Why does your Allium cepa have yellow leaves? Diagnose the cause and fix it with our step-by-step guide.
Nitrogen is critical for the vegetative growth of Allium cepa. When nitrogen is lacking, the plant cannot produce sufficient chlorophyll, causing older leaves to turn pale yellow before progressing to the tips.
Onion bulbs are highly susceptible to waterlogging, which displaces oxygen in the soil. This leads to root hypoxia and can trigger fungal pathogens like Phytophthora, manifesting as yellowing foliage.
This fungal pathogen causes lesions that often appear as yellowing or chlorotic patches on the leaves. These spots eventually develop purple-to-black necrotic centers.
As onion bulbs reach full maturity and prepare for harvest, the plant naturally redirects nutrients from the leaves to the bulb. This process causes the tops to turn yellow and eventually collapse.
Your plant might also be experiencing one of these issues:
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