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Biostimulant Use in the Turf Industry

May 16, 2011

Editor’s Note: This is a short summary of an essay submitted by Quincy Law to the GCSAA Student Essay Contest that received second place. The topic was selected based on an undergraduate research project completed by the author in 2010.

As environmental stewards, golf course superintendents need to produce the highest quality turf while retaining a healthy environment for both people and wildlife. Turf areas need to be maintained with environmental sensitivity while controlling pests and combating harsh environmental conditions. Despite increasingly stringent environmental regulations, water quality issues, and negative public perceptions of pesticides and fertilizers, golfers still expect their local course to appear and play as those on television: uniformly green and perfectly manicured.

Outside of chemical control and fertility, a superintendent has various options to maintain a high turf quality throughout the growing season. Mowing practices, species selection, water management, and cultivation can all improve plant vigor. Unfortunately, many of these options have already been implemented by the superintendent, cannot be changed, or are simply not feasible. There is, however, an alternative that has slowly been gaining popularity and is supported by research.

Biostimulants are materials that, in small quantities, stimulate plant growth. Although they can be synthetic chemicals, naturally occurring organic materials are excellent sources. Since the category includes a diversity of substances, biostimulants are defined by what they do more than by what they are. They stimulate growth, but they do much more too; stress tolerance is perhaps the most important benefit. Biostimulants can assist turfgrass in surviving dry, hot, high salinity, and even disease.

Products may contain one or more of a broad range of ingredients, including nutrients, organic acids, hormones, amino acids, vitamins, microbial inoculants, plant extracts, and others. They have limited nutritional value and promote plant growth by providing amino acids, chelating nutrients, and altering the hormonal status of a plant, which can exert large influences in plant growth and health.

Seaweed is the most widely used biostimulant in both agriculture and turfgrass management. Humic substances are another common component of biostimulant products. Both seaweed and humic acid have been shown to effectively stimulate plant growth and increase stress tolerance. In addition, these materials also complement each other when used in combination.

Seaweed and humic acid may affect the plant in several ways because they contain various hormones, vitamins, amino acids, plant nutrients, and other components. The stimulating influences, especially for turfgrasses growing under environmental stress, have mainly been attributed to hormonal activity. Humic acid and seaweed extract both exhibit cytokinin and auxin activity, which are two classes of plant hormones. When the plant is exposed to certain environmental and cultural stresses, levels of some hormones, such as cytokinins, may drop. Under these conditions, applications of cytokinins or other plant hormones could help ameliorate the stress.

Biostimulant applications may only be beneficial where root growth, moisture stress, salinity, or other issues are present. Turfgrass typically grows well without biostimulants when the environment is favorable; plants growing under minimal stress may perform similarly regardless of biostimulants. In these situations, the positive effects of biostimulants may not be easy to identify. When the plants become stressed, however, biostimulant-treated turfgrasses perform better because they have developed a better defense system. For the maximum effectiveness, biostimulants should be applied prior to the onset of stress. Treatments may be most effective when applied early in the season when the plant is actively growing.

Golfers, greens committees, and the general public hold golf course superintendents to a double standard. Golf courses are expected to be maintained at a high quality, such as those played on the PGA Tour. However, that high level of maintenance exposes turfgrass to a significant amount of stress. In addition, the fertilizers, pesticides, water, and other controls used to combat these stresses often carry a negative stigma.

In order to keep turf plants healthy in the presence of stress with limited use of fertilizer and chemicals, biostimulants may be a viable option for superintendents. Not only can biostimulants reduce the usage of chemicals harmful to the environment, most are natural and are composed of chemicals not available in synthetic products. Turf managers may be able to “go green” while still maintaining healthy turf, and they may prove to be an environmentally friendly component to turfgrass management.


Iowa Turfgrass Field Day Review, Andrew Hoiberg

July 27, 2011

Iowa Turfgrass Field Day has returned! Everyone associated with this event are thrilled to have it back and we know the turf industry is as well. We would like to thank everyone who pitched in to help, all the speakers, the vendors, and most of all, the attendees. Without a great industry like we have in Iowa, none of this would be possible.

Below you will find a recap for the first half of the program and some take home messages from the research and demonstrations that were highlighted at this year’s event. A recap for the second half of the program will follow tomorrow.

NCERA Bentgrass Trial: Dr. Christians showed us the NCR Bentgrass variety trial that aims to maintain bentgrass with limited fungicide inputs and to test different cultivars natural resistance to disease pressure, namely dollar spot and brown patch. The trial has 24 cultivars of commercially available creeping bentgrass. This trial is still underway but there are cultivars that are standing out. “Declaration” is cultivar that others are measured against for natural disease resistance. 

Biostimulant Study: Quincy Law, a recent graduate of the ISU turf program, filled us in on his Ajinomoto study. The objective of this study was to determine the effect of an amino acid based fertilizer upon growth and shoot density of "Penncross" creeping bentgrass. Previous work with an amino acid containing product, GreenNcrease, had resulted in higher shoot densities when applied to mature turf. Treatment applications of three natural products at varying rates, along with urea, were made every two weeks to fairway height turf (0.5 inches). Color, dry clipping weight, dollar spot ratings, total nitrogen analysis of clipping tissue, and shoot densities were all recorded monthly.

Plots receiving applications of GreenNcrease, an Ajinomoto product, had significantly higher shoot densities. GreenNcrease applied as a biostimulant along with a regular fertility regime may increase shoot density. An increased shoot density provides for a more competitive turf stand and better playing surface. The trial completed in 2010 is being repeated on the same plots to investigate the effect of these products when used over time.


Imprelis update: As many of you know, Imprelis herbicide has been in the news a great deal this year as it is suspected of causing damage to White Pine and Norway Spruce trees. It appears as though the herbicide could be moving downward into the soil and being absorbed by mature root systems that extend well beyond the traditional drip line cutoff for spraying. If you have had problems with Imprelis, it is recommended that you contact DuPont. Dr. Christians also spoke about an Imprelis trial examining the efficacy of the herbicide on grassy and broadleaf weeds when applied at various timings in the spring/early summer. The results of this trial will be available this fall. Also, stay tuned for further updates concerning Imprelis as more information becomes available.

Nitrogen based establishment: This trial is attempting use increased rates of nitrogen during establishment of both Kentucky bluegrass and perennial ryegrass hasten the production of aboveground plant mass and improve the wear tolerance during traffic stress. So far, we have been able to detect differences in nitrogen rates as far as fill in and plant maturity, especially when compared to the untreated controls. From what we have seen thus far, it looks like applying 0.25 lbs N/1000 ft2 per week for 8 weeks of establishment for a total of 2 lbs of N produced the most aesthetically pleasing perennial ryegrass with regard to color and density. Incremental increases beyond 0.25 lb N per week caused ryegrass to grow excessively, which could potentially increase mowing requirements.


For Kentucky bluegrass, more nitrogen is necessary to achieve a dense stand that can withstand traffic. We have also had to use 4 applications of Tenacity herbicide at 4 oz/A spread throughout the spring and summer to keep weeds at bay and give the bluegrass a chance to establish enough for cleated traffic. It appears that at least 0.5 lbs N/1000 ft2 per week for 8 weeks during establishment is necessary to achieve maximum density. However, as we continue to collect data on this study, we may find out that rates of 0.75 or even 1.0 lbs N/1000 ft2 per week are best for rapidly establishing bluegrass.

Andrew Hoiberg
Graduate Student
Iowa State University



February 27, 2014

Here is our paper from the international Journal that was published in conjunction with the International Turfgrass Society meeting that took place in Beijing, China last summer.  The abstract is as follows:


Biostimulants are products able to stimulate plant growth and metabolism with a response not attributed to mineral nutrition. Biostimulant products have been shown to increase turfgrass tolerance to heat and drought, as well as increase tillering in wheat. The objective of this study was to determine the effects of an amino acid complex on the culture and shoot density of creeping bentgrass in comparison to nitrogen, a commercial sea plant extract, and another amino acid containing biostimulant. Research was conducted at the Iowa State University Horticulture Research Station on ‘Penncross’ creeping bentgrass mown at 1.3 cm and established on a United States Golf Association sand-based rootzone. Clipping yield did not vary among treatments in this experiment. The 2.9 kg N ha-1 rate of the amino acid complex
was found to be the most effective treatment to maintain or increase shoot density in the trial. The amino acid complex at 2.9 kg N ha-1 had 15% greater shoot densities than the same rate of N from urea and the 17% greater shoot densities than the commercial sea plant extract over the two dates out of nine that they differed, both occurring during stressful summer conditions. This research demonstrates that applications of an amino acid complex have the potential to increase shoot densities in a mature stand of ‘Penncross’ creeping bentgrass without stimulating shoot growth.

The citation for the article is:

Law, Q.D., M.A. Jones, A. J. Patton, and N. E. Christians. 2013. Influence of an amino acid complex on the growth of Agrostis stolonifera L. cv. Penncross. International Turfgrass Journal.  12:485-489.

The full text can be obtained in pdf form by clicking on the word Quincy.