I have the answer on hosta diseases

[bkay2000]

I just received my reply from Texas A&M. I have root knot nematodes. There is no treatment.

I'm not sure where I go from here since I grow exclusively in pots.

This is what they look like and the back story.

http://perennialnursery.com/forums/view ... ta#p499688

bk

[Chris_W]

That explains why they looked like they couldn't get enough water - the roots were inhabited so much they didn't function properly any longer.

Root knot isn't common in hostas, but it isn't unprecedented either. It will be more common in sandy soils than in rich soils.

Since you grow in pots there are really only two ways to get them, either they came in with the plants or they came in with your potting soil. To prevent something like this in your potting soil make sure you are only using a soilless mix - no dirt in pots. If your plants come in with any dirt make sure you wash it off before planting. I've received plants from nurseries before that were caked with mud, dirt, or sand, which can harbor pests and other diseases. And inspect the roots for the telltale hook shape at the root tips. When a hosta gets it the roots tend to be noticeably shortened with a fat, somewhat bulbous growth at the tips.

Hope that helps a little.

Chris

[Tigger]

Hmmm... So does the picture show this root appearance that Chris mentions?

[Bill Meyer]

What I'm seeing in these pictures is a plant that had a lot of rot going on. If there are root knot nematodes there too they aren't the main problem. Something killed most of the older rhizome and roots and it rotted off leaving only the new roots that formed on this year's growth. Unless there is a clear fishy smell that would indicate bacterial soft rot, there isn't any real way to be sure at this point what killed the rhizome and roots. You have to remember that dead things rot - what makes them rot isn't necessarily what killed them.

I've seen plenty of similar rot and since it's usually fungal, the best way to deal with it is to carefully scrape away any rotting tissue. Healthy tissue should look and feel like coconut meat. Once that is done, cover the leaves and healthy roots with wet newspaper and let the rhizome where you were scraping it dry for 30-60 minutes in the sun. It will dry out the cut surface and the UV probably helps too. Then use a fungicide on any cut areas and replant in new potting soil.

For the rest of the season keep the plant in shade out of the sun because the roots need to develop more to take up enough water to keep the leaves from drying out. Do not cut or remove healthy leaves.

This is about all you can do, and it will usually work in most cases. I don't lose many that I handle this way. For a fungicide I would recommend Cleary 3336 powder. It's a good wide-spectrum fungicide that doesn't require any special handling. Mostly it's the replacement for Benlate. It isn't too expensive at $60 or so for a lifetime supply. You get a lot for the money.

.....Bill Meyer

[bkay2000]

Thanks, Bill.
A&M's exact diagnosis and what they tested for is listed below.

On another plant, I had some stinky soil (I don't remember the exact smell, just that it was bad). I trashed the soil, washed the plant, repotted it and it seems to be doing much better. It put out some new leaves, so I'm hoping it's better.

I know you know what you're talking about, but I've reached the totally confused state. It's really hard to figure out what to do. I have no clue what is infected and what is not.

I'm going to re-read what you wrote. Thanks again for your input.

bkay


PLANT
Hosta (Hosta spp. x hybrids)
METHOD SUBMITTED
COURIER - FedEx/UPS
VARIETY
Olive Bailey Langdon
CLASS
ORNAMENTAL - Herbaceous
INTERNAL LAB NO.


DATE
July 15, 2015

COUNTY
DALLAS, TX
PLANT MATERIAL
PLANT/SOIL -entire, ROOTS
INCUBATION

SENDER CATEGORY
HOMEOWNER - individual
DIAGNOSTICIAN(s)
S.McBride - Extension Program Specialist
CONDITION UPON ARRIVAL
GOOD SAMPLE, COMPLETE FORM
GENERAL OBSERVATIONS
Entire plant with chlorosis; Root galling;
DIAGNOSTIC TECHNIQUE(S)
X GROSS VISUAL __ BIOCHEMICAL __ REGULATORY
X MICROSCOPE __ CHEMICAL ASSAY X SEROLOGICAL
__ CULTURE __ MOLECULAR __ SITE VISIT
__ SPECIALIZED MEDIA __ NEMATODE __ REFERRAL
__ BIOASSAY __ PCR
GROWER INFORMATION
TX
REFERRAL INFORMATION

Diagnosis/Recommendations
Diagnosis: Root knot nematode (Meloidogyne)
Category: NEMATODE
Comments: LAB SUMMARY:

-->No bacterial streaming observed
-->Serological testing for the HVX virus -->NEGATIVE
-->ELISA based testing for Phytophthora-->NEGATIVE
-->Numerous galls were observed on submitted root tissue. Close examination of the gall tissue confirmed the presence of adult and juvenile root knot nematodes.

The progressive foliar desiccation and necrosis observed on this plant specimen is the result of a loss of adequate root function due to a root knot nematode (Meloidogyne spp.) infection. Numerous small galls were observed on roots within the root tissue. Gently dissecting these galls revealed the female root knot nematodes, which produces an egg mass giving rise to new generations of nematodes. Root knot nematode infection results in a disruption of the vascular function of the root tissue. Plants with root knot nematode infection often have symptoms of moisture stress during mild periods of drought/heat, with symptoms becoming more severe and extensive as more of the root system is infected.

Currently there is no nematicide chemical treatments available for the management of root knot nematode.

[bkay2000]

Regarding Bill Meyer's comment:

I just made sense of this. I had bleach treated the hosta that I sent to A&M about a month before I sent the sample. It did not dawn on me that it was not a good one to use as a specimen, as it was still dying. I had already killed the fungi. Therefore, the only thing left to consider were the nematodes.

bkay

[Zkathy]

Bk, are you saying you think your hosta had fungus and root knot nematodes?
Kathy

[bkay2000]

Yes. I think I had both. I was almost sure it was fusarium root and crown rot when I sent the sample. I was shocked to get the answer of root knot nematodes. I even sent some photos to Bob Solberg to ask him if it looked like root knot nems. He said yes.

Then, Bill Meyer said here that it looked like root rot to him.

I couldn't put that all together and make sense of it. It looked like rot, yet A&M said root knot nems. Just a couple of days ago, I put the bleach soak and the results together. It was a "lightbulb" moment.

I'm sure the nems were there, but I don't think they were the primary cause of the problem.

Maybe I'll get some better answers with the specimens I sent this time. They have not been bleached.

bk