Over the last 2-3 years management of Microdochium nivale has changed radically with two key drivers impacting on turfgrass management:
Autumn 2018/19 proved to be a game changer in terms of our autumn/winter weather patterns. We are now quite used to periods of warm and humid air during the early autumn, with October typically the worst month for aggressive Microdochium activity. In 2018/19 we saw a different weather pattern later into the winter with high pressure located South West of the UK ushering up mild and humid air during November and December.
The period between Christmas and The New Year featured mild day and night temperatures, light winds and humid air giving ideal conditions for fungal development. Many golf courses and sports pitches that had managed to keep disease scars to a minimum up until Christmas saw very aggressive disease activity and multiple scarring through late December and early January.
Dove-tailed with climate, we continue to see the impact of E.U. legislation with the withdrawal of effective fungicide actives. Over the last 3 years we have lost Prochloraz, Iprodione, Chlorothalonil (in mixtures) and recently Propiconazole. Newer chemistries coming into the market contain significantly less A.I and so are not as effective on the grass plant pathogen as the products they replace. Less A.I also means a shorter longevity of effective control. This is further compounded by higher grass growth rates occurring late into the autumn/winter period so fungicide actives are removed in the grass clippings at a faster rate.
With Microdochium nivale proving harder to control and the ‘safety net’ of effective pesticidal options becoming more limited by the minute, there is now an increased focus on implementation of an effective IPM program. Aside from good surface organic matter management, aeration and topdressing, achanging sward composition to less susceptible grass species is also a key objective for many turfgrass managers.
Along with aeration and changing the sward composition, application of products which are non-pesticidal i.e. they do not directly act on the pathogen - is proving to be another effective management tool. These work in a number of different ways including;
Headland Amenity have been pioneering research work since 2007, carrying out independent trials at the S.T.R.I using a combination of products to minimise Microdochium nivale. Our strategy featuring the 20-20-30 tankmix of Turfite Elite, Liquid Turf Hardener and Seamac Proturf Fe has been continuously refined and improved with the recent addition of Mantle®, enhancing efficacy.
A low pH liquid iron supplemented with magnesium and seaweed to acidify the leaf surface.
A low pH calcium and magnesium liquid solution with nitrate N to facilitate faster uptake.
Now utilising potassium phosphite and supplemented with salicylic acid, a proven plant defence elicitor.
A water-soluble micronutrient package containing manganese, zinc, magnesium and the Harpin Plant Elicitor.
Headland Amenity began this journey long before there were concerns regarding pesticidal availability. Utilising independent trials undertaken at S.T.R.I, we have consistently shown a reduction in Microdochium nivale activity adopting the 20-20-30 approach. In 12 years of research trials, the 20-20-30 tankmix has reduced Microdochium nivale in every year but one (in that year there was already > 30% of the plot affected by Microdochium before the trial commenced).
The objective of an effective IPM program against Microdochium nivale is to prevent a population establishing during the autumn/winter. Research and end-user feedback has shown once a population is established it is extremely difficult to control and tends to go through periods of inactivity and reactivity leading to severe scarring. Sometimes this scarring isn’t grown out till the following spring.
Headland Amenity suggest utilising a combined approach of pesticidal and non-pesticidal treatments commencing in late summer/early autumn (depending on weather patterns).
If there is already active disease present in the sward, commence with an approved fungicide to lower inoculum levels and then follow up with the 20-20-30 + Mantle mix within 14 days of the pesticide application. Continue applications at the same frequency unless growth levels are high when intervals will need to be tightened. Usually by early November there is a significant drop off in growth rate and so application frequency can be extended to 21-28 days for the 20-20-30+Mantle mix. Vary the rate of Mantle from 10kg per ha during normal disease activity periods to 20kg per ha when disease activity is high.
Particular attention should be paid to the period leading up to Christmas when extended periods of leaf wetness can encourage significant disease activity. If disease pressure is anticipated as being high, a pesticide application may be required and again supplemented with the 20-20-30 mix + Mantle @ 20kg per ha.