Lawn anthracnose belongs to a group of diseases that affects both aboveground and underground parts of grassland. It occurs throughout the growing season.

It is manifested by non-specific yellowing of the leaves, which leads to root death in persistent stress conditions. Anthracnose occurs both in C3 and C4 grasses and also affects cereals, maize and sugar cane. The disease is caused by the fungus Colletotrichum cereale (formerly called Colletotrichum graminicola). DNA analyzes showed the presence of this agent in all climatic zones. The fungus is highly variable and produces different patotypes with a distinct host spectrum (Henle 2013). The most common occurrence of anthracnose occurs on low-mowed areas of golf lawns. Interestingly, the occurrence of anthracnose is less common on lawns less frequently mowed (albeit with heavy loads). How can macroscopically identify anthracnose? This disease is manifested in two forms – on the one hand by attacking (yellowing and drying of leaf blades) of the leaves, which leads to “optical” thinning of the stand, and on the other hand by attacking the roots with subsequent death of a part of the turf. The first “phase” of the disease – leaf death (referred to as Foliar Blight in English literature) occurs mainly in summer in hot weather with high air humidity. Infected outbreaks show both infected plants (yellowed, dying) and healthy. On the upper side of the leaves, dark lenticular structures known as acervuli can be observed, which later form typical spongy fibers (spines). Spores and mycelium are an infectious source for other healthy leaves. In cold and damp (autumn) weather, the second “phase” of the disease can occur, when the fungus attacks the basal part of the plant, resp. stalks (Bazal Rot, Stem Rot). The brown-black mycelium that occurs on this part of the plant causes its death. In general, anthracnose occurs to a greater extent, especially on grassy areas exposed to long-term stress. So what are the factors supporting the occurrence of grass anthracnose? These must be distinguished according to two different stages of the disease. Leaf disease (Anthracnose Foliar Blight) begins to manifest at temperatures of 5-8 ° C. The occurrence may therefore be supported by cold and humid weather in the spring months. Similarly, mechanical damage to the leaf area during mowing, scarifying or sanding can contribute to disease development. An important factor is also the presence of an excessive amount of organic matter, be it cut leaves or felt, which facilitate the wintering of the anthracnose agent. The consequence of these factors is an increased occurrence of unlimited spots on the leaves, their gradual yellowing and death. Plant stalk disease (Anthracnose Basal Rot) occurs more frequently in hot and sultry summer weather with temperatures in excess of 25 ° C. The occurrence is accelerated by the high air humidity associated with the formation of water film on the leaves and excess water in the root area. Increased infectious pressure also occurs during gutation (formation of water droplets on leaf tips); gut water contains a high proportion of sugar. Supporting can act as a lack of basic elements incl. microelements in lawn nutrition, as well as its “nutritional multiplication” associated with water scarcity. The occurrence of the disease can be supported by low mowing and increased grass turf load. Anthracnose is one of the diseases of the lawn that are directly related to stress conditions. The first symptoms – spots on the leaves and thinning of the turf in the spring are often overlooked. Summer dryness increases the symptoms of the disease to which other diseases may be added. In the literature, the term HAS-syndrome is used to mean the common occurrence of anthracnose and leaf disease agents (Drechslera spp., Bipolaris spp.). With regard to the fact that no fungicide is permitted against lawn anthracnose in our country or in neighboring countries, the only way to prevent this disease is to strengthen grassland vitality. A few preventive recommendations: • an increase in N-doses may reduce the risk of anthracnose, especially if it is a slightly soluble nitrogenous mineral fertilizer • the results of German experiments have shown that an increase in cutting height has led to an anthracnose reduction of up to 30% also reduce the frequency of mowing and combine with rolling • reduce permanent moisture and compaction of the lawn • reduce accumulation of dead organic matter on the lawn (the environment for overwintering the disease) • application of growth regulators as a protective measure is questionable English terms: Fusarium foliar blight, Fusarium crown and root rot) also belong to diseases strongly influenced by external stress conditions. During the growing season, especially after prolonged periods of drought accompanied by high air temperatures, outbreaks of varying size appear on the lawn. The dead aboveground part of the lawn gets a light to straw color. Outbreaks often combine to form a so-called tiger footprint. The occurrence of this disease is typical in a lawn composed of perennial ryegrass, red fescue, fescue fescue or sheep fescue. In small-scale trials, high susceptibility was also observed in the low-lipped meadow-grass. On the other hand, in a lawn composed of suitable varieties of fescue and meadow-grass, the occurrence of this fungus was not observed. On intensely mowed sites (greens) occurs rarely. Very frequent occurrence of this disease is observed near concrete curbs or stone pavement. May be confused with physiologically related turf dying. Attacked areas are very difficult to regenerate and in the case of the occurrence of a general attack is necessary total recovery, respectively. regeneration of damaged stand. Fusarium fungi (F. culmorum, F. avenaceum and other species) have been reported to cause this disease. These microscopic fungi survive in the form of mycelium or chlamydospore in soil, dead grass matter or felt. Under favorable conditions for the development and spread of the pathogen, mycelium grows rapidly and spores germinate, as well as subsequent infection of leaves and necks of grasses. As with grass anthracnose, no fungicide is allowed in our country. Protective measures must therefore consist only of reducing the risk factors: • reduce the impact of adverse factors resulting from lack of water and high air and soil temperatures by sufficient morning watering; are stations with values ​​lower than 5 and higher than 7) • to regulate the lawn mowing frequency according to external conditions

Doc. Ing. Bohumir Cagas, CSc.