Future of Biocontrols

There are now more fungicide actives available for turf than at any time over the past five years, with further new products currently in the UK regulatory process. Now Syngenta R&D has highlighted how biocontrols can add an effective integrated approach, to get the best overall results. Syngenta biocontrols specialist, Dr Eric Chen, explains how.

Recent announcements of regulatory approval for new chemistry for turf management, including Ascernity fungicide for golf tees and greens, Acelepryn for leatherjacket and chafer control in sports turf and Overtake herbicide in amenity turf, for example, has provided valuable additions to the greenkeepers’ toolbox.

At the same time, there has been a real focus and investment in the research and development of biological products, and particularly their role in integrated strategies to get more consistent and reliable results - often with the opportunity to use fewer conventional chemical inputs. 

Biocontrols for turf management can be broadly defined as products based on naturally occurring materials that are used for biotic stress management in controlling fungal and bacterial diseases, insect pests, nematodes, and weeds.

That is subtlety different from some synthetic chemicals that were inspired by nature and natural biological processes, such as the active ingredients in in Medallion TL, Acelepryn and Heritage. 

That basic compounds went through an extensive R&D process to identify the chemical action and to refine them to target specific fungal pathogens, as well as to enable it to be manufactured consistently and reliably to give the desired result every time - but the basic chemical action was still inspired by the natural process. 

It is impossible to separate plant health from chemistry, since most actions within the plant at cellular level involve chemical reactions. Even photosynthesis, the most natural process on which we depend for a healthy turf plant, is governed by the complex chemical reaction of water, oxygen and light to provide the energy for growth. Biologicals can seek to use natural processes more efficiently and effectively in the plant. 

Biocontrol agents use various modes of action to control plant diseases and pests. There are biocontrol agents that work by directly killing pests, similar to conventional chemical pesticides. These biocontrol agents are often referred to as microbial pesticides or biopesticides. They contain living microorganisms such as bacteria, fungi, or viruses that can infect and kill pests. However, unlike conventional pesticides, they are often more specific in their target and have a lower impact on non-target organisms and the environment. 

Some biocontrol agents can compete with plant pathogens or pests for resources such as nutrients, space, and water, reducing their ability to grow and reproduce. 

Other biocontrols, such as parasitic wasps or entomopathogenic nematodes, can parasitize and kill plant pests. There are also biocontrols that do not have a direct impact on the fungal pathogen, but they often have a physiological effect on the plant that can enable or elicit a natural response that allows the plant to be more resilient to the disease attack and mitigate effects been seen.

Research has shown biocontrols offer real value to improve plant health and enhance integrated strategies, especially in the areas of improving utilisation of resources, including water and nutrients inputs, as well as strengthening disease and pest control programmes. 

That makes them extremely valuable as a boost where new or existing chemistry has restrictions imposed on the number of applications available or limited areas where they can be used. They are also a useful tool in resistance management strategies for the chemistry that is available. 

Importantly many of the biocontrols are highly host specific and can be targeted at particular issues, without any wider impacts.

The challenges identified by R&D programmes and practical use in golf course situations, is the lower levels of efficacy generally achieved, compared to what would normally be expected with conventional chemistry. Results may be sufficient in some instances, but typically biologicals have been seen to give less consistent performance in practice.

Biologicals can often be very effective in the lab when applied direct to the target pest – providing 100% control. But since biologicals tend to be adversely impacted by a wide range of environmental factors during application and utilisation by plant, the results in practice can be far less consistent. Many of those issues have historically been associated with the relatively short shelf life of many biological products, compatibility of mixing products and storage and application.

Extensive Syngenta research with NemaTrident beneficial nematodes, for example, demonstrated across a series of trials that the biocontrol nematodes achieved an average 45% reduction in leatherjacket larvae, from an average 35 larvae per m2 in untreated areas. Within the spread, the control ranged from 75% in one trial, to 13% reduction in another.

By comparison, treatment in the same trials using Acelepryn insecticide alone gave consistently higher levels of control, compared to the nematodes.

But when the two products were used together in an integrated approach, a further step change in efficacy resulted in an average of 90% control of leatherjacket larvae.

The trials have helped to identify techniques to optimise the performance of biologicals in an integrated approach. Documented research with Acelepryn in the US has indicated that when the insecticide paralyses soil pest grubs, they are more susceptible to infestation by nematodes - which is especially important to help target larger larvae. 

Furthermore, the work reported the optimum timing for Acelepryn treatment at the end of October to coincide with insect activity, with NemaTrident applied at a rate of 2.5 billon nematodes per hectare within seven days of the insecticide - while soil temperatures were still sufficiently warm and moist for nematode activity. The new Turf Advisor app has specific data to support the timing of applications when soil moisture and temperature conditions are appropriate.

The work has also identified the need to focus on nematode storage and application techniques, to successfully deliver the maximum number of viable nematodes applied onto the surface at the right time - along with managing moist soil conditions to enable nematodes to seek out their prey and maximise the numbers targeting the pests. 

Syngenta’s experience with an R&D approach to effective integrated control strategies, utilising biocontrols and conventional chemistry together, has highlighted the potential for emerging innovations that will influence turf health and resilience in the future.