Disease management - time to be proactive

John and David Lawrencein Technical

In recent years, we've seen a continually changing landscape in our industry, relating most notably to the chemical armoury we have available to us. The days are gone where we can reactively treat disease, nor now is there an approved chemical out there to inhibit worm casting or the activities of chafer grubs and leatherjackets. David Lawrence, Grounds Manager, and John Lawrence, Assistant Grounds Manager at Edgbaston Priory Club, spoke to Kerry Haywood about the changes they are making.

As turf managers, we are having to become better at predicting what is going to happen to our surfaces; not just in terms of sward health, but also activity in the soil and the impact of the surrounding environment. As a result, we have had to come up with management approaches which offer greater and greater levels of integration. Buzz phrases, such as Integrated Pest Management, Integrated Disease Management, and Integrated Management Plans, are ways of describing approaches that we as groundsmen have probably always been implementing. Ultimately, they're just a fancy way to describe 'joined up thinking.' In our eyes, this has meant assessing each maintenance task we carry out, and every chemical and nutritional input we apply, to determine what its positive impact will be and what, if any, the negative side effects may be.

The challenge we now have of course is that, as we alluded to at the start, we now have less and less chemical inputs we can turn to solve problems. This is meaning that we are having to be exclusively proactive; reactive management is now longer possible.

This is exemplified by the evolution of the fungicides available to us. Around a year ago, Pitchcare published an article penned by John Handley titled 'Iprodione loss - the best thing that could ever happen.' We suspect that there were plenty of raised eyebrows from some quarters within the industry as a chemical which had been a staple of most people's defence against disease outbreaks was no longer going to be available. Iprodione was the last of the old school curative fungicides available to us, and the idea of having no reactive response to disease pressure was an understandably uncomfortable position for some. However, the salient point of the article, as we interpreted it at least, was that in order to continue progressing the quality of sports turf surfaces, innovation would be key.

Historically, we've always referred to fungicides as being our industry's equivalent to antibiotics in humans. This was of course true of curative active ingredients such as Iprodione - the plants got sick, and we gave it the antibiotic to make it better. The problem we have now is that the antibiotics have gone, so we have to think differently. Preventative fungicides are very different to the curatives we used to have. Where the curatives we had in the past could be applied reactively, we now have to be proactive in our approach to disease management. In that sense, the preventative fungicides we now have are more like vaccines. This means we're now in a situation where we have to vaccinate our plants before they get sick - a little bit like going to get your winter flu jab before flu season begins.

Left: Spraying - Centre Court - March 2019, Right: Events lawn and Clubhouse - Spring 2019

On paper, this sounds great; if the plant doesn't get sick in the first place, then there will never be any disease outbreak in the first place. The problem, of course, is that our preventative fungicides only work for a limited time-frame, much like some vaccinations which need topping up. The challenge then is to identify periods of disease pressure and make applications before outbreaks occur.

This is easier said than done; applying too often will lead to wasted money on unnecessary chemical applications, whilst not applying often enough (or at the right times more specifically) will allow disease outbreaks to occur - and with no curative fungicides to then treat the outbreak, as turf managers, we're still stuck!

So, how does all of this impact us at Edgbaston Priory? Well, for us, it has necessitated a change in mind-set with our approach to managing our eight championship grass tennis courts. Perhaps the biggest piece of work we undertook was back in 2017, when our Senior Groundsperson, Sue Lawrence, was tasked with carrying out an audit of all the chemicals we had applied in recent years, as well as anything we had in our chemical cabinet. The key thing we wanted to understand was what we were trying to achieve with each chemical we used, and to begin to try and come up with alternative ways to achieve our goals, should the chemicals go off the market.

In reality, this is a process that we had been implementing in the long term anyway on an ongoing basis. For example, anyone who has read our articles on dealing with casting worms will know that we'd been investigating alternative avenues to Carbendazim long before it was taken off the market. However, with the changing climate in relation to chemical usage and the sudden rush of chemical withdrawals, we felt it would be prudent to carry out a full audit of our processes.

The bottom line is that we just do not know how long each active ingredient will be around for, and so we wanted to try and put ourselves in a position whereby, if we suddenly, for example, lost all fungicides, we would already have a plan in place to deal with such a scenario. We should stress that this doesn't mean that we are going to stop using fungicides, but rather we're trying to reduce our reliance on using fungicides to as close to zero as possible while we still have them as a safety net option. It's much less daunting to try and do something different and innovative if we know that, in the event our experimenting goes off course, we still have a solution in the chemical cabinet to bail us out!

Renovation - Scarifying - September 2018

On that basis, going in to the 2018/19 winter, we identified two key threats to the quality of our grass courts for the following season; disease pressure and damage from casting worms. Our plan then was to come up with an alternative approach to using fungicides through the winter, whilst integrating a maintenance approach which would also mitigate any potential damage caused by casting worms. One of the first things we've considered in this light is soil pH. In reality, we've been addressing this issue for several years now, primarily with regular applications of sulphur chips through the winter to lower our pH. One of the challenges we face is that the mains water we irrigate with through the summer is alkaline. If left unaltered, the soil pH will become more and more alkaline over time. As well as the use of sulphur chips, we've also been paying more attention to the pH of everything we apply to our surfaces; whilst many of the chemicals and fertilisers we use will equate to relatively small pH movements in the soil, we buy in to the principle of marginal gains. In our minds, a lot of small adjustments could lead to one big jump in the right direction.

The most obvious reason for monitoring and manipulating our pH, is to try and discourage casting worms. It's well established that worms prefer neutral or slightly alkaline soils and so altering the soil in which they live will hopefully discourage and reduce their activity. We have noticed a reduction in casting activity in the areas where we are attempting to amend our pH, versus some of the ornamental areas we are responsible for where we do not have the budget to carry out such treatments.

Of course, this isn't a complete solution, rather part of a wider process we undertake, but more on that later. Maintaining a lower soil pH also has a number of benefits to the health of the grass plant. For example, there are plenty of research papers relating to soil pH, and prevalence and growth of diseases such as fusarium. In short, the majority of turf diseases are less prevalent where the soil pH is slightly acidic.

In addition to this, many of the nutrients needed to support healthy turf become unavailable to the grass plant, or are 'locked up' at higher pHs, particularly micronutrients (with the exception of molybdenum) which tend to become locked up at pHs above 7.5. A note of caution should be applied here, as it is also possible to lock up nutrients at lower, acidic pHs too. Phosphate is a good example of this; at pHs above 7.5, phosphate ions will combine with calcium and magnesium. Similarly, at lower pHs, phosphate ions will attach to aluminium and iron readily. In both scenarios, the compounds formed by these chemical reactions are not easily taken in by the grass plant. This means that managing pH is essential to ensuring nutrients in the soil are accessible to grass plants, which will in turn have a direct impact on the health of the sward.

Left: Mowing and sarel rolling Right: Wildlife Area - Spring 2019

Our target is to get our pH to a value as close to 5.5 as possible. This is of course slightly acidic, which is considered ideal for growing rye grasses, such as those that we use for tennis courts. It also allows for the many additional benefits listed previously, such as discouraging casting worm activity, inhibiting the prevalence of turf diseases, and whilst improving the availability of many nutrients in the soil profile. There will be some that will, correctly point out that, at a pH of 5.5, we may end up locking up a small number of nutrients (such as phosphate, as mentioned above), however we have also then looked at the way in which we feed our courts, particularly through the winter.

Another aspect of our winter management plan has involved looking at the way in which we feed our courts through the winter. In previous winters, we've combined some granular feeding with the use of liquid foliar feeds; those who have read some of our previous articles will know that, in recent years, we've incorporated turf hardeners into our winter programmes. However, for the 2018/19 winter, we've moved entirely to liquid foliar feeds in order to get as much of our chosen inputs in to the plant, as quickly and as directly as possible. This means we have to get on to the courts more often, as foliar feeds do not have the same longevity as some granular feeds, however they are likely to be more accessible to the plant.

For this winter, we combined a number of different products to form our winter nutritional programme. Each product was applied every six weeks between the start of November and mid-March, with the aim being to improve turf health and therefore reduce incidence of disease. The first component of our programme was Maxwell Turf Hardener, of which the primary ingredient is a chelated calcium (CaO). In recent years, more and more research has been carried out on the benefits of using calcium, rather than traditionally used products such as iron, as hardening agents to toughen the plant up during periods of potential stress and disease pressure. The take away from these research projects has been that calcium is much more effective at literally hardening the grass plants than iron. In basic terms, calcium literally hardens, or toughens, the cell walls within the grass plant, which makes it tougher for diseases to penetrate in.

Renovation - Top Dressing - September 2018

We also chose to apply phosphite to the courts, in the form of Maxwell Bullet Phosphite. Our reasoning for this lies in the results of work conducted by John Dempsey, the Course Superintendent Curragh Golf Club in Ireland. We would implore people, if they haven't already come across it, to seek out John's article for Pitchcare, 'Phosphite - what's all the fuzz about?' The article has since been followed up by a thesis in 2016, 'Suppression of Microdochium Nivale by Phosphite in Cool-season Amenity Turfgrasses.' The basis of Mr. Dempsey's research has been on the effect the use of phosphite has on Microdochium Nivale, commonly known as fusarium. The interesting thing for us with phosphite is that it has the capability to inhibit the ability of the Microdochium Nivale pathogen to grow and spread. As Microdochium Nivale, either in the form of fusarium or snow mould, tends to be the most prevalent disease we see, it has therefore been a no brainer to include phosphite in our programme.

In addition to the calcium and phosphite inputs, we've also included the Maxwell Bullet Trace Element mix, to ensure that all micronutrients required by the plant are available and accessible. We also included Sea Action liquid seaweed as a bio-stimulant to promote good soil health, in order to stimulate beneficial fungal and bacterial activity within the profile. As a final component, we also included Maxwell Bullet Chelated Iron; whilst we've noted some success with using iron as a turf hardener historically, in our case it has been included purely for its aesthetic value. Research has shown, pretty conclusively, that calcium based turf hardeners are far more effective than doses of iron. However, being a private members club means there is always pressure to maintain the courts in an attractive condition, and so being able to 'darken' them up a little in the winter with the use of iron is a plus point for us.

As we alluded to above, this approach is only effective if we can get on to the courts with enough regularity to apply the products. This is where granular feeds would have their most obvious advantage, due to their comparative longevity within the soil profile. That being said, foliar applications do allow for the nutrients being applied to get in to the plant more directly. This means that as well as offering faster results, we also bypass the soil profile and reduce the risk of locking up some of the ley nutrients we are attempting to get in to the turf.

Left: Practice Courts and Match Courts (right) - March 2019

As part of our longer term approach, we are investing a lot of time and effort in to researching what is actually in our soil profile and how we can alter it beneficially, however as we're sure readers will be aware this is not something that is a quick fix. In order to create a base line for the chemicals and elements within our soil profiles, we have started carrying out annual broad spectrum soil chemical analysis. From this, our aim is to amend the make-up of our soil profile in order to further reduce our reliance on synthetic inputs through methods such as spraying and applications of granular products. This, of course, will take time so for now we've settled on a programme of foliar products as a means to keep our courts in good health.

To allow for this approach though, we've had to develop an aeration plan to ensure that, during the wetter months of the year, the courts drain as freely as possible. Our starting point with aeration is the use of solid tines during our end of season renovations. This not only helps with alleviating some of the consolidation that has built up through the playing season, but also aids the amelioration of new top dressing in to the profile during those works.

On top of this, we also make use of an Air2G2 air injector during the autumn (normally late October or early November) in order to open the profile up at greater depths. Currently, we alternate between 7 and 11 inch tines annually as we only have the means to hire in the machine once a year. However, the results from the Air2G2 have been so impressive that we have added the machine to our capital expenditure wish list. We've no doubt if we had greater access to a machine, we'd be carrying out the process several times each winter, as a minimum.

The major advantage of the Air2G2 is the depth at which it can reach, with very little surface damage or displacement. It's a little bit like putting a drainage down pipe through the profile, as the machine is able to blast right through the soil profile and in to the drainage layers below. 2018/19 was the fifth winter that we've utilised the machine on our courts. In the first few years we only worked on off court areas, and as we began to see the positive results we were having, as well as no evidence of any adverse effects, we extended our work to include the in-court playing areas.

Of course, as well as improving drainage through the profile, the Air2G2 also benefits the health of the overall soil profile. The strap-line 'Air is anything to everything that lives' sums the machine up fairly well. Getting more air in to the profile promotes increased beneficial microbial activity, for example, which also ties in to our aim to reduce our use of synthetic inputs to maintain turf health.

Air2G2 in use

The final part of our winter aeration plan is regular sarel rolling, which is a very simple process but has also proved extremely effective. We've moved to a point now where, after any mechanical works during the winter months, such as mowing for example, we always follow up with a sarel pass. Obviously, this does not open the profile up to any sort of depth, but helps to get moisture away from the surface more quickly, in part by opening the very top of the profile up, but also helping to break up any moss ingress which will otherwise help to hold moisture at the surface.

All of this aeration has contributed to keeping the courts drier through the winter months, which in turn has allowed us to move to applying foliar feeds with more regularity. That being said, aiming to keep the courts and the soil profile drier is generally a good idea regardless. It promotes a healthier soil profile which in turn aids turf health. It also helps to reduce incidence of disease by keeping the profile drier, reducing the opportunities for disease pathogens to spread.

Having a drier profile, and surface, have helped us to reduce disease incidence. However, it isn't the only thing we have done which will have helped to reduce incidence of disease. For the winter of 2018/19, we made the decision to lower our winter height of cut from 15mm to 12mm, in effect a twenty percent reduction. The reduction in height has allowed for greater air movement across the turf sward, reducing disease pressure. Additionally, the shorter height has allowed us to spot potential disease more quickly and deal with potential signs before they result in serious outbreaks. Because our disease pressure has reduced so much, with the management plan we now have in place, we are in a position to spot treat potential signs, rather than spraying whole courts. This offers a huge cost saving as a bottle of fungicide goes a lot further this way, and also reduces the probability of pathogen resistance building up.

In truth though, reducing the height of cut was not actually primarily a tool for easing disease pressure. In fact, the direct rationale for reducing our winter height of cut was to allow us to manage worm casting better on the courts. Anyone who has read our previous articles on managing casting worms will know that we prefer to take a more holistic approach to dealing with the issue. Therefore that is why, as mentioned above, we pay so much attention to soil pH, in order to deter worms in the first place, rather than other methods. Even before Carbendazim lost its licence approval, we were already moving towards other control methods, and since then we've avoided the temptation to use other products off-label to stimulate a side-effect solution.

Ultimately then, we do have to accept that we will have casting worms within our profile, and as a result we will get some casts (albeit a diminishing amount as the pH becomes less hospitable) on the surface. This is something we accept because the positive impact of having worms within our profile outweighs, in our opinion, the negatives related to the casts they leave. Worms aid with aeration, they help to filter our organic matter and they aid nutrient availability. This does however mean that we have to come up with a way of dealing with the casts that do occur.

This is where the idea for the shorter mowing height came in; if the grass is shorter, it is much easier to clear the casts up. The biggest problem we have faced in previous years with worm casts has been trying to clear them up prior to carrying out work on the courts; no matter how much time was invested, it's incredibly difficult to find and clear every cast from the surface when the grass is longer. As a result, when mechanical operations such as mowing took place, the outcome was a lot of smeared casts on the court surface, which then had to be addressed.

Our plan therefore, was to reduce the height of cut through the winter to make it easier to clear casts from the surface prior to mechanical works, thus avoiding the smearing in the first place, rather than having to address the problem afterwards.

In addition to reducing the height of cut, we've also adjusted the way we clear casts off the surface. Whilst on sandier soil types using a dew-switch cane can be effective in breaking up casts, we find on clay soil the cane just smears the casts in to the grass. The same can be said for drag brushing, and even drag matting.

As a result, we've taken to bolting dining forks to 3 foot lengths of wood; this has resulted in some fairly strange looks from passers-by, but has been incredibly effective in dispersing casts. We then follow up behind with a blower to clear the dispersed casts off of the courts completely, which also helps to clear any additional surface debris, prior to carrying out activities such as mowing. This may sound time consuming, but in reality it is an extremely quick process. For example, we can send out a three person team to clear eight courts of worm casts, and the job is normally complete within a couple of hours.

This approach has been extremely effective this winter. It has meant we have been able to continue working on the courts, as and when the weather allows, without causing damage to the surface by smearing casts.

Centre Court - Winter 2019

This sort of success has been evident across our whole approach this winter. For example, we've also drastically cut our use of fungicides through the winter. Ordinarily, we'd expect to apply at least three fungicides between October and March. Normally, we'd expect to react to disease pressure at least twice, perhaps once in the autumn, and again in late winter/early spring. Additionally, we'd look to apply a preventative around Christmas when traditionally staff take annual leave and so we have less of a presence to spot and treat proactively.

In reality, since October, aside from occasional spot treatments, we've only applied one full fungicide treatment. This was in November when we felt that the amount of spot treating we were having to carry out indicated that a significant disease outbreak may be possible. There is a chance that with the programme we had in place that a serious disease outbreak would never have manifested, but whilst we still have access to the safety net solution, we have the option to use it if necessary.

Having the safety net also gives us the chance to try and refine our programme in order to improve its effectiveness. For example, for next winter we're considering reducing the window between applications on our practice courts from six weeks to just four weeks. Whilst on our Centre Court and match courts, visually the courts have maintained their colour and health, we noticed a deterioration in the aesthetic quality of the practice courts between the fourth and sixth week of our programme cycle. This deterioration is a good visual indicator that turf health was likely suffering and would therefore require addressing.

This observation also ties in with the results from the broad spectrum analysis we had completed across all the courts. The results showed that our block of three practice courts have a lower Cation Exchange Capacity (CEC) than the rest of our courts on site. Pitchcare Technical Sales Area Manager, Mark Allen, describes CEC as 'the pantry of the turf; the bigger the CEC, the bigger the pantry.' In relation to our observations on our practice courts, this makes complete sense. Effectively, our practices courts appear to have a lower holding capacity for nutrition within the soil profile, so in order to maintain turf quality and health, we have hypothesised that reducing the time between foliar applications of our winter programme, we should be able to improve the consistency of turf health throughout the programme cycle.

Centre Court - Autumn 2018

This sort of observation, and willingness to adapt our approach, is kind of what we feel like John Handley was talking about in his article last year, referenced earlier. It isn't enough anymore to just continue doing the same things we've done in the past because they worked before. Improvements can only be borne out of change, and whilst some of the changes we are having to make are borne out of necessity with changes in chemical legislation, having a perspective that sees these changes as an opportunity, rather than an obstacle, is key to continually improving our surfaces.

This is why we're being ambitious with our approach to chemical inputs; we don't know what is going to be next in terms of label approval revocation, and so any changes we can make to reduce our reliance on synthetic products, such as fungicides, whilst improving turf health in the process is, we believe, a sensible move.

We should note that we don't profess to be taking a totally 'organic' approach; realistically that will always be a tough ask, especially when considering the environmental challenges we have and the pressures of hosting an international sporting event. We will probably never manage to be one-hundred-percent fungicide free, but to aspire to be is a sensible and hopefully sustainable philosophy. Similarly, we accept that nothing we apply is truly non-synthetic - applying seaweed through a sprayer, for example, isn't exactly natural! However, by moving towards what we would identify as lower-risk products, such as leaning on phosphite applications rather than true fungicides, means that the products we rely on are products we're fairly comfortable aren't going to be disappearing any time soon!

This to us is also where Integrated Management Plans are so vital. Applying joined up thinking to the processes we implement is becoming ever more important; everything we do has the potential to provide gains, however small, but also create additional problems too. Everything we do has consequences, so it is vital we consider each action in a broad context, in order to avoid creating those aforementioned potential additional problems. There's no point solving one issue by creating another, especially in a legislative climate where we have less and less access to chemical safety nets. Reducing our reliance on chemicals, and coming up with alternative maintenance methods is vital to ensuring that we continue to improve the surfaces we care for.