Anthracnose is not a disease that is rearing its head right now, but we know enough about the disease to say that it will be very common across the UK over the next few months. Now is the time to start planning your practices if you historically suffer from anthracnose. By the time you see visible signs of the disease, it’s quite often too late to do anything effective about it, so good work now will prevent damage further down the line. Anthracnose is definitely in the ‘prevention is better than cure’ category.
These mini heatwaves and downpours over the last few weeks have put the plant under stress and I’m already seeing golf clubs with soaking wet greens all winter having to hand water and then flooded again days later – perfect stress conditions that can induce anthracnose. This technical sheet will give you a good guide to disease identification, prevention and cure.
Potassium for Prevention?
Hopefully, this article will get you on the right road to prevention. One recent piece of research on anthracnose came up with some interesting observations. Measuring potassium levels in the leaf tissue showed strong correlation between potassium levels above 2% and a big reduction in anthracnose (the opposite result was noted for microdochium; high leaf potassium produced higher microdochium). Not all sites and trials are the same and this research was from the USA, but the evidence was quite compelling and the data very strong. We know potassium is important for cell turgidity and stomatal opening regulation (and thus moisture retention in summer), so applying a liquid potassium supplement on anthracnose-prone sites before disease occurs would appear a very prudent move.
Without doubt the most important factor in anthracnose development is nitrogen availability. Low nitrogen levels will make anthracnose more likely. Getting nitrogen applications correct is a fine balance and its importance in fine turf management cannot be overstated. Too much or too little can cause equal problems.
What are you trying to achieve with nitrogen? You should be aiming for just enough nitrogen to maintain a smooth surface – no more, no less. That differs from site to site, species to species and soil to soil. That is why measuring clip yield is becoming more popular and this is great to see as I’ve been advocating this practice for many years. Once you start to measure yield, you can put a figure on how much growth you want to obtain the response you require. This video gives a nice overview of how you go about measuring yield. In this example they measure clippings by weight. You can also measure by volume by pouring clippings into a bucket/jug with ml/litres marked down the side. Whatever method you use, be consistent.
Clipping yield measurement WILL reduce thatch build up and help keep disease attacks down. This particular pathogen lives as mycelium or conidia within the thatch layer, so less thatch = less likelihood of disease.
If you choose to (or must) go down the preventative fungicide route, one good option for anthracnose is azoxystrobin. This may be a particularly good choice of active ingredient if you have issues with any of the following diseases: rhizoctonia, take-all patch or type 2 fairy rings. It has label approval for all these diseases and an early application will help knock down the fungal pathogen population before turf damage is seen. Thatch fungus/collapse is not officially on the label of azoxystrobin, but as the causal pathogen is from the same basidiomycete family that cause fairy rings it’s a fairly safe bet that it will help with that too if that happens to be an issue.
Growth Products Companion makes a great tank-mix partner for azoxystrobin and has label-approval as a biological fungicide in the USA for anthracnose, dollar spot, microdochium and rhizoctonia (brown patch). Companion is liquid blend of plant growth promoting rhizobacteria (PGPR) called Bacillus subtilis GB03 that have several independent research papers that show some very interesting improvements in turf quality and reductions in disease. Any products or practices that can improve turf health while reducing fungicide use are to be welcomed. Data is available showing the benefits of combining the two products in summer disease management.
Geoff Fenn BSc (Hons) – AGS UK Technical Manager
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