The bald cypress tree (Taxodium distichum) is a popular landscape tree known for its graceful, feathery foliage and ability to thrive in wet conditions. However, bald cypress trees are susceptible to tobacco mosaic virus (TMV), a destructive pathogen that can severely impact the health and appearance of infected trees. Knowing how to properly identify, treat, and prevent TMV is crucial for protecting your bald cypress trees.
Understanding Tobacco Mosaic Virus
Tobacco mosaic virus is one of the most widespread and damaging viral plant diseases It affects over 350 plant species, including many ornamentals like bald cypress The virus is transmitted through contact between infected and healthy plants, contaminated tools and machinery, and infected plant debris.
Once a bald cypress tree is infected with TMV, the virus replicates and spreads within the plant’s vascular tissues, interfering with nutrient transport. This leads to a variety of symptoms, including:
- Mottled or mosaic patterns on the leaves
- Leaf distortion and curling
- Stunted growth
- Discolored foliage and needles
- Dieback of branches
If left unchecked, TMV can seriously weaken bald cypress trees, leaving them vulnerable to other health problems and potentially even death. Acting quickly to manage an infection is crucial.
Preventing TMV Infection
The old adage “an ounce of prevention is worth a pound of cure” certainly applies when dealing with tobacco mosaic virus on bald cypress trees. Here are some key prevention tips:
- Purchase disease-free nursery stock and quarantine new plants before introducing them into the landscape
- Disinfect tools after working with infected plants
- Remove and destroy infected plant debris
- Control insect pests that may spread TMV
- Wash hands thoroughly after contact with infected plants
Avoiding the introduction of TMV is much easier than trying to manage it after it has already infected your trees. Make prevention practices a regular part of your bald cypress care regimen.
Managing an Existing TMV Infection
If you suspect your bald cypress tree is infected with TMV, take action right away to limit its spread and impact. Here are some effective management strategies:
Remove infected plant parts: Prune out any branches, needles, or roots that show signs of infection. Bag and dispose of this debris far from your landscape to prevent further contamination.
Disinfect tools and equipment: Clean tools, machinery, and work surfaces with a 10% bleach solution after contact with infected plants to kill any lingering virus particles.
Improve soil drainage: TMV thrives in saturated soil. Improve drainage around infected trees through grading, tiling, or planting on berms or slopes.
Apply registered fungicides: Certain fungicides may help limit the spread of TMV within infected bald cypress trees. Always follow label directions.
Increase tree vigor: Keep trees as healthy as possible through proper fertilization, watering, and pest management to make them more resistant to the impacts of TMV.
By combining good sanitation practices, cultural methods, and chemical control, you can help manage tobacco mosaic virus in your bald cypress trees. However, eradication is very difficult once it becomes established.
Protecting Nearby Plants from Infection
Since TMV is highly contagious, it is critical to protect uninfected bald cypress trees and other landscape plants in the vicinity of infected trees. Here are some key measures to implement:
- Isolate infected trees from the rest of the landscape
- Wash hands, disinfect tools, and change clothing after working with infected trees
- Scout nearby plants frequently and remove any showing symptoms
- Apply insecticidal soap sprays to uninfected plants as a protective barrier
- Increase airflow and space plants adequately to slow spread
- Disinfect lawn mowers and other equipment used near infected trees
Vigilance and proper sanitation are essential for safeguarding the rest of your landscape when TMV strikes some of your bald cypress trees. Be sure to educate all gardeners and landscapers on best practices as well.
Replanting After TMV Infection
If tobacco mosaic virus leads to the death of your bald cypress tree, you will need to take care when replanting to avoid perpetuating the disease cycle. Here are some key tips:
- Remove the stump and root system of the infected tree
- Test the soil for the presence of TMV
- Solarize the site under clear plastic for at least 6 weeks to heat-treat soil pathogens
- Select TMV-resistant species when choosing a replacement tree
- Wait 1-2 years before replanting another bald cypress to allow pathogens to die out
With proper management, many landscapes recover fully from TMV infections. But be patient, and take all necessary precautions when replanting in the same location.
Using Best Practices to Safeguard Bald Cypress Trees
While tobacco mosaic virus poses a serious threat to treasured bald cypress trees, proper control measures can effectively protect your landscape specimens. Use extreme care when introducing new plants, and act swiftly when symptoms first emerge. Rely on prevention, sanitation, cultural practices, and chemical control as needed to manage TMV. And always monitor nearby plants closely to limit the spread of this stubborn pathogen. With vigilance and timely action, your beautiful bald cypress trees can continue gracing your landscape for years to come.
How to manage plant viruses in the greenhouse
Insect management is critical for managing tomato spotted wilt virus and impatiens necrotic spot virus, while sanitation is the critical management strategy for tobacco mosaic virus.
In Part 1 of this article, Michigan State University Extension reviewed the background about some of the most common viruses (tobacco mosaic virus, tomato spotted wilt virus and impatiens necrotic spot virus, Photos 1-3) that affect floriculture crops. Details of insect transmission of Tospoviruses were explained. The type of virus and its method of transmission impact the methods of management that should be implemented when a virus is detected on plants in a greenhouse.
Growers should inspect all incoming plant material for symptoms of viruses, including speckling, modeling, leaf curling, vein clearing, chlorosis and stunting. Unfortunately for growers, viruses can be present in plants that are asymptomatic or may not show symptoms for weeks after infection. If there is a known possibility of infected plant material coming into your facility, be extra vigilant when inspecting the plant material and randomly sample plants within each shipment and variety.
Growers can buy virus testing supplies for rapid in-house testing. This allows growers to easily test suspect material identified during scouting. Plants with ambiguous symptoms can yield a positive test result. Alternatively, samples can be sent to a local diagnostics lab, such as MSU Diagnostic Services. Continue to scout the plants during the crop cycle. If possible, quarantine the susceptible or suspicious plant material. If plants test positive for viruses, immediately throw them out as virus-infected plants cannot be cured.
When there is a virus present on plants in the greenhouse, sanitation of benches, floors, watering wands and any other equipment that may come in contact with plant material is critical. Be sure to remove all weeds under any benches in the greenhouse. The primary method of spread of tobacco mosaic virus is by plants touching each other or by hands carrying the virus after touching infected plants. It is critical that those who are touching the plants are regularly washing their hands with soap and water and after touching any suspicious plants or using tobacco products.
When sticking cuttings or transplanting plugs, make sure the plants are only touching non-permeable surfaces and regularly sanitize all surfaces the plants make contact. All employees sticking cuttings should regularly use an alcohol-based hand sanitizer. MSU Extension recommends using a fresh solution of the disinfectant; be sure that the active ingredient of the product is stable enough to remain active while using it throughout the day.
Soaking areas is likely to be more effective than a “spray” or “spritz” application. Some growers use diluted dry milk, which has been shown to be effective in disinfecting tools and surfaces. Spraying milk directly onto plants to prevent virus transmission has also been shown to be effective. To read more about research findings with using milk as a disinfectant, read “Can applying milk to tools or plants be effective in reducing virus transmission?” For more information on other sanitation strategies read, “Sanitation Strategies for Greenhouse Growers.”
When trying to manage an occurrence of Tospoviruses (e.g., tomato spotted wilt virus or impatiens necrotic spot virus), management of aphid, whitefly and thrip populations are critical. As discussed in Part 1, these viruses are readily spread by insects. Western flower thrips are one of the primary vectors of these viruses. For conventional control, MSU recommends the following products for thrips control:
- Aria
- Distance
- Hachi-Hachi (do not use on impatiens or New Guinea impatiens)
- Mesurol
- Orthene 97
- Overture
- Pedestal
- Pylon
- Sanmite
For more information on how to manage tomato spotted wilt virus or impatiens necrotic spot virus, visit “Impatiens Necrotic Spot Virus.” For more information on insecticide recommendations without using neonicotinoids, read “Greenhouse insect management without neonicotinoids.”
Insect control is not as critical in an outbreak of tobacco mosaic virus because insects are not the main vector of the virus. However, according to H.J. Walters, chewing insects like grasshoppers can vector tobacco mosaic virus, but those are not common in greenhouse production. Okada et al. reported that tobacco mosaic virus could be spread to non-infected plants by bumblebees after pollinating heavily infected plants. Also, if infected leaves have exposed sap or if insects break leaf hairs, aphids have been shown to be a possible vector of tobacco mosaic virus, but it is not a major method of spread.
For more information on tobacco mosaic virus, read “Tobacco Mosaic Virus of Tobacco” or “Tobacco mosaic virus.”
To learn more about tomato spotted wilt virus, tobacco mosaic virus, or impatiens necrotic spot virus on a greenhouse crop, please see Part 1 of this article, “Common types of viruses of floriculture crops and their modes of transmission.”
The author would like to thank Dave Smitley, Zsofia Szendrei and Jan Byrne for their reviews.
How to Tell Mosaic Virus Infection from Variegation with Live Plant Examples
FAQ
How to get rid of tobacco mosaic virus?
Can you save a plant from mosaic virus?
How can we control the tobacco mosaic virus?
How do I get rid of tobacco mosaic disease in my garden?
Insects such as aphids and leafhoppers serve as vectors for tobacco mosaic disease and viruses and many other plant diseases and plant viruses. You can help control them by using reflective mulch such as aluminum foil. Some weeds and perennial weeds may also serve as hosts for mosaic viruses, and they can transfer the virus to garden insects.
What is the tobacco mosaic virus (TMV)?
The Tobacco Mosaic Virus or TMV is the first plant virus ever identified. Although it wasn’t labeled as a virus until 1930, it has plagued tobacco farmers since the late 1800s to present. Despite its name, this “tobacco” virus can infect over 350 different plant species, many of which are favorites in home gardens such as tomatoes and potatoes.
What happens if a plant is infected with mosaic virus?
Plants and plant tissue infected with mosaic viruses may also develop deformities such as crinkled or mishappened leaves. Plants infected with this virus diseases also have trouble with plant growth resulting in stunted growth. In celery, mosaic plant disease can cause the downward curling of young petioles.
What is tobacco mosaic virus on Petunia?
Tobacco mosaic virus (TMV) on petunia. The basic life cycle of the virus is very much like the common cold. The virus can be passed from host to host or by mechanical transmission. Once the virus makes contact with a suitable host plant, it begins to replicate itself using the host plant’s cells.