Turfgrass disease detection VII. Fusarium Patch

Microdochium patch or Fusarium patch, caused by pathogenic fungi Microdochium nivale (Samuels and Hallett), previously Fusarium nivaleis a common and widely distributed disease of turfgrass in temperate climates throughout the world. Fusarium patch is considered economically important in the turfgrass industry because of its tendency to cause significant damage to golf greens, thereby decreasing the quality of the putting surface.

Aetiology of Fusarium patch:

Fusarium patch is a common disease of spring and autumn on lawns in temperate zones with wet and cold climatesspread all over the world. Symptoms develop slowly, and the time from initial infection until symptoms are visible can take weeks.

The fungus may be abundant in patches, with spongy mycelial growth. Severe lesions and large patches usually occur after prolonged snow cover (more than one month) with prolonged snow melt. Patches of Pink snow mould may develop a shiny bronze-coloured stripe around the edges. Heavy mulching or leaf litter can also worsen the disease caused by Microdochium nivale.

Causal agent of Fusarium patch:

Microdochium nivale is the fungus responsible, survives during the summer as spores and mycelium in thatch and soil, and generally remains dormant when temperatures are above 20°C or when it is dry. In autumn, in cold and wet weather, spores may germinate or mycelium may grow from thatch and soil and infect leaves.

The spores are carried by wind or surface water to adjacent healthy leaves. The fungus can attack foliage under the snow cover, especially if the plants have not hardened off and are damaged by low temperatures, or have been weakened by prolonged snow cover. After thawing, the fungus remains active, especially if it remains cool and moist.

Symptoms of Fusarium patch:

Fusarium spot in autumn starts as small circular orange to reddish-brown spots a couple of cm in diameter. Under disease-favourable conditions, the spots will increase in size and the spots may enlarge and overlap to form large irregular shapes more than 20 cm wide.

When the fungus is very active, the spots have a brown to bronze ring around the outer edge. The centres of the spots may turn pale straw-coloured or sometimes retain a green colour depending on conditions at the time of infection.

In prolonged wet conditions, white to pink mycelium can be observed on the outer edge of the patch joining infected leaves. In spring, fungal activity begins at the edge of the pink snow mould scars. If favourable conditions (cold and wet) persist into spring, new patches may appear. The patches are orange-yellow to reddish-brown in colour and measure 10-20 cm, but may overlap to form larger patches with scalloped edges.

Most susceptible species:

• All lawns in cold weather, Poa annua, Lolium perenne, Agrostis stolonifera are considered to be the most susceptible. 
• Poa pratensis, Poa trivialis, Festuca arundinacea and fine fescues can also be affected by this disease.

The most intense disease occurs on Agrostis with less than one year of establishment, but on Poa greens it usually occurs when they are already mature.

Conditions conducive to infection:

• Microdochium nivale can survive in a wide range of temperatures, from 4 to 32 °C, with the optimum temperature for infection being between 0 to 13 °C .
• The optimum temperature combined with high humidity (>85%) and prolonged periods of leaf wetness (more than 10 hours) caused by rain or irrigation favour the growth of the fungus on the plants.
• Long-lasting snow cover on unfrozen ground is particularly conducive to pink snow mould, especially if the soil is alkaline.
• Lawns vigorous in autumn are especially susceptible in winter.

Cultural control:

• Removing leaf dew is one of the most effective ways to minimise Fusarium spots and reduce the number of fungicide applications for control.
• Scheduling irrigation before dawn or early morning also eliminates dew.
• Evaluate drainage and improve as necessary to ensure greens drain properly.
• Manage thatch levels. In addition to creating a stressful environment in the root zone, thatch retains moisture.
• When watering is necessary, water during the pre-dawn and early morning period.

Foliar nitrogen monitoring can be carried out indirectly by measuring the rate of nitrogen in the foliage. NDVI or by nitrogen measurements on our greens or pitches via our ionometers  with dilutions soil: water 1:2, in addition to the monitoring of soil moisture levels with measuring equipment such as the POGO.

The symptoms of Microdochium nivale are small orange or reddened areas between 2 and 20 cm in size in diameter, which can spread radially along drainage lines through mycelial growth or spore movement. When the cold is very intense, growth slows down.

Curative treatment:

Chemical control:

• Fusarium patch can be controlled using fungicides with active ingredients, in order of effectiveness: Fludioxynil, Iprodione+Chloratonil, PenthiopyradIprodione, Methylthiophanate, PCNB, Propiconazole, Pyraclostrobin, Trifloxystrobin, Azoxystrobin, Chlorothalonil, Fenarimol, Mancozeb, Myclobutanil, Triadimefon, Vinclozolin.

The doses indicated on the fungicide label should be applied at intervals of 7 to 21 days, depending on whether the application is preventive or curative. Inappropriate use of chemicals could aggravate the problem.

Analysis and diagnosis of Fusarium patch:

The most effective way to diagnose the Fusarium patch is always our analysis from qPCR fast where we can identify dozens of diseases with a single sample.

Do you need to efficiently diagnose the incidence of Microdochium Patch or your potential condition? Contact Tiloom at info@tiloom.com and in less than 48 hours you will have the answer through a qPCR diagnostic test.

Source: https://www.syngentaturf.ae/turf-disease/fusarium-patch

Source: Smith, J. D. (1953). Fungi and turf diseases Fusarium patch disease. Journal of the Sports Turf Research Institute, 8(29).

Source: Boulter, J. I., Boland, G. J., & Trevors, J. T. (2002). Assessment of compost for suppression of Fusarium Patch (Microdochium nivale) and Typhula Blight (Typhula ishikariensis) snow moulds of turfgrass. Biological control, 25(2), 162-172.

Source: MacDonald, L. Focus on Fusarium Patch.