Scouting And Preventative Measures For Tobacco Mosaic Virus (TMV) On Petunia

Dümmen is informing customers of a potential risk of tobacco mosaic virus (TMV) infected petunia cuttings from its Red Fox El Salvador farm for cuttings shipped in weeks 51 to 7.

“The nature and spread of this virus has led us to no longer be confident in the complete containment of this pathogen within our petunia production in El Salvador,” a letter from the company says. As a result, starting week 8, 100 percent of Dümmen petunia cutting shipments will be sourced from stock locations in either Ethiopia or Israel.

Here is the advice Dümmen shared with its customers on scouting and preventative measures for dealing with TMV on petunia if growers continue with product shipped in the time period mentioned above:

Scouting

For those of you who have received cutting shipments from us already, we [Dümmen] ask you to continue to be vigilant in your scouting. Symptoms induced by tobacco mosaic virus (TMV) are somewhat dependent on the host plant, as well as the variety. It can be expressed in a variety of different ways, including: mosaic, mottling, necrosis, stunting, leaf curling and yellowing of plant tissues. The following symptoms have been observed in petunia.

Scouting petunia for TMV

 

Testing 

Suspect symptoms should be tested to confirm potential infection and avoid misdiagnosis. Should you find suspect plant material, we are equipped at our corporate office to conduct a rapid test for pathogen presence. It is our preference that growers submit samples to the below address so we can ensure the fastest turnaround possible, however samples can also be submitted to your diagnostic lab of choice.

How To Ship Samples:

  • Do not allow specimens to dry out or get too hot.
  • Send specimens as soon as possible after collecting. Refrigerate any specimens that cannot be shipped immediately.
  • Samples that might break down quickly should be shipped by an express mail service.

Ship to Address (United States):
Dümmen North America
Attn: Dr. Kate Santos
5544 Hilliard Rome Office Park
Hilliard, Ohio 43026

Ship to Address (Canada)*:
University of Guelph
Laboratory Services
95 Stone Road West
Guelph, ON N1H 8J7
*Sample submission form is required for Canada shipments.

Minimize Transmission

By not pinching/shearing a petunia or a Confetti combination containing petunia during the propagation or finished stages, you will minimize the chance for pathogen spread.

Petunia and Confetti growth can alternatively be controlled in the following ways:

  • High light, cool growing and high fertility with low phosphorous fertilizers
  • Apply B-Nine and Florel (2500 ppm and 300 to 500 ppm respectively) about two weeks after sticking when cuttings are rooted.
  • At around three weeks after transplant, Confetti with Aloha calibrachoa (NOT Aloha Kona) respond well to a 1.0 ppm Bonzi, Paczol or Piccolo (paclobutrzol) drench
  • A late drench of 0.5 to 1.0 ppm Bonzi, Paczol or Piccolo (paclobutrzol) when plant has reached saleable size improves plant form. Use drench volumes appropriate for container size.

Transplanting

  • Step 1: Before loading plant material for transplant, scout for symptomatic plants.
  • Step 2: If a symptomatic plant is found, place a label or stake in the suspicious plant.
  • Step 3: Spray milk solution on all liners.
    • 10% non-fat dry milk solution (Wt/vol) just before uploading for transplant.
    • This spray will inactivate any surface or exposed TMV virus and prevent spread to uninfected plant material.
  • Step 4: Load all trays without markers for transplant while liners are still wet. The effectiveness of milk is lost when it dries.
  • Step 5: Discard/destroy marked trays. Follow protocol below.
  • Step 6: Contact your Dümmen representative and we will issue you a credit for the destroyed amount of cuttings.

Disposal And Disinfection

The TMV virus is only spread mechanically (by hands, clothing and plant-to-plant contact) therefore, it is important that you use caution when removing and destroying infected varieties at your facility.

  • Step 1: Isolate infected plants.
  • Step 2: Do not contact other plants in the area (particularly other petunia, calibrachoa, verbena and impatiens).
  • Step 3: Discard the infected plants and all associated plastic, tags, plant and soil into plastic garbage bags in the greenhouse, at the point where they are on the bench.
    • Have one worker hold the plastic garbage bag open for a second worker and to discard the materials into the bag.
    • Workers should wear disposable plastic gloves when placing the materials into the plastic garbage bag and the gloves should be discarded afterward.
  • Step 4: Carry sealed bags with infected plants out of the aisles and discard well outside the crop area. Do this work at the end of the working day. Those individuals carrying out this task should not work in any other area of the greenhouse for the remainder of the day.

Any greenhouse area with possible infected plants should be washed with the label rate of trisodium phosphate solution to remove any possible virus contamination. Tools that could have come into contact with infected liners or plants should be washed thoroughly with hot, soapy water containing a dish detergent. Those tools can be surface disinfected with a solution of 1 percent Virkon S, 20 percent NFDM (Nonfat dry milk) plus wetting agent, or a 1:10 bleach solution, as long as it is freshly made and not reused.

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