I don't know about the bud rot but I had powdery mildew and I used the baking soda and water solution spray, as well as upping the air flow and temps as well as trimming off any affected leaves. After one application and improved environment, I've been 2 weeks with no signs.
alkaline pH helps with mold/PM, but usually potassium bicarb' is used for this,... baking soda can too, but be careful about overuse and concentration, BS is Sodium bicarb' and Na is toxic at low levels,...hence the use of K-bicarb',....