From Dr. Frank Rossi’s blog: The toughest 6-8 weeks of the growing season are upon us [in the Northeast at least]. Increasing evening temperatures, adequate to excessive soil moisture, persistent humidity and showery conditions, and high levels of traffic from turf use and turf maintenance all conspire to establish a baseline of stress expected for the next 6-8 weeks.
At this time of year water management is most critical. If you are not using a soil moisture meter, especially on putting surfaces, you are increasing your risk of failure. Any failure to supply adequate amounts of water or if your turf holds water at the surface, expect many stress-induced issues such as basal rot anthracnose and summer patch to become more challenging. At the same time, persistent leaf wetness from rainfall, humidity or poor air movement will lead to increases in foliar diseases such as dollar spot, brown patch and Pythium. Now is not the time to attempt to extend spray intervals, or reduce traditional preventative or curative rates. With so much stress abound, minimizing disease stress is critical.
Weed populations having expanded due to the early season dry conditions that weakened desirable turf as well as voids in turf unable to be filled from seed or failed sod from poor irrigation and NO rainfall.
Some post-emergence crabgrass control can still be effective IF you have actively growing desirable turf in place. It seems even dense turf areas have their share of crabgrass. Same would be true for any broadleaf weed control that is NOT recommended at this time of year as leaves establish thicker cuticles, making herbicide penetration more difficult. Plan for late-summer/early-fall treatments.