Do seeds carry diseases?

From a previous thread

Arthur Wierzchos wrote:Do we really need to worry that much about disease transmission with seeds?

This made me think, and I couldn't find a thread where it was discussed. There are cross border restrictions in most countries for seed movements. How much of this is sensible precautions, and how much is just red tape for the sake of it? Obviously plant material such as tubers and cuttings are more likely to carry organisms such as fungi and bacteria, but what about seeds? What risk do we take if we smuggle a packet of beans in our luggage?

Thoughts?

(Lets try and steer clear of politics, and keep to the seed safety side please!)

My impression is that seeds can carry viruses, at least, but it's much less common. I remember reading something more extensive about that by Bill Whitson at Cultivariable, related to potatoes (not all plants) but all I'm finding right now is this:

At the bottom of this blog post:

There are very few diseases that spread in potato seeds compared to potato tubers, so you can often grow your seed-grown potatoes for more generations before they become burdened by disease.

This paper makes it sound relatively normal and even notes that viruses use their positioning in seeds as a survival and distribution mechanism:

Parent-to-offspring vertical transmission through seeds has been known for a century, and for some plant viruses such as persistent (also known as cryptic), viruses is the only way to infect new hosts.

Hi,

the term you are looking for is "seed borne diseases". Here an example of diseases transmitted by cereal seeds, (they discuss pesticides, the point I am trying to make is the diseases, not the treatments) https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/seed-borne-diseases

Diseases can be transmitted in different ways through seeds: either the disease in ON the seed, or it is IN the seed. Some treatments can kill some diseases, mainly bacterial diseases which are on the seeds. Several organic treatments are discussed here:
https://www.eorganic.org/node/749

So to reply to your question: it depends. In some cases, like with potatoes, if you introduce a new strain of Phytophtora outside its native range, it can have a huge impact on the livelihood of many people. In other cases, for example if you transport seeds across neighbouring countries which anyway exchange agricultural products and have other biological exchange, it may have no impact. Crossing natural barriers like oceans or mountains increase the risk.

Researching "quarantine organism" together with your crop name might help find some pathogens.

I remember some discussion (in the master gardener course?) about bacteria being present in the seeds as well. I think it was in the context of beneficial relationships, but I guess pathogenic bacteria could be there too?

Hey! I've just remembered my oat smut (discussed here) that was a fungal disease that probably came on the oat seed (pretty endemic in the UK I gather).

Thanks for making this post Nancy.  You got me looking into this more also, and as always the responses given by those who decide to chime in are better than a quick google search can provide.  

Its great to know how to be more sensitive, and selective, in order to prevent unintended harm to others within ones own community/region.  

The main thing I get out of this is to know the source!  To be very selective of were the plant materials, such as seeds, are coming from.  Setting up quarantine areas on ones own land can be another step in making sure that problems aren't spread out to a wider area.  

I realize that most people won't be so considerate or careful, and this is often why regulations are put in place. If people were more trustworthy (moral) then there would likely be less need for such control measures.  

Amen!  The more people who govern themselves responsibly, the more freedom everybody can be trusted with.

I currently believe that sterilizing seeds caused more harm than good, because seeds contain the symbiotic endophytes that allow the plants to thrive in the next generation. I believe that many of modern agriculture's problems originate because seed sterilization disrupts the natural synergy between plants and the endophytes that they invite into their tissues.

Joseph Lofthouse wrote: I believe that many of modern agriculture's problems originate because seed sterilization disrupts the natural synergy between plants and the endophytes that they invite into their tissues.

That's a really interesting concept Joseph. Logically if we accept that plants grow better with good soil bacteria, then the sooner that relationship develops the better.
Are seed routinely sterilised? I gather this can be done for oat seeds to reduce smut in the crop, Is this how seed companies get certificates for sending seeds between countries? I wouldn't have thought generally it would be worth the effort involved, unless like the smut, you have a particularly debilitating pathogen likely.

Nancy Reading wrote:Are seed routinely sterilised?

I don't know the answer to this, but I have declined to participate in hobby-scale seed exchanges because they expected me to bleach or TSP the seeds and I thought it was irresponsible. So it's at least prevalent enough that I've bumped into it as a not terribly serious seed steward.

Here some seed borne viruses are described, and the legal implications in the USA
https://www.cultivariable.com/americans-should-be-careful-of-ukraine-true-potato-seeds-tps/

I think that the benefits of the endophytes has to be balanced with the costs of importing new diseases .

These costs and benefits are not only individual, but also for the whole society: If, for example, someone imports (illegally and without checking for diseases) American hazelnuts with Easter Filbert Blight into Turkey (the world leader in production), this person will be responsible for the financial ruin of thousands of small-scale farmers along with century-old sustainable agroforestry practices.

This is the same as what happened with the import in the US of the chestnut blight, which destroyed whole ecosystems and reduced a sustainable food production to basically zero.

(edited for clarity)

Nancy Reading wrote:

This made me think, and I couldn't find a thread where it was discussed. There are cross border restrictions in most countries for seed movements. How much of this is sensible precautions, and how much is just red tape for the sake of it? Obviously plant material such as tubers and cuttings are more likely to carry organisms such as fungi and bacteria, but what about seeds? What risk do we take if we smuggle a packet of beans in our luggage?

Thoughts?

(Let’s try and steer clear of politics, and keep to the seed safety side please!)

Regarding beans in particular, infestation by weevils/beetles is a pretty common problem; there are several threads discussing this on permies. Inspecting for marks and Freezing is a common strategy for dealing with them. Personally, I am frustrated when people drop off bean seeds to our seed library that show signs of infestation, I worry that pests will burrow out and ruin other seeds nearby.

I have pretty much adopted the strategy that I freeze received seeds before adding them to my stash or food storage.