The following tools and techniques are meant to provide some examples of organic pest management (IPM) tactics for Colorado potato beetle (scientific name Leptinotarsa decemlineata) using the “Four T” method.
Our target for the Colorado potato beetle (CPB) changes. The adults are the first (1st) to emerge from their overwinter places. The second (2nd) target will be the eggs that are laid by the female adult Colorado potato beetles. The third (3rd) target will be the young larvae that emerge from the eggs that are most vulnerable to treatments.
General calendar time: adults emerge between late April and late May (in Minnesota)
Biofix: When eggs are first scouted
Degree days: For CPB, the emphasis is on taking action when the larvae are young and vulnerable. Degree days for Colorado potato beetle are counted as soon as the eggs are first observed. 1st instar larva @ 185 DD, 2nd instar larva @ 240 DD, 3rd instar larva @ 300 DD, 4th instar larva @ 400 DD, Pupation occurs @ 675 DD
Tool #1: Yellow sticky cards (Type of tool: Mechanical/Monitoring)
For all-sized plots: Place yellow sticky cards at regular intervals. around perimeter and within plot area at at least one day before earliest expected emergence. Note: Yellow sticky cards are not as effective for trapping larger insects like CPB as they are for trapping smaller insects, but the point here is to trap a few so that you know when CPB is emerging. Suggested placements:
- For a very small (12×12 sq. ft. or less) plot, place at least one trap at each corner, and one or two within the plot to monitor for CPB.
- For a small (18×18 sq. ft or less) plot, place one trap every six feet around the perimeter of the plot and at least three to four at selected intervals within the plot to monitor adult CPB.
- For a moderate (24×24 sq. ft.) plot, place one trap every six feet around the perimeter of the plot and place additional sticky traps within the plot area to monitor for adult CPB.
Tool #2: Plant a “trap crop” (Type of tool: Cultural)
Plant a trap crop that is more attractive to CPB than potatoes, such as the elongated Italian or Japanese eggplant, ‘Vittoria’. This particular variety has been determined to be preferred by CPB, and when used as a perimeter trap crop, may discourage If either of these are a problem on your eggplant or your tomato, using Vittoria. Border trap crop plants can be sprayed with a one-time treatment of azadirachtin (neem oil) or rotenone/pyrethrin spray when CPB arrives to provide initial interference or knockdown of adults. You may, if you like, use a propane torch to “flame” the CPB adults on the trap crop OR if the adults are numerous enough you may elect to apply a one-time treatment of a botanical insecticide with a short half-life / approved for organic production) such as Pyganic to effectively knock down their numbers on the trap crops.
Tool #3: Release the egg parasitic wasp Edovum puttleri (Type of tool: Biological control)
The parasitic wasp species Edovum puttleri is a commercially available parasitic wasp that lays its eggs inside of CPB eggs. Release them between one and two weeks after observing your first Colorado potato beetle adult. Ideally, the ambient average daily temperature should reach at least 62-65 degrees and night time temperatures should not fall below 50 degrees for more than a couple hours overnight for the parasitic wasps to do well after they are released.
Apply Bt or Beauvaria bassiana on (Type of tool: Bio-chemical)
If you are able to suppress a certain number of adults, reduce their egg lay, then the next thing to do is to apply a biological insecticide such as Bt or Beauvaria bassiana. These formulations, when ingested by young larvae, will kill them as they ingest plant material that has the Bt enzymes or the Beavaria bassiana spores.
Tool #4: Use row cover material to protect crops
Row cover material may be time intensive to setup, take down, and store, but its effectiveness is guaranteed to protect against Colorado potato beetles is guaranteed.. In addition to protection from insects, row covers may also provide additional protection from sun/wind exposure, heavy rains, hail, and other weather-related pressures.
Technique for tool #1 (Type of tool: Material / yellow sticky cards)
Attach yellow sticky cards on long (eight to 10-inch wooden craft/popsicle sticks) using hot glue gun. Place the yellow sticky card at least three-to six inches from the plants you intend to monitor. Place at least 3 to four inches of the stick into the soil so that the stick is firm in the ground and not easily blown away. Press down around the stick so that it remains firm in the ground.
Technique for tool #2 (Type of Tool: Cultural + Chemical / botanical insecticide)
Plant a trap crop that is more attractive to CPB than potatoes, such as the elongated Italian or Japanese eggplant, ‘Vittoria’. This particular variety has been determined to be preferred by CPB, and when used as a perimeter trap crop, may discourage If either of these are a problem on your eggplant or your tomato, using Vittoria as a PTC may help, although results are not yet conclusive. Border plants can be sprayed with a one-time treatment of azadirachtin (neem oil) or rotenone/pyrethrin spray when CPB arrives to provide initial interference or knockdown of adults.
Technique for tool #3 (Type of tool: Chemical / bio-insecticide)
Apply Bt and/or Beauvaria bassiana formulations under the leaves or where the eggs are laid. One general rule is that when 20-30% of eggs have hatched (make sure to crush eggs that you see when you monitor!) that you spray
Technique for tool #4:
Use row covers in conjunction with any of the other three tools (or all four) to maintain protection and protect plants from plant-feeding insects.
Control measures outside of the season
Preserve habitat such as around your growing area so that beneficial insects that may feed on adult CPB might have something to eat. Consider releasing beneficial nematodes in the soil ares where you think the CPB are overwintering.
For more information
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