With lower temperatures and increased humidity, fungi find the perfect conditions to develop. The seedlings we have in the nursery are the perfect hosts for the fungi that are so much in our minds.
There are several fungi that attack our plants when we have them in the seedbed, which is when the plant is in its weakest phase and is more susceptible to develop associated phytopathologies. Sometimes plants can be infested and not show symptoms, which causes greater damage if we then plant them in our garden.
The plants that are most frequently attacked by fungi in their primary stages are horticultural and ornamental. The conditions that favor the appearance and propagation of pathogenic fungi are: low temperatures, high humidity due to high doses of irrigation or poor drainage, low light density and high density of plants.
Next we detail the most frequent fungi in the first stages of the plants:
- Pythium spp: the fungus attacks the neck of the seedlings (between the root and the stem) producing a strangulation that hinders the normal passage of nutrients and causes the plants to wither and lie down. Sometimes the plants seem to recover but symptoms reappear at later stages.
- Rhizoctonia solani: the symptoms are very similar to those caused by Pythium, although a dark wound (called chancre) may appear.
- Fusarium spp.: symptoms are usually not detected in the seedling stage so the risk of further spread if plants are infected is very high. This fungus is present in all soils although most strains are not harmful. The pathogenic forms of this fungus are usually very specific, affecting a particular species or variety. The main symptoms they cause are withering, flaccidity and dehydration.
- Acremonium spp: as in the previous case, its symptoms are usually not detected until the plant develops. The main symptoms are yellowing in the neck area that evolves to browning and necrosis. The main roots become brown and their growth is slowed down, which can cause the death of the plant if the attack is very serious.