Sunday, August 31, 2008

Turf - Biostimulants and Stress

Use of biostimulants in turf has been shown to have some positive effects in research. The following is some basic information on how they work to reduce stress.

Plant Stress and Biostimulants

Under favorable growing conditions, plants synthesize hormones in sufficient amounts and do not require additional supplements. However, when plants are subjected to various stresses (i.e., mechanical, chemical or environmental) the normal production of these important plant hormones can be compromised. Research studies have shown that biostimulants improve plant quality, especially when they are under harsh, stressful conditions.

Research at Penn State and Virginia Tech have shown that root growth enhancement (root length and root dry weight) of plants supplemented with biostimulants occur during the greatest stress periods of the summer. In addition, improved root strength appears to be a major benefit of biostimulants. Improved mechanical stress tolerance can be of particular value on athletic fields. Further studies have also shown that biostimulants have increased chlorophyll content and photosynthetic capacity of plants, especially during periods of stress.

Tests have shown the common turf disease Dollar Spot can be suppressed by up to 50% by some biostimulants. However, it is important to be aware that during non-stress periods, control plots (where no biostimulants were added) showed no significant differences in the above tested qualities when compared to plants receiving biostimulants. Therefore, biostimulants can prove most important to plants when their functional processes are disrupted by less than favorable growing conditions. They can be particularly important when managing high valued ornamentals.

Some typical examples where biostimulants are most practical include golf courses, sod farms, athletic fields, and during the transplanting of small trees and shrubs. They are also of use when managing exclusive residential and commercial turf areas when the quality of turf needs to be maintained during stressful periods. In many respects, biostimulants and turf endophytes are similar in their abilities to perform as “insurance policies” by improving stress tolerances of the grass plants. Little value is gained when all conditions are optimal, but when less than ideal situations occur, then the endophytes and biostimualnts can enhance plant functions and reduce the loss of turf/plant quality.

Reprinted in part from "Unraveling Some of the Mysteries of Plant Biostimulants" by Steven K. Rettke, Ornamental IPM Program Associate, in the September 7, 2008 edition of the Plant and Pest Advisory, Lanscape, Nursery, and Turf Edition, from Rutgers University.

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