Our IPM specialists at Fargro look after a wide range of customers from ornamental growers to interior landscapes, green offices, hotels and living walls which have become increasingly popular recently. We know that using biologicals to control pests and diseases in these environments are not only more environmentally friendly but if done so correctly are extremely effective.
One of the key pests found in interior landscapes are sciarid fly, so we thought we would give you some top tips on what to look out for and how to control them.
What are sciarid flies?
Also known as fungus gnats, sciarid fly are one of the most common pest species we observe most notably within interior settings. Sciarid's have the potential to be very damaging to plants, with the larvae doing most of the damage to roots. With a rapid lifecycle exacerbated within interior heated environments allow populations to increase dramatically at times.
HOW TO KEEP SCIARID FLY POPULATIONS DOWN
1. Inspect your compost
Recent changes in soil mixes and movements to peat free mean we are observing, at times higher populations of sciarid. We suspect this is brought on by the increased presence of organic materials such as wood fibres and green waste present in the mixes being broken down, creating an environment for fungi to be more prolific in certain peat free mixes.
The increase in fungal populations provides a greater food supply to the adults, thus increasing pest pressure. The change in soil mixes also carries with it an adjustment in watering and irrigation practices, as the retention of water fluctuates from what would be expected from peat-based soils.
The areas we observe high populations of sciarid are where the soil is kept moist or wet, especially in the top layer as the increase in moisture levels bring with it an increase in the development of fungi, which creates a more suitable environment for the adults to lay their eggs and the larvae to move more freely through the soil media.
2. Be mindful of watering techniques
Preventative methods of control play a key role in managing this species and ensuring the environment is as inhospitable as possible, creating a challenge for each stage of the lifecycle. Within these cultural controls, watering techniques are the most important, if plants can be watered from below this will keep the top layer of the soil relatively dry.
The drying of the soils top surface will make it harder for all aspects of the sciarid lifecycle, as the adults have less food available with active growth of fungi greatly reduced and are deterred from egg laying into dry soil. The larvae also find it harder to move though a dry environment which allows for increased predation from predatory species.
An exception to this is when nematodes are applied, as they require moisture in the environment to move through, if the nematodes are hitting a dry topsoil when applied or if the soil is allowed to dry out soon after application, this will kill the nematodes. Hygiene on site is also important, ensuring biofilm and moulds are not present around plants, as again, this will create a food source for the adults.
3. Use sticky traps
The use of sticky traps are highly effective for providing a level of control for the adults, with yellow traps being the most effective colour. Sticky traps work purely from light reflection to attract the adults, so ensure they are facing towards the light as much as possible. These traps should be used in conjunction with biological control, as all the predatory species available target the larval stages of sciarid; the addition of the yellow traps alongside biological control allows for control of the entire lifecycle and the rapid knockdown of sciarid populations if applied correctly. Traps can be cut down to make them less noticeable if they are being applied in a public area.
4. Monitor the setting
The monitoring of incoming plants from off site is important, making sure the larvae are not present in large numbers in the soil structure. If monitoring practices are carried out and high populations of sciarid observed, it gives a chance to apply a biological control before a potential mass emergence of the adults occurs.
If you notice a high number of larvae or adults on plants brought in from offsite, if possible, create an area to quarantine infested plants to limit spread of the sciarid. This will also allow time for the biological control to do its work and for sticky traps to be placed.
5. Use biological controls
When looking to apply biologicals it is important to apply on a regular basis to keep beneficial species working in the background, we generally advise applications every 2-3 weeks during peak times, with applications of Hypoaspis, nematodes or Atheta, extending to monthly applications if sciarid levels are low.
Good application is key when applying biologicals, ensuring the predatory species are reaching their target and are applied uniformly, any areas missed can create hotspots for pests to persist and migrate into treated areas.
Running a biological programme through the year is the easiest way to go about this, we can tailor a programme to your needs and situation to establish a comprehensive level of control with the orders coming out automatically which you are free to edit throughout the year if situations change.