0
points
Virus or nutrient deficiency?

Tomato    None Given

I'm really worried about these tomatoes. They are in a fairly new aquaponic system, so I was thinking nutrient deficiency, but I'm getting more and more afraid that they have a virus. All but one plant is affected. They new growth looks pretty good, this is mainly on older growth. Also, the blossoms are atrophying at the flower and falling off. When they do get fruit, it is very small. The plants are really tall, but the stems are hardy as thick as a pencil. Most of them are at least six feet tall with the tallest being almost nine feet tall.


Posted by: Tami Hallam (1 point) Tami Hallam
Posted: July 19, 2016




Answers

2
points
From the series of slides it can be deduced that the symptoms are typical of viral origin. It all starts on the leaves with small chlorotic lesions that coalesce and become necrotic , covering larger parts of the leaves; giving the leaves a burnt appearance. Judging from the distribution over the branches the diseases is spreading systemically over the tomato plant.
The best thing to do is roguing, and start with virus-free certified plants in an insect- free environment.

Ferdinand


Posted by: Ferdinand Klas (4 points) Ferdinand Klas
Posted: July 21, 2016




0
points
Part of your problem is that the plants are not getting enough light. That would explain tall, spindly stems. Tomatoes need at least 8 hours of full sun a day for best production.


Posted by: Dennis (7 points) Dennis
Posted: July 20, 2016


Tami Hallam commented,
Yes. I think when it is time to replace my roof, I am going to go with clear panels. Live and learn.
about 4 years ago.



0
points
I got some feedback from one of our senior vegetable pathologists here at Penn State.

" My guess would be that it is a nutrient deficiency or imbalance of some type rather than a virus especially since it is a newer aquaponic system (or possibly a hydroponic system – can’t tell from the pictures). The leaves don’t have the more typical mottling/puckering that I associate with viruses."

Hope this helps. To establish definitively if it is a virus, you would need a lab test. Where are you? Is that something you can get? And how are the symptoms now?



Posted by: David Hughes (54 points) David Hughes
Posted: July 25, 2016


Tami Hallam commented,
I am in Northeast Wisconsin near Green Bay. I'm fairly certain that I could get a lab test somewhere in the city. Unfortunately, I freaked out when I read the first answer and tore them all out and burned them. At least I know now though that my greenhouse and aquaponic beds are likely not harboring a virus and I'll be able to put more tomatoes in at some point without completely swapping out all the gravel in my beds. It was so hard to tell if it was nutrient related from the photos I see on some online deficiency guides because I'm pretty sure that if it is a deficiency, it is more than one element. I'll see if I can find a place to test them though in case it happens again and then I can know definitively. Thank you so much for your answer.
about 4 years ago.

David Hughes commented,
what a shame! The crucial thing to remember about viruses of plants is that they are almost always transmitted by insects. So, check to see if you have insects that vector them. Some viruses can be transmitted as broken up plant material is distributed (such as with mowing) Good luck and let us know how the next trial goes
about 4 years ago.

Ferdinand Klas commented,
Every school kid knows that viruses can be transmitted by insects. They can also be transmitted mechanically , by seeds and by the planting material itself. Every school kid also knows that to confirm symptoms of virus diseases you need to lab tests like ELISA or other serological tests or PCR tests. The problem with the Plant village system is that it is merely based on symptoms on the leaves or the stems. From some pictures you are expected to come to a diagnosis. In this era of ELISA tests and PCR technology the system followed by Plant Village is outdated and inadequate. It needs some thorough revision. Diagnoses at Plant Village are based largely on GUESSING ; as is manifested above in the reaction by David Hughes, saying: "My GUESS would be that it is a nutrient deficiency or imbalance of some type rather than a virus especially since it is a newer aquaponic system ............." Dear David, in Plant Pathology we do not GUESS !! In Plant Pathology we ASSESS !!! If you guess it is a it is a nutrient deficiency or imbalance, let it be. However, where is the proof ?
about 4 years ago.

David Hughes commented,
Ferdinand The "guess" was from a senior plant pathologist at Penn State Extension with decades of experience in tomatoes. You are correct, we should assess but you must also admit that in the first instance plant pathologists make an informed guess based on symptoms. At PlantVillage/Penn State we are also doing PCR and histological slides of infected material. We are also using spectrophotometry. We can do that and many US growers have fabulous Land Grant Universities to send samples to for the type of diagnosis you suggest. But what about the majority of the world that doesn't have such a services like Penn State or Cornell provides. What should they do? PlantVillage is attempting to make diagnosis by images broadly available. We have pioneered a development using computer vision that accurately diagnosis 26 diseases >99% accuracy. http://arxiv.org/abs/1604.03169 You are correct: PCR is the definitive test but for initial assessment visual images are very useful and the plant pathology community has been using these since 1926. http://www.apsnet.org/publications/ap... So, join us. Share your knowledge. Help the world. Tell us which tests one can use for which virus diseases? You can contribute to our library and help people. I hope you do.
about 4 years ago.

Ferdinand Klas commented,
Dear David, you wonder what the majority of the world that does not have access to PCR facilities and other diagnostic techniques, should do. Well, in most developing countries FAO is conducting excellent programmes, that also include setting up laboratory facilities. I know this, because for several years I have , as an FAO consultant, also participated in such programmes in Guyana, The Bahamas, Trinidad and Tobago, Suriname , Mauritius etc. I would therefore suggest that Plant Village collaborate and link with FAO to establish adequate laboratory facilities in these countries, on a regional basis. Regional FAO/Plant Village advanced laboratories where samples of a particular region can be sent to will satisfy the need for adequate diagnoses and recommendations. What the farmer needs is not just an initial guess based on visual images, but clear-cut assessments and recommendations telling him how to improve the crop conditions and to attain better and higher yields. I am sure FAO will welcome the a collaboration with Plant Village.
about 4 years ago.



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