Start clean and stay clean with classic integrated pest management (IPM) is the advice for managing sciarid fly, which has the potential to damage all protected ornamentals and salads.
Wet weather encourages development of sciarid fly populations as a result of the rise in humidity within the glasshouses or growing tunnels, explains Martin Donnelly, Certis’ Account Manager. “These are favourable conditions for sciarid fly development; they can develop even in lower temperatures,” he adds.
He advises that a dry growing media environment will provide a less favourable habitat for the larvae. “Using a water management compost additive like Celcote will achieve this whilst ensuring the plant receives sufficient hydration.”
Monitoring then plays a vital part in managing the levels of adult sciarid flies. But, Martin warns that sciarid can be wrongly identified as fungus flies, or as shore flies, with white spots. “Look for the beaded antennae that are characteristic of the sciarid,” he says.
If both shore flies and sciarid are present, then good crop hygiene is the best defence, as part of everyday management, notes Martin. “By ensuring there is no scope for algae to develop, there is less opportunity for shore fly adults to feed which will severely impede the growth of the population.
”Utilising yellow sticky traps from the beginning of the crop cycle will help identify where and when adult flies emerge. “This will provide an indication of the adult population level, and the species involved, following which an effective IPM compatible control programme can be developed.”
However, Martin notes that it is important to remember best practice and regularly change the traps to give a clear picture of the adult sciarid fly population.
He recommends introducing a biological predator that is ideally matched to the target pest, like Certis BCP Hyposure (m) (Hypoaspis miles), as a preventative measure. “They should be routinely released every two weeks from an early stage - ideally immediately after sowing or inserting cuttings - in the crop at a rate of 50 - 500 per square metre, depending on pest levels,” advises Martin.
“The Hypoaspis predates on the larval stage of the sciarid fly, so reducing population growth, at an early stage in the life cycle.”
If pest populations persist and plant damage is still being seen, nematodes can be applied. “By drenching BCP Steinersure (f) (Steinernema feltiae) into the compost in conjunction with releasing Hypoaspis, larvae should be effectively managed,” he adds.
Chemical control is the final part of a classic IPM approach and should be employed where cultural control and biological predators fail to deliver strong enough control and sciarid flies are still being seen in large numbers. “Spruzit, as a natural pyrethrin, that acts on contact and is IPM compatible, will attack the adult flies. It is best applied through a knapsack sprayer at a rate of 200-400ml.”
Martin concludes that with the year on year changes to the climate and the extremes in the weather, sciarid flies are going to continue to be a challenge for growers. “Classic IPM with cultural, biological, and chemical control alongside effective monitoring is going to be crucial to manage this established pest.”