Plant Propagation

Biocontrol for Plant Propagation (cuttings, seedlings)

Plant propagators are tasked with the difficult job of producing large numbers of high-quality young plants for the pickiest of customers (other growers). For many years, pest control for these crops has been all about producing “clean plants.”

A “clean plant” used to mean that pests and diseases could not be detected, but another meaning is being added to the phrase “clean plants.” The idea that a ‘clean plant’ can be produced and protected, without pesticide residues is increasing in popularity.

Increasingly, growers of finished plants are requesting young plants that have been protected with biological control agents as the primary means of defense. These growers have learned first-hand the many benefits of biocontrol, and receiving residue-free plants, allows their pest control program to function without incident.

Strategy

Seedlings and unrooted cuttings are very susceptible to pests and diseases. As a result, propagators use a pro-active approach with biocontrol agents. Instead of trying to establish a population of predators and parasites, mass-releases are done periodically to eliminate the first pests and ‘stop them dead in their tracks.’

The choice of a biocontrol agent is dependent upon the growing system – plants rooted under mist/plastic or trays germinated in growth chambers are treated with pest-killing nematodes, then inoculated with

‘regular’ (see table below) biocontrol agents after the moisture is reduced. Growing systems not using a lot of moisture, should inoculate their plants with ‘regular’ (see table below) biocontrol agents right away. The propagation phase of the plant’s life is quite short and this guide is specific for this phase. It is not a ‘stand-alone’ program. It is critical that the recipient of the ‘clean’ plant, initiate their own pest control program immediately.

Pests

Fungus Gnat: Release Stratiolaelaps scimitus (Hypoaspis miles) preventively onto newly sown or newly-planted/transplanted pots, plug trays etc. Apply to all ‘dry’ crops or after crop has finished ‘wet’ phase. Usually one application is all that is needed.

For ‘wet’ growing systems, apply the nematode Steinernema feltiae and then place plants under mist/plastic. It is possible to apply nematodes during and after this phase too. Check with your Beneficial Insectary representative.

Shore Fly: Dalotia coriaria (Atheta coriaria) is a beetle that devours all stages of immature shore fly. Apply to all ‘dry’ crops or after crop has finished ‘wet’ phase. Usually one application is all that is needed.

For ‘wet’ growing systems, apply the nematode Steinernema carpocapsae and then place plants under mist/plastic. It is possible to apply nematodes during and after this phase too. Check with your Beneficial Insectary representative.

Thrips: For all “dry crops” release Neoseiulus cucumeris preventively. Release Orius insidiosus on hot-spots. For ‘wet’ crops, apply Steinernema feltaie.

Spider Mite: For all “dry crops” release Phytoseiulus persimilis upon detection of spider mite. Apply this biocontrol agent to hot-spots or throughout the crop in what is called a ‘blanket’ treatment.

Whitefly: For all “dry crops” apply the parasites Encarsia formosa and/or Eretmocerus eremicus. These parasites attack the young stages of whitefly and not adults.

Aphid: For all “dry crops” make preventive releases of multiple aphid parasites weekly. The parasite mix products are designed to be used when the species of aphid is unknown. Release Chrysoperla rufilabris (Green lacewing) on hot spots

Note, the above is intended as a guideline and is not a written recommendation.