Soil Health

Soil that has been severely compacted often breaks into large massive plates.

For those interested in soil health – we all should be – the Soil Health Institute has release a 60-minute documentary featuring innovative farmers and soil health experts from throughout the U.S.

You can view the film at https://livingsoilfilm.com/

 

Dog Days and Cool-Season Grass

 

Cool-season lawn struggling to grow in shallow soil on a south-facing slope during dog days.

According to Merriam-Webster, dog days is the period between early July and early September when the hot sultry weather of summer usually occurs in the northern hemisphere; a period of stagnation or inactivity.

The dog is actually the Dog Star – also called Sirius – which rises simultaneously with the sun during the hottest days of summer in the northern hemisphere. Plutarch (Greek writer, 46-120 AD) referred to the hot days of summer as hēmerai kynades (literally, “dog days”); the Latin translation dies caniculares is the source of our English phrase. But I digress…

You most likely have noticed that cool-season grasses have recently entered a period of stagnation or inactivity (dog days) and, in some cases, are spent. The hot summer days have steadily increased soil temperatures to the point that the soil is now warmer than air temperature for much of the daylight hours and all of the night. During the last 10 days at Hort Farm No. 2, soil temperature at 3-inches has oscillated between 76 and 90 °F and at 2-inches 78 and 92 °F. These soil temperatures are well above the optimum temperatures for root growth and clearly explain why cool-season grasses are lethargic at this time.

What to do? Be patient and do not “push” the grass. This is not the time of year to stress out turf – the grass has very little resiliency and will not tolerate much abuse or recovery quickly. I recently witnessed utility vehicle traffic on subtly drought stressed turf during the hottest part of the day result in classic tire-track damage. Root systems of cool-season grasses are weakest and shallowest at this time of year. Thus, localized drought stress can develop rapidly – within a couple hot, sunny days – during the dog days.

These cultural practices can be helpful in getting high value turf to survive dog days. Once the turf has drained after drenching thunderstorms (2-3 days), program daily, very-light (50-65% of reference ET), deficit irrigation using a rainhold setting (such as 0.2-inch rain) to stop irrigation from adding to over-wetting from storms. Deficit irrigation assures that thunderstorms will be the reason for excess wetness, not the irrigation schedule. This irrigation plan should encourage the turf the dry without over-drying between irrigations (or thunderstorms). If excess drying does occur with this irrigation plan, it probably will start in highly localized (small) areas, which can be effectively managed with well-timed syringing to re-hydrate dry leaves and prevent crispy thatch during the heat of the day. Crispy thatch means that surface adventitious roots either are or will soon be crispy as well. Moist to dry thatch is good, whereas crispy and crunchy thatch in the heat is bad. Weekly, low-rate fertilization (N and possibly P, K and micronutrients) is crucial on sand-topdressed and sand-based rootzones commonly found on golf course putting greens and some sports turfs. These rootzones have very little mineralization capacity to supply essential nutrients during dog days. Weekly low-rate fertilization provides a steady, consistent slow-growth and avoids the “surge-crash” cycle of growth that results from less-frequent and higher application rates. Typically, low-rate N is no more than a 0.1-lbs. per 1,000-sq. ft.

Managing Thatch

Recently received a couple of questions about managing thatch.

One question was concerning the recent trend in the industry to not core putting greens and only use solid tines. 

Non-coring programs rely on topdressing to dilute the organic matter (thatch) that accumulates, thus forming a mat layer as opposed to a thatch layer. Turgeon defines mat as a tightly intermingled layer composed of [Read more…]

Cadmium and Phosphate Fertilizer Debated in EU

Fertilizer derived from phosphate rock, which naturally contains cadmium, is being debated in the European Union. More than half the cadmium, a toxic heavy metal, in some agricultural soils originated from phosphate rock derived fertilizer. Sedimentary phosphate rock mined in northern Africa contains naturally high cadmium levels. Phosphate from mines of igneous rock in Russia has much lower levels.  Read more…

Weeds off to a Slow Start

Despite a quick start to the spring, soil temperatures remain low across the much of the state. Average soil temperatures (3-inch depth) have been hanging around the mid 60s in central NJ and many warm-season weeds such as crabgrass have hardly developed despite germinating over 6 weeks ago. This crabgrass at our research facility has not advanced past the leaf stage and I have observed this across the region over the past few weeks.

Smooth crabgrass in the leaf stage

The peak of annual bluegrass seedhead production has passed. It was a very difficult spring to properly time ethephon applications for optimum seedhead suppression. If the results of our seedhead suppression research trial are indicative of the region, then I suspect those that made a fall (December at the snow mold fungicide timing) application of ethephon were happy with suppression. Spring-only applications did not perform very well in our research.

A very seedy annual bluegrass putting green at Hort. Farm No. 2

When warmer weather arrives, warm-season weeds will develop rapidly. If you are relying exclusively on post-emergence herbicides for crabgrass control, an application of a post-emergence herbicide in the next few weeks may be warranted. This will only control what has already germinated and not what will emerge as we continue into the summer, so additional applications will be necessary. Especially if using fenoxaprop (Acclaim Extra, Last Call), lower herbicide rates often can be used when treating smaller plants. Mesotrione (Tenacity) is another post-emergence crabgrass herbicide that is most effective on smaller plants. Quinclorac (Drive XLR8, Quinclorac 75DF) is another post-emergence option but is often more effective against larger (> 4 tiller) plants than the smaller plants present right now. Topramezone (Pylex) has efficacy some against crabgrass but is an extremely effective product for goosegrass control. See the herbicide labels for more information.

We observed goosegrass emergence two weeks ago at certain sites but not others. This event is not particularly relevant for those who applied a pre-emergent herbicide. However, you may want to scout areas with a history of goosegrass problems to make sure your pre-emergence herbicide is working. Goosegrass seedlings can be difficult to differentiate from crabgrass seedlings. Goosegrass seedlings have a ridged adaxial leaf surface (ridges look similar to perennial ryegrass) and a blunt leaf tip while crabgrass seedlings are relatively smooth with a sharper leaf tip. If you applied a pre-emergence herbicide and are already seeing goosegrass germination please contact me.

Goosegrass seedlings

If you plan to make an herbicide application to control broadleaf weeds, the weather continues to be ideal for control and growth of the cool-season grass into voids. This is especially true for the summer annual knotweed.

Prostrate knotweed observed mid-May in New Brunswick

 

Prostrate knotweed is more easily controlled now while it is still relatively immature. Standard three-way or other broadleaf herbicides that contain 2,4-D may not provide complete control. So in the case of severe infestation, products that contain triclopyr (e.g., T-Zone, Battleship III, 4-Speed XT, Cool Power, others) will provide more control. Cultural practices such as aerification to reduce compaction and improve conditions for turf growth are also essential. For more information on whether you will disrupt the pre-emergence herbicide barrier by aerifying, see this information from Dr. Aaron Patton.

To Aerify or Not to Aerify when Using a Preemergence Herbicide

 

Sedges and Kyllingas

This week I visited several golf courses and other sites along the Garden State Parkway from Exit 9 (Cape May) to Exit 171 (A few miles from the NY State line. In terms of plant development, northern NJ seems to be about a week behind central NJ and southern NJ seems to be a week or two ahead of central NJ. The most noticeable difference across locations is the difference in kyllinga emergence from dormancy. In southern NJ, kyllinga is close to full emergence while kyllinga northern NJ is at approximately 50% emergence. In all locations, but especially those in southern NJ, now would be a good time to begin making applications if you haven’t already.

False-green kyllinga dominating a stand of tall fescue

False green kyllinga (foreground) has a lime green color compared to the tall fescue (background).

 

Our research indicates that halosulfuron-methyl and imazosulfuron are effective options for control. Multiple applications will likely be necessary for effective control. Make follow-up applications after you observe re-growth from the previous application (usually 3 to 4 weeks later). For more information see this previous blog post by Dr. Murphy. https://turfblog.rutgers.edu/?p=934#more-934.

Soil Temperatures

Soil temperatures have been steadily warming since late March at Hort Farm No. 2 (North Brunswick). Temperatures consistently ran above 50 degree Fahrenheit in early April, and between 50 and 60 degrees from 10 to 27 April.

May 1st was the fifth consecutive day of the maximum soil temperature reaching at least 65 degrees. Thus, soil temperatures are essentially entering into an ‘ideal’ period for the growth of cool-season turfgrasses.

Those experienced with managing summer patch may recall that 5 consecutive days with a soil temperature maximum of 65 degrees is the threshold for initiating a preventive summer patch control program. Isn’t it ironic that ideal growth of the fungus that causes summer patch is synchronized with ideal growth temperatures for cool-season turfgrasses.

Damage from summer patch disease, however, typically is not seen until later in the summer when heat and drought stresses make it challenging for plants with a compromised root system to survive.

summer patch disease on hard fescue

Severe summer patch disease on hard fesuce at Hort Farm No. 2 in July 2013.

Some Early Disease Activity

Sorry no pictures for this post, but thought I would share some recent observations. The recent rains and warm night on Friday/Saturday brought out two diseases on annual bluegrass earlier than we typically experience at the research farm in North Brunswick NJ (Hort Farm No. 2).

Saturday morning, our graduate student found nickel- to quarter-sized spots of foliar Pythium on his annual bluegrass plots. Tended to be more spots on his plots with greater N fertility but the disease was also on low N plots. This is the earliest I have experienced foliar Pythium, but the Friday/Saturday nighttime temperature didn’t get much below 65 degrees F, ‘good’ for Pythium.

Also on annual bluegrass, was a slight outbreak of dollar spot on Saturday morning. Dollar spot in April is early but not unheard of in NJ.

You might notice that the pests mentioned have shown up first on annual bluegrass.

Warm Air, Cool Soil

Warm air temperatures build anticipation of plant growth but keep in mind that cool soil temperatures will strongly moderate growth during the spring. Turf growth typically will be very slow until [Read more…]

Weather Ideal for Pythium and Brown Patch

The weather this summer has been very conducive for brown patch and Pythium blight diseases. I have received number requests this summer to address turf problems related to one or both of these diseases in lawns, sports fields, sod and now my own plots.

Suspected initial outbreak of Pythium on velvet bentgrass maintained at a 0.110-inch height that occurred over the weekend (August 7) in a cultivation trial at Hort Farm No. 2 in North Brunswick NJ.

Suspected initial outbreak of Pythium on velvet bentgrass maintained at a 0.110-inch height that occurred over the weekend (August 7) in a cultivation trial at Hort Farm No. 2 in North Brunswick NJ.

The weather forecast for the rest of this week indicates [Read more…]

Kyllinga Awakens as Soil Temps Increase

Daily high soil temperatures at the 2-inch depth are consistently getting into the 60s °F. Yesterday, temperatures in sunny locations reached into the upper 60s. This means that the warm-season species are, or will be soon waking from winter slumber.

Leaf tips emerging from rhizomes of kyllinga on 15 April 2015 in central New Jersey.

Leaf tips emerging from rhizomes of kyllinga on 15 April 2015 in central New Jersey.

For the last three weeks, I have been watching the emergence of false green kyllinga (Kyllinga gracillima). Most sites infested with kyllinga are probably showing active shoot growth. So it appears that kyllinga needs soil temperatures that reach consistently into the 60s to emerge from winter dormancy. As temperatures continue to warm, re-growth of kyllinga should accelerate.

False green kyllinga is a perennial sedge species with well-developed rhizomes (underground lateral spreading stems). Kyllinga is relatively low growing so it [Read more…]