Hosta Diseases, Hosta Virus X, and Foliar Nematodes
About Common Hosta Diseases
Plant diseases or foliar nematodes are expensive, time consuming, and frustrating. Diseases and nematodes can spread fast and at times are impossible to cure once they are in your soil or plants. Be careful about the materials you put in your garden and practice good plant disease-prevention.
In our years in business, HostasDirect, Inc. has never had a report of selling a diseased plant. Sources of plant diseases vary by the disease and plant but include: nurseries (including online sources), amateur's selling or sharing plants, neighbors' yards, gift plants, contaminated soil added to your garden, infected shoes, tools or animals entering your gardens.
Starter Hostas (TC) and Advanced Starters are disease-free. They are tested for diseases before being grown in "clean room" laboratories and greenhouses.
Mature Division hostas were started as Starter (TC) or Advanced Starters, planted and grown in the ground in quality soil.
We monitor plants and growing locations regularly and practice preventative proceedures with sterilizing shoes and tools, watching our plants closely and being very careful with soil selection and contamination.
You can find a brief disease overview here. Hostas are low-maintenance and quite disease-free, but there is still a chance that a disease could enter your garden. Try to prevent any diseased plants, soils, or plant matter from entering your garden and promptly remove and destroy any suspicious plants. Hosta diseases or pests include: Fusarium, Anthracnose, Botrytis Leaf Spot, Foliar Nematodes, Sunscald/ Drought, Crown Rot– Southern Blight, and Hosta Virus X(HVX). See additional information below.
HOSTA VIRUS X (see new HVX research dated January 1, 2011 below)
Hosta Virus X in 'Striptease'. Note green lines in center of leaf.
Heavy HVX symptoms in 'Sum and Substance'. Note how green tissue is looking thin and wrinkled.
HVX-infected 'So Sweet' held to light to better see mottling.
'Gold Edger' with HVX. Note sunken, glaucous green areas.
'June' showing classic "inkbleed" symptoms along the veins.
'Blue Cadet' showing lighter "inkbleed" areas along veins.
Hosta Virus X: New Research and Information - January 1, 2011
Grace Anderson, MAg, UM Department of Plant Pathology recently completed her 23rd year as a Master Gardener in Hennepin County. She is a scientist in the Soybean Pathology Project at UMN and recently received the Master of Agriculture degree in Horticulture at the University of Minnesota. Conducting this research was one of the requirements for receiving this degree. The American Hosta Society, under the leadership of Cynthia Wilhoite (VP Genus Hosta, Indianapolis, Indiana) initiated an effort to obtain research-based, empirical data on the nature and transmission of the virus. Funds were obtained and the research effort was led by Dr. Ben Lockhart. Research experiments were designed to replicate the actions taken by gardeners and growers while maintaining and propagating hosta.
Hostas Virus X (HVX) is a plant virus in the Potexvirus group first identified in 1996 by Dr. Ben Lockhart a highly esteemed Plant Virologist working at the Department of Plant Pathology at the University of Minnesota, St. Paul Campus less than one mile from HostasDirect headquarters.
HVX is thought to be host specific and is not transmitted by traditional insect fungi, nematode vectors, seed or pollen. Hosta Virus X is transmitted mechanically through wounds created during propagation, transplanting, or sap to sap contact through dividing or trimming plants. Vegetative propagation of infected plants, whether by micro-propogation (tissue culture propogation) or division, will produce infected plants. Once a plant has HVX, there is no cure and it must be destroyed properly. HVX reduces plant vigor. It also destroys foliage appearance through leaf distortion, color bleeding, and necrosis. Symptoms of HVX vary among cultivars and may take years to surface.
1) Hosta virus X transmission was made during research experiements through the use of contaminated tools and by planting in soil containing pieces of infected plant material.
2) Infected plant materials kept in a refrigerator remained infective for more than 9 weeks. Fresh infected plant material was always infective. Soil with HVX infected plant debris and root material had the ability to infect for more than two years.
3) As long as tools, hands, and pots were intensely scrubbed well and not just soaked decontamination methods including:
a) household detergent (Dawn)
b) 70% alcohol solution
c) 10% household bleach solution
were effective at eliminating infectivity of the virus.
4) There was no difference in infectivity or speed of infectivity that was related to dosage of the virus isolated. A significant difference in the rate of infectivity was dependent on the stage of of the hosta's growing cycle. The HVX virus was most easily transmitted prior to flowering and when the plant was rapidly growing in the spring. Researchers were not able to transmit the virus while the plants were flowering in late summer/fall or dormant. 5) Researchers collected and mechanically transmitted 15 isolates of HVX. The success of transmission was not only dependent on mechanical injury but also the season of the plant's growing cycle in which the contact occurred.
6) Researchers were able to infect all hosta varieties tested under the proper conditions in the field, home garden or greenhouse. At this time, they believe all hostas are susceptible to the virus.
7) The best way to test for the virus is ELISA testing through Plant Disease Clinics and certified labs. The new rapid test strips are accurate, reliable, and portable. The strips can be used in the field or greenhouse and will work with leaf or root material.
HVX testing strips can be obtained from Agdia, Inc.
8) The best protection against HVX is to know whether the original sources of plants tests for HVX. Don't be afraid to ask your neighbor, non-profit, retail or wholesale source for this information.
Always thouroughly scrub and sterilize tools and pots and wash your hands after getting hosta sap on them.
Once you get foliar nematodes in your garden, they are difficult if not impossible to eradicate. Folair nematodes spread via water, rodents, pets, infected garden tools, and shoes.
Foliar nematodes, in particular Aphlenchoides fragariae, are capable of infecting hundreds of species of plants. However, once popular nemacite chemicals have been banned for years.
Symptoms: foliar nematode damage appears as brown streaks in tissue between veins towards the end of summer in northern USA and as early as late June in the southern USA. It is normal to see healthy tissue next to damaged tissue.
How to see nematodes: Although symptoms are visible by eye, to see the nematodes themselves may require a 10X lens. Tear a suspected leaf and place in a dish of water. After approximately 12-24 hours examine the water with the hand lens. The nematodes will look like little round worms.
Where foliar nematodes live: Unlike most plant pathogenic nematodes, foliar nematodes live in and feed upon the aerial portion of the plant. After eggs hatch, there are four larval stages prior to the mature adult stage. The entire life cycle can be completed in 2 to 4 weeks, and even sooner if temperatures are higher. An infected leaf will contain multiple generations of nematodes.
How are foliar nematodes spread? Water transports nematodes between plants. They move through the surface of the plant and enter the small gas exchange pores called the stomates. It is thus recommended the plants be well spaced to allow foliage to dry between waterings. Drip irrigation or watering close to the root system with a watering wand can help. However, nematodes are very tolerant of dry conditions and can remain viable for years in decaying plant material.
How to help prevent foliar nematodes:
1) inspect plants with a magnifying glasses as noted above before putting them in your garden.
2) consider growing plants in a separate area (quanantine them) for a year or two before placing them in your garden.
3) remove and destroy infected leaves during the season and during fall clean up.
4) use Insecticidal soap or Zero Tol (a concentrated solution of hybrogen peroxide - wear gloves, this can burn your skin).
5) soak infected plants in hot water (124 degrees F.) for up to 10 minutes, then plunge the plants back into cold (as cold as a faucet will chill) water. Do not leave plants in the cold bath for more than 5 minutes. It is best to provide this treatment as the plant breaks dormancy but remember that foliar nematodes can also survive in the soil.
An educational video shows and explains foliar nematodes as well as nematode treatment. A two part video.