Technical - Soil Biology


Natural Ways to Reduce


Turf diseases spoiling your sward


Symbio’s Martin Ward says that turf diseases are an inherent part of the design of sand based pitches and USGA specification greens, relying as they do on relatively high levels of fertiliser and water input to maintain a playing surface. In the 1960s, when the USGA specification for greens was introduced fungicides were quite cheap, toxic and very effective but, in recent years, restrictive legislation, qualifications, the cost of fungicides and spraying equipment, are all reasons for reducing reliance upon fungicides to control disease


120 I PC APRIL/MAY 2016 I


n previous articles, we have looked at ways of reducing inorganic inputs and creating healthy rootzones to improve the quality of playing surfaces and, in the case studies of turf managers implementing healthy soil


management practices, you will have noted that the incidence of plant diseases and fungicide use is substantially reduced when you manage grass grown in healthy soil.


Turf diseases are almost unknown on natural grasslands and study of the plants and rootzones of healthy grass has shown how nature helps plants become disease resistant. We now know how to recreate many of the natural defence mechanisms against diseases in sports turf rootzones to the benefit of the plant, players and company purse.


Plants provide the food for the tonnes of microbial life that live in every hectare of healthy soil. If the plant dies, the microbes lose their source of food so, over millions of years, plants and microbes have developed a variety of defence mechanisms to keep the plant alive.


Arm the battlements


The easiest defence mechanism that a turf manager can manipulate is to make sure that the plant has strong cell walls that are resistant to invasion. This can be achieved by ensuring


that fertiliser applications are limited to prevent lush growth and by applying biostimulants that strengthen the cell wall, like potassium silicate, fulvic acid or chitin. You will have noted that fescue, with its hard cell structure, is more resistant to disease than soft celled poa annua. This is because the fescue cell structure contains a lot of lignin which is harder for the attacking pathogen to digest than the softer cellulose and sugars that make up the structure of poa annua.


When a plant comes under attack, pathogenic fungi will invade the plant through wounds, pores or by producing enzymes that break down the cell wall. In nature, plants have coexisted with the diseases that attack them for millions of years and have developed a range of defence mechanisms that come into play as soon as the plant comes under attack.


The plant senses what is happening and responds by producing toxic chemicals and pathogen degrading enzymes, some of which produce hormones called phytoalexins which flood the attack site and act as toxins to kill the invading pathogen.


Greenkeepers can stimulate the grass to produce these immune responses and phytoalexin production by using biostimulants


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