Sunlight is at a premium during the fall months and essential for turfgrass to develop enough hardiness to survive the winter. Everything the plant does during this time of year is a preparation for winter. Besides the path of the sun as it moves through the sky, the only detriment to light reaching the turf is shade from trees. Even if the tree only shades for a couple hours it becomes significantly detrimental to turf due to the shortness of the day.
On the other end of the spectrum, during the late winter and spring months, sunlight is again limited (but becoming more prevalent). Shaded areas melt snow/ice slower and retain the amount and duration of frost in the soil profile. This exposure to prolonged cold temperatures and ice build up is a leading factor in winterkill.
|Note the injured section is directly in the shape of the Spruce tree behind the 10th Green|
Sunlight is also a factor mid-season. Poa annua can handle shade better than bentgrass due to higher and more efficient photosynthetic rates but it does have a breaking point. Not only does the tree canopy limit sunlight, but tree roots compete for the same moisture and nutrients that the turf requires.
|Density loss on the 14th Fairway due to Maple Tree|