stadium FERTILISERS of light AND CHEMICALS
Spotting the early signs of
disease
With the risk of Microdochium Patch peaking this autumn there is no time like the present for greenkeepers to hone their disease identification skills to assist in rapid identification and treatment. Dr Colin Mumford, Bayer Technical Manager, gives his top tips on spotting the signs of Microdochium Patch, in order to help tackle the disease in the most effective, preventative way.
Stage one “Before signs of disease start to occur in turf, it’s highly likely that Microdochium disease spores will be present, but dormant among the sward. “This is the prime time to ensure that all cultural and biological practices have been carried out, in order to achieve the healthiest sward possible and minimise environmental conditions that aid the spores in developing into disease,” said Colin. “I’d recommend ensuring that your cutting blades are sharp enough to give a clean cut, as blunt edges can tear the grass leaf tissue, leaving a larger wound than necessary. This gives a greater surface area for disease to infiltrate the plant.” Colin explains that carefully managing nutrition levels can assist in preventing certain diseases such as Red Thread (Laetisaria fuciformis) and Anthracnose (Colletotrichum spp.) as well as help maintain good turf health. “Excess fertility, however, can encourage Microdochium Patch, so it’s important that nutrition is adequate, but not in excess. When it comes to biological practices there are a couple of options. Firstly, consider introducing new grass species that are tolerant
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to stress factors, such as drought or shade, that can make turf more susceptible to outbreaks of disease. “In addition to this, the use of microbial inoculants can help to enhance the microbial population in the root zone. This aids in the breakdown of organic matter to release vital nutrients to the plant. However, it’s important to analyse the turf properly to determine if this treatment is appropriate,” noted Colin. “Following the cultural and biological practices, when the weather is right, generally in temperatures below 15.5°C in still and damp conditions, a preventative fungicide, such as Exteris® Stressgard, is the best way to tackle Microdochium Patch before it can do any damage.
Stage two The second stage of Microdochium Patch sees the very first signs of disease developing. These will be visible to the naked eye in the form of slight discolouration or browning of the turf. “At this point, a fungicide with early curative properties can be used to help stop the disease continuing to develop. Again, I’d recommend using Exteris® Stressgard (fluopyram and trifloxystrobin) or alternatively Dedicate® (tebuconazole and trifloxystrobin).”
Stage three “Once the first signs of Microdochium Patch can be seen, it can quickly start spreading, so it’s essential to try and spot the signs before the brown or
bronze coloured patches spread. “This is because, following the loss of the popular curative fungicide active ingredient, iprodione, there are very few products remaining on the market to treat this damaging disease, after the early stages of development.”
Stage four At the penultimate stage, the patches continue to spread and darken in colour, often joining into larger patches. “It’s not uncommon to see mycelial growth surrounding the patches, especially when there’s dew on the ground, which shows as a white, slightly ‘fluffy-looking’ fungal growth.
Stage five “During the fifth and final stage of Microdochium Patch, the circular brown areas can reach up to 20cm wide if left untreated. A orange or ginger coloured ring forms around the edge of the spot, with the inner circle remaining a shade of brown, often developing a wet or greasy look. After this stage, it’s likely that scarring will occur on the turf, negatively affecting playability due to the uneven surface created. This damage isn’t completely irreparable. When conditions are right and grass growth is active, the turf can recover from the disease. “However, as this most commonly occurs in the autumn, subsequent cool temperatures can often mean that full regrowth won’t happen until the following spring, hence the importance of preventative or early treatment,” explained Colin.