I’m located in Santa Clara, California which is typically dry and has been hotter than average yet humidity is usually low between 40-55%.

My indoor Diva cucumber seedling appears to have developed a fungal disease (see below image) and I wonder if the seedling can be salvaged. Can you please identify the disease and treatment method? What could have caused it?

The seed was soaked for 24 hours on 5/13 and planted in hydroponic solution on 5/14. It's been under a 45-watt grow light from 5/22. I check the seedlings daily and only noticed the problem on 6/1. Thanks.