I`m having trouble with silver beet in the last year,
The plants start out healthy and vigourous and when they mature a brown colouration spreads up the stem and through the hole leaf not just the veins.
Can you help with the diseases.
Your silverbeets/chard may be suffering from Cercospora leaf spot which is a fungal disease. This disease usually occurs when the planting bed is slow to drain. Improve the planting beds by adding lots of aged compost–compost is well drained, but holds moisture as well. If plants are in the bed now, do not overwater. Often you can cut away affected stalks, and new ones will grow and not be affected.