Preemergence crabgrass control on athletic fieldssturf.lib.msu.edu/article/2010mar20a.pdf · control on athletic fields Large and smooth crabgrass can be differenti-ated by examining

20 SportsTurf | March 2010 www.sportsturfonline.com

CRABGRASS SPECIES areannual grassy weeds that areproblematic on most every ath-letic field. If left uncontrolled,crabgrass infestations will

decrease the aesthetic and functional qualityof any athletic field.

The forthcoming loss of an effective,economical postemergence herbicide likeMSMA renders the use of preemergenceherbicides for crabgrass control increasinglymore important. While registrants ofMSMA for use on sports turf can no longersell the product, distributors will be able tosell products purchased before December31, 2009 until December 31, 2010. After

December 31, 2010 existing stocks ofMSMA can legally be used for weed con-trol on sports field turf until they areexhausted provided that these uses complywith the EPA-approved label and labelingof the affected product1. Once supplieshave been exhausted, preemergence herbi-cide applications will be one of the maintactics used to control crabgrass infestationson athletic fields.

CRABGRASSCHARACTERISTICS

There are two primary crabgrass speciesthat infest athletic fields: large crabgrass(Figure 1) and smooth crabgrass (Figure 2).

Preemergence crabgrasscontrol on athletic fields

Large and smooth crabgrass can be differenti-ated by examining the leaves and stems ofeach species. Large crabgrass has pubescence(hairs) on its leaves and stems, while theleaves and stems of smooth crabgrass havevery little pubescence except on the collarregion (the intersection of the leaf and stem ofthe plant). Both large and smooth crabgrassare summer annuals that germinate primarilyin the spring, grow through the summer, pro-duce seeds in the fall, and die following thefirst killing frost.

GERMINATION ANDPREEMERGENCE HERBICIDES

Correct application timing is an integralpart of controlling crabgrass with preemergence

FieldScience

By Greg Breeden & James T. Brosnan, Ph.D.

>> Left: Figure 1. LARGE CRABGRASS (Digitaria sanguinalis).>> Inset: Figure 2. SMOOTH CRABGRASS(Digitaria ischaemum).

The blooming of the forsythiaplant, also known as goldenbells (Figure 3), is a visualindicator that soil tempera-tures are increasing to a levelconducive for crabgrass seedgermination. Using this visualindicator, the first preemer-gence herbicide application ofthe season should be madebefore the last forsythia bloomfalls from the tree.

>> Figure 3. FORSYTHIA in bloom.

Fors

ythi

a br

anch

imag

e co

urte

sy o

f is

tock

phot

o.co

m

www.sportsturfonline.com

herbicides. A common misconception is that preemergence herbicides actby preventing weed seeds from germinating. These herbicides actually pre-vent germinating seedlings from developing into mature plants. For pre-emergence herbicides to work properly, they must be applied before seedgermination and need approximately 0.5 inch of rainfall or overhead irri-gation within 24-48 hours after application in order to be activated.

Large and smooth crabgrass seed germinates in the spring when soiltemperatures exceed 55 F for 4 consecutive days and nights. Initialapplications of preemergence herbicides for crabgrass control should bemade before these temperatures occur in your region. In the transitionzone applications are normally made in late February through earlyApril.

The blooming of the forsythia plant, also known as golden bells(Figure 3), is a visual indicator that soil temperatures are increasing to alevel conducive for crabgrass seed germination. Using this visual indica-tor, the first preemergence herbicide application of the season should bemade before the last forsythia bloom falls from the tree.

Preemergence herbicides will generally provide crabgrass control for12-16 weeks after application depending on application rate. However,the level of control provided will dissipate over time. Using a split appli-cation strategy where an herbicide is applied twice at a lower rate canextend the length of residual control provided by that application.Additionally, a split application strategy will offer improved preemer-gence goosegrass control.

FieldScience

Preemergence crabgrass herbicidesTHERE ARE SEVERAL PREEMERGENCE HERBICIDES marketed

for crabgrass control on athletic fields. The following informa-tion is provided as a guide for herbicide selection. Always refer tothe product label for specific information on proper product use,tank-mix compatibility, and turfgrass tolerance.

Trade Name: DimensionChemical Name: dithiopyrFamily: PyridineUse Areas: Golf course (except putting greens), athletic fields, sod farms, residential and non-residential areas.Turf Safety: All major established turfgrass species.Rate: Dimension EC - 2 qt/a (0.5 lb ai/a)Application Type: Sprayable and Granular

Trade Name: EchelonChemical Name: prodiamine + sulfentrazoneFamily: Dinitroaniline + protox-inhibitorUse Areas: Golf course (except putting greens), athletic fields, sod farms, residential and non-residential areas.Turf Safety: All major established turfgrass speciesRate: Echelon 4SC – 18-36 oz/a (0.57-1.125 lb ai/a)Application Type: Sprayable

Trade Name: RonstarChemical Name: oxadiazonFamily: OxadiazoleUse Areas: Golf course (Except tees and putting greens), athletic fields, sod farms, and non-residential areas [Not labeled for residential lawn use].Turf Safety: All major established turfgrass species.Rate: Ronstar G - 100 to 200 lb/a (2 to 4 lb ai/a)Application Type: Granular or Sprayable to Dormant Turf Only

Trade Name: Pendulum Aquacap Chemical Name: pendimethalinFamily: DinitroanilineUse Areas: Golf course (except tees and greens), athletic fields, sod farms, residential and non-residential areas.Turf Safety: All major established turfgrass species.Rate: Pendulum Aquacap - 1.5-3 qt/a (1.5 to 3 lb ai/a)Application Type: Sprayable and Granular

Trade Name: Barricade 4FL and 65 WGChemical Name: prodiamineFamily: DinitroanilineUse Areas: Golf course, athletic fields, sod farms, residential and non-residential areas.Turf Safety: All major established turfgrass species.Rate: Barricade 4 FL- 10 to 48 oz/a (0.5 to 1 lb ai/a)Application Type: Sprayable and Granular

22 SportsTurf | March 2010


RESEARCHEach year the University of Tennessee evaluates numerous pre-

emergence crabgrass herbicides in different locations and environ-mental conditions. In most years, labeled rates of prodiamine(Barricade), dithiopyr (Dimension), pendimethalin (PendulumAquacap), oxadiazon (Ronstar), and prodiamine + sulfentrazone(Echelon) all provide effective crabgrass control (> 90%) throughoutthe season when applied properly.

Some preemergence herbicides do provide activity against crab-grass plants that have emerged from the soil seedbank. Early poste-mergence applications of Dimension (1 tiller or less) and Echelon (1-3 leaf) have been found to provide a level of smooth crabgrass controlsimilar to applications of the same herbicides at recommended pre-emergence timings. While these are the only two preemergence crab-grass herbicides that exhibit postemergence activity, control fromthese applications has been reported to be inconsistent in other loca-tions. In general, preemergence herbicides should be applied beforecrabgrass seed germination. Any postemergence activity should beconsidered an added bonus when these herbicides are made at laterthan optimal timings

DEVELOPING A PREEMERGENCE PROGRAM Step 1. Choosing a preemergence herbicide. While many athletic

field managers hold strong opinions as to which preemergence herbi-cides work better than others, research data collected at theUniversity of Tennessee has found all of these products to performsimilarly when applied properly. Therefore, be sure to select a prod-uct that is available in a formulation that is compatible with yourapplication equipment. In many cases granular products may be bet-ter suited than sprayable formulations for some turf managers.

Step 2. Apply in a timely manner. After choosing a preemergenceherbicide make sure it is applied in a timely manner. Keep in mind

FieldScience

Preemergence herbicidesmust be applied beforeseed germination and needapproximately 0.5-inch ofrainfall or overhead irrigationwithin 24-48 hours

SportsTurf 25www.stma.org

that all preemergence herbicides need rain-fall or irrigation to be activated. The opti-mal time to apply preemergence herbicidesfor crabgrass control varies greatly fromregion to region. Contact your localExtension office for more informationregarding crabgrass seed germination timingin your area. For extended residual activitymake a second application 6-8 weeks afterthe initial application.

Establishment of grassy weeds, like crab-grass, can often be prevented with a timelypreemergence herbicide application in thespring of the year. Research has found thatthese herbicides perform similarly whenapplied correctly at the proper timing.Using a split application strategy canextend the length of residual control pro-vided by a single preemergence herbicide.With the forthcoming loss of an effective,economical postemergence herbicide likeMSMA, preemergence control of crabgrasswill become increasingly important.

Always refer to the product label for spe-cific information on proper product use,tank-mix compatibility, and turfgrass toler-ance. For more information on turfgrassweed control, visit the University ofTennessee’s turfgrass weed science website,http://tennesseeturfgrassweeds.org. ■

Greg Breeden is weed science extensionassistant and Dr. James T. Brosnan is assistantprofessor-turfgrass weed science at theUniversity of Tennessee.

Establishmentof grassy weeds,like crabgrass, canoften be preventedwith a timelypreemergenceherbicide applica-tion in the springof the year.


SPORTS FIELD MANAGERS, particularlythose working in a K-12setting, do not alwayshave access to state-of-

the-art spray application equipment.In these settings, the application ofliquid materials is frequently con-tracted out or the sports field man-ager must often work with availableequipment.

The sports fields and grounds atOverbrook High School (Pine HillPublic Schools, Pine Hill, NJ) areoverseen by Rich Watson, groundssupervisor and sports turf manager,and Bill Loftus, sports turf manager.The school owned a simple, func-tional, 30 year-old sprayer thatcould be used for the application ofliquid materials. The sprayer consist-ed of a 100-gallon tank mounted ona tractor three-point hitch and apump powered by the PTO. The

boom was equipped with nine flatflan nozzles commonly used in turf-grass applications.

Rich Watson’s goal was to prop-erly calibrate this sprayer, with littleor no modification to its existingset-up, to correctly apply a selective,systemic broadleaf weed herbicide.

What we knew about thesprayer and what we needed todetermine. While there are variousmethods and techniques that can beused to calibrate a sprayer, we usedthe following formula to sort-outwhich variables we knew and whichvariable(s) needed to be determinedto accurately deliver the broadleafherbicide: GPM = [GPA x MPH xW] / 5940, where GPM = gallonsper minute (per nozzle); GPA = gal-lons per acre (spray volume); MPH= miles per hour (tractor operatingspeed); and W = width (inches)between nozzles. The value of 5940

Sprayer calibrationin a pinch

is a constant needed to convert units and is not derived inthis article.

The sprayer was equipped with nine (9) XR TeeJet8004VS nozzles positioned on 20-inch spacings across theboom. Per manufacturer specifications (TeeJet Technologies,Spraying Systems Co., Wheaton, IL), the nozzle output isdesigned to be 0.4 GPM and each nozzle will produce an80-degree spray angle at an operating pressure of 40 poundsper square inch (psi).

Note that this calibration formula, nozzle nomenclature,and other technical information can be accessed at theTeeJet Technologies website (www.teejet.com).

The label of the broadleaf herbicide chosen for this appli-cation states that the product should be applied in 20 to 220gallons of water per acre. While this is obviously a widerange, the product being used was a systemic broadleaf her-bicide. The goal of applying a systemic herbicide is to simplydeliver the product onto the leaf of the plant (as opposed touniformly covering turfgrass leaves in the case of a contactpesticide). Thus, a target application rate of 40 GPA(approximately 1.0 gallon per 1000 sq ft) was appropriatefor the systemic herbicide. Also, applying the product at thisspray volume (as opposed to 80 GPA or greater) wouldrequire fewer tank refills to spray large acreages.

FieldScience | By Brad Park

(All

phot

os b

y B

rad

Park

, Rut

gers

Uni

vers

ity).

>> THE GOAL was to calibrate an existing 30-year-old sprayer (withminimal equipment modification) to properly apply a systemicbroadleaf herbicide.

The formula: Variables:

Our calculations:

Figure 1. Using a calibration formula

GPA x MPH x W5940

GPM =

GPM = gallons per minute (per nozzle)

GPA = gallons per acre (from label)

MPH = miles per hour

W = nozzle spacing (inches)

GPM = 0.4GPA = 40W = 20MPH = ?

5940 x GPMW x GPA

MPH =

5940 x 0.420 x 40

MPH =

MPH = 3.0


Thus, with the existing sprayer components in mind (XR8004 nozzles positioned on 20-inch spacings), it becomes clearupon examining the calibration formula that operating speed isthe variable that needed to be determined to calibrate thesprayer to deliver 40 GPA of spray solution. Inputting ourknown variables into the equation, we determined that thesprayer required an operating speed of 3.0 mph (Figure 1).

CALIBRATING THE SPRAYERA 100-foot course was measured, the spray tank was filled halfway

with clean water, and the tractor was operated numerous times overthe course at varying ranges and forward gears at an engine rpm of2100 (rpm necessary to maximize PTO performance) until thecourse was completed in 23 seconds. A speed chart was used to deter-mine that 23 seconds were required to complete the 100-foot courseat 3.0 mph; however, a calculation and unit conversions could havebeen performed to obtain the same information. Through trial anderror, we determined that the tractor had to be operated in 3rd rangeand 2nd gear at 2100 rpm to complete the course in 23 seconds.

All nozzles, screens, and seat gaskets were removed from the boomthe day before and soaked in an ammonia solution for 24 hours.Once cleaned, nozzle assembly components were then reassembledon the boom. This was an important step because clogged nozzlesand screens will often produce an uneven appearance of the spray,

whichwill affect sprayvolume and theuniformity of theapplication.

With the tractor engine rpm set to 2100 in an idle posi-tion and the PTO engaged, the sprayer was operated with clean waterwith the pressure regulator set to 40 psi. This allowed us to observethe operating appearance of the “fan” pattern produced by each noz-zle, which we determined to be satisfactory.

Next, a graduated cylinder was used to confirm that each nozzle

>> Left: A 100-FT COURSE was set-up to determine the tractor’s range andforward gear necessary to achieve an operating speed of 3.0 mph.>> Right: EXISTING nozzles and components were allowed to soak in an ammo-nia solution for 24 hours before being reassembled on the sprayer boom.


was delivering 0.4 GPM (Figure 2). At 0.4GPM, each nozzle delivers 380 ml (~13fluid oz) of water over 15 seconds. Anacceptable margin of error is + 5%; hence,

the acceptable amount of water to be collect-ed ranged from 361 to 399 ml. Actual quan-tities collected ranged from 340 to 360 ml.The spray pressure was adjusted to 50 psi to

increase spray output. An upward adjust-ment in pressure was not unexpected sincethe pressure gauge was mounted to the pres-sure regulator and the operating pressure atthe nozzles was likely less due to frictionassociated with the spray solution movingthough the hose lines. Spray output wasincreased to the acceptable range after thepressure adjustment.

FINAL STEPSPer manufacturer specifications, the XR

TeeJet 8004VS nozzles positioned on 20-inchspacings should be set at 17 to 19 inchesabove the intended target. Thus, the boomheight was adjusted to set the nozzles at 20inches above the paved surface; this height isapproximately 18 inches above the 2-inchhigh turfgrass canopy (the intended target).

We then operated the sprayer (filled withclean water) across a dry, paved surface at thecalibrated speed and pump pressure to

FieldScience

>> A graduated cylinder (ml) was used to check each nozzle for a calculated spray volume equivalent to 0.4 GPM (i.e. 380 ml in 15 seconds).

Figure 2. Calculating how much water to collect per nozzle

Steps we took:

Our goal was to collect a quantity of clean water equal to 0.4 GPM per nozzle.We had a graduated cylinder (ml).We recognized that 15 sec is an appropriate amount of time to perform a sprayvolume check.

Calculations

2) We needed to collect 380 ml (±5%) per nozzle in a 15 second period.3) The pressure regulator was set to 40 psi (per manufacturer specifications).4) Our collected volume ranged between 340 and 360 ml (outside 5%). 5) We increased the pressure regulator to 50 psi to reach desired input.

0.4 gallons1.0 minute

3785 ml1.0 gallon

1.0 minute60 seconds

x x x 15 seconds = 380 ml (~13.0 oz)


observe the drying pattern of the spray solu-tion. The spray dried in a uniform pattern(i.e. there were no visible streaks resultingfrom improper overlap); hence, the nozzlespacing and height were set properly.

The following day, the broadleaf herbi-cide was applied using the sprayer set to thecalibrated speed and pressure. A minimalamount of spray solution remained in thetank after the application was made—anindication that our calibration efforts weresuccessful. The remaining solution was dilut-ed and “sprayed-out” multiple times in out-of-play border areas at the far-end of thefacility. Within 2 weeks, white clover controlwas judged to be “excellent.”

Laws pertaining to fertilizer and pesticideapplications are becoming increasingly restric-tive, particularly on school properties.Heighted parent and environmental interest-group awareness of chemical tools used onpublic grounds drives much of this regulatorypolicy. It is important that chemical applica-

>> Water was sprayed on a paved surface usingthe calibrated sprayer to observe the drying pat-tern. A uniform drying patter, absent of skips andstreaking, indicates proper nozzle performanceand positioning.

tions are made thoughtfully and in accordance with their product labels. A thorough under-standing of the sprayer calibration process allowed the application of a broadleaf herbicide atOverbrook High School to be successful. ■

Brad Park is Sports Turf Education and Research Coordinator, Rutgers University and mem-ber of the Board of Directors, Sports Field Managers Association of New Jersey (SFMANJ).

Within 2 weeks,white clover controlwas judged to be“excellent.”

BERMUDAGRASS is a tropical/sub-tropical warm season perennial grassnative to southeastern Africa. It isbelieved to have entered the UnitedStates around 1751, probably through

coastal Georgia and/or the Carolinas. There areapproximately 10 species that include the com-mon seeded wild types as well as many interspecif-ic hybrids. The most commonly used for turfgrassare the sterile hybrids of the C. dactylon x C trans-vaalensis types.

Originally used in this country for pasture andhay production, it has become one of the best per-forming turfgrass species available. In my mind,Tifway (Tifton 419) bermudagrass is still the stan-dard in the industry for golf fairways and athleticfields where it can be grown. It has a rich greencolor and produces aggressive rhizomes and stolons

making it very tolerant to wear with rapid recoveryfrom turfgrass stand loss.

Some specific cultivars of bermudagrass can begrown as far as 53 degrees north latitude, however,most are best suited for growth below 37 degreesnorth—the limiting factor being winter kill. Forinstance Patriot bermudagrass, released by theOklahoma Agricultural Experiment Station(Oklahoma State University), is being used as farnorth as Purdue University in Indiana.

Most bermudagrasses are quite well adapted tohot (85-95 F, day) dry climates and can performwell under moderate drought. However,bermudagrass does not perform well under eventhe slightest of shade. For example, bermudagrassrequires between 800-970 langleys (a unit of radi-ation = one gram calorie per square centimeter ofirradiated surface) per day solar radiation (390-


THE PERILS of growing bermudagrass on the California coast

470 watts per square meter perday). This equates to at least 6hours of full sun per day.Compare this to many cool sea-son grasses that can thrive withonly 245-490 langleys per day.This represents a very significantdifference in shade tolerance.

Growing bermudagrass inshade is especially difficult whenmanaged at low mowing heightsunder any traffic stress like athlet-ic fields. Fortunately, most athlet-ic field designs provide for mini-mal structural shade throughoutthe day. This is not always truewith golf course designs, as plant-ing or leaving a “strategic” tree(s)can be an important part of golfhole design yet can pose hours ofshade per day.

This brings me to the subjectat hand—growing bermudagrassin the coastal regions ofCalifornia which includes SanDiego in the southern most partnorth to the central coastalregion of San Luis Obispo—approximately 300 miles northof the Mexican border. This areais characterized as having a mildMediterranean climate with aver-age summer temperatures rang-ing from 75-90 F (day) withwinter temperature ranging from40-60 F. This is perfect weatherfor humans but not very idealfor growing many warm seasongrasses. This is especially truewhen you consider the rapiddrop in night time temperaturesin the summer.

Add to this the “coastal”influence which includes fog andclouds, you can see that thisregion may not always be con-ducive to growing bermudagrass.Not only do you not have tem-peratures suited for bermuda-grass growth but cloud inducedlimitations in radiant energy ade-quate for photosynthesis may belacking as well.

FieldScience | By Dr. Terry L. Vassey

Growing bermudagrass in shade is especially difficult when managedat low mowing heights under any traffic stress like athletic fields.

www.stma.org

COMPARE WITH PHOENIXComparing the percent growth potential

(GP) for bermudagrass in Phoenix, AZ (wherebermudagrass is highly preferred) with that ofSan Diego, CA there is a significant differencein potential for growth. Growth potentialreaches 100% in Phoenix for approximately 6months of the year (late May to mid-October). The highest GP in San Diego,however, only reaches a high of 40% and foronly about 3 months (July to mid-September). In Sacramento (further inlandbut also further north of San Luis Obispo) theGP still only reaches a high of 60% for July tomid-September.

Gelernter and Stowell state that bermuda-grass still performs adequately at and above50% growth potential, but does poorly belowthat mark. So you can see why turfgrass man-agers struggle along California’s coast to growquality bermudagrass.

What this means is that even though itappears these coastal regions should be idealfor bermudagrass growth, low average temper-atures (especially at night) and cloudy/foggydays prevent adequate carbohydrate produc-tion and therefore limited growth inbermudagrass.

FESCUESThis is not the case for most cool season

grasses, however. I have found that both tallfescue and the fine fescues do very well inthese coastal regions as they have moderateheat and drought tolerance and do well undercloudy/foggy (slight shade) conditions. Thepotential problem with growing these coolseason types, however, whether here in SanLuis Obispo or in San Diego, are the drysummer conditions and the poor quality waterresulting in salt and carbonate accumulations(Bowman, et.al., 2006). As an aside, Kentuckybluegrass does not perform well in southernCalifornia because of the occasional high sum-mer temperatures and the water requirementsfor its survival.

MANAGEMENT STRATEGIESManaging bermudagrass on the California

Coast involves treating the stand as if it weregrowing in shaded condition, because ulti-mately it is. Shaded bermudagrass developsthin, etiolated leaves, increases internode

SportsTurf 33

length, and a poorly developed root system. Over time, shade results in a thin canopy

intolerant to traffic. Under traffic stress, thestand will rapidly thin to the point of standfailure, weed intrusion, and finally, poor sur-face performance.

Therefore managing bermudagrass underthese conditions require maximizing photo-synthetic efficiency and traffic control.Managers should be aware that “normal”management strategies need adjustment.

One of the most important considerationsis how much and what kind of nutrition toemploy. The principle being to avoid exces-sive succulent growth by using high rates ofsoluble nitrogen sources which leads to plantsill equipped to handle stress.

As the plant will use any and all carbohy-drate reserves for leaf growth and not forstolon and rhizome growth, re-growth poten-tial from heavy stress will be reduced.Potassium should be used judiciously to pro-mote carbohydrate synthesis and leaf harden-ing as well as increased water conservationand winter hardiness.

Mowing height should be maintained atthe higher limit allowed for the intended use.For instance, using bermudagrass for fairwaysvs. athletic fields vs. home lawns require dif-ferent mowing practices and, therefore, differ-ent tolerances.

Managers may have to cultivate moreoften yet less aggressively. Compaction reliefand aeration are important but recovery fromthese activities, especially if they are intensive,may be slow and therefore, may promotepoor recovery, quality, and weed envision.

Overseeding is a very popular and impor-tant practice to those that manage athleticfields during the winter months. Overseedinginvolves planting (seeding) a cool season (CS)grass into an existing canopy of a warm sea-son (WS) grass (usually bermudagrass). Thisprocess starts in the fall as the bermudagrass isgoing dormant and results in good color andplaying conditions during the winter from theCS grass.

On the California coast, those that over-seed have very interesting concerns as itrelates “spring transition.” This is whenmanagement switches away from the CSgrass and shifts to promoting the annualrecovery (green-up) of the WS grass.

In the coastal regions of California, it iscritical that the spring recovery (transition)of the bermudagrass not be delayed.Bermudagrass relies on stored carbohydrates,accumulated the previous summer and earlyfall, for re-growth of new shoots in thespring. As we may assume that bermudagrassgrown on the California coast may not havestored a great deal of sugar, we can alsoassume that there may be times when theremay not be enough sugar to overcome ahighly competitive CS grass during transi-tion, especially if the perennial ryegrass isgrowing at its best.

Therefore, managers on the Californiacoast should considered a well timed chemicalapproach to removing the CS grass.Something like Revolver, Manner, or Kerbcan provide quick reliable removal of the CSgrass during the spring (Figure 1).

Using Figure 1 you can see that timing isthe critical factor. I would recommend apply-ing the product when the bermudagrass hasreached approximately 50% green-up of anyun-overseeded areas (create a test area). It isimportant to consult the label and your serv-ice professionals as there are several considera-tions for use, specifically grass species toler-ances, movement of the material along thesoil, and soil temperature at application.

Using bermudagrass cultivars tolerant toeither cold, shade, or both may provideanother possibility. Although not everyonecan or will renovate to new species of onegrass or another, there are some newbermudagrasses available that may providechoices for quality turfgrass in these difficultcostal conditions.

For instance, the University of Georgia’sWayne Hanna recently released a new“Tifton” bermudagrass called TifGrand which

has been developed as a shade tolerantbermudagrass. This hybrid will be availablesometime in 2010.

Another shade tolerant bermudagrassalready available is Bull’s Eye (West CoastTurf). It was recently installed on the baseballfield at PETCO Park, home of the San DiegoPadres. It was chosen for its color, durability,and tolerance for shade. This grass is alsofound on the Bank One Ballpark, home ofthe Arizona Diamondbacks.

Lastly, in a 2-year study conducted byBaldwin and Lui, they were able to rank sev-eral different bermudagrasses for response toshade. They found, using 64% continuousshade that the best cultivars for shade toler-ance were Celebration, TifNo.4 (TifGrand),TifNo.1 and Transcontinental based on turf-grass quality, chlorophyll content, root bio-mass, and root length.

I think that it is easy to see that growingbermudagrass on the California coast can bedifficult at times. Cloudy conditions withperiods of less than ideal high summer tem-perature make growing bermudagrass a chal-lenge. With good management, though, andthe right cultivar choices whenever possiblecan make management easier.

Actually, whether growing a warm seasonor a cool season grass on the beautifulCalifornia coast practitioners will experienceproblems. Whether it is the climate, the soil,or the water turfgrass managers in Californiamust stay on top of their managementstrategies to ensure the best turfgrass qualitypossible. ■

Dr. Terry L. Vassey is an assistant professorat California Polytechnic State University, SanLuis Obispo, CA. For references, see www.sport-stur fonline.com.


FieldScience

Figure 1. Chemical products used to remove cool season grasses from overseeded bermudagrassduring spring transition.

Kerb 50WP 1 lb / A - - -Manor or Blade 60DF 0.5 - 0.75 oz / A - - -Revolver 0.19SC 9 oz / A 17-26 oz / ATranXit 25DG 0.5 oz / A 1-2 oz / AMonument 75WG 0.1 oz / A 0.3 oz / A

Trade Name Slow Activity (3-6 Wk), Fast activity (1-2 Wk) Applied late April - May Applied mid-May - late May


W HY SHOULD THE EAST ANAHEIM LITTLE LEAGUE MATTERTO YOU? The league’s field, once a treacherous battle-ground where bad hops usually led to bloody mouths, hasnow become a proving ground for professional baseball.

When the East Anaheim Little League came to Barney Lopas, headgroundskeeper for the LA Angels of Anaheim for help on their field, itwas a challenge to adapt a major league maintenance schedule to afield that lacked tools, budget and had a fluctuating base of volunteermanpower. Lopas, a concerned parent and coach, asked himself, “whatcan I focus on right now to make the biggest impact on this field with-in the league’s budget and volunteer help?”

Being that 70% of a baseball or softball game is played on the infieldskin, Lopas decided to focus his efforts there. If a ground ball made itover the infield lip, player’s had to expect the unexpected with theunpredictable infield. The loose infield mix not only created dangeroushops, it made it difficult for the players to find stable footing. While theaddition of moisture provided a somewhat better surface, too muchmoisture compromised the immediate game and the field’s usabilityfor days.

Replacing the infield mix was definitely not within the league’sbudget. Lopas realized that the one thing he could carry over from hismajor league field, and still stay within budget, was an infield amend-ment.

PARTICLE SIZE ANALYSIS IS A MUSTThe first step in amending an infield is knowing where you stand

right now. We have all heard the numbers, an infield mix should be 70%sand, and 30% evenly split between silt and clay. Without a true particlesize analysis you may think you have plenty of clay content, but youmay actually be playing on silt. Too much sand can usually be improvedby adding more clay (depending on the parent material of the mix).

On the flip side, too much clay can generally be remedied by addingmore sand. Too much silt to begin with, and you are better off startingwith a new infield mix altogether. While silt is a necessary componentof making a good infield work, too much of it can put you in a ‘noman’s land’ of poor drainage and no cohesion, similar to what Lopashad to deal with. Only extreme cases warrant adding silt.

This brings us back to the particle size analysis; if you don’t know thecomposition of your infield, you may be adding unnecessary silt, sand,or clay.

Of course a quality infield mix is the best starting point. Infield mixesvary by use and region; a major league mix is going to be closer to 60%sand and 40% silt and clay, with more of a focus on the clay. This type ofinfield will be difficult for a little league or heavy use municipality tomaintain properly. These fields should be closer to the 70/30 range.

Many high school, municipality, and even college fields use soils thatmay be classified as “clay loam” and fit within the recommended particlesize, but contain too much organic matter (broken down plant materiallike mulch). While organic matter is great for plants, it is bad for players.

Too much organic matter can loosen soil, impede lateral surfacedrainage, and disrupt the structure that hard soil particles provide to

support the player. The biggest problem with organic matter is that itbreaks down and turns into silt. Many laboratories provide a separateorganic matter content test, sometimes included with the particle sizeanalysis. This test can provide you with valuable information that canhelp you plan ahead for future silt from organic matter breakdown.

Find an infield mix that derived from a good parent material,processed mechanically and produced specifically for baseball and soft-ball to avoid high organic matter content. If you don’t have the luxuryof purchasing a new infield mix, proceed with an infield amendment.

SELECTING AN AMENDMENTThe next step is to know your goal. The East Anaheim Little League’s

main objective was player safety. A municipal field’s goal may be ReturnOn Investment—maximize field use while reducing maintenance. Acollege may want to enhance home field advantage and get morepractice time despite the elements.

While most desire all of these goals, really focusing on one or twomotives will help in matching the right amendment with your existingsoil conditions. Infield amendments should be used cautiously and for aspecific reason, not just thrown onto an infield and expected to “dosomething.” If not used properly, they could end up doing more harmthan good.

Infield amendments come in all shapes and sizes, but mainly fallunder two categories: mineral and organic-based. If your goal is toincrease drainage, beyond adding sand and risking a loose infield, min-eral amendments such as gypsum and calcium carbonate can help youimprove your infield’s natural drainage properties. Take care in applyingthese mineral amendments as over application can be a problem.Especially note that calcium carbonate should only be applied to highclay soils. Further soil tests, such as pH studies, should be done to deter-mine the exact amount needed.

While vertical drainage is crucial for playability on an infield, mostwater should exit the infield via lateral drainage. The best way to improvelateral drainage is building a 1/2% slope into your field at the onset andmaintaining a level field over time. Keeping a field level during a game isdifficult, as low areas are bound to form and collect puddles.

Conditioners can be a good way to absorb puddles and continueplay in rainy weather. The most popular conditioners are calcined or vit-rified clay, mineral amendments made from fired clay particles thatmaintain a loose consistency and absorb water. Conditioners also workwell as topdressings on higher clay infields. They provide the loose“cushion” needed to drag and slide on.

Conditioners work great for what they are designed to do, but MarkRazum of the Colorado Rockies warns, “infield conditioners are not acure-all. Before adding them, you need to make sure your infield is leveland your holes filled in with a good infield mix. I see it time and again,groundskeepers think they can just level their field with a topdressing,but the end result is like playing in a sand pit. When infield conditionersare substituted for good groundskeeping, they can turn against you.”

Organic infield amendments are used to increase safety and fieldusage. They are incorporated into the soil to help stabilize the infield

“AMENDING” INFIELDS ON A BUDGET

FieldScience

Mon

ey im

age

cour

tesy

of

isto

ckph

oto.

com

.

Editor’s note: This article was written by former MLB groundskeeper Clayton Hubbs, now with Stabilizer Solutions, Inc., Phoenix, AZ.


and improve cohesion and absorption. Goodorganic amendments will effectively bind soilparticles to help turn loose, even unplayableinfields into cohesive and stable footings.These products make silt particles act morelike clay particles, which is a great defenseagainst weather extremes.

The East Anaheim Little League actuallyapproached Barney Lopas several years ago.Now Lopas has crafted a yearly maintenanceprogram, which builds upon the progressfrom previous years. “Small incrementalchanges each year can lead up to equal thebig immediate renovation,” says Lopas. Whilethe maintenance program focuses on newareas of development, like turf health andmound renovation, the importance of theinfield amendment, Stabilizer®, is never forgot-ten. You don’t need to add the same amountas the initial installation, but adding the rec-ommended amount each year can ensurethat you don’t undermine the progress you’vealready made.”

A recommended infield amendment pro-

gram should include ripping and tilling yourfields once a year. Fines do sink to the bot-tom, which in a small amount can be a goodthing. When fines sink, larger particles remainon top, providing the loose cushion or slidingsurface. Too much sinking and your surfacebecomes too loose and drainage layers mayform. The surface soil particles themselvescan also become crushed from overuse,depending on the parent material of theinfield mix. Also, soil particles weather andbreak down the same way that the GrandCanyon was formed: exposure to rain, snow,and sun. Ripping and tilling once a year even-ly blends soil particles, brings fresh soil parti-cles to the surface, and provides a goodopportunity to level the infield by addingadditional infield mix.

Adding infield mix once a year is a goodidea, as the mix is washed into the grass,players pick up the mix on their cleats andgroundskeepers throw infield mix awaywhen picking up debris. Before tilling,amendments that are incorporated into the

soil such as mineral and organic amend-ments, should be spread at the recommend-ed rates via drop spreader or topdresser.Tilling incorporates infield amendmentsevenly throughout the profile. Alwaysbeware of getting into your base materialwhen you are tilling. After tilling, the infieldshould be leveled, preferably by a laser grad-er to achieve the 1/2% slope, watered, androlled if necessary. This program should beperformed more than once a year for fieldsthat receive extremely heavy use. ■

Clayton Hubbs is a former groundskeeper forthe Arizona Diamondbacks and Director ofOperations for Stabilizer Solutions, Inc.,[email protected]. Productsfrom Stabilizer Solutions, Inc. are used by littleleague, college and numerous professional fieldsincluding: L. A. Angels of Anaheim, ArizonaDiamondbacks, San Diego Padres, Oakland A’s,Colorado Rockies, Philadelphia Phillies, New YorkMets, and New York Yankees.

Preemergence crabgrass control on athletic fieldssturf.lib.msu.edu/article/2010mar20a.pdf · control on athletic fields Large and smooth crabgrass can be differenti-ated by examining

Documents