Turf disease detection V: Helminthosporium

The disease detection in turfgrass is an arduous and difficult task. The common name Helminthosporium is derived from the former scientific name (Helminthosporium spp.) of this leaf spot disease complex, which has now been established, following changes in taxonomy, to be caused by species of mushrooms of the genera Drechslera spp., Curvularia spp., Bipolaris spp. and Exserohilum spp.

The fungi Dreschslera spp. and Marielliottia spp. in the most extreme cases, can cause great losses on our sports surfaces.

Source: L.B.McCarty, Best Golf Course Management Practices

Symptomatology includes brown to purple leaf spots, black with grey centres on leaves, etc. depending on the host. In the most extreme cases the entire lawn may fade completely. Drechslera occurs predominantly on winter turf in spring and autumn.

These fungi are very active continuously, except when the soil is frozen or excessively warm. The roots, rhizomes and lower leaves become infected by the mycelium which grows from the remains of mowing and thatch, being necessary this thin layer of dew or humidity (for more than 10 hours and consecutive days), so it is necessary this microenvironment of humidity and optimal temperatures between 15 and 18ºC (although they can occur with wider intervals of Tº, between 3 and 27ºC), low light intensity (new football stadiums much more closed) and excessive nitrogen fertilisation.

The use of systemic fungicides and hormonal herbicides for broadleaf control may favour the incidence of these diseases.

These fungi produce a brown mycelium that grows inside and along the grass blade, producing conidia and conidia that are spread to healthy blades by wind, rain, irrigation water, mowers, etc...

Do you have similar symptoms? Get out of doubt by writing to info@tiloom.com and we will send your samples for analysis via qPCR.