Organic fertilizer, timing, microflora fungal pathogen activity
The summer months are not the most conducive periods for fertility, the plant ( monocot ) is using carbohydrate reserves to stave off heat and stay alive while dormant / under stress meaning high" respiration "or the use of reserves at a cellular level.
At this time for C-3 plants ( cool season ) photosynthesis is very low or the production of food by the photo sites in the leaf.
When nitrogen is applied ( especially soluble ) the plant will increase water uptake to move the nutrient through the transpiration stream or water conducting tissue called xylem this consumption causes increased cell turgor ( elasticity ) of the cell weakening the plant at a very susceptible time. Nitrogen is best utilized in the fall when plants are storing carbohydrates, also in early to mid spring during early stages of shoot growth when photosynthesis is high and the plant is producing abundant photosynthates with plenty of available water. The carbohydrates built off spring production are then utilized for periods of high respiration in summer.
Organic matter such as the type utilized for fertility are converted to nitrate by a process called mineralization which includes dozens of bacteria which simplify and hydrolize to elemental ammonium then finally to a soluble form of nitrate. In the heat this process is accelerated, especially with materials that are susceptible to easy breakdown such as feces, blood meal, ect............
Microbe activity is stimulated in the soil and thatch by organic materials, they strengthen the growth medium and the plant life, microflora such as fungi will fall into a natural spectrum of activity in a heathy organic soil plant spectrum and will rarely take out healthy organic managed turfgrass growing in healthy organic soil profile with all the natural predation thriving in that soil.
Eventually a soil that is only sustained by synthetic materials will lose precious natural bacteria, and organic macro & micro fauna from excessive amounts of ammonium, urea, sulfur and the like. These plants are continuously on a jag. There needs to be a balance in the growth medium.
If the scenario is what it seems to be then adding organic fertilizer in the dead heat of summer on a mostly synthetic managed medium microbes start feeding quickly on probably the only organic compounds there " the fertilizer " which would In that spectrum stimulate even the microflora ( fungi ) to a point.
Soluble fertility usually curbs rhizoctonia " brown patch " activity ( in fact any fertility ) Pythium however is stimulated by nitrogen and will take off like wild fire. I believe your answer resides in something other than the fertilizers applied. What exactly did the material consist of ? We're all enviro/ cultural conditions similar such as shade & thatch? There is more to be questioned.......