DISEASE prediction
Online
Can Syngenta’s Greencast be used to optimise fungicidal control of microdochium?
Following extensive tests at The STRI headquarters in Bingley Dr. RUTH MANN believes so.
PREDICTING when pathogens will attack turf is a learned art. Once you have been caught out and suffered the consequences of widespread angry patches of microdochium (fusarium) patch during a mild and wet autumn, you learn to ‘feel’ the right weather conditions as you walk out the door. I often state that we are experiencing ‘good fusarium weather’ and everyone knows what I mean.
Added to this, the application time for most fungicides to achieve good disease control can be crucial, especially with the newer fungicides that have come onto the amenity market in the last couple of years. Strobilurins (e.g. azoxystrobin) and DMIs (e.g. propiconazole) should be applied before Microdochium nivale has extensively colonised the grass plant to provide their best control. In reality, this means applying them before the first sign of disease. An 'indicator' green can be a good way of establishing when to
Plate 1: Untreated control plot showing high level of microdochium patch
treat all of the other greens as it will develop disease first. As soon as disease is observed on the indicator green, all other greens should be treated. However, if you do not have an indicator green or if you want to keep all greens clean from microdochium patch, without having to use an expensive and environmentally unsound prophylactic fungicidal programme, could disease occurrence be reliably predicted? Syngenta Crop Protection has developed an online decision support tool called Greencast, that is being commonly used in the States, to try to reduce prophylactic use of fungicides and encourage application only when occurrence of the disease is predicted. This system uses forecasted weather to determine the likelihood of certain diseases occurring. From winter 2005 until spring 2007, STRI and a number of golf courses throughout the UK and Ireland have been assessing Greencast to
Plate 2: Heritage @ 0.5 kg/ha applied monthly (4 applications)
determine how accurate it was in predicting the occurrence of microdochium patch. STRI also conducted a field trial to determine whether there was any difference in the optimal timing of fungicidal control using Heritage (azoxystrobin, an acropetal penetrant) and Daconil Turf (chlorothalonil, a contact). Heritage systemically moves into new growth and provides at least 28 days control of microdochium patch while the grass is still growing during mild autumnal weather. It is particularly effective when applied just before symptom expression. Chlorothalonil gives good knockdown of microdochium patch and is especially useful later in the season, where soil temperatures are low, leading to reduced uptake of acropetal penetrants. Greencast gives predictions of no risk,
low, medium and high disease risk presented as a map of the UK and Ireland for any given date with regions
Plate 3: Heritage @ 0.5 kg/ha applied at high disease risk (2 applications)
“I often state that we are experiencing ‘good fusar
©Angers University, France
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