Recurring problem with delphinium

For several (many? I forget) years my delphinium plants have blackened. This can happen throughout the season and doesn't always affect the whole plant. But they are not thriving. I use a variety of fungicides, Safer, copper, funginex, etc. This year I've used mostly copper toward the end of the summer because that's what was in the sprayer for tomatoes for late blight. I have two widely separated beds for delphinium, and it affects both.

Often advice about fungicides says "read the label." But the label with detailed info is not accessible on lots of them unless you buy it first. Anyway, if I don't know what the problem is, I don't know what to look for on the label.

I acquired a digital camera mainly so I could post this problem. I hope someone can help. I love delphiniums!

In this first picture, the stems/leaves on the left have blackened. Those on the right are healthy.

TIA
LAS

Here is a second picture.

Here's a third picture. Blackened leaves mixed in with healthy stems.

This message was edited Sep 3, 2009 9:57 PM

Picture #4

And here's the last photo. This shows the problem in its early phase - leaves are not completely black yet.

This message was edited Sep 3, 2009 9:58 PM

Can't help with the black problem, but your new camera shows it to be 2010- Please don't lose us a year! LOL! Seriously, that looks like a horrible problem- I hope someone can help you.

COL (chuckling out loud). Thanks for spotting that!!

Possibly Black Blotch? http://www.rhs.org.uk/advice/profiles0401/black_blotch_delph...

Does it start out as black spots and then grow until the leaf turns black?

I'll look in my reference book and see what else I can find.

Does it start out as black spots and then grow until the leaf turns black?

I'll look in my reference book and see what else I can find.

Here's some good info also http://www.ipm.ucdavis.edu/PMG/r280111211.html

Does it start out as black spots and then grow until the leaf turns black?


Thanks Joan,
It doesn't start out as round spots. I don't know how to describe it, but picture #5 is a pretty good example of the problem in its earlier stages.

las14

I don't know the problem either but I'd cut off anything black and just leave the healthy leaves and stems.

I'll also ask JasperDale to come over and try and help you with them.

Bacterial leaf spot or 'delphinium blacks' which is caused by cyclamen mites? Both are quite common to delphs.

From Iowa State "Spraying the "blacks" on Delphiniums with a fungicide for disease control These are caused by mites and are best controlled by sprays containing rotenone or nicotine or dusting with fine sulphur."

Hmmm..Not sure what happened with the link above. For some reason the link becomes broken when it's copied.

Try this, it's the first link in the google search http://www.google.com/#hl=en&source=hp&q=Delphinium+Black+Blotch&aq=f&aqi=&oq=&fp=6ae025ff2e4e975d

Las, I sure wish I could help, but most Delphiniums (the tall showy ones) won't even get that far for me- they so dislike our hot, humid summers. So, what you've got is about as good as I've ever seen with them, LOL. I'm thinking you're in an appropriate zone for growing them, perhaps your local extension office could be of help. They typically work with research universities in their area.

A member here recommended the Dowedswell web site and I took advantage of the "contact us" link and sent Terry Dowedwell my pictures. I'm posting his response here for the benefit of others who may be watching this thread.

Interesting. I f anyone should know it would be him. Please let us know what you find out when you check for nematodes.

Sorry I cannot help anymore than anyone else. The only thing that I had a problem with this year other than a nip from a late frost early in the season was slugs. A big increase in their numbers because of all the rain this year. They like delphs, a lot. They will climb up at night and slime the leaves that will eventually turn black. This also can effect the stems. If you have not noticed any munching or missing leaves before the backening starts then it is not the slimers at work. I think taking a look at what is going on at the roots would be a good idea as suggested above. Also you may want to have a soil sample done at the county agricultural lab to check for ph mineral content etc. I hope you can get an answer. If no other plants are effected and you cannot determine a reason for the on going problem it would seem likely that the soil that came with the plants or a pathogen specific to delphs was imported with them as already suggested. I would remove these plants and soil and trash them. Perhaps grow from seed or new plant from a different source and plant in a different location and see if the same problem reoccurs. Let us know how you make out.

This message was edited Sep 7, 2009 12:54 PM

Thanks! Interesting note about slugs. I do watch for them, and use Sluggo, but mostly early in the season when slugs can destroy all the new shoots. I haven't paid much attention to whether blackening leaves have also been chewed. I will do that.

This problem has been with me for quite a few years with a variety of vendors and different spots in the garden.

Thanks again,

LAS

Well, given all the feedback, I feel that the problem may be slugs. I have looked for the telltale holes and nibbled edges, but I didn't know that the slime can blacken and kill leaves, as ngam describes. This seems to fit the blackening that does not follow the leaf structure. And there is always damage to the edges of the leaves. I've posted another message in this forum, in the thread entitled "Pests: Calling all slug experts.... "

Thanks to all who have responded to my problem!!!!

LAS

Just thought of something, have you tried Delphiniums in various spots in your yard with the same results?

I have this problem too at times.. the best answer for me has been rotonone dust - dowdswell probably doesn't have this problem at all in new zealand.. but we do here in the north east usa. i also get the same problem on late aconites. i kind of do think it is some kind of critter or mite.. and the fact that critter killing stuff works best seems to point in that direction.. i think you have to be early in treating, and keep it up.. i'm an organic gardener, so don't use the stronger sprays, but they probably work too!

I just noticed this on delphs and on other plants as well this year. Since there was a huge explosion in the slug population due to the endless days of rain and damp cloudy days. I began to look for the reason so many plants were being either totally defoliated munched and turning black. I have found slugs at noon time sitting a top l plants leaving their slime trails even 7 feet up clem vines and just as high up the trunks of oak trees. I also noticed plants they liked eventually were turning black and the ones they didn't munch did not. Is it the slime itself? I don't know. It is more likely they eat the system that nourishes the plant and or destroy the plants ability to fend off disease or mites etc. The combination of a large attack by slugs, low sunlight, and constant dampness no doubt all contribute to a plant biting the dust, but if it is a random section of the plant that turns black then re-grows when the slugs are removed then they may have some relationship to what is happening. That is what I found in my garden anyway. Just an observation with no scientific proof.

This message was edited Sep 14, 2009 10:38 AM

Well, it's the next spring, and I'm 99% sure that it was slugs. I found advice somewhere that copper would repel them. That is, copper foil, not spray. So I made little copper rings and paperclipped them closed and set them around my sprouting delph plants. BINGO! No blackening. I also did it around other plants that seemed to suffer similarly, Campanula medium, lillies, some veggies. I got the foil at Home Depot, about $60 for a role. I cut it into 1 inch strips and clip them around tin cans. (When I started, I used 4 inch wide strips and worked them into the soil. The can approach is quicker and easier and cheaper.)

This has been WONDERFUL!!! Finally I can really enjoy my garden. For the veggies I put copper in a square around the beans (lost a whole crop to slugs while we were away during sprout time). Then collars around squash hills. Some collars around some individual plants (for some just a short tight collar around a single stem.) The initial investment is noticeable, but think! The copper collars will last longer than the plants!!!

I hop this helps other folks.

Thanks,

LAS

The joy of living in zone 4 my delphs are happy. Sorry Laurie.

Mine are grand. Beyond grand...fantastic and I thank the person who sent me the Misty Mauves. I just love them.

Soferdig, I hope your good fortune continues, but it is good fortune. My delphs are in zone four also. :-)

We are very dry here and that prevents lots of trouble. Irrigate irrigate.