Fertility Management for

Annual Bluegrass

Tom Cook & Brian McDonaldOSU Horticulture Dept.

Oct 30, 2007

Eugene Country Club

MichelbookCountry Club

Putting greens in Oregon range from 80% to almost 100 % annual bluegrass.

The reality of golf course maintenance in the PNW is that annual bluegrass will eventually dominate turf on tees, greens, and fairways. The sample on the left is nearly 100% annual bluegrass. The sample on the right is 94% annual bluegrass on a shoot count basis.

T Cook photo

Perennial type Annual type

Virtually all Poa annua biotypes in PNW greens are perennial types. Annual types are rare. T Cook photo

Compact spreading perennial type

T Cook photo

In older greens, it is easy to find 25-30 different phenotypes of annualbluegrass. The best turf quality comes from compact spreading types.On greens they often appear tight, dense, and fine textured. Many of theseflower heavily in spring, very little in summer, with a slight burst in fall. Somedon’t flower at all.

Erect growing perennial type

T Cook photo

Erect growing perennial types tend to be among the early colonizersand tend to flower during most of the growing season. Most are coarse in texture and are generally easy to spot in between the distinctive compact spreading types.

0

50

100

150

200

low med-low

med med-high

high

Prevalence

Natural occurrence of Poa annua in soils of different P levels

From: Kamp 1981Relative soil P level

Basically, as P levels in soils Increased the researchers found more annual bluegrass.

020406080

100120140

low med-low

med med-high

high

Prevalence

From: Kamp 1981Relative Soil K

Natural occurrence of Poa annua on soils of varying K content

If K was adequate, the annualbluegrass levels were fairly constant. K had less impact onannual bluegrass than P.

020406080

100120140160

<5 5-5.5 5.5-6 6-6.9 >7

Prevalence

From: Kamp 1981

Natural occurrence of Poa annua at varying soil pH levels

Annual bluegrass occurred over a wide range ofsoil pH levels. In the range from 5-7 it was very common.

1937Annual bluegrass and its requirements for growth.Sprague, H.B. and G.W. Burton. N.J. Ag. Exp. Sta. Bull 630, 24 pp.

General findings:

1. Acid soils (pH 5 or lower) do not favor annual bluegrass.

2. At optimum pH (6.5), balanced nitrate and ammonium favor annual bluegrass.

3. Liberal phosphate, nitrates, and calcium favor annual bluegrass.

4. In sand cultures, nitrate nitrogen was preferable to ammonium.Balanced nitrate and ammonium produced best shoot to root ratio.ex.) 1.8 vs. 2.4 – 3.0.

5. Sulfate of ammonia reduced root and shoot growth.

There has been a modest amount of research on annual bluegrass fertility requirements. The following summaries detail what we have learned from these studies.

1969Nutritional requirements of Poa annua L.

Juska, F.V. & A.A. Hanson. Agron. J. 61: 466-468.

Findings:1. On loamy sand pH 6.5 produced 2X as much top growth as pH 4.5

2. Added P on loamy sand at pH 4.5, increased top growth.

3. Highest top yields from NPK on loamy sand and silt loam occurred at pH 6.5.

4. Roots increased with pH in loamy sand but not in silt loam.

5. Seedhead production on loamy sand increased with pH increase.pH had no effect on flowering on silt loam.

General conclusions:Annual bluegrass is competitive on acid silt loam soil. It responds to lime and NPK on poor light textured soils.

1975

The effects of N, P, K, and S on Poa annua L. in bentgrass putting green turf.Goss, R.L., S.E. Brauen, & S.P. Orton. J. Sports Turf Res. Inst. 51:74-82.

General Findings:

1. Unbalanced N-P-K reduced annual bluegrass encroachment.

2. Consistent high rates of Sulfur is detrimental to annual bluegrass.3.5 lbs S/1000 sq ft per year reduced annual bluegrass.

3. Long term application of S lowered pH from 5.6 to 4.6.

3. Increased P levels increased annual bluegrass.

4. Adequate but not excessive S + P tended to increase annual bluegrass.

1978

The effects of nutrient supply on flowering and seed production in annual bluegrass.

Ong. C. K., C. Marshall, & G.R. Sagar. J. Br. Grassland Society. 33:117-121.

General Findings:

1. Seed production increased 30X as nutrient supply increased.

2. High nutrient levels increased flowers at the expense of roots.

1981

Influence of N & P fertilization on the growth and development of Poa annua L.

Dest, W.M. & D.W. Allison. In Proc. of 4th Int. Turfgrass Res. Conf. pp. 325-335

General Findings:

1. On low P soil, annual bluegrass maintained adequate tissue P without added fertilizer P.

2. Leaf tissue P levels increased only slightly with added P

No P = .42 % dry wt. High P = .56 % dry wt.

Synthesis of historical research 1937-1981

1. Annual bluegrass tolerates a wide range of soil pH’s.Optimum is probably 5.5 – 6.5.

2. Annual bluegrass tolerates low soil P but responds to high P fertilization.

3. Flowering and seed set increases on fertile soils withadequate N & P.

4. Balanced nitrate & ammonium sources produce healthy annual bluegrass and optimum shoot/root ratios.

5. Excessive S on mineral soils is deleterious to annual bluegrass

6. Annual bluegrass responds vigorously to fertilizer on sandy soils.

What’s the catch?

>All historical studies were trying to figure out why annual bluegrass invaded other grasses.

>The goal was to learn to manipulate fertilityto discourage Poa annua .

>None were directed at growing healthy annual bluegrass.

00.5

11.5

22.5

33.5

44.5

5

N P2O5 K2O S

Best Guess optimum N-P-K-S ratios

Based on historical research trial results

OSU Poa annua fertility trial

Questions:1. How does N level affect turf ?

2. How do Ca and S affect turf?

3. Does fertility affect disease incidence?ex.) Microdochium patch

Anthracnose

Sand based Poa annua green at OSU L.B. Farm, Corvallis, OR.

Constructed in spring 2004: 90/10 greens mix donated by Walrath Sand Products, Tacoma,WA.Established from aerifier cores from Corvallis Country Club.

Basic maintenance:Mow 5X/week at .110” Toro Flex in summer, .140” in winterTopdress every two weeksCore and heavy topdress 2X per yearGroom as neededIrrigate as needed

T Cook photo

Basic N, P2O5, K2O: Andersons 28-5-18 soluble with.02% B, .07% Cu, .10% Fe,.05% Mn,.05% Mg,.0005% Mo, .05% ZnN sources include KNO3 and Urea

Applied 2X per month at .125 lb N or .25 lb N.

S: Elemental Sulfur

Applied 1X per month as per treatment plan

Ca, Silica & Humates:Calcium Carbonate (35% Ca)Huma Ca (Ca from gypsum 18%, SO4 from gypsum 5%, Humates 35%)Huma Phos (P2O5 5% , Ca from gypsum 20%, SO4 from gypsum 5%,

SiO2 10%, Humates 14%)

Applied 2X per year after coring in spring and fall

3.52.554.252.11.833.25128.7504.54.252.10.583.2511

008.754.252.10.583.251000032.10.583.259

3.52.552.752.11.833.2588.7504.52.752.10.583.257

008.752.752.10.583.2560001.52.10.583.255

3.52.551.252.11.833.2548.7504.51.252.10.583.253

008.7502.10.583.25200002.10.583.251

HumatesSiO2Ca SK2OP2O5Ntrt #

Low N trial annual nutrient target values in lbs/1000 sq ft

3.52.554.254.22.416.5128.7504.54.254.21.166.511

008.754.254.21.166.51000034.21.166.59

3.52.552.754.22.416.588.7504.52.754.21.166.57

008.752.754.21.166.560001.54.21.166.55

3.52.551.254.22.416.548.7504.51.254.21.166.53

008.7504.21.166.5200004.21.166.51

HumatesSiO2Ca SK2OP2O5Ntrt #

High N trial annual nutrient target values in lbs/1000 sq ft

Trial Timeline:

2004: Establish green with aerifier cores

2005: Initiate fertilizer treatmentsPlots treated all year but no data taken.

2006: Fertilizer treatments are modified to improve basic quality oflow N plots. Temporarily increased N rates to 4+ lbs N per 1000 sq ft per year. High N plots receive 2X the low N plots.

Data collected include soil tests, turf quality, and Microdochium patchactivity.Fungicides applied three times through winter to manage disease.

2007: Fertilizer treatments adjusted back closer to design rates.All plots receive Primo applications through summer.Data collected include soil tests, turf quality, and Microdochium patch.Fungicides applied after disease ratings as needed to avoid turf damage.

Results:

5.95045.55514.250126.66305.77394.2525106.67605.95972.752567.17555.874102526.23665.3589001

pHCa ppmpHCa

ppmlb/1000lb/1000Trt.

SCaCO3

20072006

Soil test values from Low Nitrogen Trial

Calcium alone or with sulfur has raised the pH notably and sulfur alone appears to be lowering pH slightly compared to no sulfur and no calcium.

Results:

65075.25934.250126.56955.85954.2525106.77865.76362.752566.77875.877002525.96025.5669001

pHCa ppmpHCa ppmlb/1000lb/1000Trt.SCaCO3

20072006

Soil test values from High Nitrogen Trial

With calcium alone or calcium plus sulfur, soil pH has gone up. Where no calcium has been applied, the pH has stayed constant so far.

0.50.50.50.50.51.00.7 LSD @ 05

5.04.3NPK12

4.54.3NPK11

8.84.3NPK10

0.03.0NPK9

5.02.8NPK8

4.52.8NPK7

8.82.8NPK6

0.01.5NPK5

5.01.3NPK4

4.51.3NPK3

8.80.0NPK2

0.00.0NPK1

Ave.May-07Apr-07Feb-07Dec-06Sep-06Aug-06Jul-06CaSFert.Trt

Low N Trial: Turf quality ratings

5.36.06.44.45.44.75.34.7

5.46.16.34.25.85.15.84.7

5.55.96.23.75.45.66.45.1

5.66.76.64.35.45.35.65.0

5.46.36.44.45.65.15.24.5

5.66.36.44.15.75.76.15.2

5.14.95.93.35.35.16.54.9

5.66.36.34.45.85.26.25.2

5.45.96.24.15.26.06.04.7

5.36.06.24.15.55.05.44.9

5.45.35.83.74.85.96.75.3

5.46.26.34.35.15.25.65.2

Target quality ratings = 6+ . Under low N, none of the plots had high over all quality ratings.

ns0.50.50.50.5ns0.7LSD @ 05

6.67.27.96.16.35.76.96.05.04.3NPK12

6.67.27.96.16.35.37.16.44.54.3NPK11

6.67.26.85.76.26.07.56.78.84.3NPK10

6.46.87.76.36.05.36.95.60.03.0NPK9

6.57.17.26.06.55.47.25.85.02.8NPK8

6.67.17.45.95.86.27.66.24.52.8NPK7

6.26.86.45.75.95.37.16.18.82.8NPK6

6.37.27.25.85.95.37.35.70.01.5NPK5

6.37.16.85.56.15.67.35.95.01.3NPK4

6.57.26.75.46.45.67.66.44.51.3NPK3

6.16.86.64.65.45.67.76.18.80.0NPK2

6.37.16.75.95.65.86.76.30.00.0NPK1

Ave.May-07Apr-07Feb-07Dec-06Sep-06Aug-06Jul-06CaSFert.Trt

High N Trial: Turf quality ratings

Target quality ratings = 6+. Turf quality ratings were notably higher at the high N rate.

1.36.65.35.04.3NPK121.26.65.44.54.3NPK111.16.65.58.84.3NPK10.86.45.60.03.0NPK9

1.16.55.45.02.8NPK816.65.64.52.8NPK7

1.16.25.18.82.8NPK6

.76.35.60.01.5NPK5

.96.35.45.01.3NPK41.26.55.34.51.3NPK3.76.15.48.80.0NPK2.96.35.40.00.0NPK1

Dif.High NLow NCa SFert.Trt

Low N Trial vs High N Trial: Turf quality ratings

High N plots

T Cook photo

General turf quality is acceptable for annual bluegrass putting turf.There is a balanced mix of bentgrass and annual bluegrass in most plots. Annual bluegrass is dominant in fall winter and spring and bentgrass comes on in summer.

Fertility effects on Microdochium patch

T Cook photos

2.03.33.52.55.04.3N, P, K + Huma Phos

1.31.78.80.04.54.3N, P, K + Huma Cal

4.08.70.00.08.84.3N, P, K + CaCO3

1.31.00.00.00.03.0N, P, K

4.72.73.52.55.02.8N, P, K + Huma Phos

4.34.78.80.04.52.8N, P, K + Huma Cal

5.06.70.00.08.82.8N, P, K + CaCO3

3.33.30.00.00.01.5N, P, K

4.36.33.52.55.01.3N, P, K + Huma Phos

4.09.08.80.04.51.3N, P, K + Huma Cal

5.017.00.00.08.80.0N, P, K + CaCO3

4.34.00.00.00.00.0N, P, K

4 9 0710 26 06

NPK + S Ca SiO2 Humates # Spots Activitylbs / yr lbs / yr lbs / yr lbs / yr per plot 1 – 9

9 = worst

Microdochium (Fusarium) patch activityHigh N Trial Fall 2006, Spring 2007

Disease response:

Based on visual observations we have observed an increase in Fusarium patch activity when lime is applied to the turf.

This trend is dramatic in the high N trial and less apparent in the low N trial.

The other trend that has emerged so far is that plots receiving higher levels of sulfur have less Fusarium patch activity than plots receiving lower levels of sulfur.

Estimating % area affected by diseasevia image analysis software.

Software developed by Doug Karcher &Mike Richardson at U of Arkansas.

We have utilized image analysis software to help us distinguish differences in disease activity. The red spots indicate turf damaged by Microdochium nivale.

Software computes area of damaged turfbased on color differences between healthy and injured turf.

NPK + S Ca SiO2 Humates # Spots % plotlbs / yr lbs / yr lbs / yr lbs / yr per plot area

Results: Microdochium (Fusarium) patch activityHIGH N Plots Fall 2006, Fall 2007

0.23.33.52.55.04.3N, P, K + Huma Phos

0.41.78.80.04.54.3N, P, K + Huma Cal

8.28.70.00.08.84.3N, P, K + CaCO3

0.61.00.00.00.03.0N, P, K

1.92.73.52.55.02.8N, P, K + Huma Phos

2.24.78.80.04.52.8N, P, K + Huma Cal

3.16.70.00.08.82.8N, P, K + CaCO3

4.23.30.00.00.01.5N, P, K

3.06.33.52.55.01.3N, P, K + Huma Phos

7.39.08.80.04.51.3N, P, K + Huma Cal

8.517.00.00.08.80.0N, P, K + CaCO3

4.94.00.00.00.00.0N, P, K

10 23 0710 26 06

LSD .05 = 5.6

Microdochium patch activity Fall 2007

Low N Trial Sulfur levels lbs./1000/yr.0-1.3 1.5-2.75 3-4.25

% plot area affectedN,P,K 3.5 2.3 2.4N,P,K + CaCO3 2.6 3.2 2.3N,P,K + Huma Cal 3.0 4.7 3.8N,P,K + Huma Phos 3.3 3.2 1.6

High N Trial Sulfur levels lbs./1000/yr.0-1.3 1.5-2.75 3-4.25

% plot area affectedN,P,K 4.9 4.2 0.6N,P,K + CaCO3 8.5 3.1 8.2N,P,K + Huma Cal 7.3 2.2 0.4N,P,K + Huma Phos 3.0 1.9 0.2

LSD @ 5% = 5.6

General Trends Through Fall 2007 *:

1. Two full years of treatments starting to affect soil pHHigh lime plots are showing a slight pH increaseHigh sulfur plots are showing a slight pH decrease

2. High N plots have higher plot quality

3. Microdochium patch generally worse in High N plots

4. High lime plots tend to have worse disease

5. High N without lime but with high S has less disease

6. No apparent effect from Humates

* Variability in ratings makes interpretations difficult

Thanks to:

Western Canada Turfgrass AssociationNorthwest Turfgrass AssociationWalrath Sand Products

For financial and in kind support for this trial