Implement an IPM strategy to limit the damage of plant pathogens

With the temperatures we experienced during winter, what was the fate of plant pathogens? Follow these integrated pest management (IPM) tactics to limit plant diseases.

Plant pathogens can be naturally occurring in the soil or be introduced inadvertently on seed, tubers or transplants. For pathogens that are introduced in seed or propagative material, management strategies should focus on preventing the introduction of these pathogens into the greenhouse or field.

Plant pathogens that thrive, reside and overwinter in the soil are commonly called soilborne pathogens. They can form resting structures that are resilient to the cold temperatures and can survive cold winters. Many of these pathogens can survive in the soil for several years and can be a challenge to manage. Some examples of soilborne pathogens that occur in Michigan are presented in the table below.

Examples of soilborne pathogens

Type

Examples

Bacteria

Streptomyces scabies causes potato common scab.

Pectobacterium carotovorum causes soft rot in potato.

 

Fungi

Several Fusarium spp. cause wilts, crown and root rot in many crops.

Verticillium dahliae causes wilt in cucurbits, Solanaceous and cole crops.

Rhizoctonia solani wire stem in cole crops.

Oomycetes
(watermolds, fungal-like)

 

Several Pythium spp. cause damping off and root rot in many crops.

Several Phytophthora spp. cause fruit, crown and root rot in many crops.

Michigan State University Extension advises growers to implement an integrated pest management (IPM) strategy to limit the damage pathogens can cause.

Effective disease management requires implementing the following IPM tactics:

  • Reduce the risk of introducing pathogens into fields by using certified seed and disease-free transplants (learn to recognize diseases on vegetable transplants in the greenhouse).
  • Use pathogen-free irrigation water and avoid overwatering (see irrigation and disease management).
  • Work fields with diagnosed soilborne diseases last to avoid moving soil particles that carry pathogen propagules from problematic fields to clean fields.
  • Select well-drained sites.
  • Get an accurate disease diagnosis (see a checklist for submitting samples to diagnostic lab) as one is required to implement effective management. Control strategies differ by pathogen as fungicides are often specific to a particular type of pathogen.
  • Keep records of the soilborne pathogens diagnosed in each field.
  • Rotate crops and avoid crops susceptible to the pathogens confirmed in each field.
  • Select crop varieties with resistance to problematic pathogens when available.
  • Power wash equipment to avoid moving pathogen propagules among fields.
  • During the season, monitor and scout fields to detect symptoms early, practice sanitation and, when needed, rogue diseased plants.

The author would like to thank Martin Chilvers, Willie Kirk and Mary Hausbeck for their reviews.

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