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Colonial Bentgrass Can Lower Fairway Inputs By Stacy A. Bonos

Higher energy prices have increased the costs of almost everything, including grass seed, fertilizer and pesticides. As the costs of energy rise, many are looking for ways to cut costs. Additionally, more emphasis is being placed on conserving

natural resources and reducing inputs. With all of that in mind, colonial bentgrass on your fairways might make sense for some golf courses.

Creeping bentgrass (Agrostisstolonifera) is currently the most widely used bentgrass for golf courses. Its prostrate growth habit and ability to produce vigorous spreading stolons allow it to tolerate low cutting heights and quickly recover from damage. This makes creeping bentgrass a good choice for golf course putting greens in the cool, temperate climates and some cases in warm climates. However, creeping bentgrass as a species is very susceptible to dollar spot disease (caused by Sclerotinia homoeocapa F.T. Bennet) and typically requires regular fungicide applications and rigorous cultural practices for acceptable quality.

Dollar spot disease is probably the most c o m m o n disease on golf course turf in the Northeast. Although breeders have developed creeping bentgrass cultivars with improved resistance, they still can require several fungicide applications per year. Colonial bentgrass [Agrostis capillaris) generally has bet ter tolerance o f dollar spot disease than creeping bentgrass (Photo 1).

Colonial bentgrass, also known as brown top, has traditionally been used on lawns and golf courses in areas o f Northern Europe and New Zealand that have mild (cool

and humid) summers. Com-pared to creeping bentgrass, colonial bentgrass has a more upright growth habit and spreads by short rhizomes instead of stolons. In addi-tion to differences in growth habit, colonial bentgrass also differs in genetic color.

Colonial bentgrass ranges from light to medium green while creeping bentgrasses typically range from medi-um green to a dark blue-green color (Photo 2, p. 60 ) .

Dollar spot disease resistance of colonial bentgrass Additionally, colonial bent-(left) compared to creeping bentgrass (right). Continued on page 60

IN THIS ISSUE

• Disease Con t ro l Cultural practices play a big role in limiting turf grass loss from pathogens 64

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Q U I C K T I P

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Continued from page 57 grass typically retains more green color during winter compared to creeping bentgrass. Colo-nial bentgrass also does not accumulate thatch as aggressively as creeping bentgrass cultivare with high shoot density. High-density creeping bentgrasses can require adjustments in man-agement practices, including increased top-dressing and cultivation (aeration, verticutting and grooming) to manage thatch development. Colonial bentgrasses typically do not require aggressive cultural management. Additionally, it has been documented that colonial bentgrass exhibits faster recovery from drought stress compared to creeping bentgrass (DaCosta and Huang, 2 0 0 7 ; DaCosta and Huang, 2 0 0 6 ) . T h e drought recovery, reduced maintenance requirements and increased dollar spot resis-tance o f colonial bentgrass make it an inter-esting choice for golf course fairways during a time when environmental conservation, using lower inputs and energy conservation are on the minds of many people.

However, colonial bentgrass does have a major weakness affecting its use in temper-ate areas o f the United States. It is susceptible to brown patch disease (caused by Rhizocto-nia solani Kühn) (Photo 3) . Brown patch can cause some loss o f turf density on creeping bentgrass, mainly during July and August, but

severe damage from brown patch disease is unusual on creeping bentgrass in the North-east and north-central United States. Colonial bentgrass cultivars, however, are quite suscep-tible to brown patch disease, and loss o f turf density (damage) can be strongly evident from June through September.

It has been the goal o f the breeding program at Rutgers for the past 10 years to improve the brown patch resistance in colonial bentgrass so that it will be more useful as a potential grass for fairways and tees. Prior to this research, there were no studies conducted on the inher-itance o f brown patch resistance in colonial bentgrass. It is important to understand how disease resistance is inherited in order to opti-mize selection procedures.

Traits can be inherited in different ways. Quali tat ive inheritance typically involves one (or a few) genes that confer complete resistance and are not strongly influenced by the environment. Quantitative inheritance involves a large number of genes that confer partial resistance and are strongly influenced by the environment. If brown patch is inherited qualitatively, then selection could be conduct-ed in one environment, possibly with limited replications. If brown patch is inherited quan-titatively, then steps need to be taken to deter-mine the extent o f environmental influence

Color differences of colonial bentgrass compared to creeping bentgrass. Colonial bentgrass plots have a bright, medium-green color compared to the dark, blue-green color of creeping bentgrass plots.

on the disease compared to the genetic influ-ence. It also would typically require evaluation in a number o f environments with multiple replications. Preliminary research on brown patch resistance in tall fescue indicates that resistance may be quantitative (Simmons and Hamblin, 2002 ; Bonos et al., 2 0 0 4 ; Bokmeyer et al., 2 0 0 6 ) . W e have previously shown that dollar spot resistance in creeping bentgrass is most likely quantitatively inherited (Bonos et

al., 2003 ; Bonos, 2 0 0 6 ) . W e have been investigating several selection

techniques to improve brown patch resistance in colonial bentgrass. Selecting plants based on turf plot evaluations has only resulted in mod-erate improvements in brown patch resistance. However, we have found that selecting plants based on mowed spaced-plant evaluations has resulted in greater improvements in disease resistance compared to turf plot selection.

Individual colonial bentgrass progeny plants from seven controlled crosses between toler-ant and susceptible parents were planted into a stand of perennial ryegrass in the fall of 2(X)1. T h e mowed-spaced plant trial was maintained at 1.9 centimeters ( % inch). Tolerant and sus-ceptible parent plants were planted with three replicates. All plants were inoculated with a mixture o f two different brown patch isolates isolated from colonial bentgrass. T h e isolates were grown on sterilized Kentucky blue-grass seed and applied with a drop spreader at approximately 0 .25 grams per square meter (g/ m-'). Brown patch disease was evaluated weekly after symptoms began to develop using a scale from 1 to 9, 9 representing least brown patch disease and 1 representing completely suscep-tible. T h e symptoms occurred approximately two weeks after inoculation. After two full sea-sons o f brown patch disease pressure, significant differences in brown patch disease among colo-nial bentgrass clones were evident (Figure 4) .

From this trial, we found that susceptible parents were not significantly more suscep-tible than the tolerant parents. Plants crossed between two tolerant parents were not more tolerant than crosses between tolerant and sus-ceptible parents. These results indicated that brown patch resistance is significantly affected by the environment and suggests that inheri-tance is quantitative.

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Broiirn patch disease on colonial bentgrass.

• V • • • . • • • • £ Mowed-spaced plant evaluation trial for broum patch resistance in colonial bentgrass.

T h e colonial bentgrass clones with high levels o f disease resistance in the mowed plant trial were selected and moved to isolated cross-ing blocks and allowed to inter-pollinate. Seed was harvested individually from each plant to establish single-progeny turf plots. And equiv-alent amounts o f seed from each plant were bulked to make a composite in order to estab-lish replicated turf plots in the fall o f 2 0 0 2 .

Entries in the turf plot evaluation trial included standard cultivars and experimental selections from numerous turfgrass breeding programs. Entries in each test were seeded using a maximum of 0 .22 g/m2 [ 1.3 pounds per 1 ,000 square feet (ft2)] o f seed. Between 8.9 grams of nitrogen per square meter (g N/m2)

Continued on page 62

MM.wrfgrasstrends.com N o v e m b e r 2 0 0 8 TURFGRASS T R E N D S

Colonial bentgrass cultivars selected for brown patch resistance compared to susceptible cultivars.

J O H N D E E R E

Q U I C K T I P

Soil pH is an essential factor t o consider in the management of h igh-per formance tur f , as it inf luenc-es chemical solubi l-ity and avai labi l i ty of p lant essential nutr ients, pesticide performance and organic matter decomposi t ion. Soil pH values are easily determined by using a simple soil test. For more in format ion on prepar ing your tur f for the fal l , contact your local John Deere Golf sales representat ive or visit w w w . j o h n -deere.com.

Continued from page 61 and 6.5 g N/m2 (2.2 pounds and 1.6 pounds of N per 1 ,000 ft2) were applied annually ( 2 0 0 3 and 2(X)4 respectively). No single N application exceeded 2 g N/m2 (0.5 pounds N per 1 ,000 ft2). T h e annual fertilization program included two granular N applications in the spring and fall at approximately 2 g N/m2 and biweekly liquid N applications during the summer months at about 0 .8 g N/m2 (0.2 lb N per 1,000 ft2). T h e trial was maintained at approximately 0 . 4 8 cen-timeters (3/16 inch) cutting height. T h e trials were rated throughout the growing seasons for turf quality (color, brightness, leaf texture, den-sity, uniformity, amount o f disease and amount of insect damage) and brown patch disease. T h e turf trial was not inoculated with the brown patch pathogen. All disease outbreaks were a result of natural infection.

T h e mowed-spaced plant selection tech-nique has resulted in dramatic improvements in brown patch resistance in colonial bentgrass. T h e experimental selections developed using

this technique ( B C D , 9 1 1 0 - 8 - 1 0 , 9 1 1 1 - 6 - 1 2 ) had higher brown patch ratings than standard cultivars that were not selected for brown patch resistance (SR 7100 , S R 7 1 5 0 ) (Photo 5). This data indicates that this technique is effective in improving brown patch resistance.

This technique was also used to evaluate new collection sources o f colonial bentgrass, for brown patch disease. W e have identified more than 150 colonial bentgrass plants from

2 0 European collection sources with improved brown patch resistance. T h e addition of new sources o f resistance helps to maintain the genetic diversity o f the species and may increase the durability o f resistance. These new European sources o f brown patch resis-tance have been crossed with colonial bent-grasses used in the Rutgers breeding program that are adapted to our climate in the United States. These new experimental selections o f colonial bentgrass are able to maintain very good quality' even in the presence o f heavy brown patch disease pressure.

T h e results reported here indicate that new colonial bentgrass cultivars selected for improved brown patch resistance should be useful on fairways where reduced inputs are anticipated. Newly developed cultivars can maintain acceptable quality with limited fun-gicides; they can recover from drought stress quickly; and they do not accumulate thatch aggressively and therefore do not require excessive cultural practices to reduce thatch accumulation. These attributes make colonial bentgrass an attractive alternative to creeping bentgrass for superintendents interested in reducing inputs and conserving energy on golf course fairways.

Dr. Stacy Bonos is an assistant professor of turf-grass breeding in the department of plant biology and pathology at Rutgers. Her research focuses on integrating classical and molecular genetics to improve and more efficiently breed grasses. She has received grants from several funding agencies, including the USGA, OJ Noer Research Foundation, and USDA NRI-CSREES Plant Genome Program and the USDA/DOE Rural Development Program. She can be reached at bonos@AESOP.Rutgers.edu.

REFERENCE Bokrreye' , J., W.A. Meyer, and S.A. Bonos. 2007. Genetic inheritance of b rovm patch resrstance in tall fescue. In Aqrooomy Abstracts. A.S A , Madison, W l Bonos, S.A. 2C06. Heritabil i ty o f dollar spot resistance in creeping bentgrass. Phytopathology 96 :808-812.

Bones, S.A., M.D. Caster, a r d W.A. Meyer. 2033. Inheritance of dollar spot resis-tance in creeping bentgrass. Crop Science. 4 3 : 2 1 8 9 - 2 1 % .

B o n o s . S A , E . W a t k i n s , a n d W A Meyer . 2 0 0 4 . Heritabi l i ty o f b r o w n p a t c h res is -tance i n tal l fescue. In A g r o n o m y A b s t r a c t s . A S A , M a d i s o n , W l .

DaCosta, M . and 8. Huang. 7007. Drought survival and recuperative abil ity of bentgrass associated w i t h absdsic ac id and cytokinin product ion. J. Am. H o n So. 132(1):6Q-66.

DaCosta, M. , a r d B. Huanq. 2006 . Charges in carbon part i t ioning a n d accumula-t i on pat terns dur ing d roogn t arxJ recovery for colonial bentgrass, creeping bent-grass, and velvet bentgrass. J. Am. Soc. H o f t Sci. 131:484-490.

Simmons, K.L a r d A M . Hambl in. 2002 . Inheritance of b r o w n patch resistance in tall 'escue. Agronomy Abstracts. ASA, Madison, W l .