Why does your Onion Keep Well F1 have tiny black flies? Diagnose the cause and fix it with our step-by-step guide.
The tiny black flies are likely fungus gnats whose larvae thrive in the moist, organic-rich soil around onion bulbs. They feed on decaying organic matter and can damage emerging onion roots, potentially leading to stunted bulb development.
Certain species of small black flies are attracted to the high moisture content and nitrogen levels in onion beds. While they don't feed on the bulb directly, their presence indicates an environment that is overly damp.
High levels of nitrogen in onion cultivation can stimulate rapid microbial growth and fungal blooms, which attracts small dipteran flies. This creates a feedback loop where more organic decay attracts more pests.
Your plant might also be experiencing one of these issues:
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