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Greenhouse Updates: Jan 20, 2016

Biological Control - Getting Started
January 20, 2016

Ask your plant supplier what specific pesticides were applied to your incoming plant material to ensure that no long lasting pesticide residues adversely impact the biological control agents.
 
One week before opening a greenhouse,  order beneficial nematodes, Steinernema feltiae, (Nemasys, Nemashield, Scanmask) for fungus gnats; Steinernema carpocapsae  (Millenium) for shore flies;  Stratiolaelaps scimitus (formerly  Hypoaspis miles) for fungus gnat larvae and  thrips pupae;  Dalotia (Atheta) coriaria  for fungus gnats, shore flies, and thrips in the growing media; and Neoseiulus (Amblyseius) cucumeris  for thrips larvae.

When your order arrives, open up the package immediately to inspect their quality. See “Grower Guide: Quality Assurance of Biocontrol Products”: http://vinelandresearch.com/sites/default/files/grower_guide_pdf_final.pdf.

Scott Creary, Biocontrol specialist spoke on The Art of Releasing Biocontrols at our recent Biological Control Program on Jan. 12.  Quality control is important at the time of releasing. Shipping is stressful and you are receiving fragile, starving creatures so do not place them in the refrigerator, which is too cool and dry (except for beneficial nematodes).    Nematodes can be stored in a dedicated refrigerator so the temperature is constant (38-42°F).

Upon arrival, check to see that the cold packs are still cold. Write the arrival dates on the outside of all materials.  Keep the predatory mites and rove beetles at cool at room temperature and use the same day.

Nematodes are best applied either late in the afternoon or on a cloudy day. Remove the nematode package from refrigerator and allow the nematodes to warm up a little before mixing with water. Nematodes can be applied with a dosatron set at 1 to 100 ppm (to deliver 100 gallons final solution). Remove the filters to prevent clogging. The hose nozzle should have large openings so the nematodes can move freely through this opening.  Wet the plant leaves and media as much as possible during application.  Some growers drench greenhouse floors with the nematode solutions.

Plant material that is unrooted, can be stuck into trays, then watered in with the nematodes. Pots that are filled with media and will be transplanted the next day or two can also be watered in with the nematode solutions.  Two applications spaced 2 weeks apart usually provide 6 weeks of protection.  Beneficial nematodes can also be applied with Trichoderma (RootShield or Rootshield Plus). Hydrogen dioxide (XeroTol) and fertilizer solutions are not compatible with the beneficial nematodes and need to be applied separately.  

Stratiolaelaps scimitus (Hypoaspis miles) is applied once during seeding or sticking. S. scimitus are very mobile and will colonize the surface of the growing media. They come in a tube of vermiculite-peat. Sprinkle across the treated area so they are evenly distributed.  Re-reapply  when transplanting or repotting.

Dalotia (Atheta) coriaria  only needs to be  applied once during seeding or sticking cuttings. The nocturnal rove beetles are easily established in greenhouses. All three stages of the rove beetle  (egg, larva and adult) are present in the vermiculite-peat carrier.  Open the container to sprinkle them evenly across the area to be treated.

Neoseilus (Amblyseius) cucumeris is available loose in a tube of bran or as mini-sachet packets.  N. cucumeris can be applied by gently sprinkling (broadcasting) the loose mites over the unrooted and rooted plant trays. They can also be placed in a small pile (about a teaspoon) of loose mites in the middle of each plug tray.  Inspect a small sample under the microscope to be sure the predatory N. cucumeris are active. Sometimes, growers confuse the larger white bran mites, which are used as a food source, for the beneficial N. cucumeris.   If you are using the mini- sachets, the new formulation of packets on sticks works well for plug trays. Neoseiulus should be reapplied when transplanting or repotting.

When using the mini-sachets for hanging baskets, place them in the plant canopy, where they will stay more shaded so there is more relative humidity.  If placed on the side of the hanging basket, with the added sunlight and heat, the relative humidity is too low, so the predatory mites do not reproduce or survive as well.   Sachets placed on the side of the hanging baskets can easily fall off the baskets, too.

As each new shipment of plant material arrives, follow this same procedure.  Keep the packing slips and write down where and when you release the biological control agents or have a separate scouting form to do this.

Tina Smith, UMass Extension and Leanne Pundt, UConn Extension

Resources

Selecting a Supplier, UConn Extension

Beneficial Nematodes: An Easy Way to Begin Using Biological Control in the Greenhouse, UConn Extension
Biological Control of Western Flower Thrips, UConn Extension
Biological Control of Fungus Gnats, UConn Extension
Biological Controls for Greenhouse Pests, UConn Extension

Biological Control: Using Beneficial Nematodes, UMass Extension
Scheduling Biologicals, UMass Extension and D&D Farms

Handouts and Presentations from program held Jan 12, Biological Control in Greenhouses