For the second year in a row, fairy rings and thatch fungi were the most queried subjects at the STRI pest & disease clinic writes Ruth Mann, Head of Research STRI.
It was an excellent year for basidiomycete activity, due to the wet/dry cycles we have experienced. Spring was cool and pretty dry, followed by a cooler, dry start to the summer. We then experienced warm dry periods, interspersed by wet cycles allowing the basidiomycetes to develop well. Thatch Fungi were more of a problem in spring and autumn and Fairy Rings popped up all season long.
Thatch Fungi symptoms were much more widespread in 2013 compared to 2012. It is possible that we are encouraging Thatch Fungi to proliferate with current management practices. Aeration methods used to physically remove organic matter and top dressing to dilute thatch will encourage a more aerobic root zone enhancing microbial activity. We therefore may be creating an area more attractive to these fungi and they are helping to reduce the thatch material by recycling the nutrients in it.
However this may not be welcome news as the symptoms of these fungi 'helping' are depressions on golf and bowling greens, which affect playability!. It demonstrates the fine lines between using necessary cultural controls to encourage natural processes and these cultural methods may be working very well, but could lead to unintended consequences. The ideal situation is to develop equilibrium where the organic matter reaches an ideal level, allowing growth beneficial microbes, without their effects reducing surface quality and playability.
It was also a bad (or good, depending on your point of view!) year for Dollar Spot. Symptoms did not appear to be widespread as in previous years, but more difficult to control where did it did occur. We have now seen an improved result in many trials by using a combination of liquid fertiliser with a fungicide application (either as a convenience tank-mix with physically compatible products or liquid fertiliser following the fungicide application). The fungicide stops the Dollar Spot preventing the spread and the fertiliser helps to strengthen the plant and improve turf quality. Just remember that the fungicide element will wear off and, if high risk weather conditions persist, further infection may occur if the grass plants are not protected.
For the first time ever Microdochium patch did not make the top three!. So far this year, the microdochium season seems to be quite short. Major outbreaks occurred in late summer as wet weather returned when soil temperatures were still quite warm. It has then gone either very wet or pretty dry, depending on where you are in the country, which has reduced the severity of most infections. The ideal was to have preventative control down just before the outbreaks in late summer or very early curative control. Unfortunately, weather conditions have not been conducive to recovery after infection and patches may last a long time. Keeping the turf well protected will also have paid dividends if the forecast snow arrives and hopefully existing patches of microdochium patch do not develop into snow mould.
Expanding potential uses of plant growth regulators such as Primo Maxx was a common query over the past year. When to start in spring is always a difficult decision as consistent growth is needed. The cool spring of 2013 led to later starting of programmes in some areas. The past year also showed just how flexible applications of growth regulators may need to be to maintain optimal regulation. Even in our trials work, applications designed to last 4 weeks, needed a reduced interval to keep the plant in full regulation, depending on environmental conditions and corresponding turf growth.
Flexibility in dose rates may also be important to allow optimal effects in each situation. For example reducing the dose rate in the first spring application is normal. However, higher dose rates may be needed in certain environments, such as shaded areas, to ensure optimal effect of the growth regulator. Therefore experimenting with different dose rates and application frequencies in different situations may be needed to find the rate that will produce the best turf quality for you. Once determined, don't carve it in stone, as altering rates and frequencies depending on environmental conditions and turf grass growth may produce even better results for you.
Top 10 Queries in 2013
- Fairy Ring
- Thatch Fungi
- Dollar Spot
- Take-all Patch
- Tank-mixing problems
- Microdochium patch
- Plant growth regulators
- Red Thread