Pumpkin Viruses and their Control

No plant or animal can be cured of a virus disease.
Prevention is the only economic control for virus diseases.

Viruses get blamed for many things as in "He is not here today, I guess he has a virus." If you are not a virus expert please first visit my Introduction to Virus page. That page will lead you to the Introduction to Plant Viruses page which will lead you back to this paged armed the knowledge to understand our pages on pumpkin viruses.

While I have many years experience testing sweetpotato, strawberries, raspberries, and blackberries for viruses, I have not done any work with the viruses which attack cucurbits (cucumber, pumpkins, squash, and melons). However, I am not a newcomer to cucurbit viruses because I often studied research reports on them when looking for info about small fruit viruses. I have experience using all the methods which you read about on my Introduction to Plant Viruses page.

You will soon learn that the viruses and vectors which attack one crop often attack another crop. While a few dozen viruses may be able to grow on the crop of interest to you, usually just a few viruses are of major importance on any given crop.

Growers of Atlantic Giant will probably have the greatest interest in seed-borne diseases which limit the size of the fruit. At present, I do not yet know whether any virus is carried within the AG seed, but it is likely some of the tobacco viruses which are seed-borne can grow on AG. Learning wether a virus can affect size of a fruit is very difficult to learn because local climate and culture are so important.

If you have a virus-free plant of any kind, you need to consider keeping it virus-free. Usually every little effort pays. Virus-free sweetpotato needs to be planted miles away from infected fields to be almost free of risk of infection. However, plants separated from infected plants only by a dirt road in a field have greatly reduced reinfection rates. Sweetpotato plants growing in the same row with infected plants often survive the summer without reinfection.

Disclaimer: I have no experience which indicates whether viruses are commonly of any importance to Atlantic Giant growers. I welcome your comments on this subject.

Looking for Viruses on your Pumpkin.

As you study my virus pages you may learn to identify some viruses by their effect on leaves of any crop. However, the symptoms may vary on host species. Any plant which has leaves of strange shape or patterns of pale areas should be considered as virus infected. If the plants are cheap, remove such plants without further consideration. If we eventually learn that virus infected AG have no chance of reaching record weight, we should destroy those plant no matter how important they are. That would be especially true if the virus is seed-borne.

I will add much more to this section

You can aid our Study of AG Viruses

Please send me any information about possible past virus infections or questions. I do not have a picture scanner, but if you have any .GIFs or .JPGs, or etc of normal, infected, or questionable leaves or other plant parts of pictures of whole plants I have unlimited space for posting them.

I will add more here.

I will look for virus pictures on the web and link to them. Once we have a gallery of normal and infected plant pictures, it will be easy for you to get an idea of what to look for.

Virus symptoms

Any pale, white, or yellow streaks in any plant may be indication of virus. Immediately get rid of all weeds having such patterns. An aphid, nematode or other sapsucker could transfer that possible virus to your crop. Sometimes the only symptom is a slight abnormal bending of the plant tip and that might last only a few days. In some crops the tip dies and a lateral bud becomes the new stem tip.

I will add more.

Virus Identification

My first step is to go the Idaho URL which lists all host species which have been tested. Their home pages is http://image.fs.uidaho.edu/vide/ You need not go there now, but visit it some time. There is much there which you can learn

The URL for the Cucurbit family is http://image.fs.uidaho.edu/vide/famly050.htm You will see a list of about 30 species of Cucurbits. Go down the list and click on Cucurbita maxima which is the species of Atlantic Giant. (later you might try C. pepo and C. moschata as they are smaller squash and pumpkins which may have contributed genes to our big pumpkins)/ That will take you down to a list of 40 viruses which are know to grow on C. maxima and list of 57 viruses which have been tested on C. maxima but did not grow.

Now click on anyone of the 41 viruses which is known to grow on C. maxima. If you have time read about most of the 41 viruses as that will give you a good general introduction to viruses which may be of importance to you.

Let us click on Squash mosaic comovirus . That takes us to a huge page giving lots of info.

I will add more here to help you understand that page. Meanwhile e-mail me if you have questions.

Laboratory Confirmation of Suspected Virus

Notice the info below which I copied from the page. That data tells us what happens when we inoculate various indicator plants with sap from a plant infected with Squash mosaic comovirus.

Diagnostically susceptible host species and symptoms

Diagnostically insusceptible host species (no symptons seen on these indicator plants)

Viruses most likely to Infect Atlantic Giant

I am looking into this. It will be some time before I have info. I am particularly interested in seed transmitted viruses.

Recomendations to Alantic Giant Growers

Nothing yet. If it turns out that some viruses are seed borne, perhaps we should try to get rid of the infected lines. In some crops growers have practically eliminated virus by making an effort.

----- items below to be used in writing this page.

http://image.fs.uidaho.edu/vide/famly050.htm lists the species of the Cucurbit family (Atlantic Giant is C. maxima). Go down the list to C. maxima and there you will find a list of ~40 viruses which have been found to attack C. maxima. Then comes a list of ~40 viruses which do not attack C. maxima. Barb, you asked me specifically about mosaic virus. Mosaic is a sort of catchall name for plant viruses, but it does mean a specific virus when the name is given in full. Notice at the above URL you find "Cucumber mosaic cucumovirus" listed as causing damage to Cucurbita maxima. You will notice it is underlined as a link to the URL: http://image.fs.uidaho.edu/vide/descr267.htm [notice further down the list is Squash mosaic comovirus which you will want to look at also]. You will find lots of info at descr267. We find it is seed transmitted in 19 species, but seed transmission is variable. That seed transmission is a real shock to me--I was hoping against that. Under strains, you find there are many known strains: "numerous, the better known include: A-CMV, E-CMV, L-CMV, N-CMV, P-CMV, Z-CMV and WAI/WAII; there seem to be two antigenic groups, ToRS and DTL (Devergne, 1975)." Under transmission you find: "Transmission Transmitted by a vector; an insect; more than 60 spp. including Acyrthosiphon pisum, Aphis craccivora and Myzus persicae; Aphididae. Transmitted in a non-persistent manner. Virus transmitted by mechanical inoculation; transmitted by seed (in 19 species, but in variable extents)." It is primarily transmitted by certain aphids. I know Myzus persicae, the green peach aphid, and it attacks many species of plants and is really good at transmitting viruses. Some viruses can grow inside the aphid and be transmitted for a long time. "Non-persisent" means this virus does not grow inside aphids. after hours or a day or so the contaminated aphid will no longer be infective. Sap transmission is slightly worrisome. Perhaps the virus could be transmitted from plant to plant by the gardener. In particular, pruning vines might transmit this virus. The URL does not say that. The authors probably did not think about folks pruning vines. I am certainly going to be very careful about pruning. 1 volume of chlorox + 9 volumes of clean water is the standard disinfectant used in AIDS laboratories. I have used that on pruning shears and they lasted about one day (the spring on the shears rusted away in a few days). If you only have a few vines, you can consider pruning them on different days using a stainless steel knife, chlorox and soap. Remember your hands will carry the virus. You could wear rubber gloves and wash them in chlorox and soap. Drying will kill some viruses but not all. We commonly identify viruses by there action on certain indicator plants. That information is given under: "Diagnostically susceptible host species and symptoms Chenopodium amaranticolor, C. quinoa - chlorotic local lesions. Cucumis sativus - systemic mosaic. Vigna unguiculata - necrotic local lesions. Lycopersicon esculentum, Nicotiana × edwardsonii, N. glutinosa, N. tabacum - symptoms depend on virus strain." ----- I will someday have a web site written to introduce the general reader to viruses and experiments for k-12 and amateur scientists.but that is not very likely--I hope we can give it a try. Since orange color is so important, I should think we would concentrate on color at first. We already know from the Curcurbits Genetics Cooperative that 3 or 4 genes are required to get orange color. Go to Ned's and other sites for pedigrees and progeny results. I do not plan any such data on my site.

You may send private e-messages to Dr. Eddleman and he will reply, usually within 24 hours.

First installed 1999 April 3      Revision #0 1999 April 3      indbio@disknet.com
Written by Harold Eddleman, Ph. D., President, Indiana Biolab, 14045 Huff St., Palmyra IN 47164
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