Vegetable Production Update-April 13, 2018

— Written By

From Dr. Amanda Strayer-Scherer (Postdoctoral Research Scholar, Plant Pathology, Tomatoes) and Inga Meadows (Extension Associate, Plant Pathology Specialist)

Background: The information presented in this vegetable production update contains a summary of the details discussed in the one-hour, biweekly vegetable production conference calls entitled Veggie Calls. These open forum sessions were developed to allow extension personnel (agents, area specialized agents [ASAs], and specialists) to discuss challenging cases, seek advice on recommendations, report emerging issues, and share training opportunities related to vegetable production. These calls are hosted by Inga Meadows, Dr. Amanda Strayer-Scherer, and/or Dr. Lina Quesada-Ocampo every two weeks throughout the vegetable production season.

Attendees (description) of the April 13th Veggie Call: Shawn Banks (County Extension Director, Carteret County), Hannah Bundy (Extension Agent, Rutherford County), Kira Chaloupka (Extension Agent, Davidson County), Minda Daughtry (Extension Agent, Lee County), Chris Leek (NCDA Agronomist), Brad Hardison (Extension Agent, Sampson County), Bruce McLean (Extension Agent, Bladen County), Inga Meadows (Extension Associate, Plant Pathology Specialist), Laura Oliver (County Extension Director, Martin County), and Amanda Scherer (Postdoctoral Research Scholar, Plant Pathology).

Vegetable Production Updates: Overall, there was not a lot to report for this Veggie Call as the weather is still cool and it is still early in the season.

  1. Report of Timber rot (also known as white mold and Sclerotinia stem rot), caused by Sclerotinia sclerotiorum, on tomatoes in a greenhouse in Lee county. The agent reported some cracking, but symptoms were not severe.
  2. Report of Rhizoctonia solani on greenhouse tomatoes in Bladen County.
  3. Report of aphids on cucumbers in Lee county. The producer and extension agent are trying to develop a management plan involving a systemic insecticide such as Admire Pro or similar. Admire Pro also provides control against leaf hoppers and thrips in addition to aphids.
  4. Although not a vegetable production problem, report of a reduction in flowering and a loss of bees has been reported in strawberry production in Lee county.

Pest News and other Announcements:

  1. Inga Meadows (Extension Associate, Plant Pathology Specialist): Explained to the group that we plan to publish summaries of the “Veggie Calls” with important pest information in the NC State University Extension Pest News and will keep track of the names of the attendees to give them credit in the published summaries. These published summaries will be accessible to vegetable producers, ASAs, county extension agents, extension specialists, and researchers with an interest in North Carolina’s vegetable production industry.
  2. Amanda Strayer-Scherer (Postdoctoral Research Scholar, Plant Pathology): Amanda is a new postdoctoral research scholar with Inga Meadows at the Mountain Research Station in Waynesville, NC. Part of her research is to look at the pesticide sensitivities of the bacterial spot and early blight of tomato pathogens.
    1. For bacterial spot, they are focusing on tomato transplant producers and are asking for help from extension agent in collecting greenhouse tomato samples with bacterial spot symptoms.
    2. For early blight, they are focusing efforts on collecting tomato samples with early blight symptoms from commercial fields in North Carolina.
    3. These samples will help provide us with valuable information on how to better advise growers in North Carolina to manage these two diseases. If you are interested or available to help them with this project, then they can send shipping labels and simple instructions for collecting samples. Please contact Amanda (alstraye@ncsu.edu) or Inga (inga_meadows@ncsu.edu) for more information.

Additional Information on the Vegetable Plant Pathogens Mentioned in this Vegetable Production Update: 

  1. Timber rot (also known as white mold and Sclerotinia stem rot) is caused by Sclerotinia sclerotiorum and can be a problem on tomato under cool, moist conditions (59-70 °F). Timber rot causes loss of plant vigor, wilting, and eventual death of the plant.
    1. Symptoms: Infection begins in leaf axils or in stem joints where slower petals fall off, which results in the development of water-soaked areas. Stems will then become infected, soft and turn a bleached, white gray. Infected fruit are gray and develop a watery rot.
    2. Signs: Sclerotia inside the stem and around the calyx, and white, cottony mycelium on diseased stems.
    3. Management: Preventative application of appropriate fungicides (i.e. Priaxor and Cabrio EG; see label for details) is key. Application of a broad-spectrum fumigant can be effective in destroying sclerotia in the soil. Manage crop growth to prevent formation of a dense canopy and deep plowing to burry sclerotia.
    4. Resources:
      1. Jones, J. B., Zitter, T. A., Momol, T. M., and Miller, S. A. (Eds.). 2014. Compendium of tomato diseases and pests(pp. 48-49). St. Paul, MN: APS press.
      2. Miller, S. A. 2016. White Mold/Timber Rot Management in Tomato High Tunners. Retrieved on April 16th, 2018 from https://u.osu.edu/miller.769/2016/06/22/white-moldtimber-rot-management-in-tomato-high-tunnels/
  2. Rhizoctonia Diseases of Tomato are caused by Rhizoctonia solani and include damping-off, root rot, basal stem rot, stem canker, and fruit rot. In young tomato seedlings, pre- and postemergence damping-off can occur in both greenhouse and field plantings. R. solani is a common soil inhabitant and survives as actively growing or resting mycelium and sometimes as sclerotia.
    1. Symptoms: Before emergence, R. solani kills the growing tips of the seedlings which causes them to rot. Germinating seedlings display tan to reddish brown lesions. After emergence, R. solani infection causes lesions to form near the soil line that are brown, reddish brown, or black in color. Young stems become constricted and soft causing the plant to fall over and die. Under certain conditions, older seedlings or older, mature plants may also display symptoms.
    2. Signs: Mycelium can be seen in the soil. When observed microscopically, mycelium is hyaline or light tan and have right angle branching. 
    3. Management: Seed should be treated with a fungicide or fungicide mixture to control R. solani. Tomatoes that are grown under optimal temperature, moisture, and nutritional conditions are less susceptible to the disease. In the greenhouse, planting media should be sterilized. In field plantings, the soil should be fumigated with a broad-spectrum fumigant.
    4. Resources: 
      1. Jones, J. B., Zitter, T. A., Momol, T. M., and Miller, S. A. (Eds.). 2014. Compendium of tomato diseases and pests(pp. 39-40). St. Paul, MN: APS press.
      2. Mila, M., Gutierrez, W. A., Shew, H. D. 2010. Rhizoctonia Diseases in Tobacco Greenhouses. North Carolina State University. Plant Disease Fact Sheets. Retrieved on April 19th, 2018 from https://projects.ncsu.edu/cals/plantpath/extension/clinic/fact_sheets/index.php?do=disease&id=20