Armyworms Invade Indiana

There appears to be a wide-spread outbreak of armyworms [Pseudaletia (=Mythimna) unipuncta (Haworth)] infesting residential turf across southern Indiana. These insects typically have 2 generations per year in this part of the country and we are in the midst of the 2nd generation of larvae. Adult armyworm moths lay their eggs in large masses and when the eggs hatch, the resulting caterpillars begin to feed and move across the infested area. When the larvae are small, this feeding causes little damage and may go unnoticed. However, As development proceeds, the larvae increase in size, consuming larger amounts of turf.
 
Armyworm taken from turfgrass in southern Indiana. Photo courtesy of B. Voges.

Where heavy infestations occur, a typical home lawn may seem to disappear almost overnight!! Feeding damage often appears to radiate out from a central point where the main infestation likely started. Although the damage can be alarming, armyworms are easily controlled with insecticides and the damage they cause, although unsightly, will not permanently damage the turf unless it is already stressed from drought.


A home lawn in southern Indiana showing typical armyworm damage. Photo courtesy of B. Voges.

Fortunately, most of Indiana has been experiencing adequate rainfall for the last few weeks, so turf should be resilient to this damage. Still, expect damage to get worse before it gets better. Good cultural practices including adequate fertility and irrigation will help the turf recover more quickly. The caterpillars we are seeing now will pupate by the end of September and attempt to remain in the soil over winter. Unless we experience an exceptionally mild winter, most pupae will not overwinter successfully.

For control information go to: http://extension.entm.purdue.edu/publications/E-61.pdf

Doug Richmond, Turf Entomologist
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Words You Might Hear a Turf Nerd Use

A nerd is an intelligent but single-minded person obsessed with a nonsocial hobby or pursuit1. Therefore, a turf nerd is someone single-minded towards turf, obsessed with turf, and a bit nonsocial. I suppose that described me pretty well.


To help increase your turf nerd quotient (only nerds use words like quotient), I thought I would educate you about 12 words that you might hear a turf nerd use. Try your best to weave one of them into a conversation this week.



12 Words You Might Hear a Turf Nerd Use:

agrostology – the branch of systematic botany that deals with grasses2. Some of the first turf scientists in the country were first called agrostologists in the early 1900s.

anaeraobic – the absence of molecular oxygen2. This term is usually used when discussing soils. A soil that is anaerobic is lacking on oxygen. A wet or water-logged soil is anaerobic. Without oxygen in the soil plants suffer and shifts in bacterial populations occur.

apomixis – the laymen’s definition is “clonal reproduction through seeds” which is also known as agamospermy.  This one gets complicated, but all you need to know is that Kentucky bluegrass is apomictic which means that when you buy a particular cultivar of Kentucky bluegrass (Poa pratensis), all the seed you plant will essentially grow-up to be genetically identical to the parent plant. With many other cool-season turfgrass species, the individual seeds are produced through sexual reproduction (intercrossing) of plants with similar traits which results in individual plants within a cultivar that are almost identical or very similar but technically genetically different than one another. Vegetative apomixis can also occur such as with bulbous bluegrass (Poa bulbosa).

cation – a positively charged ion2. Examples include calcium (Ca), magnesium (Mg), sodium (Na), and hydrogen (H). These will commonly be referred to as cations on a soil test report. Cation exchange capacity is a measure of the soils ability to retain these positively charged cations on the soil colloid which is negatively charged.



desiccation – the process of being desiccated (which is to dry up) due to the deprivation (another nerdy word) of water2. Desiccation or drying out is a common term used to describe a specific type of winterkill than can occur in turf when no snow fall is present and when wind speeds are high and windy days are frequent. Desiccation injury to turf is more common in the plains in states such as Nebraska.

dioecious – having staminate and pistillate flowers on separate plants2. A plant that has separate male and female flowers that usually occur on separate plants. Buffalograss is an example of a turf that is dioecious.

Male flower

Female flower or burr.


glabrous – having a smooth surface, without hairs2. When you want to describe that a grass plant is smooth and without hairs, use the term glabrous. The Kentucky bluegrass had a glabrous leaf blade. The opposite is pubescent which means covered with short hairs3.

hygroscopic – readily capable of absorbing and retaining water from the atmosphere, under normal conditions of temperature, pressure, and humidity2. You all have experienced this phenomenon whether you know it or not. Most fertilizers are hygroscopic. When you open the fertilizer bag and then come back a few weeks later and all the fertilizer is stuck (caked) together, it is due to the fertilizers hygroscopic nature.

marcelling – A wavy or washboard pattern on the surface cutting plane of mowed turfgrass; usually results where the clip of the reel exceeds the mowing height4. Marcelling is specific to reel mowers and not an effect seen with rotary mowers.

Look for the parallel lines running NNW. This is Marcelling.


mat – Thatch intermixed with mineral matter that develops between the zone of green turf vegetation and the original soil surface; commonly associated with golf course putting greens that have been topdressed2.

rachilla – subdivisions or branchlets of the rachis that support individual flowers, (seeds), within the spiklet of grasses2. The axis of a grass spiklet3. This is the little golf tee looking appendage on a turf seed.



verdure – the quantity of green living plant tissue per unit land area remaining above the soil following mowing at a specified height and usually expressed on a dry weight basis2. Essentially, this is how much turf is left above the soil surface after mowing. We often measure the mass or the quality (carbohydrates, mineral content, etc.) of verdure in turf research.

I hope you enjoyed this post.

Aaron Patton, Turf and Weed Scientist, Purdue University

Footnotes:
  1. http://dictionary.reference.com
  2. From or adapted from Beard, J.B., and H.J. Beard. 2005. Beard’s Turfgrass Encyclopedia for Golf Courses, Grounds, Lawns, Sports Fields. Michigan State University Press, East Lansing.
  3. Harris, J.G., and M.W.. Harris. 2001. Plant identification terminology: an illustrated glossary. Spring Lake Publishing, Payson, UT.
  4. Turgeon, A.J. 2008. Turfgrass Management. Pearson Education, Inc. Upper Saddle River, New Jersey.
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Weed of the month for August 2014 is Prostrate Spurge

Prostrate Spurge  

Biology: Prostrate Spurge (Euphorbia humistrata) is a summer annual broadleaf weed that can be found in dry/sandy and/or nutrient-poor soils along with compacted, weakened or disturbed turfgrass and landscape sites. Look for it first in driveways and sidewalks or in potted plants in a landscape or nursery as temperatures start to get warmer. Prostrate spurge can also be found in cultivated fields, brick walls, and parking lot cracks. It germinates from seed in June and July in Indiana and spreads via low-growing prostrate stems than form a dense mat as they invade the turf canopy. Its ability to establish and grow in multiple soil/climate conditions and highly compacted soils, as well as its ability to withstand low mowing heights, make prostrate spurge a common turfgrass weed throughout the state of Indiana.

Identification: Prostrate spurge is a low-growing summer annual weed in Indiana. The plant is anchored by a central shallow taproot and, as suggested by its common name, it forms a ground-hugging mat with prostrate stems that grow outward throughout the turf canopy. The plant produces these spreading stems along with viable seed very quickly, often within a couple of weeks after germination.






The leaves of prostrate spurge are pale green, hairy, egg-shaped, widest at the apex, and located opposite of each other on the stems which are pinkish in color and distinctly hairy. Prostrate spurge continually flowers from July to September and produces large quantities of viable seed throughout its life cycle. These flowers are small but numerous, originate from the base of leaves located on the upper-stem, and are composed of several male and female flowers within a cluster. It produces a fruit that consists of a 3-lobed, 3-seeded capsule with stiff hairs on its surface.






Prostrate spurge is very difficult to distinguish from other spurge species, particularly spotted spurge (Euphorbia maculata). In fact, some taxonomists consider the two plants to be the same species. An identifying characteristic of both species is a small reddish-brown splotch at the mid-vein/base of the leaves which acts almost as a camouflage; thus, making the weed difficult to distinguish from the desired turf. The primary difference between these two species is that spotted spurge leaves are often darker in color and the nodes do not produce roots when they come into contact with the soil.


Additionally all spurges exude a milky/white sap when damaged that can be toxic to animals if ingested.

Cultural control: None known specifically for prostrate spurge. Proper turf management such as adequate mowing heights, irrigation, and fertilization will help to produce a dense, aggressive turf which is the greatest defense against invading weeds. Prostrate spurge also thrives in compacted soils; thus, soil cultivation (hollow-tine aeration) may aide in management of the weed. Due to its shallow taproot, prostrate spurge can often be hand pulled when populations are small enough; however, it is important to remove weeds as soon as possible due to its ability to produce copious amounts of viable seed very quickly after germination.

Biological control: None known specifically for prostrate spurge.

Chemical control: Control options for prostrate spurge can include both pre- and postemergence herbicides. Preemergence control can be achieved with spring applications of isoxaben (Gallery, Isoxaben) prior to germination in summer. Dinitroaniline herbicides (such as Barricade, Pendulum) can also be applied for prostrate spurge control though the results are often less consistent than applications of isoxaben.

Once spurge germinates, control in cool-season turf can be achieved with applications of two- or three-way mixtures of 2,4-D, dicamba, MCPP, or MCPA which are available in multiple product formulations at local retailers. Repeat applications may be necessary due to the germination of new seedlings.


For more information on weed control, search this blog and check out our Turfgrass Weed Control for Professionals Publication.

For archives of past weed of the month postings, visit our Weed of the Month Archive.

Aaron Patton, Turfgrass Extension Specialist
Leslie Beck, Postdoctoral Research Associate
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Plant Turf Seed or Control Weeds First?

A common question this time of year is whether to plant turf seed now and control weeds later OR to instead control the weeds now and then seed later. Here are my thoughts.

Cool-season turf seed mixture.

Option 1 for areas with mainly broadleaf weeds and a few annual grasses: Plant now and control weeds later.
The optimum time to control perennial broadleaves and germinating winter annual broadleaves is in October. As such, seeding in late August and early September should allow enough time for seeds to germinate, grow, and be mown twice (assuming you irrigate and fertilize these newly seeded areas) prior to an October herbicide application. You can delay the herbicide application until late October and early November if you get a late start on seeding or if your seedlings are slow to establish (like Kentucky bluegrass). Most broadleaf herbicide labels suggests delaying application until newly seeded areas have been mown twice. Some herbicide labels allow a shorter interval between seeding and an application. These shorter interval herbicides include Quicksilver, SquareOne, and Drive (shorter interval tall fescue compared to perennial ryegrass and Kentucky bluegrass).

Typical language about postemergence herbicide application delays after seeding turf.

Drive XLR8 label instructions regarding application timing and seed and seedling emergence.

Option 2 for areas where you have lots of weed competition: Spray weeds now and seed tomorrow.
When there is a lot of crabgrass or broadleaf weed cover, then you would likely benefit from spraying the weeds now and seeding afterwards. Tenacity, Pylex, and SquareOne, and Drive are among the herbicides that can be applied today and allow seeding as soon as tomorrow (after the herbicide has had a chance to translocate in the target weed). Once the turf germinates, then follow the guidelines in option 1 above to provide follow-up weed control if needed.

SquareOne application instructions allowing seeding one day following the herbicide application.


Option 3 for areas perennial grassy weed competition: Spray weeds now and seed later.
When there are a lot of perennial grassy weeds such as quackgrass, fountain grass, etc., then your best bet to remove these perennial grasses before you seed as there are few herbicide options afterwards.
Best results with a non-selective herbicide like glyphosate are seen on perennial grassy weeds when multiple applications are made. Ideally, you would have started this process several weeks ago. Why? It is not uncommon for the weed to regrow from stolons or rhizomes (if a spreading grass) a few weeks after the first glyphosate application. One must allow the weed to regrow (wait at least three weeks) before the next application. At least two applications are recommended, but three or more may be needed. One must realize that the area will be dead and unsightly for a number of weeks or months if optimum control is desired.

Starting this process now, means that you won’t be able to seed until after the optimum seeding window of August 15 to September 15. If you are still committed to renovating this year, another seeding option is to seed in December through March as a dormant seeding after you have finished killing your perennial grassy weeds. Learn more about dormant seeding by clicking here.

If there are only a small number of patches, spot applications can be made with glyphosate. Reseeding can take place a day or two following final herbicide application. Once the area has been infested with a large number of patches, killing the entire area will be most effective with multiple applications of glyphosate. Renovation can begin five to seven days following final glyphosate application. Refer to AY-13, “Lawn Improvement Programs” for information on reestablishment.

One caveat to the above, Option 3 recommendation, is that we have a few selective herbicides for perennial grassy weed control that might be options for use during turf renovation.

Table 1. Non-selective and selective herbicide options for controlling perennial grassy weeds in cool-season turf.

Weed in cool-season turf
Non-selective herbicide option Selective herbicide option
Bermudagrass glyphosate Pylex (topramezone), Acclaim Extra (fenoxaprop)
Creeping bentgrass glyphosate Tenacity (mesotrione)
Dallisgrass glyphosate No effective selective control
Field paspalum glyphosate No effective selective control
Fountain grass glyphosate Drive (quinclorac) and other quinclorac containing herbicides
Nimblewill glyphosate Tenacity (mesotrione), Pylex (topramezone)
Orchardgrass glyphosate No effective selective control
Quackgrass glyphosate No effective selective control
Rough bluegrass glyphosate Velocity (bispyribac-sodium) for golf courses and sod farms.
Tall fescue glyphosate No effective selective control, formerly Corsair (chlorsulfuron)
Windmillgrass glyphosate Tenacity (mesotrione)
Zoysiagrass glyphosate Pylex (topramezone)(based on preliminary results following labeled instructions for bermudagrass control)

With any of these options, it is especially important to read the herbicide label and understand the application restrictions both before and after seeding and other application instructions (such as adjuvant and timing recommendations) so that you can maximize weed control and maximize turfgrass establishment.

For more information on weed control, search this blog and check out our Turfgrass Weed Control for Professionals Publication.

Aaron Patton, Turfgrass Extension Specialist
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Fescue. You mean there’s more than one kind?

Typical conversation about fescues.

Bill: What kind of grass do you have?
Bob: Fescue.
Bill: What kind of fescue?
Bob: You mean there’s more than one kind?
Bill: Yes.

As I travel around the region and give presentations or respond to email and phone questions, it is very common for me to enter into a dialogue with a person about planting, maintaining, controlling, etc. some kind of fescue. Usually in my interactions with people, they are unaware that there are many different kinds of fescues.

Festuca is the genus (first word in scientific name) for fescue species. Hence, Festuca’s are name Fescue. However, recently tall and meadow fescue were reclassified by scientists into the genus Schedonorus (see table below) although they still retain their same common name of fescue. Tall fescue and meadow fescue are similar with meadow fescue being used sparingly for overseeding in warm-season turf or as a forage grass and tall fescue commonly being used in lawns, roadsides and pastures. The remaining fescues including slender creeping red fescue, strong creeping red fescue, Chewings fescue, sheep fescue, blue fescue, and hard fescue are often grouped together and called “fine fescues” because of their narrow (fine) leaves. Another reason for grouping them all together is because they are difficult to distinguish from one another. Blue fescue is another fine fescue species used as an ornamental landscape grass.

Below is a breakdown of the common (and a few not so common) fescues used in turf (and ornamentals) and a short description of each.

Table 1. Description of the common and uncommon fescues used in turf (and ornamentals).

Common name
Species Comments
Slender creeping red fescue Festuca rubra ssp. littoralis Similar to strong creeping red fescue but with shorter, more slender rhizomes. Both slender and strong creeping red fescue tolerate some close mowing.
Strong creeping red fescue Festuca rubra ssp. rubra Strong creeping red fescue has more rhizome growth (spreading ability) than slender creeping red fescue. Strong creeping red fescue is a common ingredient in “Sun & Shade” mixes because of its good shade tolerance and its suitability in seed mixtures.
Chewings fescue Festuca rubra spp. fallax Named after George Chewings. Excellent shade tolerance and turf density, this fine fescue is similar to creeping red fescue but it lacks rhizomes.
Tall fescue Schedonorus arundinaceus (Schreb.) Dumort. (also = Lolium arundinaceum (Schreb.) S.J. Darbyshire; formerly = Festuca arundinacea Schreb.) Improvements in tall fescue have transformed this grass from a forage type grass to many improved turf-type cultivars. Today, both "forage" and "turf-type" tall fescue are used. Kentucky-31 (KY-31) is a forage type and not a lawn type. Known for its ability to maintain green color during moderate droughts due to its deep root system, tall fescue is more commonly used today on lawns than in the past.
Sheep fescue Festuca ovina Excellent drought tolerance. This fine fescue with fair turf density does not tolerate close mowing. It is often used in unmown, “native” areas of golf courses.
Blue fescue Festuca glauca Ornamental grass. Common variety is ‘Elijah blue’
Meadow fescue Schedonorus pratensis (Huds.) P. Beauv. (formerly Festuca pratensis Huds.) Similar in appearance to tall fescue. Little current use in high value turf.
Hard fescue Festuca brevipilla Excellent shade tolerance, this fine fescue does not tolerate close mowing. It is often used in unmown, “native” areas of golf courses.
Red fescue Festuca rubra Today, red fescue is classified into two groups: 1) Slender creeping red fescue or 2) Strong creeping red fescue. However, some seed labels may still just say, red fescue.

Figure 1. Unmown, fine-fescue used on a golf course. These areas are often described as no-mow, native areas, or environmentally sensitive areas to the golfers.

Figure 2. Chewings fescue. Notice the fine leaf texture (narrow leaf width) compared to tall fescue below.
Figure 3. Tall fescue (turf-type).




Aaron Patton, Turfgrass Extension Specialist

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Start Seeding Cool-Season Turf Now


The best time to seed a cool-season lawn is in the late summer to early fall. Adequate soil moisture, warm soil, and limited weed pressure allow for excellent seedling growth. Normally, we recommend seeding between August 15 and September 15 as the optimum seeding window. However, due to our cool summer and a relatively cool forecast for August, we are recommending that you can start seeding anytime now and there is no need to wait until mid-August.



It is critical to seed as early as possible within this window. Even when seeding within this window, waiting one week later to seed may mean the turf will take 2 more weeks to mature as germination and subsequent growth slows later in the fall as temperatures cool. Additionally, annual bluegrass and other winter annual weeds will be more problematic with fall seeding dates than late summer seeding dates.

Seeding early (later summer) allows the turf to maximize its establishment and rooting prior to the next summer's heat and drought.

For more information about establishment, see:

Aaron Patton, Turfgrass Extension Specialist
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Watering Newly Seeded Areas



Water is necessary to initiate the germination process in seeds. As the seed imbibes water, enzymatic reactions within the seed trigger the germination process. Enzymes breakdown the energy stored inside the seed endosperm and this energy is used by the seed embryo for growth. The first visible step in the germination process is the emergence of the radicle (this is the first root)(Figure 1). Next, the coleoptile (an opaque protective sheath) emerges. The coleoptile functions to protect the emerging leaf. Lastly, the green color of the first leaf can be seen as it emerges through the coleoptile. Once the first green leaf emerges, the plant can begin to make its own energy through photosynthesis and it no longer relies on the energy that was stored in the endosperm.

Figure 1. Pictured left to right in the order of the germination process are a newly planted seed, a seed with the radicle emerging, the coleoptile emerging, the leaf emerging through the coleoptile, and the leaf and root elongating.


Once the first irrigation or rainfall occurs after seeding, it is important to keep watering! Seedlings are very susceptible to moisture stress during the first few weeks after seeding (Figure 2). The upper 1 inch of soil should be kept moist with frequent irrigation for the first two or three weeks after planting. Germination will occur in 5 to 14 days depending on the temperature and the species planted (Figure 3).

Figure 2. Tall fescue seedlings emerging in a hydroseeded area. As new seedlings germinate they need to be watered frequently enough to avoid drying.

Figure 3. Pictured left to right in the order of germination are perennial ryegrass (PR), tall fescue (TF), creeping red fescue (CRF), and Kentucky bluegrass (KBG). This photo was taken six days after planting. NOTE: Kentucky bluegrass has not yet germinated in this photo.
 
After the seed germinates and seedlings develop roots into the soil, the lawn can be watered less often. Once established, the lawn should be watered deeply and infrequently only when the plant shows signs of water stress.

Aaron Patton, Turfgrass Extension Specialist
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