated. Thank you for your time.
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Hi grny28, I am going to refer to The Ortho Problem Solver, seventh edition on this, because I am no expert on Petunias (zinnias are my "thing"). The book's coverage on Petunia problems starts on page 262 and continues onto page 264. It has articles on Gray Mold (everywhere in the US), Smog Damage (limited to relatively small coastal areas), Caterpillars, Cutworm Damage, and the last article on Crown and Root Rot (everywhere in the US) seems the most likely culprit. Crown and Root Rot is caused by Phytophthora (I don't think you can say that without spitting a little), a fungus that lives in the soil. It initially attacks the roots or stem at or just below the soil level. The dark dry decay of the lower stem tissue and roots reduces the flow of water to the leaves and flowers, causing the petunia to wilt and die. Crown and Root Rot is common in heavy poorly drained wet soils. The fungus (Phytophthora) is spread by contaminated soil, transplants, and tools. The solution is to remove and destroy infected plants and all the soil within 6 inches of their roots. How do you destroy soil? Well, I guess you could throw it into an incinerator, but I would just put it a plastic bag and send it to the landfill with the rest of the garbage. To prevent a recurrence of Crown and Root Rot, you should improve your soil drainage and drench it with a fungicide containing Captan. That's what the Ortho book says. Repeat the drench monthly during the growing season and let the soil dry out between waterings. I try to avoid problems of this sort with my zinnias by adding a lot of sand to my garden soil to create a sandy loam, and I add Perlite to my indoor growing medium to increase its drainage. "They were planted in larger containers along with other plants that are fine, What are the chances of a disease from so many different nurseries?" Many plants aren't susceptible to Phytophthora, and the problem is in your soil or growing medium, and not at the different nurseries. ZM (not associated with any product or vendor mentioned or linked)
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zen_man
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Your second picture looks like severe iron deficiency. I guess you could give them a little iron, and see if they perk up. Make sure it is just a little. Too much iron can be toxic (phytotoxic in the case of plants.)

But in case it isn't a nutrient problem, try to eliminate soil-borne diseases. Carefully remove one or more of the plants from the pot, shake off the growing medium, and inspect the stem at the soil line for signs of stem rot, either bacterial or fungal. And inspect the root system. Try to determine if the roots are alive or dead. If the roots are dead, then the plant is obviously dying and done for. If the stems and roots of the sick seedlings are alive, then an environmental or nutrient problem is a possibility.

Incidentally, just because you "are not dropping dead when we walk in" doesn't mean the heater couldn't be behind the problem, possibly by not keeping the greenhouse warm enough. Make sure your heater is getting actual propane, and not a mix containing some butane. Butane is bad for plants. You might want to check with your County Agent on this problem.

ZM
snarg
Original Author
10 years ago
Zenman,

Thank you for your reply. Attached is a picture of one of the pepper plants that was also out in the greenhouse with the petunias. As you can see, all of the leaves have fallen off. However, inspecting the stem, there are no signs of discoloration or weakness, The roots are white and seem to be in good shape.
ken_adrian Adrian MI cold Z5
10 years ago
two things...

first.. at your photo site.. at the very bottom right.... it says ... GET EMBED CODES ...

copy the HTML code... and paste it right where you type.. on preview.. if you see it.. we will see it ...

second ...

you dont have to turn up the heat.. the close end proves such ...

you need to MOVE AIR ...

what about two box fans .. in the middle .. one to each side... facing each direction.. to create a circular air pattern ... i think thats the definition of circulation.. lol ...

zenny is prime on seed growing.... but those look like good roots to me ... with what??... 95% of your crop being good.. i would be leery to go changing much of anything ....

you used new media.. yes???

if recycled ... that could be a problem.... but the location thing begs to differ...

that was a third thing.. so i ..

wish you luck

ken
snarg
Original Author
10 years ago
Thank you Ken. I didn't know that GardenWEB allowed embedded HTML. I will remember that for future use.

I don't think the pictures are really showing the extent of the damage. I only wish it were 95% good :(

The greenhouse is set up the same way it was last year but, I'm willing to embrace change. Circulation fans were on my to-do list for this year anyway, I guess I will just be getting them a little earlier.

The media is all new, no recycled potting soil.
bugbite
10 years ago
ZM and Ken, I strongly feel you are correct.
My young petunias last year were all over the yard. Suddenly I would get one like the ones you show. They would just die. I freaked thinking this would spread. I carefully pulled each plant that was affected. The adjoining plants continued to grow. I determined that some petunia seedlings were genetically resistant to the Phytophthora virus attack.
Something that has stuck in my mind every since I read it years ago on the Wave Petunia site. It said never plant petunias in the same bed the following year, rotate because of disease. I haven't; I get some that get attacked; the rest flourish.
Another interesting observation for me this year:
The seedlings this year have weathered freezing temperatures (not a prolonged deep freeze) without being cover.
Regarding the peppers, I get that also. For me it is the soil disease: Phytophthora blight. Similar thing that kills the petunias (Phytophthora nicotianae)

What is killing my Petunias?

Comments (7)

ken_adrian Adrian MI cold Z5

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What is killing my Petunias?

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ken_adrian Adrian MI cold Z5

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