As the anticipated registration of Magister for cyclamen mite control approaches, it's the perfect time to discuss how to optimize chemical applications for these challenging pests. To gain expert insights, we spoke with Slim Doghri from Gowan, representing Magister, and Eric Richter from Syngenta, representing Agri-Mek during the 2025 Nova Scotia Hort Congress which took place at the Old Orchard Inn outside Wolfville.
Challenges of Cyclamen Mite Control
Cyclamen mites (Phytonemus pallidus) present a significant
challenge due to their ability to hide within plant structures and reproduce
rapidly. Compounding the issue, growers are restricted to one application of
Magister and two applications of Agri-Mek per season. This makes timing and
strategy essential—not a matter of choosing one product over the other, but
rather using both effectively for maximum control.
Preventing Cyclamen Mite Infestations
With limited chemical options, the best approach is prevention.
Cyclamen mites have a narrow host range, meaning they do not move between
hedgerows or survive on native plants. They are most commonly introduced
through:
- Infected
planting stock
- Spread
from older fields to newer ones
In June-bearing matted row fields cyclamen mite populations
will increase rapidly from over wintering adults. Once eggs are laid they will hatch in 11 days,
producing a population of mostly females.
The next generation will reach maturity in two weeks and start the cycle
over again, each female producing about 90 eggs, laid in clusters.
Regular scouting is critical to detect problems early. Most growers lack the patience and microscope skills to intensively scout for cyclamen mite. Intensive scouting requires collecting plant parts including developing buds, and young unfolded leaves and intense examination under the microscope. This is better left to a dedicated employee or a professional crop scout as it requires an abundance of patience and time. Most growers are left scouting for symptoms appear, such as:
- Compacted
plant centers with stunted, crinkled leaves
- Wilting
and die-off of flowers
- Severe
yield and fruit quality reduction
Once symptoms appear, populations have already surpassed
treatment thresholds, making immediate action necessary before canopy closure
of the rapidly developing strawberry plant restricts spray penetration down to
the new leaves and crown area.
Magister: A New Tool in Cyclamen Mite Control
How Magister Works
- Magister
targets nymphs and adults, and controls eggs to a lesser extent.
- Fast
knockdown within 24 hours and residual control on treated leaves.
- Effective
against a broad spectrum of mite species.
Application Guidelines
- Anticipated
cyclamen mite label approval in July 2025.
- Insecticide
group 21A
- Apply
no more than one application per season, with a 1 day PHI.
- Use a
non-ionic surfactant at 0.25% v/v for better coverage.
- Maintain
agitation in suspension concentrate formulations.
- Magister
is a non-systemic contact product with a long residual. Thorough coverage is key.
- Use
high water volumes (1000 L/ha or 105 gallons/ac).
- Magister
also controls powdery mildew.
Bee Safety Considerations
- Toxic
to bees if exposed to fresh residues (<3 hours old).
- Do not
apply to blooming or pollen-shedding plants unless exceptions apply (see
label).
Agri-Mek: A Key Component in the Rotation
How Agri-Mek Works
- Translaminar
movement (absorbed into leaf tissue, but not systemic).
- No
effect on eggs; mites must ingest the chemical to be affected.
- Causes
muscle paralysis, stopping feeding within hours.
- Mites
take 2-4 days to die.
Application Guidelines
- Limit
of two applications per season, with a 3-day PHI.
- Insecticide
group 6, Which is different from Magister and great for rotation and resistance
management.
- Use
0.1%-0.5% v/v non-ionic surfactant.
- Apply
in 1000 l/ha. Effectiveness drops
off rapidly below 500 l/ha as shown by Justin Renkema, AAFC Vineland.
- Rainfast
in 2 hours, but effectiveness will be better given a longer rain free
period of up to 24 hours.
- Avoid
applying to hardened leaves, as absorption is reduced.
- Do not
tank-mix with oil-based products in strawberries.
- If
treating after renovation, apply 5 days after mowing to allow penetration
before canopy regrowth
- Growers
should think about how they are going to achieve the high-water volume
required. Increasing spray pressure
may produce excessively small water droplet leaving the spray prone to
drift and fogging the exterior of the canopy. Medium sized droplets maybe better at
canopy penetration and coating the crown.
This may require two consecutive passes of the sprayer at opposing
directions at 500 l/ha and a ½ rate of chemical in the tank.
- Growers
may need to think about spray water access in the fields to cut down on
fill time and maintain efficiency in application.
- After the
decision has been made for an application for cyclamen mite the race maybe
on to make the application before canopy closure, bloom and bee presence and
harvest.
Understanding the Impact of Group 3 Insecticides
Group 3 insecticides (pyrethroids, such as Matador,
Silencer, Zivata, Decis, Up-Cyde, and Poleci) can have unintended consequences:
- They may
kill beneficial predatory mites (e.g., Neoseiulus cucumeris, Amblyseius
swirskii), allowing cyclamen mites to increase in population
unchecked.
- Potential
for hormoligosis—some mites, including two spotted spider mites, have been
shown to increase egg reproduction when exposed to sublethal pyrethroid
doses.
Final Takeaways for Growers
To achieve the best control of cyclamen mites, growers must:
- Prevent
infestation by ensuring clean planting stock and minimizing field-to-field
transfer.
- Scout
early and frequently to detect mites before symptoms appear.
- Use
Agri-Mek strategically, focusing on early applications when leaves are
still soft and just after renovation.
- Apply
Magister closer to harvest but avoiding bee exposure, ensuring canopy
penetration before closure. This will also provide powdery mildew control
as temperatures and powdery mildew increase early summer.
- Ensure
thorough coverage by applying before full canopy closure, and high-water
volumes of 1000 l/ha.
Acknowledgments
A huge thank you to Eric Richter from Syngenta for his
insights on Agri-Mek and Slim Doghri from Gowan for providing expertise on Magister
during the Hort Congress presentation. Their knowledge is invaluable in helping
growers maximize the effectiveness of their cyclamen mite control programs.