Virus

Today a significant number of threatened, endangered or extinct (in habitat) geophytes species are grown ex situ by hobbyists, institutions for conservation, as well as commercial growers large and small. In some cases only one clone of an endangered or rare species has been introduced into general cultivation. Sometimes tragically, the single clone becomes infected, and if it is self-sterile, there is little hope to obtain virus-free seedlings from it. Therefore, it is of utmost importance for all to exercise due diligence in ferreting out infected plants from our collections. This can be a tedious and an emotionally charged task, due to the rarity of and personal bonds formed with some of our cherished specimens.

Virused plants may show symptoms such as streaked or mosaic patterns on flowers and foliage. Leaves and stems can be twisted, distorted, and necrosed. Some apparently healthy plants do not show viral symptoms and only under stress that a latent virus may begin to show. In other cases, there are plants that do not show signs of disease at all. Example of such stress could be incorrect watering, inappropriate light exposure, temperatures outside ideal range, or fertilization. The best manner to determine the status of a plant in question is to have it tested by a lab.

Viruses may be spread by insects such as aphids, leaf hoppers, mealybugs, nematodes, fungi, or mechanically (this includes cutting tools, hands, etc...). Not all of the viruses listed below spread in the same manner, but for those who desire to keep a virus free collection, a few generally accepted precautions can be taken:

Virused plants should be discarded, along with any containers and soil that has been in contact with the diseased plant. If containers are to be recycled (plastic only), they need to be submerged in a 10-15% bleach solution overnight, then washed with warm soapy water.
Sterilise tools with a bleach solution (15-20%) or a source of heat strong enough to kill viruses, between cutting EACH plant.
Keep a keen eye out for sucking insects that often spread virus, and treat infestations as expeditiously as possible. It is entirely possible for these insects to spread viruses from non-geophytic plants.
Those who smoke may unknowingly carry a mosaic virus on their fingers (due to tobacco's notorious reputation as a reservoir for many strains of mosaic viruses) thus, thorough washing of ones hands ought to be done before handling leaves, flowers, etc.
One has a better change of obtaining virus-free material from growers that certify that their stock is seed-grown. It is wise to keep newly acquired plants quarantined. Plants should be tested if one has any doubts.
With a few exceptions, the most reliable manner in which to obtain virus-free stock is by germinating ones own geophytes from seed.
In the case of a an infected rare specimen that is hard to part with, a suggestion would be to quarantine it in hopes of getting virus-free seeds before discarding the mother plant. This can be a painful decision if the plant is not self-fertile. When pollinating a virused clone with a healthy clone of a species, it may be better to use the virused plant as the receptor of the pollen (mother of the seed), as sometimes pollen from a virused plant may infect the healthy plant if applied sexually.

Leaf problems on this Clivia. Photo by Germán Roitman. This clivia may have more than one problem. Virus can make is susceptible to other things.

Crocus are susceptible to virus disease. This is usually visible in the flowers. This distortion may take the form of twisted petals, streaking (as in tulip fire,) sometimes the flowers are depauperate and fail to open properly. The virus also reveals itself as light and dark blotching in the foliage which is most visible when the foliage first emerges. The pictures here have been manipulated to exaggerate the streaking in flower and foliage to make it more apparent. (Massive hike in contrast levels does this.) All crocus pictures courtesy of Tony Goode. The third picture shows one with distorted petals.

The vectors are aphids which find refuge especially on the backs of the leaves. These pictures below show a clean Crocus medius and one that has streaking in the petals that is virused.

The pictures below taken by Germán Roitman show the mottled and streaked leaves of these Hippeastrums

Virus in Phaedranassa, Eucrosia, Eucharis, Stenomesson, Griffinia and Eustephiashows as longitudinal ridges (those leaves are perfectly flat if healthy), besides the mosaic stripes. Virused Phaedranassa photographed by Jennifer Hildebrand

The pictures below show Sparaxis with color breaks in the flowers. These plants were very vigorous and increased rapidly in the garden and I had no idea they were virused. Photo by Mary Sue Ittner

The list below was created by Nhu Nguyen and Jacob Knecht as a resource for bulb growers who are concerned about bulb viruses. The focus is on geophytes and is by no means inclusive. Most of the data came from the NCBI (National Center for Biotechnology Information) Universal Virus Database which gathered these data from many sources over decades of research. A few important caveats about the list below: Species and families listed are limited to those subjected to testing. This does not mean that these are the only ones that can be infected. Some geographic information date back to the 1950's. As a result of bulb movement throughout the world, some of these viruses have likely spread further than reported here. From this database, it seems that some viruses are host specific, but others spread prolifically and rapidly. Because of unknown species range, it is assumed that all members of a family are susceptible if one species is susceptible. You will find below that sometimes this is not the case, revealed only through testing of multiple species within a family. All families known to be susceptible are listed as a precaution for those who grow both dicots and momocots. And finally, non-persistent means that the virus is lost when the host insect molts; it does not mean that the virus has or will disappear from the plant.

Alstroemeria mosaic virus

Susceptible geophyte: Alstroemeria caryophylla and Alstroemeria psittacina
Susceptible families: Alstroemeriaceae, Chenopodiaceae, Solanaceae, Tetragoniaceae
Symptoms: some flower break and variable leaf chlorosis
Transmission & vector: by aphids such as Myzus persicae; non-peristent; by mechanical inoculation, not by contact between hosts, seeds, nor pollen.
Geographical distribution: The virus spreads in Eurasia and North America. The virus occurs in the Netherlands and the USA.

Alstroemeria streak virus

Susceptible geophyte: Alstroemeria spp.
Susceptible families: Alstroemeriaceae, Chenopodiaceae, Solanaceae, Tetragoniaceae
Symptoms: streaking, stunting and mosaic of leaves.
Transmission & vector: by aphids such as Macrosiphum euphorbiae and by mechanical inoculation; not transmitted by contact between hosts.
Geographical distribution: The virus is found, but with no evidence of proliferation, in Netherlands, UK and USA.

Alstroemeria virus

Susceptible geophyte: Alstroemeria caryophylla 'Ligtu' hybrids.
Susceptible families: Alstroemeriaceae, Amaranthaceae, Chenopodiaceae, Fabaceae, Solanaceae, Tetragoniaceae
Symptoms: faint chlorosis.
Transmission & vector: by mechanical inoculation; not transmitted by contact between hosts.
Geographical distribution: The virus is found, but with no evidence of proliferation, in England.

Amazon lily mosaic virus

Susceptible geophyte: Eucharis grandiflora
Susceptible families: Amaryllidaceae, Chenopodiaceae, Solanaceae
Symptoms: Leaf mosaic
Transmission & vector: insects, particularly aphids Myzus persicae; non-persistent.
Geographical distribution: unknown

Dahlia mosaic virus

Susceptible geophyte: Dahlia pinnata
Susceptible families:
Symptoms: chlorotic vein-banding, mosaic and leaf malformation.
Transmission & vector: by 16 species, notably Aphis fabae, Myzus persicae and Macrosiphum euphorbiae; non-persistent.
Geographical distribution: probably distributed worldwide.

Crinum mosaic virus

Susceptible geophyte: Crinum ssp.
Susceptible families: Amaryllidaceae
Symptoms: pale streaking, then mosaic and general chlorosis.
Transmission & vector: unknown
Geographical distribution: Australia and Fiji (Brunt, 1980)

Eucharis mottle virus

Susceptible geophyte: Eucharis candida
Susceptible families: Amaryllidaceae, Amaranthaceae, Chenopodiaceae, Cucurbitaceae, Fabaceae-Papilionoideae, Solanaceae, Tetragoniaceae
Symptoms: leaf mottling
Transmission & vector: by mechanical inoculation; transmitted by seeds.
Geographical distribution: Peru

Freesia leaf necrosis virus

Susceptible geophyte: Freesia refracta
Susceptible families: Iridaceae, Chenopodiaceae, Solanaceae.
Symptoms: chlorotic flecks and spots in leaves, which become necrotic. Symptoms more severe when plants are stressed by bright light or waterlogging. Flowers and corms unaffected.
Transmission & vector: transmitted by chytrid fungi such as Olpidium brassicae, and by mechanical inoculation (with difficulty). Not transmitted by seeds.
Geographical distribution: The virus spreads in Eurasia. The virus occurs in Germany, Ireland, Italy, the Netherlands, and the United Kingdom.
Control: Studies reported by The virus occurs in soil and is spread by infected corms, hence it is controlled by soil treatment and corm choice. This virus, together with freesia mosaic virus, causes freesia streak disease (Brunt, 1974; Van Dorst, 1973).

Freesia mosaic virus

Susceptible geophyte: Freesia refracta, Lilium formosanum
Susceptible families: Iridaceae, Liliaceae, Amaranthaceae, Caryophyllaceae, Chenopodiaceae, Asteraceae, Cruciferae, Cucurbitaceae, Fabaceae, Solanaceae.
Symptoms: mild chlorosis to symptomless
Transmission & vector: aphid vectors such as Macrosiphum euphorbiae, Myzus persicae; non-persistent; mechanical inoculation, not by contact between hosts, seeds nor pollen.
Geographical distribution: occurs in Australia, Ireland, the Netherlands, and the United Kingdom. The virus is found, but with no evidence of proliferation, in New Zealand.

Hippeastrum mosaic virus

Susceptible geophyte: Hippeastrum hybridum, Hippeastrum equestre, Eucharis grandiflora; (Belamcanda chinensis, Dahlia pinnata, Tropaeolum majus do not show signs of susceptibility)
Susceptible families: Amaryllidaceae, Chenopodiaceae, Solanaceae.
Symptoms: chlorotic streaking of leaves and flower stalks
Transmission & vector: by aphids such as Aphis fabae, Aphis gossypii, Myzus persicae, mechanical inoculation; not by contact between hosts, seeds, nor pollen.
Geographical distribution: unknown

Hyacinth mosaic virus

Susceptible geophyte: Hyacinthus orientalis; (Lilium formosanum does not show signs of susceptibility)
Susceptible families: Hyacinthaceae
Symptoms: leaf chlorosis, stem spotting, occasional flower break.
Transmission & vector: by aphids such as Myzus persicae, Macrosiphum solanifolii; non-persistent; mechanical inoculation, not by contact between hosts, seeds, nor pollen.
Geographical distribution: Australia, Bulgaria, the Netherlands, the United Kingdom, and the United States of America.

Iris fulva mosaic virus

Susceptible geophyte: Iris fulva and hybrids with Iris fulva, Iris sibirica; (Iris spuria, Neomarica gracilis do not show signs of susceptibility)
Susceptible families: Iridaceae, Amaranthaceae, Chenopodiaceae.
Symptoms: faint to prominant mosaic, necrosis, malformation of leaves and seed pods.
Transmission & vector: Virus is transmitted by mechanical inoculation; not transmitted by seeds.
Geographical distribution: USA

Iris mild mosaic virus

Susceptible geophyte: Iris ssp., bulbous irises, Iris xiphoides, I. xiphium, I. tingitana x I. xiphium, I. reticulata, and I. danfordiae, Belamcanda chinensis
Susceptible families: Iridaceae, Chenopodiaceae, Solanaceae, Tetragoniaceae.
Symptoms: mild mosaic
Transmission & vector: by aphids such as Aphis gossypii, Macrosiphum euphorbiae, and Myzus persicae; non-persistent); but not by Macrosiphoniella sanborni. Virus is not transmitted by seeds.
Geographical distribution: The virus is probably distributed worldwide (most important cultivars are totally infected).
Geographical distribution: unknown

Iris severe mosaic virus

Susceptible geophyte: Iris ssp., Iris x hollandica, Crocus vernus cv. King of the Blues, Belamcanda chinensis; (Freesia refracta cv. Imperial do not show signs of susceptibility).
Susceptible families: Chenopodiaceae, Iridaceae, Solanaceae.
Symptoms: Crocus vernus shows leaf mosaic, striping of flowers (either white or yellow). Belamcanda chinensis shows severe chlorosis. Iris ssp. show leaf striping, stunting, flower breaking. Plants die prematurely.
Transmission & vector: by aphids such as Macrosiphum euphorbiae and Myzus persicae; not by Myzus pelargonii, M. circumflexum, Anuraphis tulipae, Rhopalosiphum tulipaella. Virus is transmitted by mechanical inoculation; not transmitted by grafting nor contact between hosts.
Geographical distribution: Australia, Czechoslovakia (former), Denmark, Japan, the Netherlands, Sweden, the United Kingdom, and the United States of America (and probably wherever bulbous and rhizomatous irises and crocus are grown).
Control: Studies reported by Deutsch and Loebenstein (1967), the spread of the virus in bulbous iris can be partially controlled by spraying crops with mineral oils or pyrethroid and perimicarb insecticides.

Leek yellow stripe virus

Susceptible geophyte: Allium porrum, Allium cepa var. ascalonicum; (Allium fistulosum do not show signs of susceptibility)
Susceptible families: Alliaceae, Amaranthaceae, Chenopodiaceae, Solanaceae.
Symptoms: yellow leaf stripes
Transmission & vector: by aphids and mechanical inoculation; not by contact between hosts nor seeds.
Geographical distribution: The virus spreads in Eurasia; occurs in New Zealand (Aotearoa).

Lily mottle virus

Susceptible geophyte: Lilium spp.
Susceptible families: Liliaceae
Symptoms: not listed from the source, but probably mottling of leaves as the name implies.
Transmission & vector: unknown
Geographical distribution: Germany, Israel, the Netherlands, and the USA.

Narcissus degeneration virus

Susceptible geophyte: Narcissus tazetta cv. Grand Soleil d'Or
Susceptible families: Amaryllidaceae
Symptoms: not listed from source, but probably degeration of plants as the name implies.
Transmission & vector: unknown
Geographical distribution: unknown

Narcissus late season yellows virus

Susceptible geophyte: Narcissus pseudonarcissus
Susceptible families: Amaryllidaceae
Symptoms: not listed from source, but probably yellowing of leaves as the name implies.
Transmission & vector: unknown
Geographical distribution: unknown

Narcissus latent virus

Susceptible geophyte: Narcissus pseudonarcissus cv. Golden Harvest, Gladiolus cv. Scarlet Royal, Iris xiphium cv. praecox x I. tingitana (syn. Iris hollandica), other bulbous irises, Narcissus pseudonarcissus, Nerine sarniensis cv. Rotherside.
Susceptible families: Amaryllidaceae, Iridaceae, Fabaceae, Solanaceae (highly infectious in many species), Tetragoniaceae.
Symptoms: systemic to non-systemic chlorotic spotting, faint to dark local lesions, veins bending. These symptoms occur differently on different hosts.
Transmission & vector: aphids such as Acyrthosiphon pisum, Myzus persicae, Aphis gossypii; non-persistent; mechanical innoculation, not transmitted by contact between hosts, seeds, or pollen.
Geographical distribution: unknown

Narcissus mosaic virus

Susceptible geophyte: Narcissus pseudonarcissus, Lilium speciosum, Nerine spp.
Susceptible families: Amaryllidaceae, Amaranthaceae, Apocynaceae, Chenopodiaceae, Asteraceae, Fabaceae-Papilionoideae, Solanaceae, Tetragoniaceae, Umbelliferae.
Symptoms: symptomless in N. pseudonarcissus; in Lilium severe yellow stripe on leaves, leaf-deformation and stunting, as well as, in some cases, premature death of the plants.
Transmission & vector: mechanical inoculation; not transmitted by contact between hosts (between narcissus plants), not transmitted by seeds.
Geographical distribution: The virus is probably distributed worldwide (in all countries which have imported narcissus and nerine from Europe). The virus occurs in particularly the Netherlands and the United Kingdom.

Narcissus tip necrosis virus

Susceptible geophyte: Narcissus pseudonarcissus, N. tazetta, N. poeticus (Belamcanda chinensis, Dahlia pinnata do not show signs of susceptibility)
Susceptible families: Amaryllidaceae, Chenopodiaceae, Solanaceae, Tetragoniaceae.
Symptoms: usually symptomless; sometimes general leaf local chlorosis (2mm), elongate chlorotic areas near leaf tips, later becoming brown and necrotic, premature leaf senescence, not systemic.
Transmission & vector: Virus is transmitted by mechanical inoculation; not transmitted by grafting. Hosts become infected only by inoculation with purified virus preparations, never directly from infected Narcissus sap.
Geographical distribution: Netherlands and the United Kingdom.

Narcissus yellow stripe virus

Susceptible geophyte: Narcissus ssp.
Susceptible families: Amaryllidaceae
Symptoms: not listed from source, but probably yellow stripping of leaves as the name implies
Transmission & vector: unknown
Geographical distribution: The virus spreads in Eurasia and possibly occurs in Australia.

Nasturtium mosaic virus

Susceptible geophyte: Tropaeolum majus
Susceptible families: Tropaeolaceae
Symptoms: vein clearing, mottling and slight leaf malformation; occasionally flower breaking.
Transmission & vector: by aphids such as Aphis fabae, Dysaphis apifolia, Myzus persicae, Aulocorthum circumflexum, Rhopalosiphum padi; non-persistent; by mechanical inoculation.
Geographical distribution: Brazil, South Africa, the United Kingdom, and the USA.

Nerine latent virus

Susceptible geophyte: Nerine bowdenii, Hippeastrum hybridum; (Belamcanda chinensis, Dahlia pinnata, Tropaeolum majus do not show signs of susceptibility).
Susceptible families: Amaryllidaceae, Amaranthaceae, Chenopodiaceae, Solanaceae.
Symptoms: symptomless in H. hybridum
Transmission & vector: by aphids such as Myzus persicae; non-persistent; by mechanical inoculation but not by contact between hosts, seeds nor pollen.
Geographical distribution: The virus occurs in the Netherlands and the United Kingdom.

Nerine virus X

Susceptible geophyte: Nerine sarniensis, Agapanthus praecox ssp. orientalis; (Allium cepa, Belamcanda chinensis, Dahlia pinnata, Hippeastrum hybridum, Lilium cv. Enchantment, Lilium formosanum, Narcissus pseudonarcissus do not show signs of susceptibility).
Susceptible families: Amaryllidaceae, Amaranthaceae, Chenopodiaceae, Fabaceae, Solanaceae, Tetragoniaceae.
Symptoms: symptomless in N. sarniensis and A. praecox ssp. orientalis to chlorotic or necrotic local lesions, then systemic chlorosis.
Transmission & vector: mechanical inoculation, contact between hosts; not by seeds nor pollen.
Geographical distribution: unknown

Nerine Y virus

Susceptible geophyte: Nerine sarniensis
Susceptible families: Amaryllidaceae
Symptoms: severe leaf chlorosis
Transmission & vector: unknown
Geographical distribution: New Zealand (Aotearoa) and the United Kingdom

Nerine yellow stripe virus

Susceptible geophyte: Nerine sarniensis, Nerine bowdenii; (Alstroemeria caryophylla, Belamcanda chinensis, Dahlia pinnata, Lilium formosanum do not show signs of susceptibility).
Susceptible families: Amaryllidaceae, Chenopodiaceae, Solanaceae, Tetragoniaceae.
Symptoms: causes chlorotic streaking in N. sarniensis and chlorotic mosaic in N. bowdenii.
Transmission & vector: by aphids; transmitted by mechanical inoculation but not by contact between hosts.
Geographical distribution: the Netherlands and the United Kingdom.

Nothoscordum mosaic virus

Susceptible geophyte: Nothoscordum fragrans; (Allium cepa and Lilium formosanum do not show signs of susceptibility).
Susceptible families: Liliaceae
Symptoms: not listed from source, but probably leaf mosaic as the name implies.
Transmission & vector: unknown
Geographical distribution: the USA (Louisiana) and the Canary Islands

Ornithogalum mosaic virus

Susceptible geophyte: Ornithogalum thyrsoides, Ornithogalum spp. and hybrids, Lachenalia spp. and hybrids; (Iris germanica, Lilium longiflorum, Narcissus jonquilla, Nerine bowdenii do not show signs of susceptibility).
Susceptible families: Hyacinthaceae, Chenopodiaceae, Solanaceae, Tetragoniaceae.
Symptoms: Ornithogalum ssp. and hybrids show mottling of leaves and stems, flowers deformed. Lachenalia ssp. and hybrids show mosaic or mottling of leaves and flower stems, flowers deformed.
Transmission & vector: by aphids such as Myzus persicae and mechanical inoculation.
Geographical distribution: The virus occurs in the Netherlands, South Africa, and the USA.

Tuberose mild mosaic virus

Susceptible geophyte: Polianthes tuberosa
Susceptible families: Liliaceae
Symptoms: irregular foliar mottling
Transmission & vector: unknown
Geographical distribution: New Zealand (Aotearoa).

Tulip breaking virus

Susceptible geophyte: Calochortus, Fritillaria pudica, Lilium (cvs. Concorde, Sterling Star), Lilium formosanum, Lilium longiflorum, Ornithogalum thyrsoides, Tulipa spp., Tulipa hybrids, Zigadenus fremontii; (Allium cepa, Hippeastrum hybridum, Hyacinthus orientalis, Narcissus pseudonarcissus show no signs of susceptibility).
Susceptible families: Calochortaceae, Hyacinthaceae, Liliaceae, Melanthiaceae.
Symptoms: Tulipa ssp. and Darwin hybrids show colour-breaking of flowers and leaf chlorosis. Lilium ssp. and Mid-Century hybrids show leaf chlorosis and degeneration.
Transmission & vector: by aphids such as Myzus persicae, Aphis gossypii, Aphis fabae, Macrosiphum euphorbiae, Dysaphis tulipae, Aulocorthum circumflexum; non-persistent.
Geographical distribution: probably distributed worldwide.

Tulip chlorotic blotch virus

Susceptible geophyte: Tulipa ssp.
Susceptible families: Liliaceae, Amaranthaceae, Chenopodiaceae, Fabaceae-Papilionoideae, Solanaceae, Tetragoniaceae.
Symptoms: blotching or streaking of leaves in Tulipa spp; Flower break symptoms indistinguishable from those caused by tulip breaking virus. In other hosts, symptoms include systemic chlorotic mottle and chlorotic local lesions.
Transmission & vector: Virus is transmitted by mechanical inoculation.
Geographical distribution: Australia.

Tulip virus X

Susceptible geophyte: Tulipa spp., Lilium formosanum.
Susceptible families: Liliaceae, Amaranthaceae, Amaryllidaceae, Chenopodiaceae, Cucurbitaceae, Fabaceae-Papilionoideae, Solanaceae, Tetragoniaceae, Umbelliferae, Violaceae.
Symptoms: chlorotic or necrotic grey-brown streaking of leaves; streaks of intensified pigment (or of necrosis) in petals.
Transmission & vector: not transmitted by a vector; manual inoculation of tulips is only occasionally successful, thus spread by contact between plants may be rare; not by mechanical inoculation and probably not transmitted by contact between hosts.
Geographical distribution: unknown

Tropaeolum virus 1 & 2

Susceptible geophyte: Tropaeolum tuberosum
Susceptible families: Tropaeolaceae, Asteraceae, Solanaceae
Symptoms: leaf chlorosis
Transmission & vector: by aphids such as Myzus persicae; by mechanical inoculation; not by seeds. Tropaeolum viruses 1 and 2 frequently occur as a mixture = isanu mosaic virus in Tropaeolum tuberosum.
Geographical distribution: unknown

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