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The Spring Poa
Bloom By: Jim Taylor, Golf Enviro Systems It’s a common complaint of Golf Course Superintendents in Colorado. Throughout the Rockies we hear, “ I’m really proud of the putting surface we provide to our players, except during that x#!xo!#! poa seed head bloom in the spring. Depending upon location and elevation, this undesirable fact of life usually occurs between the end of April and early June, causing Superintendents to retreat to their offices until the haunting voices stop repeating “Where did we get all that POA!” and “Why are the greens so bumpy”. This is indeed a frustrating time for Superintendents and players alike and the frustration has brought on many attempts, with many different products, to try and reduce the amount of seed heads produced during this time. Most of these efforts have yielded results that were less than impressive and generally not worth the time and stress involved in carrying out the program. One of the big issues with our “Spring Bloom” is that it occurs at the time when most golf courses are either recovering, or have just recovered from the core aeration process. So, any means to suppress the seed head formation, must also allow the green to recover quickly from aeration. With the help of Superintendents on the Internet, University research, manufacturers research, countless phone conversations and valuable input from many Rocky Mountain area Golf Course Superintendents trying different programs, we have information and results that are very encouraging. In looking at the different modes of action of the growth regulators available today, it is generally agreed upon that the active ingredient in “Embark T&O” interrupts the gibberellin’s production cycle at the point “most likely” to reduce or suppress seed head production. Due to industry-shared stories of discoloration from phytotoxic responses, many Superintendents have discounted “Embark” as a possible choice for use on putting greens. Current information and testimonials on timing, rates and combination products shown to reduce or eliminate phytotoxicity, has many superintendents thinking that the “Embark” product can be used safely for seed head suppression on putting greens. Across the Country rates of “Embark T&O” used on putting greens varies from 3 oz./acre to as high as 80 oz./acre. The products tank mixed with Embark” also varies widely including, but not “limited to wetting agents, liquid fertilizers, iron, minor nutrient packages, biostimulants and amino acid products. Comments about discoloration also vary widely from “slight” to “cooked”. The exceptions to this are cases where MacroSorb foliar from Nutramax was added to the tank mix, and no discoloration was observed. Briefly, these Nutramax products are blends of L-amino acids that have proven to reduce the phytotoxicity sometimes seen with the use of growth regulators. These compounds appear to reduce the “stress” caused by the regulator but not reduce its ability to regulate growth or interrupt seed head production. Observations indicate they may in fact enhance typical growth regulation due to their ability to move active ingredient into the plant system more efficiently. So lets cut to the chase. What might be a good base program for Colorado and how do we know that? Thanks to help from Mike McLaren, Golf Course Superintendent at Boulder Country Club, we have some great food for thought based on his experience in the spring of 2000. After much research and discussion here was the plan. * The first application will be made when mid-day soil temperatures at a depth of 2”-3” reach 45 degrees F, at least four consecutive days. * The application rate will be: 4 tenths (.4) oz. Embark T&O / 1000 square feet and one (1) oz. MACRO-SORB foliar / 1000 square feet. Mike also added low rates of other products based on his past experience and soil tests. These additional materials varied with each of the three applications. * Subsequent applications will be made at two week intervals using the same rates of Embark and Macro-Sorb foliar and continue until seed head pressure subsides or unfavorable results are observed. That was the plan and here is what actually happened. The first application was made on March 30th. The weather on that day deteriorated as the application was in progress. Greens on the Par three course were not done as by that time snow was actually beginning to accumulate on the ground. We believe that the MACRO-SORB helped get some active into the plant, however; we most certainly did not have optimal absorption given the falling temperatures, decreasing sunlight and lack of adequate dry time. The second application was made on April 12th and the third on April 26th. Both of these applications were made in good weather using the same rates of Embark and Macro-Sorb as in the first application. Recovery from aeration was excellent and on came the usual spring flush of happy turf. There was no noticeable suppression of vertical growth on the greens during this time. The lack of seed head production however was evident as most of the other courses in the area were experiencing the typical seed head extravaganza. A non-sanctioned rating committee consisting of Superintendent Mike McLaren, Assistant John Schleuning and a former Boulder Country Club Superintendent, suggests that the percent reduction in seed heads varied slightly from green to green and ranged from 60 to 90 percent. There was also a marked decrease in member comment about poa. It did not however appear to be proportionate to the estimated decrease in poa seed heads. At the time the fourth application was due, Mike made the decision to transition to his normal Primo regime, as there was pressure to increase green speed. He was happy with the results of the three applications and is planning a similar program for the spring of 2001. There are a number of Superintendents who have indicated successful seed head suppression with a single application of Embark T&O at higher rates. Please keep in mind that this program was not implemented with a goal of reducing the population of Poa Annua, only to reduce seed head production. In fact, some data indicates that this seed head reduction may promote a stronger POA root system. This is most likely due to the fact that typically the Poa plant would cease to produce new roots during seed head production as all of the plant energy is being utilized for this production. Interrupting this cycle appears to allow continued root growth through this period. Conditions and expectations are different on every golf course and the information given in this article is intended only as a basis for discussion as to what might benefit your golf course. It is important to continue to strive for optimal soil health and maintain well-balanced fertilization practices during any growth regulation program. Please contact your GES representative at 800-225-1311 for more information on developing your seed head suppression program.
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