Whether you like it or not, spring highlights the amazing ability of Poa annua to produce seed.  The ability to produce copious seed is an evasive characteristic of Poa annua's evolution of different survival strategies (Cline et al., 1993).   I think one of the most amazing characteristics of Poa annua, and also a detriment from a golfing perspective is the flowering ability of Poa annua under low mowing heights. 

Crabgrass (Digitaria spp) is a major problem in both cool-season and warm-season turfgrasses As a general rule, crabgrass tends to be more of a problem in temperate climates and less of a problem in tropical regions. In temperate regions the most important and likely the first weed control practice of the year is the proper timing of a pre-emergent herbicide application for crabgrass.

Diseases caused by Drechslera spp. were formerly classified as Helminthosporium leaf, crown, and root diseases. The fungus attacks cool season turfgrasses during the cool wet weather of spring and fall.

Typhula blight, also known as gray snow mold or speckled snow mold, is most severe under extended periods of deep snow that covers a wet turfgrass on unfrozen soil. The pathogen Typhula incarnata is most active when temperatures are 1-2 C. Grayish to straw colored circular patches ranging from 2.5 cm to 1 meter in diameter appear at snow melt. A grayish mycelium may be present infected turf, which gives it the grayish or speckled look.

Covering greens to protect them from winter injury (see Winter Injury publication) are often used in the northern temperate regions. Covers can be broken down into two major categories permeable and impermeable. Permeable covers allow for air, light, and water to penetrate the cover. Permeable covers are used to protect greens from wind and sun exposure (desiccation). In addition they are often used in the spring to promote spring green-up and where turf has been damaged used to help in turf recovery.