SportsTurf provides current, practical and technical content on issues relevant to sports turf managers, including facilities managers. Most readers are athletic field managers from the professional level through parks and recreation, universities.
Issue link: http://read.dmtmag.com/i/517437
action of most biostimulants is poorly understood, but their function in plants has been associated with the presence of various plant signaling molecules or molecules that facilitate the trans- port and efficacy of mineral nutrients. Determining the exact function of biostimulants is difficult since many products contain naturally occurring or commercially added micronutri- ents, sugars, amino acids and other compounds that may have synergistic, complementary or no plant/soil health effects or may have been added merely for marketing or commercial registra- tion purposes. Thus, separating the effect of one or more ingredients from the others is difficult. Some sports turf managers have to think about reducing their reliance on synthetic fertilizers due to community pressures or fertilizer laws, and look to biostimulants for help. The difference between biostimulants and traditional fertilizers is that biostimulants operate through different mechanisms than fertilizers, regardless of the presence of nutrients in the products. DIFFERENT "TYPES" OF BIOSTIMULANTS Biostimulants are derived from a wide range of materials such as living micro- bial cultures; extracts from microbial, animal or plant products; soil organic residues (i.e., humic and fulvic acids); industrial by-products and chemicals, synthetic molecules, and others. The Biostimulant Coalition (www.biostimu- lantcoalition.org) is a non-profit group of various companies that cooperate to "address regulatory and legislative issues involving biological or naturally-derived additives and/or similar products, including but not limited to bacterial or microbial inoculants, biochemical mate- rials, amino acids, humic acids, fulvic acid, seaweed extract and other similar materials." From their stated purpose, biostimulants are grouped into several categories. Plant Hormones. Also referred to as phytohormones (phyto = plant), they are considered "chemical messengers." Abscisic acid (ABA) is involved with water regulation as indicated by an increase in ABA concentrations in plant leaves under drought stress. Auxins are responsible for phototropism (shoots bend toward the light), gravitrop- ism (roots grow downward) and cell enlargement leading to root and shoot elongation. Indoleacetic acid (IAA) is one of the more common auxins used in biostimulant products. Cytokinins promote cell division and delay leaf www.stma.org June 2015 | SportsTurf 9 Some biostimulant products may have these certifications on their label and mar- keting information. The Organic Materials Review Institute (Eugene, OR; www.omni. org) provides manufacturers and suppliers of organic products an independent review based on compliance with their organic standards, and acceptable products are OMRI Listed®. The U.S. Department of Agriculture's BioPreferred program (www. biopreferred.gov) has been reauthorized by the Agricultural Act of 2014 (~the 2014 Farm Bill). Managed by the USDA, the goal of the BioPreferred program is to increase the purchase and use of biobased products, which are derived from plants and other renewable agricultural, marine, and forestry materials. The USDA Certified Biobased Product label assures a consumer that the product contains a verified amount or per- cent of renewable biological ingredients or "biobased" content. Managing abiotic (environmental) and biotic (traffic, use and wear, pests) stresses on athletic fields must begin before the stress appears. Therefore, pre-stress management strategies are needed to ensure the turf has an abundant about of carbohydrate reserves: start with a good fertility program including soil testing to assure nutrient requirements are met; apply nutrients using foliar applications, with light rates and frequent applications; with foliar applications, include products containing biostimu- lants (particularly cytokinins, antioxidants and vitamins, and others); use growth regulators prudently to manage growth and con- serve carbohydrates; be aware of using biostimulants that contain gibberellic acid when also using plant growth regulators that inhibit the effects of gibberellic acid. monitor rooting to be sure that all cultural inputs are improv- ing rooting and/or preserving the current level of rooting. Irrigation management also is an important part of pre-stress conditioning. Pay close attention to detail here, and monitor rooting depth and keep adequate moisture available throughout that depth or else roots will be. Soil surfactants can certainly help as well and have become an important water conservation method in turfgrass management. Remember that letting the rootzone get too dry does not encourage deeper rooting, since roots do not have "eyes" and therefore have a hard time "looking" for water. By not letting the rootzone get too dry, localized dry spots will be less of a problem as summer stresses becomes a problem. Scouting your sports fields and monitoring weather conditions for disease and insect occurrence also should be part of an overall stress management program. Early detection is mandatory in order to insure optimum control and efficient use of pesticides and/ or plant and soil health products. Also scout for early indication of excessive wear areas. Biostimulants and Pre-Stress Turf Management