We lost the ice cover on our Poa annua trials two weekends ago (March 7-8th) and initially the turf looked okay. But now… it doesn’t. And it will probably get worse, if we are reading the symptoms correctly.

Last Friday (March 13), my graduate student, Chas Schmid, informed me that I needed to look at his potassium trial on our Poa annua turf. There was a huge difference between no‑K and K fertilized plots. The no-K plots have steadily lost green color and become very blotchy. Plants taken from those plots are water-soaked and feel mushy when squeezed (How is that for a scientific description?). Dr. Lindsay Hoffman has a lot of experience with winterkill on Poa annua in Massachusetts and she is convinced that many of the plants are dead. And it smells like it – silage on a dairy farm!

Blotchy, tan-colored plots and borders around this potassium trial are suffering from winterkill. Green, healthier looking turf received K fertilization; dying turf did not.
(15 March 2015)

Take home for me – don’t let your Poa annua turf become potassium deficient! Chas’ data for suppressing anthracnose severity indicates that a soil test (Mehlich 3) ≥50 ppm K and a tissue level of ≥2% K in the clippings are indicators that the K level is good. And winterkill in March 2015 hasn’t changed my mind about that data!

Looks like this might be the end of this Poa annua field. Dr. William Meyer said, “Good riddance.”

Damage to landscapes from traffic can be severe during winter and especially now during the thaw. Soil conditions currently range from being frozen to partially thawed/frozen to thawed.

Partially frozen soil will be thawed and very wet at the surface while being frozen at some depth below. Under this condition, soil and turf will be extremely vulnerable to shearing and rutting damage. Traffic, even light foot traffic, must be withheld when this condition exists otherwise severe rutting (soil displacement) will occur.

Severe rut caused by a wheeled vehicle driving on partially thawed soil.

[Read more…]

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.