Date: 01/29/2026

Authors: Olivia Lake- Koppert Biological Systems and Dave Jones -Sr. Agricultural Scientist, Ocean Spray Cranberry

Reviewed by: PJ. Liesch and Allison Jonjak

Flea Beetle Control in WI Cranberry

Storage and Guidelines for Nematode Products

When your nematodes arrive, immediately take the nematode boxes out of the shipping container and refrigerate at 36-42F.
Store in a well-ventilated refrigerator/cold room.
Freezing will kill the nematodes – do not place the boxes too close to the back or top of a fridge as freezing can occur in some units, particularly if they are already filled with other items.
Store the product in the original box, away from direct sunlight. Do not remove the plastic bags from the box, and do not remove powder from the individual bags prior to application day.
If the above guidelines are followed, the shelf life is 12 weeks.

Application for Flea Beetle

A season total rate of 1.5 billion Steinernema carpocapsae nematodes per acre is recommended for full control.
This 1.5 billion season total rate will need to be divided into 2-4 applications in the month of June. Consult your Crop Scout, Agricultural Scientist, and/or Koppert Representative to discuss timing of application.
4 separate 375 million/acre applications (total of 1.5 billion/acre total) are strongly recommended for the 2026 calendar year. These applications should be timed weekly in starting the first week of June. (Timing example: June 6^th, 13^th, 20^th and 27^th)
- If three applications are used, an application at 500 million/acre the last three weeks of June is recommended.
- If two applications are used, two applications of 750 million/acre on the 2^nd and 4^th week of June are recommended.
- Anything other than 4 weekly applications at 375 million/acre in June should be viewed as experimental in 2026 and carries efficacy risk.

Avoid sprayers fitted with piston or centrifugal pumps.
Maximum pressure is 290 psi.
Remove all pump and nozzle screens, especially if finer than 50 mesh.
Nematodes can be mixed with many crop protection products, please check the compatibility with your local Koppert Rep.

Pre-irrigation and keeping beds moist prior to application will increase nematode efficacy. Turn sprinklers on 15-30 minutes before the boom application begins.
Nematodes are UV light sensitive, do not apply in direct/intense sunlight.
The recommended time to apply nematodes is at dusk or dawn when the UV index is low or when there is no sunlight.

You will need a clean 5-gallon bucket and a mixing utensil/device. (A paint stirrer attached to a drill set to the lowest speed is recommended for mixing based on previous grower experience.)
Get your spray tank filled with water and ready prior to prepping nematode mixture in a separate bucket. Temperature of tank water should not be above 77F.
Take nematodes out of cold storage when you are ready to use them.
Fill the clean bucket with at least 2-3 gallons of water.
Cut open packets and slowly pour nematodes into the water.
Start stirring/mixing them slowly until the powder is completely dissolved and no clumps are visible in the solution.
It is important to keep the nematodes in suspension and in motion to avoid them sinking to the bottom and suffocating.
Nematodes will need to be used immediately after mixing with the water and should NEVER be stored for any length of time in the bucket after mixing.
Once the nematodes are mixed, dump the bucket into the prepared spray tank.
Immediately begin your spray application at standard boom operating speed and pressure for conventional pesticide applications.

Keep the sprinklers that you turned on 15-30 minutes prior to the application running during the boom application.
Make sure your agitator is running as this will ensure that nematodes do not sink to the bottom of the tank and get applied unevenly.
Pause at the beginning of each bed when you turn the boom on and bring it up to pressure to make sure that the solution containing nematodes is actively flowing through the nozzles PRIOR to moving the boom forward and running the length of the bed.
Nematodes will not travel a long distance within a season from where they are applied, so avoiding skips at the ends of beds is critical for avoiding spotty flea beetle emergence in areas where application was missed.
Applying the total allocation in more than one pass around the bed helps to ensure that no areas are missed. Some growers do this by adding 2x the water they would normally apply to a bed to the tank and then applying the weekly nematode allocation by driving around each bed twice rather than once.

Continue to irrigate beds after spray application for at least one hour to ensure nematodes are washed into the soil. Nematodes that are not washed into the soil after application will die if exposed to drying and UV light.
Time to relax, millions of nematodes have started hunting pests in your beds!