Cerebella of cereals

The fungus forms dark, dense stroma on the surface of infected plant organs. It is a classic example of a "secondary" pathogen that rarely attacks healthy, undamaged cereal tissues.

The biology of the pathogen is closely linked to the development of other fungal diseases, specifically smut fungi. The fungus grows as a symbiont or competitor on the mycelium of smut fungi, which makes diagnosis dependent on primary infection.

Spores of the fungus are spread by wind and rain droplets, facilitating rapid infection of neighboring plants in the field. Optimal temperatures for conidial growth are between 20–25°C, provided there is sufficient humidity on the plant surface.

The development of the fungus leads to the formation of specific growths that often take on a convoluted, brain-like shape. Due to this external feature, the disease is named after the Latin word cerebellum.

The first visible sign of the disease is the appearance of characteristic black growths on the ears or panicles of cereals. These formations have an uneven, folded surface that resembles a human brain.

The growths are located directly on the spikelets that were previously infected by smut spores. As the fruit bodies of the fungus mature, they harden and turn coal-black, becoming very prominent against the healthy parts of the plant.

Infected spikelets are often deformed, and their development stops. In severe cases, the affected panicle can be completely covered by a black coating, which prevents the normal formation of grains and their filling.

Unlike common smut, cerebella-affected areas have a specific texture. When touched, the growths feel hard and dry, and they do not disperse as easily as the spores of smut fungi.

Diagnosis of the disease is complicated because the external manifestations are often masked by the symptoms of the primary smut infection. Microscopic examination of samples is necessary for accurate determination.

The primary factor promoting the development of cerebella is high relative humidity during the flowering and grain-filling period. Prolonged fog or frequent rainfall creates an ideal environment for spore germination.

Temperature plays a secondary role, although moderately warm weather facilitates faster fungal development. Sharp fluctuations in temperature combined with high humidity trigger massive stroma formation.

The presence of plants infected with smut in the agrocenosis is a key condition for the appearance of this pathogen. The fungus finds a nutrient medium in the metabolic products of smut fungi.

Poor agricultural practices that weaken cereal immunity indirectly accelerate the spread of the disease. Crop density and the lack of proper crop rotation increase the risk of accumulating an infection reservoir.

Plant debris from the previous year left in the field serves as an infection reservoir. The overwintering mycelium is capable of surviving in adverse conditions, posing a threat to the next season's crop.

The harmfulness of cereal cerebella primarily lies in the reduction of overall grain quality. Affected ears do not produce a full crop, as the plant's energy is consumed by the parasitic fungus rather than grain development.

Massive infection leads to a decrease in the thousand-kernel weight, which directly impacts yield indicators. Grain from such fields may be shriveled and lose its milling and baking properties.

The disease leads to a loss of marketability of the grain, making it unsuitable for sale. The presence of black growths requires additional costs for grain cleaning and sorting.

In some cases, fungal development may be accompanied by the production of mycotoxins. Although Cerebella itself is not always considered highly toxic, its presence often correlates with high levels of other pathogens.

Severe infection leads to thinning of the crop stand. This creates space for weed growth, which becomes an additional competitor for water and nutrients.

The main method of control is strict adherence to crop rotation. Using crops that are not susceptible to specific smut species allows breaking the fungus's nutrient cycle.

High-quality seed treatment with systemic fungicides helps prevent primary smut infection. No smut means no nutrient medium for Cerebella andropogonis.

Timely weed control, which can act as secondary hosts or infection reservoirs, significantly reduces the inoculum level in the field. Regular removal of crop residues is also mandatory.

Using resistant cereal varieties is the most effective preventive measure. Genetic resistance to smut diseases automatically protects crops from secondary cerebella infection.

If signs of the disease are detected during the growing season, the use of broad-spectrum fungicides is recommended. It is important to consider the crop growth stage to ensure the treatment is as effective as possible.