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Leatherjackets and Chafers: How to boost natural turf defences without pesticides

As caretakers of bowling greens, we are faced with more challenges than ever before. Extremes of weather are far more common now, so that we find ourselves dealing with prolonged dry and hot spells and conversely, prolonged wet spells more regularly. These conditions are causing problems of greater severity than weโ€™ve commonly been used to, and this couldnโ€™t have come at a worse time in the evolution of UK bowling greens. At the end of four or five decades of continually adding sand, spraying pesticides and the routine use of high salt synthetic fertilisers, the soil/turf eco-system of many greens has never been less well prepared to fight off the increasing problems we are encountering now. Root herbivores such as Leatherjackets and Chafer Grubs, fungal diseases such as Fusarium and Dollar Spot and of course the most frustrating and widespread problem of them all, Localised Dry Patch seem to be lining up to have a go at our turf, and in many cases the quick fixes we perhaps relied too heavily on in the past are not available anymore. In any case, we maybe failed to recognise that these so-called quick fixes were only masking the symptoms and not actually helping to cure the root causes of these problems for the long term.

How can we get back to sensible greenkeeping?

This month, letโ€™s take one of the most urgent greenkeeping issues as our guide and consider the burgeoning problem of insect pests on turf health. Of course, we could use insecticides when they are allowed, on small areas of our greens to deal with these bugs, but that’s simply a sticking plaster solution. It doesn’t fix the real problem, which is the poor health of our soil and the inability of our turf to withstand and repel attacks, which it can do naturally, given the chance and the right conditions. Pesticides only deal with the urgent symptoms and not the long-term problem, which will keep recurring until we tip the ecological balance against insect damage. By looking to see what nature has already come up with as solutions we can harness these. We need to tap into the natural processes that have helped grass thrive for millennia. Grass plants can naturally repel, withstand and recover from insect herbivore infestation and there is a three-pronged natural greenkeeping strategy we can deploy to help our greens recover this ability.

Chitin (pronounced: Ky-tin)

Chitin is a natural substance found in the exoskeletons of insects and the cell walls of fungi. When it breaks down in the soil, it turns into chitosan, a substance that can boost plant growth, improve soil structure, and stimulate helpful soil microorganisms. These microorganisms can help control harmful pests and diseases, making the soil and plants stronger and more productive. In conventionally managed turf (using pesticides, high salt synthetic fertilisers and excess sand), the soil can become almost lifeless. This means that the natural microbes and processes that break down chitin are disrupted, leading to a lack of beneficial substances like chitosan. Leatherjacket exoskeletons are rich in Chitin, meaning that by boosting the population of Chitin loving bacteria in the soil, we automatically boost the ability of the soil to provide at least a partial solution to damaging root feeding insect grubs. By reducing our reliance on artificial inputs and adding natural substances like chitin or chitosan directly, we can help restore the soil’s natural balance, promoting healthier, more resilient turf.
Chitosan isnโ€™t limited to helping with leatherjackets as it does a lot of good things for our soil into the bargain:
โ€ข It improves soil structure, which helps with water retention and nutrient availability.
โ€ข It boosts plant defences, making them more resistant to diseases.
โ€ข It influences the soil microbiome, suppressing harmful microbes while promoting the growth of beneficial ones.
โ€ข It can be used as a biocontrol agent to manage soil-borne pathogens.
โ€ข It can even play a role in bioremediation, helping to neutralise or remove contaminants from the environment.

Potassium Silicate

The second prong of this natural strategy to deal with root herbivores is the regular application of Potassium Silicate. This is a beneficial soil amendment that can be added to your greenkeeping toolbox in place of chemicals, and again, it offers several advantages that contribute to the overall health and resilience of plants.
Here are some of the key benefits of using potassium silicate:

  • Strengthening of plant cell walls: Potassium silicate is known to strengthen plant cell walls. This is achieved through the deposition of silicic acid (Si(OH)4), which is taken up by the roots and deposited in plant cell walls as SiO2. This process enhances the structural rigidity of the plant,
    making it more resistant to physical stress and damage.
  • Enhancing disease and pest resistance: Potassium silicate has been linked to disease suppression in plants. Research has shown that silicon can help reduce the incidence of various common fungal diseases of turf. This is achieved through the creation of a mechanical barrier beneath the cuticle in cell walls and the activation of defence genes and enzymes.
  • Stronger plant growth: reducing susceptibility to pests and disease
  • Cell Wall thickening: Thicker cell walls increase the grass plantโ€™s natural
    defence mechanisms
  • Improved leaf erectness: which helps with the control of annual meadowgrass and improves green speed and smoothness without lowering the height of cut.
  • Reduced susceptibility to attack from fungal pathogens like Fusarium and Dollar Spot.
  • Reduces susceptibility to attack from root herbivores and sucking insects like Leatherjackets and Chafers.
  • Increases resistance to drought, heat and cold stress.

  • Molasses derived biostimulants

  • Some Molasses-derived bio-stimulants contain a variety of components that contribute to their effectiveness in turf grass management. These components work together to enhance soil health, promote plant growth, and increase stress tolerance. Some of the most important components of properly formulated molasses-derived bio-stimulants are:
    1 Carbohydrates: Molasses is rich in carbohydrates, such as glucose, fructose, and sucrose, which serve as an energy source for beneficial soil microorganisms. A thriving microbial population leads to improved nutrient cycling, enhanced soil structure, and better overall soil health, supporting robust turf grass growth.
    2 Organic acids: Organic acids, such as citric, malic, and succinic acids, act as chelating agents that can increase the solubility and availability of essential nutrients, facilitating their uptake by turf grass. This results in more efficient use of applied fertilisers and improved plant health.
    3 Vitamins: Molasses contains various vitamins, such as B-vitamins, which can stimulate plant metabolism, growth, and stress tolerance. These vitamins can also support the growth of beneficial soil microorganisms, further improving soil health and turf grass performance.
    4 Trace minerals: Molasses-based bio-stimulants provide trace minerals, such as iron, manganese, zinc, and copper, which are essential for various physiological processes in turf grass. These trace elements contribute to the overall health, growth, and stress tolerance of turf grass.
    5 Amino acids: Amino acids in molasses can serve as building blocks for proteins in plants and stimulate plant growth by acting as precursors to plant hormones. They can also enhance nutrient uptake and promote the growth of beneficial soil microorganisms.
    6 Growth-promoting substances: When properly formulated for turf use, Molasses contains growth-promoting substances, such as auxins, gibberellins, and cytokinins, which regulate various aspects of plant growth and development, contributing to a healthier and more vigorous turf grass. Regular application of a properly formulated Molasses derived turf bio-stimulant can:
  • Promote the availability and the ready uptake of mineral nutrients
  • Increase the plantโ€™s ability to resist and recover from environmental stresses like heat, cold and disease and pest problems.
  • Reduce root feeding insect and nematode damage. Some products contain useful levels of furfural (typically 50mg/kg), high in sugars (> 40%), which can help build resistance root herbivores like Leatherjackets and Chafers.

  • Building turf strength and resistance

  • Itโ€™s becoming increasingly clear that as greenkeepers our approach to green maintenance and improvement must shift from a reliance on synthetic solutions, which in many cases simply mask symptoms, to a greater emphasis on harnessing the power of nature. Tackling the growing barrage of turf health problems we are seeing now requires an understanding and revitalisation of the natural ecosystem once naturally present in our greens. Through the strategic use of chitin, potassium silicate, and molasses-derived bio-stimulants, we can improve the soil’s structure, encourage beneficial microorganism activity, and build stronger, more resilient turf that performs better for bowling. By adopting this approach, we not only deal with the urgent issues, but simultaneously lay a path towards a healthier, self-sustaining green for the future. Itโ€™s easy to under-estimate the extent of the damage we have inflicted on our soil and turf health
    over the years, but the sooner we start to redress the balance, the sooner we will see better results in terms of turf health and green performance.
  • If you have any questions or need help with a greenkeeping problem, please drop me a line on john@bowls-central.co.uk