Virus and Nutritional problems

Bessie · 2023-02-17T00:21:26+00:00

Continuing the conversation about virus, coming from the "Taking Dahlia Cuttings" thread... I found this video a beginner's overview of Dahlia virus. There's...

MA_Dahlias

Can anyone help with these symptoms that seems to be impacting a few dahlias in the patch. Plants showing this issue are surrounded by plants with no symptoms. At first I thought it had gotten dry and didn't rebound, but I've got probably four plants scattered around with similar necrosis. I'll do some digging on YouTube for possible nutrient causes, but thought I'd ask incase anyone else had seem the same thing. My first guess is it's a potassium issue, thought I've been doing a good job of feeding regular with a low nitrogen fertilizer.

Bessie

MA_Dahlias what part of the plant are the symptoms on? Uppermost, middle, lower leaves? Do all plants show the same damage on the same region of the plant?

MA_Dahlias

Bessie They seem to be mid to upper level leaves on all of the plants. The four or five plants that are affected do seem to have similar symptoms on about the same region of the plant, that inter-veinal necrosis. They kind of dry up from the edges toward the middle of the leaf with the impacted leaves being primarily in the middle part of the plant.

Bessie

MA_Dahlias my best guess is Potassium (K) deficiency. Potassium deficiency usually shows up on the older leaves, and the necrosis happens rapidly. If the symptoms were on my plants I'd treat with an all purpose water soluble fertilizer that contains micronutrients.

MA_Dahlias

Bessie Thanks Bessie! I have been giving them a soluble fertilizer, but perhaps not heavily enough. From a "gallons" perspective, how much water do you to allocate for each plant when you feed? I get the dilution per gallon math, very straight forward, but I do feel like I'm guessing when it comes to how much I'm supposed to be using per feeding on my entire patch. I wonder if I'm too frugal.

Bessie

MA_Dahlias there is no one right way to fertilize. From years of experience, I fertilize based on what the plants look like. I like to see leafy growth and nice dark green leaves(varies by variety) throughout the plant. For healthy growing plants I mostly use a soluble 24-8-16 fertilizer that contains micronutrients, mixed to recommended dose. Soil type plays a role in how the nutrients are available to the plant. I have a "sandy loan" soil that leaches out nitrogen during the rainy season. I used to have clay soil years ago and found that typically much less fertilizer is needed.
Fertilization of plants is a rather involved topic based on the plant nutrition needs, the soil and organic matter content, the growing environment coupled with plant water requirements, and the chemistry of soil fertilizers and soil amendments.

MA_Dahlias

Bessie I certainly know you are spot on in your comments and approach and I know this is a frequent topic of conversation. I keep bees as well as dahlias and I know that you can never get a black and white answer to any "how" question from a beekeeper because the answer always starts with "Well, it depends..." I need to continue to learn my plants and try to translate what they are telling me into what they need. Perhaps right now, it's as simple as... more food! So, that's a good start 🙂

Bessie

As I was trimming up my tuber clumps I wanted to know if ethanol(rubbing alcohol) was a good disinfectant. Short answer is "No". I plowed through this technical paper, to learn some very interesting facts. 1) Concentration of the active ingredient of disinfectant is important. 2) Not all "disinfectants" work on all viruses. 3) 10% sodium hypochlorite solution ( for 60 seconds) kills most all viruses. 4) Lactoferrinin at .5% is an effective disinfectant, and is safe for human contact.
I think the Background, Discussion, and Conclusion sections are a good summary of the experiment.
https://virologyj.biomedcentral.com/articles/10.1186/s12985-020-01479-8
Title:
Effectiveness of disinfectants against the spread of tobamoviruses: Tomato brown rugose fruit virus and Cucumber green mottle mosaic virus

Teddahlia

ADS says that Dawn Detergent is effective.

Cosey

Teddahlia I would like ADS to cite their source for their suggestion that Dawn dish soap is effective against TSWV, TSV and DMV.

SteveM

Milk is also effective against virus transmission but is probably more expensive (and messier) than Dawn. I would be more concerned with bacterial transmission than virus. Or nematode transmission.

calico20hill

Things I wonder about....I have seen talk of using DAWN for years. Is there something in it that works better then any other dish soap or is just that it is the one that was tested?

SteveM

calico20hill Noni, I think any liquid dish soap with 'sodium laureth sulfate' as an ingredient would work to kill virus. Just a guess.

Bessie

What i think i read... The study referenced showed Tri Sodium Phosphate and milk were not effective for killing 100% of the virus tested. The virus tested do not have an outer coating. When an outer coating is present, the coating is destroyed by some of the disinfectants. Covid 19 had an outer layer, that would be destroyed by the ethanol based disinfectants and some other disinfectants. Some of these disinfectants that kill the covid-19 virus will not kill the plant viruses under test. These facts were very surprising to me and why I thought the study was worth sharing. It's also important to note the viral disinfectants only work when used at the recommended concentration in solution and for the recommended soak time.
Excerpt From https://virologyj.biomedcentral.com/articles/10.1186/s12985-020-01479-8

The effectiveness of four treatments from three disinfectants (0.5% and 2% Virocid, 0.5% Lactoferrin and 10% Clorox) were most significant, generating 0% infectivity on test plants. Five other treatments displayed some effect but not enough, generating only 10–45% infection rates on the test plants. These treatments were 2% Virex (11.1% infectivity), 2% Virkon (22% infectivity), 50% Lysol (26% infectivity), 2.4% SP 2700 (30% infectivity), and 10% trisodium phosphate (TSP, 44.4% infectivity). Overall, ten treatments were considered no effect, as they generated 50–100 percent infection rates on the tested plants. These treatments included 0.1% Lactoferrin, Ethanol/Urea/Citric Acid (EUC), 2% Kleen grow, 1.2% SP2700, 2% Simple green, 50% Purrell, 50% Protecteav, 10% Non-fat dried (NFD) Milk, 400 ppm Microside and 50% Microsan (Fig. 2). However, it is important to note that 2% Virex, 2.4% SP2700, and 2% Virocid showed some level of phytoxicity to the test plants upon treatment (Additional file 3: Fig. 1).

Krista

Bessie I’m in over my head in this thread unsurprisingly but is this reporting that 10% bleach is in fact more effective than the 2% Virkon that folks are opting for this year?

SteveM

Good article! Those tests were on tobamoviruses, it would be interesting to see the same tests on DMV.

When I started raising heirloom tomatoes 15 years ago the Tobamoviruses were my biggest concern (especially TMV and ToMV) The latest research at that time suggested milk was very effective at inactivating TMV. Some commercial growers would have their workers wash their hands in milk every 30 minutes when working on the tomato plants. I used latex gloves and a milk rinse when planting tomato seedlings to the field. This study suggests that it might not have been very effective. (although, field results can vary from in vitro results if some unknown variable is missed).

Cosey

SteveM Nonfat Dry Milk has been proven effective against some viruses, but given our collection in dahlias we should consider a disinfectant practice that treats to the most difficult pathogen.

10% bleach has been the most consistent across numerous studies. Unfortunately, DMV hasn't been specifically studied and might be an area ADS considers to invest in. When searching for disinfectant practices for caulimoviruses (class DMV is in) there isn't much field/practical management info out there, but bleach has been included. I find it incredibly frustrating that contact times are excluded from many trials which is a key component to disinfecting.

Bessie

Krista 2% Virkon resulted in a 22% infection rate. The study was not done on dahlias as @SteveM points out, nor the study was not on the viruses Dahlia are infected by(I think). However, I personally take the results as guidance that I should use 10% bleach which is a very cost effective solution! For a brief time this morning I considered purchasing Lactoferrin, which I'd never heard of before reading this article. I decided that 10% bleach for 60 seconds was my best option.

ksc

I use a small butane torch. I believe that a few seconds of 2000f will kill everything that might infect plants. No mess, ruined clothing, and it fits in my shirt pocket.

blown_dry

ksc That seems like a really good idea. I find those little torches indispensable for dealing with drip irrigation tubing. I heat up a small screwdriver to punch holes in mainline tubing for spurs and it's a game changer for attaching the tubing to fittings. I can make do with a lighter, but the torch is better. Now I just have to hope I remember this tip. 🙂

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