Why does your Onion Keep Well F1 have sticky leaves? Diagnose the cause and fix it with our step-by-step guide.
Aphids are small, soft-bodied insects that pierce the onion leaves to suck out sap, excreting a sugary substance known as honeydew which creates the sticky residue. This is a common issue for Allium species during the active growth stages.
Scale insects attach themselves to the onion foliage and feed on plant fluids, leaving behind sticky honeydew as a byproduct of their feeding process. They are often less mobile than aphids and can look like small bumps on the stem or leaves.
While not the primary cause of stickiness, sooty mold is a black fungus that grows specifically on the honeydew left by sap-sucking insects. If you see black, powdery coating on the leaves alongside the stickiness, it confirms an insect pest presence.
Your plant might also be experiencing one of these issues:
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