Malseco on lemon plant

Disease name: Malsico on lemon plant

Scientific name: Phoma tracheiphila

Type of disease: fungal

Disease family: Didymellaceae

(Lemon plant infected with malisco disease)

• The causes of disease:

The Phoma tracheiphila fungus causes drying at the tops of branches, as it attacks the xylem and enters through the root or leaves. One of the unique characteristics of this fungus is its ability to produce asexual spores called phylloconida, which are spores that form in the plant xylem.

• Symptoms of the disease:

The pathogen advances slowly downward from the infected young shoots to the main branches and limbs, where symptoms of infection begin with the wilting of leaves and new branches that turn red, dry up and fall. Spore masses form and appear in the form of dots on the infected branches. The fungus can survive inside the branches or in Soil up to 4 months.

• Disease development cycle:

Conidia are produced in pycnidia found on branches infected with the fungus and from hyphae that grow on exposed wood, including branches, leaves, and fruits. The pathogen can also be transmitted to other trees through contaminated pruning tools. Branches and leaves found on the soil may be a source of infection from Through the roots.

• Conditions suitable for the spread of the disease:

The fungus inside the leaf tissue is able to reproduce at temperatures ranging from 10 to 25 degrees under natural conditions. The fungus can spread by wind and rain during the winter, while the symptoms of the fungus appear and reproduce within a temperature ranging from 20 to 22 degrees Celsius. While at temperatures above 28 degrees Celsius, fungal growth stops and symptoms do not appear.

(Yellowing of lemon leaves due to malsico disease)

• Losses resulting from the spread of the disease:

It is considered one of the most dangerous diseases that affect lemons and causes the death of hundreds of trees annually, especially when the fungus infects the base of the trunk or the roots. A phenomenon known as a lightning bolt can occur, and in this case the tree usually dies quickly.

• Control:

1. Use copper pesticides from fall to spring, as they prevent the growth of fungi.
2. Spraying the affected parts with a fungicide containing ziram or benzimidazole, especially after harsh weather conditions such as cold weather, hot storms, or when strong winds blow.
3. Isolate and remove infected parts before the disease spreads.

• preventive measures:

1. Purchase seeds or seedlings from approved places.
2. Cultivation of disease-resistant species.
3. Sterilize agricultural tools before use.
4. Continuously monitor the field for early detection in case of infection.
5. Removing dead branches in the field.

• Sources:
• https://idtools.org/citrus_diseases/index.cfm?packageID=2&entityID=176
• https://plantix.net/ar/library/plant-diseases/100127/mal-secco/