Blue mold fruit rot
Other names for blue mold rot are “soft rot” and “wet rot”. Its name is due to the blue color of the fungus spores. It is present in all parts of the world where apples are grown. Countries that have traditional or non-standard warehouses for storing apples are more severe and in Iran is one of the most important cause of apple fruit rot.
Symptoms of blue mold rot
In the Blue mold rot, the fruit first develops watery, soft spots and develops within the tissue at temperatures of 20 to 25 degrees Celsius. In this type of disease, a clear border is visible between the infected area and the healthy area. In humid conditions, the surface and central part of the blotch or margin of its clefts is covered with a cotton-like layer and a prominent mass, such as blue-green. These are asexual fungal spores of blue mold rot and contaminate healthy fruits in adjacent boxes and containers.
Factor of fruit rot disease
The most common species of Penicillium isolated from diseased seeds(Blue mold rot) is P. expansum and it has been isolated in Iran. The conidia and conidiophores in this fungus form in small clusters almost similar to curium. Depending on environmental conditions and species of fungi, conidia are formed either at or near the edge of the caries.
Disease Cycle and Epidemiology
Pathogenic fungus of Blue mold rot of fruit can survive in the soil in winter. Its containers are also left in contaminated transport boxes or storage walls and are always present in the open and in loading and storage areas.
In other countries, spores can prolong the life cycle of the fungus during the summer and other seasons on infected fruits inside the cellar and in the refrigerator, contaminated washing solutions or spores themselves.
Penicillium, the agent of Blue mold rot is often known as a wound parasite, but it can also enter through fruit lenses and cause fruit rot. The disease is often seen on injured fruits and fruits that have fallen to the ground and crushed. Hail can also cause this scar and the way to the fruit. Also caries caused by other pathogens on the fruit can become a place of entry for Penicillium fungi. The fungus (agent of Blue mold rot) can grow up to zero degrees Celsius, but overall the growth and transmission of the fungus is higher at warmer temperatures. Penicillium species usually produce a heat-resistant fungal toxin (fungal toxin) called “patulin” so avoid eating contaminated fruits.
Combating penicillium blue fruit rot
۱- Observing scientific and technical points during harvesting and care of fruits in warehouses and cold stores to prevent pathogen transmission to them and not to injure them.
۲- Complete disinfection of boxes, containers and storage areas with suitable fungicides and separation of infected fruits from healthy fruits.
۳- Pre-harvest spraying with benzimidazole group fungicides and washing and immersing fruits in water containing suitable fungicides. During experiments in Iran, immersion of wounded fruits in thiabendazole and benomyl toxins solution was able to control Blue mold rot of fruit disease. The immersion time should be 20 minutes.
۴٫ Treat the fruits quickly with calcium chloride after harvest. This solution increases the calcium in the fruit and increases its resistance to decay of the blue mold.
۵٫ Biological control of this pathogen is possible and experiments based on fungal, bacterial and yeast biological controls can be hoped for and used in this way.