Mid-summer ‘clean up’ applications seem to happen every year for a variety of reasons. Disease pressure, cultivar susceptibility, environmental extremes, reduced fungicide sensitivity, and budgetary restrictions are just a few factors that can lead to dollar spot breakthrough.
It is important to understand what happens when a fungicide is applied to curatively control dollar spot. First, curatively controlling the dollar spot pathogen involves the stopping the growth of the fungus both inside and outside of the plant. This is why systemic fungicides are recommended to treat severe symptoms. The time it takes to send the pathogen back into remission largely depends on the active ingredient and formulation of the selected product.
Secondly, it is important to understand that slowing down active dollar spot will take more force than simply preventing new infection centers. Meaning, a higher dose of product is usually required in a curative situation. Another consideration is shortening the spray interval in the follow up application due to the high amount of dollar spot inoculum present in the turfgrass system.
The next phase of curatively controlling dollar spot needs to come from the plant itself. Symptoms of dollar spot will remain on the turf until the plants can recover from prior damage. This is why all curative applications for dollar spot should be administered before ‘pitting’ begins. Severe dollar spot that has caused pitting can take much longer to recover compared to dollar spot ‘speckling’.
Exteris Stressgard and Mirage Stressgard are two xylem mobile fungicides that offer excellent curative and preventive dollar spot control. One of the reasons that Exteris Stressgard is so effective at curative dollar spot control is due to the inclusion of Leaf-CoteTM technology within the formulation. This new technology allows for greater leaf surface coverage, hastened rainfastness, and dew mitigation. All of these aforementioned qualities make Exteris Stressgard a valuable tool in your curative dollar spot control program. When using fungicides, always read and follow the label instructions to maximize their effectiveness.
It is important to apply a curative fungicide treatment during the early stages of infection. Dollar spot that has ‘pitted’ can result in much slower recovery. Photo: Jesse Benelli, PhD, Bayer