Why does your Allium cepa Reks F1 have tiny black flies? Diagnose the cause and fix it with our step-by-step guide.
The larvae of these flies live in the organic-rich, moist soil around the onion bulbs, feeding on decaying matter and fine root hairs. This can weaken the developing red onion bulb by damaging the root system's ability to absorb nutrients.
While the visible flies are often gnats, they can sometimes be confused with the adult flies of the onion maggot. The larvae of this pest tunnel into the neck and bulb of the Allium cepa, causing rot and significant structural damage.
High moisture levels in the substrate attract fungus gnats and provide an ideal breeding ground for their eggs. Overly wet conditions around Allium cepa bulbs also increase the risk of secondary fungal pathogens like Botrytis.
Your plant might also be experiencing one of these issues:
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