Fruit abortion in citrus!
symptoms of the disease
In strong attacks, the symptoms of the disease appear on the petals of the still closed flowers, in which areas seem to be soaked in water, but it is usually not until the open flower stage that the first typical symptoms of the disease appear. disease as reddish-brown necrotic spots on open petals. With favorable weather these spots spread rapidly and soon have invaded all the petals.
In humid conditions the petals become covered with a mucilaginous layer of abundant spores of the fungus. After the petals have fallen, the small fruits, up to 0.5 cm in diameter, present a weak yellowish discoloration and quickly detach, leaving intact the basal disk, the calyx and the peduncle firmly attached to the tree. Sometimes the small fruits remain attached to the calyx, but never develop. Persistent calyces are characteristic of this disease and are not known to be caused by physiological disorders, insects, or other diseases.
disease-causing agent
Studies carried out have shown that the fungus Colletotrichum gloeosporioides Penz is associated with the "fruit drop disease".
"FUSARIUM" spp are frequently found in the calyx of flowers weakened by natural causes or by C.gloeosporioides attack, but they undoubtedly appear as secondary colonizers. The "fruit drop disease" is the consequence of the infection of the flowers by a virulent line of Colletotrichum gloeosporioides, which differs morphologically from some isolates of C.gloeosporioides that are saprophytes of citrus. In the diseased petals there are constantly isolated C.gloeosporioides that form colonies of slow development, orange color and abundant spores. They are also occasionally found isolated from this fungus on diseased petals and which form rapidly developing colonies. These rapidly developing isolates are similar to those found in citrus stems and fruits as well. From these studies carried out in Florida it can be deduced very clearly that Colletotrichum fungi that form colonies of yellow color and slow development are the causative agents of the disease.
disease control
Even before the cause of the disease was known, treatments with hormonal products were carried out, believing it could be a physiological alteration, and also using some fungicides with the idea that the cause could also be a fungal attack. When it was seen that the The disease was caused by a fungus, so experiments were carried out to control it with different chemical fungicides. In tests that were carried out, good control of the disease was achieved with a joint spray of benomyl and captafol.
Pachamama's point of view
We at Pachamama recommend avoiding the use of chemical fungicides as much as possible. We leave this blog for you as a reference in case the disease has spread to your citrus trees.
We always recommend prevention as the best pest control method. Irrigation with Azamax every 15 days and foliar applications of Calcium, Magnesium, B complex vitamins, and Silica help to keep the immune system of plants stimulated and thus prevent the spread of diseases. In initial stages of pathologies of this type it can be useful to make foliar applications.
Thank you Jonathan Jimenez, from our San Pedro store for sharing the article with us!
