Rhizosphaera Needle Cast

Does anyone know anything about this? In our paper today, the extension agent said there's an outbreak of this in the spruce trees in our area, due to the drought and dryness we've had for the last few years.

He suggested spraying all spruce and evergreen trees, but didn't offer a suggestion of what to spray them with?

Any ideas?

this is a fungal disease,the spray recommended is a fungicidal chemical called chorothalonil, brand names Dragon Daconil and I think Ortho puts one out labeled just Daconil.The reason he's telling you to spray now is that if you can prevent the disease your way ahead of the game because it's a two year course of treatment that's required if your trees actually are infected. Spray now while needles are forming and again when they are fully elongated. You will need to contact the agent to find out if more applications are needed. Good luck, and a word of caution, I sprayed my roses with daconil when the temperatures were over 90degrees and defoliated what the disease didn't get. Don't use it during very hot weather.

This message was edited May 27, 2007 10:29 PM

Very helpful information masgard, thank you!!! I'll make some phone calls tomorrow to see if anyone has those products available. I won't be able to contact the extension agent until Tuesday, I'm sure.

Our temperatures have been very mild (read COLD) so far, so I don't think I need to worry about it being too hot at this point. I would like to get this figured out and taken care of soon though. We have roughly 300 evergreen trees on our property that we have hand planted over the course of the last 4 years. They are still young, but growing well. I really would hate to lose them now.

The culprit is Rhizosphaera kalkhoffii. You can use that to search.

Difference of opinion I guess. I don't know that I would spray any trees with anything for this more so because if you read up on the chemicals that are used to spray you wouldn't be all that thrilled. You could use Daconil (Chlorothalonil).
It's carcinogenic though-
http://www.pesticideinfo.org/Detail_Chemical.jsp?Rec_Id=PC34550#Toxicity
Actually, all of the chemicals that could be used to spray for this have some very real downsides to them.

Seems a little late in the year to spray anyway given we're full blown into summer and June is but a few days away. It was my understanding sprays were used as preventatives as well as to get the fungus under control. To the best of my knowledge, you will never be able to eradicate the fungus and reinfection is almost assured even if you do spray at appropriate intervals. I guess the benefits to spraying would be that you would have a tree that wasn't so nekkid.

Supposedly, White Spruce is resistant.

Here's some really good information on how to determine if you have RNC or not and the article also offers information as to why stress might be the real root of the problem-
http://hyg.aces.uiuc.edu/secure/subscribers/200303b.html

Thank you Lauren. What you have stated is definitely food for thought. I'm not really one to use anything carcinogenic. (We don't even char our meat for that reason). Hmm...I'm gonna print out those links, and this thread, and let DH make the call. He's the tree person in the family.

I'm so glad to hear that they are young! I've been sitting here worrying that you might poison yourself trying to spray large trees and wishing I hadn't been the one to advise you. The correct name of the one brand is Ortho MultiPurpose Fungicide Daconil2787 Plant Disease Control.There are probabley other brands, I'm quoting from a 2 year old book put out by the University of Illinois on IPM.They don't have anything less lethalor more organic listed for this disease.

Could be worse, some of the "recommended" chemicals were carcinogenic and mutagenic. I really don't like fungicides and I really don't want them used anywhere on my property where my kids play, my dogs go out to pee and poop, and my wildlife friends scurry here there and everywhere. My husband is the birder and he doesn't like these types of chemicals sprayed anywhere near evergreens because that's where many of his birds roost at night and go to find shelter from the harsh weather of winter.

We don't char our meat either but we're all going to die someday of something.

Say masgard, this is a community. We come here to pool resources. Everybody brings something a tad bit different to the table. Just because I am afraid of fungicides doesn't mean the next person is. Psst, I've got that same IPM booklet from the U of I. I like it. Welcome to DG! May you enjoy many years here.

Well, DH said he is going to do an assessment of our trees and determine if we should or shouldn't do anything, based on the wonderful information you both have provided. If we have to spray at all, he will only spray the ones that are showing effects now, and the ones in close proximity of them. None of these are in the yard area where we garden and play, so hopefully if we have to do anything at all, the effects will not harm us or our pets.

Thank you both for your input. We really appreciate it. This is one that we have never dealt with before, and I wanted some input before I talked to the extension agent on Tuesday.

Joan, I'm sorry if I offended Eqilibrium, but I tried to answer your question,not tell you what to do.The woman,Nancy Pataky, who wrote the articlefrom U of I was my plant pathology instructor. She's a very intelligent woman and I respect her opinions, but I didn't read anything in her article that would change what your extension agent told you. Plants that have been weakened by the stress of drought and dryness aren't able to fend off diseases as easily as a plant that is healthy. They don't go into dormancy with the reserves of food stored to start up at full vigor in the spring. You and your husband have to weigh the pros and cons of fungicidesor disease,and there's always the chance that your trees may not get infected....

I don't think you offended anyone masgard. When I posted this question I really wanted to hear all aspects of this situation, and you both provided us with valuable information. That's what I was after, the pros and cons. I appreciate both of your comments, as I didn't know anything about this until I posted. You have given us the information we need to determine what is right for us and our trees.

Thank you both!! You really have been helpful. When DH read this in the paper tonight, he said "Ask you DG friends". We both value the input and experience of people actually working with these types of situations, but realize the ultimate decision of what to do is in our hands.

Bad advice there, too – he shouldn't be recommending blanket spraying of all evergreen trees, regardless of whether they are susceptible to this disease or not!

Resin

Maybe he owns stock in the chemical companies? Just kidding but it does seem over the top to spray all spruce and evergreens when some aren't even susceptible to RNC and then there would still exist the issue of whether or not the plants actually have RNC or not which appears to be easily determined in the fall by looking for fruiting bodies. Looks as if this disease predominantly attacks stressed Colorado blue spruces so spraying a well sited White Spruce might be about the equivalent of trying to control a spider mite infestation with an insecticide as opposed to a miticide. One would have blown lots of money on the wrong chemical and one would still have a plant infested with spider mites.

http://lancaster.unl.edu/hort/Articles/2003/rhizosphaera.shtml

One major issue that is standing out for me is that if a plant is infected, looks as if treatment is going to have to become ritualistic… year in and year out starting in spring with a follow up spray several weeks later in order to try to retain the value of the tree as an ornamental. Something else standing out for me is that I am reading that mature plants rarely die from RNC, they just end up looking very unattractive. Resin knows everything “conifer” so I’d be interested in knowing what he thinks being as how I’ve planted several spruces here over the years.

Perhaps the newspaper misunderstood and misquoted him too. All I have to go on is the newspaper article, since it came out on a holiday weekend when the offices are closed.

We looked at all of our trees this morning:

There are two that we planted last spring that didn't make it through the winter (actually I was impressed to only see two that died. We usually lose more than that the first winter). These were Ponderosa PIne.

There is one that has been planted for 3-4 years and is about 6 foot tall that appears to be dead on the top half or so. Bottom needles are still green though. We aren't sure of the id of this tree.

There's one (Colorado Blue Spruce) in our yard that has been planted for two years and is about 3 foot tall. It's got a yellow look to it, but perhaps a shot of miracid is all it needs. We did that and will keep an eye on it.

Those are the only things we found. I don't think we are going to do any spraying. It doesn't seem worth it in the long run.

Thanks!