Hi - I started a vegetable garden this year. All of a sudden (overnight), my potatoes look like they’ve caught blight. I don’t believe this is possible as the weather conditions have not been conducive to blight. Could it be overwatering? I did water a couple of times over the weekend, and we had really heavy rain over the last 48 hours (and it’s clay soil which retains a lot of moisture). See atattached picture. Thanks!