By: Susan Albert, Freelance Garden Writer
Gladiolusis a classic, summer-blooming bulb/corm that many associate with grandma’shouse. The tall, vertical stems packed with colorful blooms are featured inmany cutting gardens for mid-summer bouquets. When issues like mosaic occur,this can naturally be alarming. Good cultural control can help prevent mosaicvirus in gladiolus.
Gladioli mosaic virus infects gladiolus as well as otherbulb plants, vegetables, field legumes and common weeds. Both beanyellow mosaic virus and cucumbermosaic virus are transmitted by aphids moving from plant to plant orthrough tools used to gather flowers and corms.
Mosaic virus produces mild symptoms unless a combination ofBYMV and CMV are transmitted, then symptoms are more severe. Symptoms ofgladiolus mosaic include a dark to light-green or yellow mottling of leavesthat are sometimes hard to see. Flowers may show a white variegation. Narrow-stripedbreak patterns also have been noted in flower coloration.
Infection by BYMV can reduce by one-third the number ofgladiolus corms produced. Also expect a shorter lifespan in gladiolus plantswith mosaic.
Unfortunately, there is no treatment or cure for mosaicvirus. The best method of control is to use stock that is tested virus free.
Gladiolus that is determined to be infected should beremoved and destroyed to prevent transmission of the virus to other susceptibleplants. Corms also can be infected during storage through aphid attacks.
The following methods of cultural control can help prevent widespread mosaic infection in healthy plants:
Practicing vigilance in the garden can help keep gladiolusand other susceptible plants free from mosaic virus.
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Fact Sheet Page: 729.30 Date: 10-1984
COOPERATIVE EXTENSION NEW YORK STATE CORNELL UNIVERSITY
by T. A. Zitter, Dept. of Plant Pathology, Cornell University and R. Provvidenti Dept. of Plant Pathology New York State Agricultural Experiment Station, Geneva
Major Bean Viruses
Bean common mosaic virus (BCMV) is still an important disease of beans worldwide, but is less of a problem in commercial bean varieties because many possess genes for resistance. The most common strains are the type virus known formerly as bean virus 1 (BV-1) and a New York strain (NY-15). Some, but not all, dry bean varieties are resistant to one or both strains (see table 1), whereas most snap bean varieties are resistant to both strains.
Typical symptoms in bean consist of green mosaic and downward cupping along the main vein of each leaflet (fig. 1). Green veinbanding, blistering, and malformation are common in leaves of the same plant (fig. 2). Plants are reduced in size, and pods may be mottled and malformed. These symptoms could be easily confused with those caused by cucumber mosaic virus (CMV). However, the BCM symptoms persist, whereas those caused by CMV are transitory. In some dry bean varieties (see table 1) resistance to mosaic is expressed as a hypersensitive reaction conferred by the I gene, leading to a condition called "black root." Infection with some strains causes root and stem discoloration, rapid wilt (systemic necrosis), and eventual death.
BCMV is seedborne in bean, especially if the seed was produced locally. The virus is rarely present in wild legumes. The virus is efficiently transmitted by several aphid species includin the following: bean aphid (Aphis fabae), cowpea aphid (Aphis craccivora), pea aphid (Acyrthosiphon pisum), potato aphid (Macrosiphum euphorbiae), and the green peach aphid (Myzas persicae).
BCMV is most effectively controlled by growing resistant cultivars and using virus-free seed.
Bean yellow mosaic virus (BYMV), also called bean virus 2 (BV-2), is the most widespread bean virus in New York State and can be found nearly every year. The symptoms of this disease may vary depending upon the variety, the virus strain, the stage of growth at the time of infection, and environmental factors.
BYM symptoms consist of leaf mosaic formed by contrasting yellow or green mosaic areas (fig. 3, 4). Pods are usually not affected, but the number of seeds per pod may be reduced.
Table 1. Reaction of selected dry bean varieties to two strains of bean common mosaic
Light Red Kidney (LRK)
Dark Red Kidney (DRK)
R = Resistant S = Susceptible. 1 Varieties that have exhibited hypersensitive "black root" reaction.
BYMV is not seedborne in beans, but may be in other legumes. The most common overwintering hosts include clovers, wild legumes, and certain flower crops such as gladiolus. The virus is spread in nature by the same aphid species that are mentioned under BCMV. Presently, only a few experimental lines and even tewer commercial varieties are resistant to BYMV, but more will be available in the future.
Cucumber mosaic virus (CMV) can infect almost 800 plant species, but only a specific strain can cause a disease of bean and certain other legumes. Symptoms consist of leaf curl, green mottle and blistering (fig. 5), and a zipperlike rugosity along the main veins. involving only a few leaves. Symptoms resemble those for BCMV as noted previously, but plants usually recover and resume normal growth.
CMV may be seedborne in some bean varieties but, more importantly, is overwintered in many weed species (chickweed, milkweed, purslane, and clover). The virus is transmitted by at least 60 aphid species.
Clover yellow vein virus (CYVV) was previously considered as the severe strain of BYMV because of many similarities in host range and symptom expression. However, this virus, in addition to causing a prominent yellow mosaic, malformation, and reduction in plant size (fig. 6). can induce pod distortion (fig. 7). In addition to infecting bean, this virus can be recovered from cucurbits, peas, wild violets, and many cultivated and wild legumes. As with all the major bean viruses, CYVV is aphid transmitted and is overwintered in legumes and some ornamentals like garden violet.
Tobacco and tomato ringspot viruses (TRSV and TmRSV) are often found infecting the crop at the same time. Initial symptoms are very prominent and consist of chlorotic ringspots, mottling, malformation, and necrosis. Plants recover from this severe stage, and later foliage may appear completely normal. These viruses are not seedborne in beans, but may be in other legumes. Unlike all other bean viruses, these viruses are spread by the nematode Xiphinema americanum, and the viruses can overwinter on many weed species in the state without expressing virus symptoms. Resistance is available in some bean varieties.
Alfalfa mosaic virus (AMV) can cause a disease of beans noted by scattered bright yellow dots on the leaves, which are characteristic for this virus when it infects other plants. AMV does not appear to reduce yield or quality of the product. The virus may be spread by many aphid species.
Soybean mosaic virus (SMV) induces symptoms closely resembling those caused by BCMV. Most leading commercial snap bean varieties are resistant to SMV, with only a restricted number showing susceptibility. SMV is spread by several aphid species, and the major source of infection is soybean, for this virus is commonly seedborne in that crop
Watermelon mosaic virus 2 (WMV-2) causes symptoms similar to those incited by some strains of BYMV. Most commercial snap bean varieties are resistant to WMV-2. The leading source of inoculum is some clover species. The virus is not known to be seedborne and is spread in nature by aphids.
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Mohammad Bazoobandi , . Mahmud-Reza Karimi-Shahri , in Saffron , 2020
Bacillus croci ( Mizusawa, 1923 ) and Burkholderia (pseudomonas) gladioli pv gladioli ( Xu and Ge, 1990 ) are among the most important saffron damaging bacterial agents.
Burkholderia gladioli (Pseudomonas gladioli) is the bacterial agent of soft rotting in saffron new buds and leaves that forms patches on saffron corms and leaves, reducing the flowering rate severely. This disease, reported from Italy (Sardinia), develops during the autumn before flowering, causing decaying of the thin white membrane (a protective layer of the leaves and flowers) of the saffron primary buds ( Fiori et al., 2011 ).
Fusarium Rot (fungus – Fusarium oxysporum f. sp. gladioli): Corms decay with a brownish-to-black dry rot of the tissue. The foliage of affected plants first turn yellow and then brown. Roots are killed. When diseased corms are planted, many may rot before producing plants while other produce weak plants that soon die. Before planting, inspect and remove all corms that have discolored areas or lesions. Healthy appearing corm should be chemically treated before planting.
Scab (bacterium – Pseudomonas marginalis): Small definitely outlined lesions appear on diseased corms. The lesions are circular, water-soaked and pinpoint to one-fourth inch diameter. A gummy ooze is produced from these spots that is yellow-to-dark brown in color. The lesions are rather shallow. Badly affected plants may die while those less affected have an unthrifty appearance. Mites that occur in the soil seem to serve as a vector and should be controlled with soil treatment if this disease is a problem. Do not plant infected corms. Rotate areas where gladiolus are planted.
Botrytis Blight (fungus – Botrytis spp.): Leaves, stems, flowers and corms are infected. Leaf spots are variable in size and shape. Infected flowers decline rapidly and have grayish fungal growth on the surface. The tissues become moist and slimy. Under severe conditions the entire top may be killed. Infected corms have irregularly shaped sclerotia attached to them. Affected corms should be discarded. Use suggested fungicides for controlling the disease on above-ground plant parts.
Other Leaf Spots (Bacterium-Bacterial Leaf Blight – Xanthomonas spp.): Water-soaked spots appear on leaves with a bacterial ooze occurring during wet periods. (Fungus – Septoria Leaf Spot – Septoria gladioli) Small rot. (Fungus – Stemphyllium Leaf Blight – Stemphyllium spp.) Light green-to-yellow lesions form on leaves. Spots turn red.
Virus or Virus-Like Diseases (Virus-Mild Mosaic): Caused by the bean yellow mosaic virus. Produces angular light and dark green mottling of leaves and flower stems. Virus is transmitted by aphids. (Mycoplasma – Aster Yellow) Flower parts remain green and fail to form normal color pigment. Plants turn yellow and degenerate prematurely. (Virus – White Break Mosaic) Caused by the cucumber mottle virus. Causes flowers to be blotched, open slowly and fade early. Plants are stunted. (Virus – Ring Spot) Caused by the tobacco ring-spot virus. Ring spots appear on leaves but flower parts are not affected.
Cause Bean yellow mosaic virus is spread by aphids. Transmission can also occur with tools used for harvesting flowers and corms. Beans and other legumes are susceptible. The virus can overwinter in perennial legumes such as alfalfa, clovers or vetch. Almost all gladiolus cultivars are infected and should not be planted close to beans or other legume crops. Mixed infections with Cucumber mosaic virus produce more severe symptoms.
Symptoms Generally symptomless or with mild symptoms. Slight dark-to-light-green mottling of leaves, often difficult to detect, early in the summer. Flowers show a variegated white mottling. Also described as faint, inconspicuous pencil-striped break patterns that are lighter in color than the normal flower color. High temperature conditions can mask symptom expression.