Cypress cancer is an infection caused by the melancholy deuteromycete fungus Seridium cardinale (Wag) Sutton (sin: Coryneum cardinal Wag).
This disease was first reported in North America in 1928. It subsequently spread to other regions of that continent and then to New Zealand (1933) and Europe (1944). In Italy it appears on the plants of the Parco della Cascina in Florence (Grasso C., 1951); subsequently it was highlighted in Romagna, Lombardy and Veneto. Currently it is present throughout Italy and causes serious damage by destroying avenues, parks and trees of scenic and historical interest. The species most susceptible to the fungus are: Cupressus macrocarpa, Cupressus sempervirens, Cupressus arizonica, Cupressus lusitanica, Thuya orientalis, Juniperus communis, Cupressocyparis leilandii.
The cypress cancer it is manifested by the yellowing, redness and subsequent drying of the twigs and proceeds, in some cases, from top to bottom and from the outside towards the inside, involving increasingly larger portions of the plant.
At the base of the affected branches, but, in some cases, also on the branches and on the stems, we note the leakage of resin (in the Cupressus arizonica and in the Cupressus glabra this symptom is not specific as the casting of resin can be physiological). The wood (below) appears a brownish color that contrasts with the light color of the healthy part. Afterwards the infection also manifests itself externally, with brownings, depressions and cracks in the bark.
An important source of diffusion is represented by the infected nursery material. The mushroom agent of the cypress cancer it also propagates with the wind, the rains. And the resin. The penetration of the pathogen into the plant is conditioned by the lesions caused by frost, hail, pruning, insects or other. The most favorable periods for contamination are spring and autumn with mild temperatures (12 ° - 13 ° C) and high humidity that allow the maturation and release of the acervuli. The disease can also be transmitted by Coleoptera (Phloeosinus aubei and Phloeosinus thujae), hosts of infected cypress plants, which can act as accidental vectors of the conidia of the fungus and transmit them to plants through tunnels that dig at the axils of the young twigs.
Cypress cancer: Fight
The fight must be above all preventive, avoiding the purchase of infected plants in the nursery, promptly removing and destroying the parts of the affected plant, treating carefully the pruning cuts with benzimidazoles, disinfecting the tools used using ethyl alcohol or quaternary ammonium salts and resorting to to treatments with copper salts (copper oxychloride - 50 - 1 kg / hl) or with benzimidazole (100 gr / hl) or using these two products in a mixture in a lower dose in spring (3 treatments at intervals of about 25-30 days) and in autumn (1-2 treatments) in relation to the weather and the severity of the attack.