Falling autumn temperatures, heavy dew and long, damp nights create favourable conditions for the development of Microdochium patch. One particularly important factor for turf health is the length of time the leaf surface remains wet.
It is one factor in a wider picture that also includes temperature, humidity, turf species, nutrition, plant health, airflow and local growing conditions.
The combination of TourTurf® EPT Respond® Extreme Penetrator Wetting Agent, TourTurf® FDC Autumn Foliar Defence Concept and TourTurf® STA Sports Turf Acidifier has proven to help increase turf resiliency and alter environmental parameters. TourTurf® FDC goes strong already for 20 years as one of TourTurf’s signature products!
A controlled-environment study by Dwyer et al. (2017) examined Microdochium patch development on creeping bentgrass (Agrostis stolonifera ‘Penncross’) across leaf-wetness periods of 24, 36, 48 and 60 hours and temperatures ranging from 8°C to 20°C.
Within the conditions of the experiment, the area affected by Microdochium patch increased as the duration of leaf wetness increased. Temperature also influenced the rate and severity of disease development, with warmer conditions generally accelerating progression.
These findings demonstrate that prolonged leaf wetness can substantially influence Microdochium patch development.
The practical takeaway is not that leaf wetness acts alone, but that reducing prolonged periods of surface and canopy moisture can help make the turf environment less favourable for Microdochium patch development. This should form part of an integrated management programme that also considers airflow, shade, drainage, nutrition, mowing practices, thatch management and overall turf resilience.
TourTurf® EPT Respond® Extreme Penetrator Wetting Agent contains penetrant surfactants designed to lower the surface tension of water and help move excess surface moisture into and through the root zone.
By supporting water infiltration and distribution, TourTurf® EPT can contribute to firmer playing surfaces and help reduce the time excess water remains at the surface. This can be particularly valuable during autumn and winter, in naturally wet areas or ahead of forecast periods of heavy rainfall.
Moving water into the root zone does not replace practices that directly address leaf wetness, such as improving airflow, reducing shade and managing dew. Instead, TourTurf® EPT complements these practices by supporting infiltration and reducing persistent surface moisture.
Waterlogged root zones can also restrict oxygen availability and create unfavourable conditions for root activity. Improving water movement through the soil profile can therefore support a healthier root-zone environment as part of a broader autumn and winter turf-management programme.
TourTurf® EPT Respond® Extreme Penetrator Wetting Agent contains 2.5% salicylic acid. Salicylic acid is a naturally occurring plant signalling compound involved in the regulation of defence responses and adaptation to environmental stress.
In plants, salicylic acid participates in signalling pathways associated with systemic acquired resistance. These pathways can stimulate the production of pathogenesis-related proteins and other defensive compounds. However, plant responses to externally applied salicylic acid depend on factors including plant species, concentration, formulation, application timing and environmental conditions.
Salicylic acid is one component that can support the plant’s natural stress-response processes.
A separate in-vitro trial was conducted in 2025 using agar inoculated with the organism associated with Microdochium patch. The agar was treated with salicylate, a salt of salicylic acid.
In this preliminary laboratory assay, a 0.5% salicylate treatment produced a modest reduction in fungal growth, while a 10% treatment produced a considerably greater reduction.
Preliminary in-vitro evaluation of salicylate concentrations on fungal growth on inoculated agar, 2025.
Because the experiment was conducted on agar without living turf plants, it did not evaluate systemic acquired resistance, plant resilience or field performance. The findings indicate concentration-dependent inhibition of fungal growth under the specific laboratory conditions used.
Further work would be required to determine how these observations relate to turfgrass under field conditions. The salicylate compound, concentration basis, pH, controls, number of replicates, assessment method and statistical analysis should therefore accompany the complete trial results.
TourTurf® FDC Autumn Foliar Defence Concept has been developed to support turf quality, colour, winter hardiness and resilience during periods of low growth and increased environmental pressure.
Development and independent evaluation began almost two decades ago. Early work included trials at Woburn Golf Course in the UK and Skovlunde Golf Course in Denmark. The concept has subsequently been evaluated through work involving the European Institute of Turfgrass Science at Hittfeld, the University of Wisconsin’s snow mould testing programme, the Agri-Food and Biosciences Institute at Queen’s University Belfast and Oregon State University.
TourTurf® FDC provides macro- and micronutrients, amino acids, plant extracts, surfactants and triacontanol. Together, these components are designed to help turf retain colour, strength and recovery capacity during autumn and winter. The surfactants also help reduce dew formation and surface moisture on the turf canopy.
The FDC field trials evaluate turf performance under practical growing conditions, rather than an isolated pathogen response or a single environmental variable.
During winter 2023/24, Brian McDonald and Alec Kowalewski, PhD, evaluated TourTurf® STA Sports Turf Acidifier, TourTurf® FDC Autumn Foliar Defence Concept and TourTurf® TAG Turf Amenity Granules—individually and in different combinations—on a Poa annua putting green at Oregon State University.
The trial was conducted under natural Microdochium patch pressure and assessed both turf quality and the performance of the different programmes. While FDC alone supported turf performance, the best result was achieved by combining TourTurf® FDC Autumn Foliar Defence Concept with TourTurf® STA Sports Turf Acidifier.
This supports the use of FDC as part of a combined turf-resilience programme, rather than relying on a single product or mode of action.
Read the complete trial details, including the treatments, application timings and results, in our Turf Corner article: Improving turf quality under Microdochium patch pressure.
Controlled-environment research demonstrates the importance of prolonged leaf wetness for Microdochium patch development.
The preliminary agar study examines the direct effect of salicylate on fungal growth under laboratory conditions.
Combined, those findings support an integrated approach focused on managing the turf environment and strengthening the plant. TourTurf® EPT Respond® Extreme Penetrator Wetting Agent supports the movement of excess surface water into the root zone. TourTurf® FDC Autumn Foliar Defence Concept supports foliar nutrition, winter hardiness, canopy moisture management and turf resilience. TourTurf® STA Sports Turf Acidifier complements the programme with nutrition and additional turf-resilience components.
The following programme combines support for turf resilience with practical management of surface and leaf moisture:
Timing |
Product and application rate |
Programme objective |
| Monthly | TourTurf® FDC – 40 L/ha and TourTurf® EPT – 10 L/ha |
Supports turf resilience and helps reduce persistent surface and leaf moisture. |
| Two weeks later (during periods of high disease pressure) |
TourTurf® STA – 20–40 L/ha |
Provides additional nutritional and physiological support when the turf is under increased stress. |
Adapt applications to local conditions and consult your TourTurf technical advisor for tailored advice.
Try this product combination this autumn and winter to support stronger, more resilient turf while managing the environmental conditions associated with Microdochium patch pressure!