The old concept of “achieving a balance” between the pest and the biological control, has been replaced with “prevention of establishment” due to the availability of fresh biological controls.
While the “balance” concept is still valid in many applications, and essential in outdoor, classical biological control, it was never appropriate for propagation.
Several years ago, Applied Bio-nomics Ltd. decided to reverse the industry trend of maximizing storage and shelf life by offering growers fresh products. We made the decision because of the results of the striking results of trials in numerous facilities, where our fresh product outperformed the stored product available by as much as a factor of 20. The tests were originally done with Encarsia, but soon spread to our entire product line.
Research in Canada and Australia has since confirmed that, aside from healthier and more vigorous insects, the avoidance of cold storage ensures “smarter” insects (Boivin). Insects exposed for even just 24 hours of refrigeration (below 8 C), were unable to make the decision to leave the plant they were on, to look for something better. This characteristic is essential for effective searching behavior.
Based on our own research and research from the broader scientific community, Applied has decided to differentiate itself from the competition by offering only fresh products. In some cases, we offer extremely fresh products, with special attributes for the grower. These products are marketed with the “Max” identification.
Before setting out
The timing of most commercial propagation, in the fall and winter, means that you will be confronted with hardened pests, desperately searching for a place to over winter. While the pest load is usually low, the few around are the champions of the species, the most pesticide resistant, and are usually physiologically enhanced for the over wintering experience.
Areas within your greenhouse where insects can hide must be cleaned, or inoculated with Biological Controls, such as Stratiolaelaps scimitus.
Spider Mites tend to the “red phase” in September, sensing the decline of day length. “Red phase” Spider Mites are more chemically resistant and many of the Biological Controls for them, such as Phytoseiulus persimilis, do not find them as attractive prey. If your house has a history of Spider Mites, control should be achieved before the fall begins. Once the Spider Mites begin over wintering, Stratiolaelaps should be applied to the bases of all of the support posts, plumbing intersections and along the perimeter walls and any other location where the Spider Mites could work their way into the ground.
For the flying pests, such as Whitefly, Aphids, and Thrips, a thorough cleanup of all plant material in the house is essential. Two weeks prior to setting out new plants, you should place at least one monitoring plant in the house to attract the surviving pests. The monitoring plant should be a bush bean, which is attractive to all pests. The bush beans can show spider mite damage within 2 hours, so they can become early warning systems even after your plants have started. Thrips and whitefly also find bush beans to be extremely attracitve and will alert you to pest issues early.
Shorefly, while not actually a pest by definition, are a true pest in your house. Not only can Shorefly move fungus spores from plant to plant, they will also transport mites. New research has shown that phoretic behavior in mites is much more widespread than previously believed. Pest mites actually “hitch a ride” by grabbing on to the legs of flying insects. Shorefly populations should be tackled by thoroughly cleaning all of the drains. Shorefly need standing water to breed. We have found that, after a good cleaning and flushing of the drain system, Atheta coriaria, released directly into the drains, will have a significant impact. Propagators with flood floors have a significant challenge maintaining drain sanitation.
The high levels of humidity during the early stages exclude many pests. The most significant pest during the germination and first stages is the Fungus Gnat. Fungus Gnats are a significant pest, as the larvae feed directly on the fine root hairs, reducing growth rates and injuring the plant, leaving it exposed to fungal disease. The adults are capable of transporting fungus spores, as well as mites. While the incidence of Broad Mite is low, it can cause considerable damage at this stage because they enjoy very high humidity.
Control of Fungus Gnats is best accomplished by applying Stratiolaelaps or, if in Canada, Geaolaelaps gillespiei at 250 mites per square meter at the beginning of the process. An additional application of nematodes may be needed if the conditions favor Fungus Gnats.
Release Encarsia “Max” at a rate of 0.5 wasps per square meter weekly. Alternate release points. Use 2 Eggplant per hectare as monitoring/trap plants. If any Whitefly are seen, increase rate to 1 wasp per square meter.
If Bemisia or any other Whitefly is seen or anticipated, release Delphastus catalinae at a rate of 0.1 beetle per square meter, every 2 weeks. Delphastus are excellent searchers, finding the Whitefly by smell, a single release point per hectare is all that is needed. Despite being reared on Greenhouse Whitefly, they prefer, and will go to the Bemisia sites first. Bemisia are harder to scout, as they tend to “clump” more than Greenhouse Whitefly.
See Pest Post – Whitefly for more information.
Release Aphidoletes aphidimyza at a rate of 0.2 midges per square meter weekly. This rate is 2 release points of 1000 each, per hectare. It is essential to ensure that the release is neutral, in that no Aphids should be nearby. This is achieved by releasing the Aa in the same location every week. This ensures that the Aphidoletes will disperse and search. Aphid Banker systems will undermine the prevention system. Consider your crop the banker – that is where you want Aphidoletes to go.
During the winter, day length can be an issue for Aa’s efficacy. The addition of low, supplemental light such as LED Christmas strings or even just the walkway lights will have a great influence on Aa’s performance. Micromus variegatus at a rate of 0.5 adults per square meter is also an effective aphid prevention, particularly during cool and darker times of year.
We have also developed a “flying aphid” trap using a modified “bug zapper”. See Pest Post – Aphids for more details.
Spider Mite Prevention
Spider mites can be prevented by applying the predatory mite, Amblyseius fallacis to any plants that are prone to spide mite or any other mite pests. Apply at a rate of 2 mites per square meter. If the house has a history of spider mites or, if the plant is exceptionally sensitive, increase the rate to 2 mites per square foot.
Bean plants should always be present around the perimeter of a sensitive crop and especially in areas where spider mites have been present in the past. Support posts, plumbing junctions, cracks in the floor and perimeter walls should be where the bean plants are focused.
See Pest Post – Spider Mites for more information.
Thrip prevention is attempted by offering a monitoring/trapping plant that is more preferred than the crop. Yellow “Hero” marigolds have proven successful at this task.
A universal attractant for thrips is vanilla. Work done more than 30 years ago by Dr. Ramakers in Holland showed that by adding vanilla to your yellow (or blue) sticky cards, you can attract up to 10 times the number of Thrips.
Anystis baccarum at a rate of 0.25 mites per square meter is currently being used as a preventative rate if some pests are present, and this inoculation of the crop serves as a preventative for thrips when pressure is low.
If Thrips occur when pressure increases, release 500 Neosieulus cucumeris per square meter to the affected site. The trapping plant should also have vanilla or other flavors applied to it. We have found that almond extract and peppermint are also effective.
As thrips are very poor flyers, they tend to enter your greenhouse through the doorways. Placing attractive marigolds or white pans filled with soapy, vanilla-flavoured water just inside the doors can attract the thrips instead of allowing them to move into the crop.