Here are the 5 tips to reduce diseases in your Marigold garden:

1. Remove the old plants: This will reduce the accumulation of diseases in the soil that may come with the marigolds or vegetables from the previous crop.

2. Adjust the soil condition: Make the soil neutral, which will slow down the growth of pathogens and help the plants grow better.
3. Prevent insects: Insects are pests and disease vectors that can infect your marigold plot. If you can reduce the number of insects in your plot, you will also reduce plant diseases.

4. Manage weeds: Weeds are sources of diseases and insects. If your plot is clean, spraying insecticides will be more effective and reduce disease carriers as well.

5. Change the watering method: Avoid watering along the rows, because this will spread the pathogens with the water and may cause widespread damage.