If the 10-day forecasts are correct, the winter thaw we’ve all been waiting for is about to begin this weekend.

Winter thaw: the most common time “nonpoint” or “runoff” phosphorus pollution enters lakes and streams.

 
As managers of landscapes, we need to keep in mind that:

• Sediment is the primary source of phosphorus (large quantities of phosphorus are attached to sediment)
• Most phosphorus runoff from turfgrass comes during winter
• Improving soil quality is one of the most effective way to reduce nutrient losses from urban areas
• Dense ground cover is good for the urban environment

[Read more…]

Recently, surface soil temperatures have been dropping below 70° F at night. While this is a good temperature range for growth of cool season grasses, it is a signal that much cooler soils are not far away. Grow of new seedings, overseedings, and turfs needing recovery will slow dramatically once soil temperatures break below the 60° F threshold. We have reached the time (October 1) where we no longer recommend seeding of most grasses except perennial ryegrass. Perennial ryegrass can be seeded as late as October 15 and still have high probability of develop a stand of turf.

Cool weather limits the establishment of new seedings. In this photo,
poor seed to soil contact will also inhibit establishment of new turf.

As stated in an early post, summer stress is developing throughout the state. Summer stress isn’t widespread or severe but it is developing, particularly wilt stress, within very localized areas of many landscapes. Landscapes that receive little to no irrigation are especially prone to wilt and drought stress right now.

6-22: Symptoms of subtle wilt stress. Healthy turf will likely to tolerate this level of wilt stress.

6-25: More advanced symptoms of wilt stress. Suspend mowing until rain or irrigation restores soil water.

Crabgrass has been emerging for several weeks now, depending on the exposure. Warmer and more open turfs will likely have more advanced (larger) plants while cooler and denser turfs will have smaller plants.
Management options for this weed at this point in the season range from doing nothing to postemergence herbicide applications.

Relatively small crabgrass plants (most pre-tillering stage) emerging
from a footpath on June 11th.

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Optimum growth of cool season grasses occurs within the temperature range of 60 to 75°F. Yesterday, the New Brunswick weather station indicated that soil temperature at 2 inches exceeded 75°F for more than 12 hours and peaked at 82°F.

This doesn’t mean that grasses will soon be dead. But it is a signal to be watchful for summer stress problems.

Summer stress is often a combination of multiple stresses. Localized drought, ponding of water, diseases, insect pests, poor culture (mowing, fertilization, and irrigation) and other stresses combined with high temperature stress can challenge the health and persistence of cool season turfs from now through the end of summer. It is important to avoid situations that compound too many stress at the same time. [Read more…]

Exactly like Dr. Bruce Clarke teaches, Memorial Day arrives and so does dollar spot disease.

Creeping bentgrass entries in one of Dr. Stacy Bonos’ evaluation trials that are
highly susceptible to dollar spot disease. Dollar Spot Disease seen in foreground.

Symptoms appear as round, brown to straw-colored spots approximately the size of a silver dollar. On short cut turf, the spots with advanced damage can become somewhat sunken. At taller cutting heights (greater than 1 inch), the damaged spots are larger and more diffuse.

Highly susceptible grasses will be the first to exhibit symptoms including annual bluegrass, creeping bentgrass (depending on cultivar), and perennial ryegrass. Tall fescue and most Kentucky bluegrasses will be more tolerant of this disease.

Cultural techniques that can suppress dollar spot disease include disruption of dew and guttation water in the morning and increasing N fertility (if it is low). Mowing early in the morning (disruption of dew) should also be helpful.