Back in April I put down clover seed in an area of our backyard lawn that had annual grass. I took the grass out with a shovel (sod roll) and put down fresh topsoil then the clover seed, watered daily and the clover came in nicely. I reduced water to match the weather. However, in the past 2 days we noticed a few patches where the clover has turned grey and fuzzy and has matted down or turned brown and died. (Please see pictures).
What we see in your photos looks like a fungal disease is attacking the leaves of the clover (note that the stems are still green).. There are a couple of fungal diseases which might be at fault, the most likely one is powdery mildew. Some of the leaves on your photos look fuzzy. There are also some tiny white spots which are unidentifiable and might be something other than powdery mildew. Fungal disease is prevalent after wet, cool springs, such as the one we have just experienced. You may have been over-watering during the rainy period. It's also possible there was disease in the soil from whatever was previously growing there. There really isn't any "fix" for this problem. Stop watering and let the area dry out. Remove all the diseased patches, along with an inch or two of soil beneath them. Most clovers are not fussy about soil, so adding a highly fertile, water-holding top layer may have contributed to your problem. You might want to take a sample of the diseased clover (plus soil under it) to the Master Gardener Plant Clinic, located at OSU Extension, 569 Hanley Road (Route 238), Central Point. Their summer hours are Monday to Friday, 10 to 2. Their phone number is 541-776-7371 in the event you cannot take the sample during regular hours.They can verify the diagnosis or suggest less radical treatment if the problem turns out to be something that can be controlled.