Record Volume 37, Number 2 March/April 1999 A PUBLICATION ON TURFGRASS MANAGEMENT BY THE UNITED STATES GOLF ASSOCIATION® 1894 MARCH/APRIL 1999 Volume 37, Number 2 Cover Photo: Plant tissues in a frozen or frosted turf are brittle and more easily damaged by traffic. Winter play on tees and greens at many northern golf courses is discouraged to protect the turf and underlying soils, and maintain the integrity of the playing surface. A well-planned putting green nursery can be a superintendent’s best friend in times of trouble. See page 9. Developing an environmental plan is more than just writing goal statements about managing the golf course property. See page 16. necora 1 Golfers’ Role in Maintenance Golfers’ actions impact the golf course and maintenance operations more than they realize. By Jim Skorulski 6 Use of Prodiamine as a Preemergence Herbicide to Control Annual Bluegrass in Roughs Knowing the period of prolific Poa annua germination is crucial to properly timing preemergence applications for its control. By Peter H. Dernoeden, Ph.D. 9 Poa/Bent Nurseries — A Perfect Match Aerification cores can be used to build a putting green sod nursery to match mature Poa annua greens. By Patrick J. Gross 12 Education Does Not End in the Classroom Developing a quality student internship program. By Todd Voss 14 Your Budget is a Sales Tool! Thoughtful budget preparation can help you inform, lead, and sell your ideas. By Chris Carson 16 The First Step in an Environmental Plan: Before you start planning what you will do to improve environmental conditions on your course, it’s a good idea to have a map of your resources. By Mary Colleen Liburdi 17 Survival Tools for the Putting Green Using a few tools can enhance stress management on putting greens. By Christopher E. Hartwiger 18 USGA Green Section Record— A Limited CD Series 19 News Notes 20 Where Is Your Loyalty? Superintendents and course officials alike have lost their sense of loyalty to each other. By Mike Huck 22 Turf Twisters Golfer etiquette and course responsibility are more important than ever before as the game’s popularity grows. Golfers’ Role in Maintenance Golfers’ actions impact the golf course and maintenance operations more than they realize. by JIM SKORULSKI IT IS A CRISP, clear Saturday morning in October. The sun is just beginning to rise as you step into a hot shower and prepare for the 8:00 A.M. shotgun start of the Fall Classic breakfast tournament. A quick bite, a cup of coffee, a peak at the sports page, and you’re off, full of anticipation for a great morning on a pristine golf course with friends. Ah, but there is trouble in the air when you arrive at the golf course. A sign reading “FROST DELAY” is posted on the message board. Tension fills the air as more and more golfers gather only to realize that the tournament is delayed indefinitely until the frost lifts. You hear the com­ plaints: “There he goes again .... Is this place ever open? ... How much damage can a few golfers create? . . . Last weekend it was too wet for golf carts, today a frost delay .... What’s next? Close the greens for winter?” Is this scene familiar? Maybe the scenario is different, but time and time again golfers question the judgement of the golf course superintendent, especially when a decision or activity directly affects their ability to play the golf course. Is the superintendent dutifully protecting the golf course, or is he overreacting to a condition that’s really not so important? As a golfer, do you realize the implications of your attitudes, demands, and actions on golf course conditioning and opera­ tions, and that you, too, are responsible for the appearance and playability of the golf course? Let’s take a closer look. Expectations There are few weekends when a beautifully maintained golf course can­ not be seen on television. It is only natural to want to emulate those con­ ditions at your home course. The largest misconception many golfers have is that the near-perfect conditions observed on television can be provided on an everyday basis. The fact is, maintenance programs are planned far in advance to peak a golf course for a special event. Major championships can require years of preparation work, a very large staff, and countless volun­ teers to produce the near-perfect con­ ditions. Trying to produce those con­ ditions every day is simply too cost prohibitive for most golf courses and usually leads to turf loss. Green Speed Many golfers have unrealistic expec­ tations or make unfair comparisons regarding green speed. An arbitrary green speed is demanded without first considering important factors such as the design of the greens, their agro­ nomic condition, the level and quality MARCH/APRIL 1999 1 of play, and the size of the operating budget. Elevating green speed tempo­ rarily for a special event is also very different from elevating green speed for everyday play. Sadly, turf loss, golfer dissatisfaction, and the demise of superintendents’ careers have occurred because too much pressure was applied to increase green speed to unrealistic levels without first considering all the potential implications of that request. Use reason, not passid*n, when deter­ mining what green speed is best for the golf course, and understand that green speed alone does not make a good green. Uniformity/Consistency Demands for uniformly green, blemish-free playing surfaces through­ out the golf course also are becoming more common. Superintendents are forced to use additional water, fertilizer, and pesticides to meet these demands. Even in cooler, temperate regions, golf courses often add irrigation to out-of- play areas solely for aesthetic reasons. Fertility and irrigation programs at some golf courses also are dictated less by the plant’s needs and more by demands for color or a green’s ability to hold a golf shot. Those programs usually result in excessive fertilizer and water applications that create a weak, shallow-rooted turfgrass that is even more dependent on water and pesticide inputs for survival. Actual playing con­ ditions also will suffer from the softer surface and more lush growth. Many golf courses have the financial capa­ bilities to provide wall-to-wall green, blemish-free turf, and a small fortune is required to do so. The issue of cost may not be a concern at those golf courses. However, the increase in water, fer­ tilizer, and pesticide use should be. There is a genuine desire with most golf course superintendents to reduce fertilizer, water, and pesticide inputs in golf course management programs. Achieving this goal will not be possible until golfers can accept and adapt to even small irregularities or imperfec­ tions in the playing surface. Golf is different from other sports in that its playing field is a dynamic living system that has a major impact on how the game is played. Golfers who learn to identify, accept, and adjust to the natural changes, as opposed to insisting they be eliminated entirely, will develop more realistic expectations, become more proficient players, and may even find the golf experience more enjoyable. Maintenance Maintenance staffs are busier than ever, trying to satisfy the growing expectations and meet the demands from increased play. Larger staffs and creative scheduling are used to accom­ plish maintenance objectives with as little interference to play as possible. Foot traffic from unknowing golfers can be very damaging to steep bunker banks. Avoid steep bank faces when entering or exiting bunkers. 2 USGA GREEN SECTION RECORD Golfers should anticipate some degree of interference when elevated levels of conditioning are expected. Pressures to open golf courses earlier in the morning and to keep golf courses open every day make it difficult to complete daily tasks, especially the more disruptive practices such as topdressing, cultiva­ tion, and spray applications. Closing the golf course for one day or at least one morning per week, implementing later starting times, and allowing for some flexibility in operations are small sacrifices that allow the staff to com­ plete their daily tasks and more disrup­ tive practices more efficiently and when they are most required. Be patient and pleasant with the staff in the field. Your cooperation allows them to safely com­ plete their work and provide the con­ ditions you demand. Traffic Golf courses are busier today than ever before. The increase in traffic has had the most pronounced effect on older golf courses that were not designed with today’s play or level of conditioning in mind. Traffic effects are most evident as worn, thin, discolored turf, or heavily divoted, bare areas. The most common traffic injury involves abrading or bruising the leaf and stem tissues. A healthy turfgrass plant can recover remarkably well from simple leaf damage if weather conditions per­ mit active growth. Heavy traffic or traffic during inclement weather can lead to more significant wear injury that extends into the lower stem or crown region of the plant. Recovery from the more severe damage is slow or may not be possible. Traffic can also dam­ age the structure of underlying soils, affecting their drainage and aeration characteristics. Foot Traffic The move from traditional metal to nonmetal spikes has helped reduce the injurious effects of foot traffic. The improvement in surface quality on greens is obvious to most golfers. What may be less obvious, but equally impor­ tant, is the improved turf vigor resulting from a reduction in wear injury. The added vigor improves the turfgrass plants’ ability to tolerate all types of stress and resist disease infection. Beware that not all nonmetal spikes are created equal. Some nonmetal spikes and shoe patterns are more damaging than others. It is conceivable that as the spikeless shoe patterns be­ come more pronounced, they could become just as damaging as traditional metal spikes. Universities around the country are field-testing the new shoe patterns to determine which provide adequate traction and create the least amount of turfgrass injury. Spikeless shoes will not prevent the surface dis­ ruption and wear injury that occurs when golfers drag or twist their feet while walking or addressing the ball. Be aware of your actions, especially on the putting surface, and make a conscious effort not to drag or twist your feet. It is true that more caution is needed when wearing spikeless shoes on hill­ sides and other potentially slippery surfaces, but a move to nonmetal spikes may be the single most beneficial act golfers can do to improve the golf course. Foot traffic also can be very damag­ ing to recently seeded areas or unstable sod. Young seedling plants are most vulnerable to traffic. There are few things more disheartening to a golf course superintendent than to see foot­ prints tracking across a recently graded and seeded area, especially when the area is clearly marked with signs and ropes. When possible, avoid any areas where seed or sod has been used to establish new turf. Human nature is such that we seek the shortest, or most economical, path between two points. The consequence of utilizing the same route repeatedly is a worn path. Often these paths are evident adjacent to sand bunkers in a green complex. Superintendents use ropes and signs to deter traffic in such areas. A design modification may ulti­ mately be required to address the traf­ fic problem. However, common sense should suggest that the ropes and signs are there for good reason, so be re­ sponsible and accept the small in­ convenience to take an alternate route that will be less damaging to the turf. Turfgrass on sand bunker banks also is vulnerable to foot traffic. The steep banks are often fragile and quickly break down from traffic pressure. Damaged bunker banks are unsightly and lead to washouts that contaminate the sand. Repairing the damage is costly and would not be necessary if golfers would avoid the steepest banks and faces when entering or exiting sand bunkers. Winter Play/Frost Winter play is often a contentious issue between superintendents and golfers in northern areas where there is intermittent snow cover and the turf is Golfers twisting and turning their feet and making multiple practice swings create significant wear injury and divot damage on the first tee. Complete your stretching and warm-up swings off the tee box and try to avoid creating a divot when taking practice swings. dormant. The superintendent’s desire to protect the course during periods when the turf is not actively growing conflicts with the pressures to keep the golf course open for play. Winter play causes wear injury, compacts and dis­ places the soil, and damages the play­ ing surface. Wear injury is more severe because of the dormant turf’s frozen condition and inability to recover. The traffic effects are not always immedi­ ately noticeable, making it harder to convince golfers of the potential for damage. Even a small number of winter golfers can create significant and long- lasting damage, depending on the soil and weather conditions. Traffic on frosted turf results in immediate injury. Cells in the frozen leaf blade and stems are brittle and are easily ruptured by the pressures exerted from the traffic. Damaged turf initially has a water-soaked appearance and then turns a straw color. Wear injury on frozen, dormant turf may be less acute. Turfgrass can recover relatively quickly from foliar damage alone, once warmer weather returns. How­ ever, longer-lasting or permanent damage can be expected when the traffic injures the crown or basal stem region where the plant’s regenerative tissues are located. The greatest po­ tential for damage to the crown area occurs during periods of thaw, when soft or saturated surface soils overlay frozen soils. Expect winter traffic to thin the turf canopy in areas where traffic is concentrated or play is very heavy. The damage can remain notice­ able well into spring and early summer. The damaged plants will be weaker and more susceptible to disease infection, and the thinned areas more vulnerable to weed encroachment. Soils also can be impacted severely by winter traffic. Frozen soils are rigid and are damaged the least. Wet or saturated surface soils are most prone to damage from compaction and dis- MARCH/APRIL 1999 3 several forces on the turf and soil. A vertical force created by the dynamic load of the wheel, sheer stress created by wheel slippage, and forces from vibration all impact the turf and surface soils. Operating carts with care and com­ mon sense will reduce traffic injury. Avoid rapid starts and stops or sharp turns that increase wheel slippage and subsequent damage to the turf and soil. Respect the cart operation rules and obey the signs and ropes set to guide the flow of traffic. The rules have been developed to minimize traffic effects and protect the operator from potentially serious injury. Golf carts or pull carts should never be operated in critical play turf areas immediately adjacent to the greens. All carts should be kept on designated paths. Avoid the tendency to park the cart partially off the path. This leads to significant wear injury and sod damage adjacent to the paths. Golf carts should not be operated in naturalized, tail-grass areas where the traffic can be especially damaging to the native vegetation and ruin the appearance of these areas. Avoid operating golf carts and pull carts through known wet areas or standing water. Saturated soils are more easily compacted and displaced. Do not operate carts where frost is evident. Avoid turfgrass areas that are suffering from water stress. Anticipate water stress on hot, dry afternoons between the hours of 12:00 P.M. and 4:00 PM. Turf suffering water stress will take on a wilted or flaccid, grayish-blue appear­ ance. The limp cells are highly suscep­ tible to wear damage, much like a tire when it is flat. The heavy weight of a cart is likely to cause more permanent injury under such conditions. Divot and Ball Mark Injury There are many who feel that the rules and etiquette of golf have been overlooked as the game has experi­ enced tremendous growth. Issues of etiquette, such as the care of the course, are probably not the biggest concern to a golfer tackling the game’s challenges for the first time. Many junior golf programs stress etiquette issues to young players. Regional golf associations and some golf courses also provide workshops or seminars to teach similar issues to new or interested golfers. The USGA has recently pro­ duced an instructional video on eti­ quette issues titled The Spirit of the Game that is free to USGA members and is also being distributed to regional Golf carts have the potential to create significant surface damage, especially in wet areas on the golf course. Obey all cart operation rules and respect the signs and ropes that are put in place to protect the golf course and your safety. placement effects. Compaction in­ volves pressing the soil particles to­ gether to create a more dense material with less total pore space. Water move­ ment through the soil is impacted and the surface becomes hard. Compacted soils remain cooler in the spring (delay­ ing growth) and retain more heat in summer. The changes in soil properties have a negative influence on root growth that can affect turf’s perfor­ mance through the entire summer season. Surface smoothness also is sacrificed as a result of the displace­ ment effects. Utilizing temporary greens and tees for winter golf in northern regions remains the best strategy for prevent­ ing traffic damage and the costly and disruptive work required to repair the damage. Respect golf course super­ intendents’ opinions and decisions re­ garding frost, winter play, and the use of temporary greens. Their knowledge and experience are invaluable for making decisions based on what is best 4 USGA GREEN SECTION RECORD for the golf course and the long-term interests of golfers. Golf Carts Golf carts, along with television, may be responsible for the game’s huge growth in recent years. The popularity of carts among today’s golfers cannot be denied. Golf carts are a significant revenue source, yet at the same time can be responsible for a large share of maintenance expenses. Cart traffic effects are minimal at new golf courses that are designed with extensive path systems, but path design obviously was not a consideration at older golf courses. Expenses associated with cart use on those courses are usually higher because carts are forced to travel more extensively over the playing surfaces. Areas where carts converge, such as the entry and exit points adjacent to cart paths, suffer the most obvious damage, but less conspicuous effects will occur wherever carts are operated over turf areas. Golf carts and pull carts exert Become more familiar with the effects of your actions and do your share to preserve the golf course and all that is special about this game. Your coopera­ tion ultimately will result in improved playing conditions and reduced main­ tenance costs for all. References Beard, James B. (1973). Turfgrass: Science and Culture, pp. 24, 368-378. Brightwell, Neville (1993). Playing During Frosts. New Zealand Turf Management Journal. Vol. 7, No. 4, p. 25. Carrow, Robert N. & Petrovic, A. Martin (1992). Effects of Traffic on Turfgrasses. Turfgrass, pp. 285-324. Ferguson, Marvin H. (1963). Effects of Traffic on Turf. USGA Green Section Record. Vol. 1, No. 1, pp. 3-5. Isaac, S. P. (1992). Winter Play on the Golf Course. Sports Turf Bulletin. Vol. 176, pp. 6-9. Lutz, Jeralyn (1994). Dealing with Divots. Grounds Maintenance. Vol. 29, No. 1, pp. 20-28. Schaffer, Laura (1995). A Short But Sweet Stroke. Golf Course Management. Vol. 63, No. 3, pp. 122-126. Vermeulen, Paul (1995). S.P.E.E.D. — Consider What’s Right For Your Course. USGA Green Section Record. Vol. 33, No. 6, pp. 1-5. JIM SKORULSKI is a Green Section Agronomist in the Northeast Region, where he visits golf courses in upstate New York and the New England states. During the growing season, severe and long-lasting wear injury occurs when carts are operated over a turf suffering moisture stress. and able to demonstrate the proper procedures. Make a conscientious effort to repair your ball mark and encourage other golfers to do the same. Golfers do have a major impact on golf course maintenance operations. The impact does not have to be negative as long as expectations are realistic and based on reason, and golfers understand and fulfill the responsibilities expected of them. Informed and conscientious golfers are an asset to any maintenance program. golf associations, the PGA, and the GCSAA for use in the field. Sadly, etiquette and course responsibility seem to be lacking in many more experienced golfers, who should know better. All golfers are expected to repair their divots, ball marks, and any other surface damage created while playing the game. Divots, ball marks, and other damage that are not repaired leave un­ sightly depressions and scars that nega­ tively influence future play and provide opportunities for weeds to become established. Golfers are encouraged to repair their divots on tees and fairways with sand or sand/seed mixes provided to them. The sand or seed mix should be placed in the divot, tamped down, and leveled even with the surrounding grade. Applying excessive divot mix creates an uneven surface and disrupts mowing operations. It also is important to replace grass divots if a sand mix is not provided. Replacing and tamping the divot in place may not ensure the turf’s survival, but it will level the sur­ face at least until a more permanent repair can be completed. Divots should not be made when taking practice swings! Ball marks also need to be repaired promptly and properly to avoid long- lasting scars. Repairing a ball mark incorrectly or carelessly may be as damaging as not repairing the ball mark at all. There are excellent pictorial guides that illustrate the proper repair methods. The golf course superinten­ dent or golf professional also is willing The tendency to pull golf carts off to the side of cart paths creates wear injury and soil compaction that damages the turfgrass. Golf carts should be parked on the path. If others approach, they can pull off the path to go around. MARCH/APRIL 1999 5 Use of Prodiamine as a Preemergence Herbicide to Control Annual Bluegrass in Roughs Knowing the period of prolific Poa annua germination is crucial to properly timing preemergence applications. by PETER H. DERNOEDEN, Ph.D. ANNUAL bluegrass is a puzzling /\ weed with diverse annual (P. X JL annua ssp. annua) and peren­ nial (P annua ssp. reptans) biotypes. Several chemical strategies involving pre- and postemergence herbicides and plant growth regulators can reduce annual bluegrass (Beard et al., 1978; Callahan and McDonald, 1992; Der- noeden and Turner, 1988; Goss et al., 1980; Kageyama et al., 1989; and Hall and Carey, 1991). Long-term or com­ plete control of the weed, however, is seldom achieved (Branham, 1991; Christians, 1996). Cultural methods, such as increasing mowing height, collecting clippings when seedheads appear, improving drainage and fer­ tility, alleviating soil compaction, appli­ cations of iron and magnesium, and flaming reduce the competitiveness of annual bluegrass (Beard et al., 1978; Belief al., 1997; Desjardins etal., 1997; Watschke et al., 1995). Among pre­ emergence herbicides, multiple appli­ cations of bensulide (i.e., Betasan, LescoSan, etc.) and tricalcium arse­ nate have been reported to consistently reduce annual bluegrass in cool-season turf (Callahan and McDonald, 1992; Goss et al., 1980). Late-summer appli­ cations of preemergence herbicides to areas in play on golf courses, however, are discouraged in the Mid-Atlantic region. The use of these herbicides in late summer conflicts with overseeding operations and can be potentially phytotoxic because of generally high air temperatures. Also, persisting herbicide residues in soil could interfere with suc­ cessful overseeding should large turf areas be killed during winter due to ice cover, crown hydration, desiccation, disease, or other factors. Annual bluegrass produces large amounts of seed, and heavily colonized areas in golf course roughs and out-of- bounds areas provide a large potential reservoir of seed. The use of a pre­ emergence herbicide in rough areas not adjacent to fairways, greens, and tees would be less risky, assuming turf 6 USGA GREEN SECTION RECORD density was good in late summer. A cursory Maryland study suggested that prodiamine (Barricade 65DG®) was an effective preemergence annual blue­ grass herbicide (Dernoeden and Krouse, 1994). The time that annual bluegrass seed germinates in the Mid­ Atlantic and most other regions, how­ ever, has not been well documented. Annual bluegrass seedling emer­ gence was monitored adjacent to a putting green at Woodmont Country Club in Rockville, Md., between September 1,1994, and May 2,1995, by Robert Larsen, a student then attend­ ing the University of Maryland. Mr. Larsen first observed annual bluegrass seedlings on September 21,1994, in 1.5- inch diameter spots created by a non- selective herbicide. No germination occurred after December 14, but he did observe some seedlings emerging be­ tween April 12 and 26,1995. Although the main germination period of annual bluegrass in the Mid-Atlantic region is likely to begin in late summer, the best timing for an application of a preemer­ gence herbicide for this weed in the region has not been established. Hence, the objectives of this study were to determine the proper timing and rates of prodiamine for preemergence annual bluegrass control in Kentucky bluegrass maintained under golf course rough conditions. Methods Treatments were applied to a mature stand of “Kenblue” Kentucky bluegrass at the University of Maryland Turfgrass Research and Education Facility in Silver Spring, Md. For several years the test site was uniformly infested each spring with P annua, but virtually all of the annual bluegrass died during each summer. Because of its apple­ green color, prolific seedhead produc­ tion in May, and inability to survive summer, the biotype at the site was considered to be P annua ssp. annua. There also was a heavy smooth crab­ grass (Digitaria ischaemum) infesta­ tion at the site when treatments were applied each fall. The soil was a Chillum silt loam with a pH of 6.2 and 2.3 percent organic matter. Turf was mowed to a height of 2.0 to 2.5 inches and was fertilized with 2.0 lb. N/1000 sq. ft. per year. The 1995 and 1996 studies were conducted on separate, but adjacent sites. Three rates of prodiamine were applied on three dates in 1995 and 1996 (Tables 1 and 2). The site was irrigated within 24 hours of each application with at least 0.20 inch of water. Pro­ diamine was applied in 50 gallons of water per acre with a CO2-pressurized backpack sprayer equipped with an 8004E flat-fan nozzle. Plots were 5.0 by 5.0 feet and were arranged in a randomized complete block with four replications. Percentage of plot area covered by annual bluegrass or smooth crabgrass was assessed visually on a 0- to-100% linear scale where 0 = no weeds and 100 = entire plot area covered by weeds. Rating for annual bluegrass cover was facilitated by the presence of seedheads between mid­ May and early June. Subjectively, annual bluegrass cover < 5.0% was considered to be commercially accept­ able control for a golf course rough. Data were subjected to statistical analysis and the results of this study were reported previously (Dernoeden, 1998). 1996 Results Large numbers of annual bluegrass seedlings were first noted emerging at the site on October 3,1995. The annual bluegrass coverage trends evident on November 27,1995, remained relatively unchanged on subsequent rating dates, including the final rating on May 24, 1996 (Table 1). All rates applied on either August 11 or September 14 sig­ nificantly reduced annual bluegrass and produced statistically similar levels of control. Complete control was provided only by 1.0 lb. ai/A applied September 14. None of the treatments applied October 13, how­ ever, reduced annual bluegrass signifi­ cantly when compared with untreated control plots. Using a subjective annual bluegrass cover threshold of 5.0%, the following prodiamine treatments pro­ vided for commercially acceptable control for golf course roughs: 0.32 lb. ai/A applied September 14 and 0.65 or 1.0 lb. ai/A applied on August 11 and September 14. Smooth crabgrass was highly inva­ sive and weed cover was rated on August 20, 1996 (Table 1). Ratings showed that 0.65 lb. ai/A prodiamine applied on October 13 and 1.0 lb. ai/A applied on September 14 or October 13,1995, provided an excellent level (1 to 6% crabgrass cover) of season-long smooth crabgrass control in 1996. These findings were similar to those reported previously for November applications of prodiamine 65DG in Maryland (Dernoeden, 1993). 1997 Results Treatments were initiated later in 1996, and prodiamine was applied at two-week intervals to better pinpoint the application window for the herbi­ cide and germination time of annual bluegrass. Annual bluegrass seedlings were first observed in the test site on September 30,1996. Except for the 0.32 lb. ai/A rate applied on September 30, 1996, all treatments provided a similar level (0 to 8% cover) of annual blue­ grass control. The only treatments not within the 5% cover threshold were the 0.32 and 0.65 lb. ai/A rates applied on September 30. On all 1997 rating dates, annual bluegrass control was better with the higher prodiamine rate applied September 30. These data sug­ gested that the high rate may have had some early postemergence activity on annual bluegrass. During the summer there was very little rainfall and only a small amount of irrigation water was applied, and the turf eventually became drought dormant. As a result, smooth crabgrass levels were very low and all treatments significantly reduced crab­ grass cover. Discussion Annual bluegrass seed germinates during cool, moist periods in late summer and fall, but in some regions seed may germinate in the spring (Beard et al., 1978). According to Dr. Bruce Branham (1991), annual blue­ grass germinates so profusely in the spring and fall in Michigan that three Poa annua’s prolific seed production provides a large reservoir of seed in rough and outlying areas that can easily be tracked to fairways, tees, and greens. annual applications of preemergence herbicides are needed to effectively control the weed. In Tennessee, the an­ nual subspecies germinates from mid­ November to early January (Callahan and McDonald, 1992). Observations and data from this study indicated that the major germi­ nation period of annual bluegrass in central Maryland was from late Sep­ tember to early December. The view that germination occurs after mid­ September is supported, in part, by the relatively poor level of control provided by 0.32 lb. ai/A prodiamine applied September 30, 1996, relative to that obtained with the August 29 and September 16 applications in 1996. There was little change in annual bluegrass cover ratings between November 27, 1995, and April 3,1996, indicating that most of the annual bluegrass emerged by late November in 1995 (Table 1). Annual bluegrass seed may have germinated at the site in April, but seedling emergence was not noted. Field observation indicated that the rapid increases in annual bluegrass cover ratings during April and May in both years was largely due to aggressive tillering of overwintering annual blue­ grass in the spring. Hence, as reported in Tennessee (Callahan and McDonald, 1992), the annual biotype appears to have one major germination period between late summer and early winter in central Maryland. As previously noted, how­ ever, there may be a brief spring germi­ nation period in April. Results from this study also showed that annual blue­ grass could be controlled effectively with as little as 0.32 lb. ai/A prodiamine 65DG applied during the first two weeks of September. This time and rate may only be appropriate for the central Mid-Atlantic region in a non-disturbed (i.e., no core cultivation, verticutting, etc.) turf maintained at a mowing height above 2.0 inches. It also is important to note that only the sprayable, 65DG formulation of prodiamine was evaluated. Granular forms of pro diamine may not perform as well as the 65DG. For example, numerous granular forms of prodia­ mine have been tested for several years at the University of Maryland for pre­ emergence smooth crabgrass control. These studies clearly have shown that there is a great variation in crabgrass control performance among the many granular forms of prodiamine available in the marketplace. MARCH/APRIL 1999 7 Literature Cited Beard, J. B., P. E. Rieke, A. J. Turgeon, and J. M. Vargas. 1978. Annual bluegrass (Poa annua L.) description, adaptation, culture, and control. Michigan Agr. Expt. Sta. Res. Rept. 352, 32 pp. Bell, G. E., E. Odorizzi, and T. K. Danne- berger. 1997. Controlling annual bluegrass and rough bluegrass in creeping bentgrass fairways: A nutritional approach. Agron. Abstr. 122. Branham, B. 1991. Dealing with Poa annua. Golf Course Mgt. 59 (9): 46,48,52, 54, 58, 60. Callahan, L. M., and E. R. McDonald. 1992. Effectiveness of bensulide in controlling two annual bluegrass (Poa annua) sub­ species. Weed Technol. Vol. 6:97-103. Christians, N. 1996. A historical perspective of annual bluegrass control. Golf Course Mgt. 64(ll):49-57. Demoeden, P. H. 1993. November applied preemergence herbicides for smooth crab­ grass control the following summer. Inti. Turfgrass Soc. Res. J. 7:291-297. Demoeden, P. H. 1998. Use of prodiamine as a preemergence herbicide to control annual bluegrass in Kentucky bluegrass. HortScience. 33:845-846. Demoeden, P. H., and J. M. Krouse. 1994. Preemergence smooth crabgrass, annual bluegrass, woodsorrel, and prostrate spurge control. Proc. Northeastern Weed Sci. Soc. 40:120 (Abstr.) Demoeden, P. H., and T. R. Turner. 1988. Annual bluegrass control and tolerance of Kentucky bluegrass and perennial ryegrass to ethofumesate. HortScience. 23:565-567. Desjardins, Y, M. Tardif, J. Gill, and C. Lague. 1997. Poa annua war calls for scorched-earth policy. Golf Course Mgt. 65(10):49-54. Goss, R. L., T. W. Cook, S. E. Brauen, and S. P. Orton. 1980. Effects of repeated appli­ cations of bensulide and tricalcium arsenate on the control of annual bluegrass and on quality of Highland colonial bentgrass putting green turf. Proc. Third Inti. Turfgrass Res. Conf. 3:247-255. Hall, C. S., and C. K. Carey. 1991. Control of annual bluegrass (Poa annua) in Kentucky bluegrass (Poa pratensis) turf with linuron. Weed Technol. Vol. 6:852-857. Kageyama, M. E., L. R. Widell, D. G. Cotton, and G. R. McVey. 1989. Annual bluegrass to bentgrass conversion with a turf growth retardant (TGR). Proc. 6th Intern. Turf. Res. Conf. 6:387-390. Watschke, T. L., P. H. Demoeden, and D. J. Shetlar. 1995. Managing turfgrass pests. CRC Press, Boca Raton, Fl. DR. PETER DERNOEDEN is Professor of Natural Resource Sciences and Land­ scape Architecture at The University of Maryland at College Park, where he conducts turfgrass research, teaches, and advises graduate students. 8 USGA GREEN SECTION RECORD Table 1 Influence of rate and time of application of prodiamine (Barricade 65DG®) on preemergence control of annual bluegrass and smooth crabgrass in “Kenblue” Kentucky bluegrass, 1995-1996 % Plot Area Covered Prodiamine 1995 1996 Rate Date Applied Annual Bluegrass Smooth Crabgrass (lb. ai/A) (1995) 27 Nov. 3 April 1 May 24 May 20 Aug. 0.32 11 Aug. 0.65 1.0 14 Sept. 13 Oct. 11 Aug. 14 Sept. 13 Oct. 11 Aug. 14 Sept. 13 Oct. 2 b2 2b 23 a 2b <1 b 19 a <1 b 0b 22 a Untreated — 16 a 3 bed 2 bed 31a 3 bed 1 cd 4 be 3 be 33 a 3 be 2 be 7 be 4 be 40 a 4 be 2c 15 abed 16 abc 18 abc 1 cd Od 18 abc 19 ab 1 c 0 c 21 ab 34 a 1 c 0 c 25 ab 38 a 90 a 46 be 39 c 61b 24 cd 4d 33 c 6 d Id 96 a 2Mean separation within columns by Duncan’s multiple range test, P = 0.05 Table 2 Influence of rate and time of application of prodiamine (Barricade 65DG®) on preemergence control of annual bluegrass and smooth crabgrass in “Kenblue” Kentucky bluegrass, 1996-1997 % Plot Area Covered Prodiamine 1996 1997 Rate Date Applied Annual Bluegrass Smooth Crabgrass (lb. ai/A) (1996) 17 Dec. 28 April 16 May 2 June 5 Sept. 0.32 29 Aug. 2 b2 16 Sept. 30 Sept. 0.65 29 Aug. 1.0 16 Sept. 30 Sept. 29 Aug. 16 Sept. 30 Sept. 0b 4b 0b 0b 3b 0b 0b 2b Untreated — 8 a 1 c 4 c lib 1 c 1 c 6 be 0c 0 c 3c 21a 3 c 4 c 20 b 2c <1 c 8c <1 c 0 c 4 c 33 a 3c 5 c 17 b 3 c 1 c 8 be <1 c 0 c 3c 35 a 2b <1 b lb