Turf managers are in a constant battle to prevent the build up of thatch and its associated soft, spongy surface. Unfortunately many intensive maintenance practices that are adopted by modern day turf managers generally encourage build up thus making the job even more difficult.
For thatch to effectively break down certain conditions must exist in order to maintain a healthy and viable microbial population. Since fungi are very important in the decomposition of thatch, some scientists have investigated whether fungicides used to control turf diseases also aggravate thatch accumulation. At least four separate research programs have addressed this subject (Cornell University, The University of Maryland, and Rutgers University, as well as UK). Their findings can be summarised thus:
Several fungicides have been found to increase thatch accumulation under certain conditions. Amongst those can be included iprodione, mancozeb and thiram.
In sites where turf management was most intensive and the potential for thatch accumulation was greatest (high fertility, frequent irrigation, frequent fungicide use), several fungicides aggravated thatch accumulation.
In sites with moderate management (moderate fertility and irrigation, regular aerification, and moderate fungicide usage), most fungicides tested did not promote thatch accumulation, including those that did promote thatch accumulation in intensively managed sites.
The conclusion to this is that whenever using any fungicide do so in moderation and if possible attempt to use those that are more selective against beneficial soil organisms. As we all know the key to a healthy disease free turf is adopting a suitable maintenance programme based on meeting the turf’s nutritional and physiological requirements
