I am planting swiss chard on my backyard of north york for two weeks since I bought them. I do not know why the leaves got yellow recently. Can you please help me?
Swiss Chard (Beta vulgaris) is very easy to grow and with recent introductions of more colourful varieties, this leafy green is pretty enough to grow in ornamental containers.
This leafy green attracts the usual culprits: slugs, leaf miners, caterpillars, rabbits and deer.
From your photo it appears that your Swiss Chard is being attacked by leaf miner. Leaf miner flies will lay their eggs on the underside of the leaf and when the larvae hatch they will begin to tunnel in between the leaf surfaces and feed on it’s tissue. Damage appears as winding trails in the leaf tissue. As the mines enlarge, they may merge and form large light-coloured blotched areas. Feeding lasts 1-3 weeks. The larvae may pupate in the leaf or in the soil and the ¼’ long gray flies emerge in 2-4 weeks.
Remove and destroy all leaves that have brown patches. Do not compost but place in yard waste bags to be picked up by the city. If you see clusters of white elongated eggs, you can brush them off. Once you have picked off all the leaves cover the crop with a floating row cover. In the future covering the crop with a floating row cover after germination will prevent damage.