This post is Part 2/3 of the series. Today we will be discussing what preventative actions you can take to reduce the risk of thrips outbreak.
Where do thrips come from?
Thrips are known to infest a range of different plants and can come from several different sources. There is a common saying, if you’ve got a plant there’s probably a thrips that loves it. Below we’ve discussed the most common entry points for thrips in greenhouses.
Cuttings, plugs and transplants: If you are not propagating in-house, it is very important to know how the plants were treated before they came to your greenhouse. Whether the cuttings are imported or purchased from a local source, always request a list of chemicals applied with dates. Having this information helps to assess their residual effects on plants which determines whether biological agents and/or chemical should be used. For example, dipping cuttings in horticulture oil helps removing chemical deposits, but if a systemic treatment was used, it will change which predators we can add. Predatory mites such as SwiLiv Amblyseius swirskii tend to do better than insects such as OriLiv Orius insidiosus when systemic treatment is used.
Always inspect the new plant materials for presence of thrips. This can be done by quarantining the plants for a designated amount of time and/or asking your cultivation team to keep a close eye for thrips when transplanting. The treatment options chosen will depend on the feeding damage threshold that the crop has. In ornamentals there is zero tolerance for thrips damage because the plants become unmarketable. Growers of this crop usually treat new plant material as if it already has thrips because they cannot afford an outbreak. For crops such as mini cucumbers, growers do have some leeway because a little bit of thrip damage does not hurt the bottom line.
Visitors and Pets: Having frequent visitors in your greenhouse can increase the chances of bringing in thrips. Try to keep foot traffic into the greenhouse at a minimum especially when the plants are young. They are the most vulnerable at this stage and can be distorted with little to no fruit yield if thrips are able to establish. Similarly, keeping pets in designated areas away from cultivation and packing rooms will reduce the probability of carrying thrips into the greenhouse.
Vents: Many pests, including thrips, are known to make their way into the greenhouse through vents. Screens are helpful. To minimize thrips entrance, hang yellow sticky traps facing the vents. This will increase the chances of catching thrips.
Packing rooms: Keeping the packing room clean and clutter free is extremely important to reduce thrips harboring areas. Remove all weeds that are growing in and around the room, clean and sanitize on a regular basis, and dispose of any leftover plant material away from the greenhouse. If your packing area has produce coming from other greenhouses, it is important to stay even more vigilant since thrips can easily travel on produce from one greenhouse to the next.
Pet plants: Having plants in the office are often overlooked but can be harboring sites for thrips that can hitch a ride on the staff and enter the greenhouse. Remove office plants if possible or have measures in place to reduce the probability of thrips establishing.
What preventative actions can you take?
Monitoring with sticky traps: Asides from adding sticky traps near vents, add them above the crop 6-9" high from plant canopy. Thrips are not great fliers so be mindful not to hang the traps too high.
Consistent scouting: Create a scouting schedule that is strictly followed and keep detailed records of your findings. This will not only assist in swift real-time decision making, but also help to predict which areas are more prone to thrips outbreak and what the dominant species is.
Empower your team: Your team is the most important factor in minimizing thrips outbreaks. We encourage you to create a learning culture and train your team to be able to identify thrips damage, level of pest pressure, and what control options they have available. Having a well-rounded picture of the interaction between the mechanical, biological, and chemical control options will result in the most cost-effective and successful plan.
Creating a preventative biocontrol plan: Depending on the crop, environment, and history of thrip problems in the past will determine what biological agents will be most effective. The most common preventative treatments for thrips are broadcasting predatory mites such CucuLiv Neoseiulus cucumeris or SwiLiv Amblyseius swirskii on young plants and switching to breeding sachets once the plants are a bit more mature. The sachets are replaced every 6 weeks. For soil stages, adding a soil dwelling predator such as AtheLiv Dalotia coriaria and/or HypoLiv Stratiolaelaps scimitus will help eliminate pupating thrips. Some species of thrips don’t pupate in the soil and require alternative control methods. If you are unsure which preventative plan to implement, reach out to our technical sales reps for guidance on the best options for you. Contact us here
Lastly, take clean up seriously. The least thrilling yet the most important step to prevent reoccurring thrip outbreaks is by cleaning and sanitizing the greenhouse. Take a step back and analyze what areas in your greenhouse can potentially harbor pests. This can include weeds in or around the greenhouse, plant debris, algae, old soil, or other protected areas.
In our next post we’ll be discussing what treatment option you have once thrips are spotted by your scouts.
If you found this helpful please leave us a comment below! 🐞