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Madera, CA

http://www.bigpumpkins.com/Diary/DiaryViewOne.asp?eid=161977

In the picture above from my diary I had something going on with the leaves earlier in the year. A member here emailed me and said he thought it was squash mosaic virus. He also said that the disease was untreatable and would be passed to the seeds of that pumpkin. Now that I have harvested the pumpkin I have people asking me for seeds and I am not sure what to do. Any advice would be greatly appreciated.

9/9/2011 12:01:41 PM

Connecticut

Hi Marty-

Looking at the picture you have a mosaic virus (only a test could confirm squash vs watermelon (1 or 2) vs cucumber,… However, the diagnosis is the same, no cure. The passing on to seeds is where your question gets interesting.

My initial question would be is/was the fruit distorted or exhibiting other virus like symptoms or were just the leaves and vines showing the mosaic look?

Next, even if the fruit was showing symptoms it is true the virus can be transmitted by the seeds. However the % of virus infected seeds is actually quite low. For example, how many seedlings have you seen or even hear about showing virus symptoms? Honestly, I have not heard of any.

So, I went the scientific route (big surprise) and found some articles that should be publically accessible via the links are below. Looking at the table you can see the percent transmission rate is actually quite low and in some cases –zero- even if the fruit was severely distorted.

https://w3.avignon.inra.fr/dspace/bitstream/2174/209/1/9_19_Tobias.pdf

http://cuke.hort.ncsu.edu/cgc/cgc26/cgc26-12.pdf

My opinion is that the threat is low of transmission so while it can happen it is not a concern. Also, in the rare case a seed you give out is infected the symptoms are going to show up very early in the season at the seedling stage and the grower will not waste a season with a sick plant.

If anyone has seen a virus infected seedling I would be interested in knowing, but the odds are strongly in favor of virus free seedlings.

Hope this helps.

9/13/2011 9:24:14 PM

Madera, CA

Thank you for the great answer, that helps a lot.

9/19/2011 4:16:54 PM

Linden, Mi.,

I am going out on that thin branch and say, seeds cary the virus and start to show up in the heat of season when the plant is under stress (stress when the plant is growing plant as well as fruit) my view!

9/19/2011 7:20:49 PM

Connecticut

Here is a great website for explaining a little about viruses in general and in relation to plants:

http://www.dpvweb.net/intro/index.php

Since viruses are involved on the DNA level they would have to always be present and do not necessarily need environmental factors to increase their abundance. Where a bacteria will replicate faster during warmer weather. I have pushed plants with heat and nitrogen to try and get them to grow faster than viruses can replicate and spread. Sometimes this works and other times it does not.

You may notice an increase of virus infections during warm weather because typically the insect vectors are more active during this time. Also, later in the season when aphids (for example) are more commonly seen can be another way overall virus prevalence can increase.

Hope this adds some background to how viruses replicate as they are quite fascinating.

9/19/2011 9:44:36 PM

Muddy Waters

Ive seen the virus in young plants that are 4-5 feet long,& suspected it carried over in seed like the MSU extension said it could carry over,but may not be in all seeds.I personally will not grow a suspect seed! Just me though not entirely scientific.

10/9/2011 8:15:01 PM