Under severe disease conditions, crowns and roots may be killed resulting in little recovery in the spring. Disease tends to be present in same areas year after year if the same environmental conditions persist.
Fusarium Patch will occur when temperatures are between 0-15 °C with leaf wetness periods of greater than 10 hours a day for several days. Both diseases are often more severe in shady areas with poor air circulation, poor drainage and a thick thatch layer. Heavy applications of fast-release nitrogen and heavy topdressing serve to increase disease levels.
Fusarium survives through the summer as spores and mycelium in thatch or soil, and is generally dormant when temperatures are above 20C or when it is dry. In autumn, under cool, wet weather, spores may germinate or mycelium may grow from thatch or soil and infect leaves. Spores are carried by wind or surface water to adjacent healthy leaves. The fungus may attack foliage under snow cover especially if the plants have not hardened off and are damaged by the cold temperatures, or have become weakened by prolonged snow cover. After snowmelt the fungus remains active particularly if it remains cool and wet.
What can we do to prevent "FUZ". There are some fantastic chemicals at our disposal in the short term but for the long term the best practice is to work on the area where the disease is born, Thatch. This is another reason why thatch removal is so important. Next we keep the amount of Nitrogen as low as possible without putting the plant under stress, too much nitrogen creates a soft fleshy leaf which is more susceptible to infection. Increase the amount of potassium we use especially coming into the autumn/winter. Potassium hardens the cell walls of the leaf helping to protect it from infection. Chemical control is favored by most. There are 3 main types of modes of action;
Contact (Protectant); Droplets are spread out on the surface of the leaf where deposited. leaves produced after the application are not protected. There is no chemical protection within the plant.
Locally Systemic (Translaminar); Droplets spread out on the leaf and move inside the leaf tissue, internal and external protection. leaves produced after the application are not protected. No Chemical, no protection.
Systemic (Acropetal); Droplets spread out on and move into the leaf tissue, external and internal protection. Fungicide on the stem moves up through the plant and protects new growth. leaves produced after the application are protected.
Each mode of action has its place. Here at Burnham we try and use a preventative strategy, prevention is better than cure. Right that's the disease covered. So why did we get it. Timing of the application is so important as systemic fungicides can take 6 days to get into the plant and give full protection. These fungicides need to be sprayed as part of a preventative programme. The first signs of the disease are environmental conditions cool nights, heavy dew, warm days, moisture etc. I applied a systemic fungicide at the sight of the disease rather than prior to the outbreak. So the plant was unprotected for up to 6 days until the fungicide had got into the plant, hence the infection we have had. On the plus side we are now protected and the temperatures are still high enough for us to get good recovery.
Thank you for reading
Regards Lee & Greenkeeping Team
Ref; kent L Smith PHD 2010
KA Noegel 2012
Draper et al 2004