The southern part of Spain, in Murcia and Alicante, devotes a large volume of hectares to the cultivation of pomegranate, a tree adapted to the Mediterranean in hot areas and periods of drought.
Although it is a resistant tree, certain diseases can affect its production, mainly in areas or periods where high humidity is concentrated.
In this article, we show you the main pomegranate diseases, their identification and possible treatments.
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Main Pomegranate Diseases
In major producing countries, such as the United States, Spain, Turkey or Iran, the most common and important pathogens that cause disease in pomegranates have been identified.
Although not a widely followed crop or disease literature, some fungal diseases have been identified.
Symptoms of these diseases can range from mottled leaves of varying size and color, to stem blight and dieback, or fruits with superficial to deep lesions that can lead to fruit rot.
The specific symptoms of the disease vary according to the type of disease, being quite frequent that they affect both the leaves and the fruits, so they are always associated with a loss of production.
Anthracnose (Colletotrichum)
Photography: KV XavierAnthracnose is a pomegranate disease caused by species of fungi Colletotrichum, and is present in many other fruit trees. In areas where relative humidity accumulates, anthracnose is one of the most important pomegranate diseases.
The most common symptoms are leaf spots, defoliation, shoot blight, twig rot and complete stem dieback. Symptoms on fruit consist of sunken lesions in which the pathogen produces large numbers of spores which may be visible to the naked eye as orange slimy masses.
Symptoms of anthracnose are usually seen on the calyx of green fruit as hard, dark brown to black necrotic lesions. After prolonged summer rains, lesions on ripe fruit appear as randomly scattered, irregularly shaped rot spots.
These pomegranate spots are sunken and often force their way through the skin, leading to fruit rot and loss of marketability.
Masses of gray to orange spores often become visible on lesions of green or ripe fruit when weather conditions remain wet for long periods.
appearance time
This disease usually occurs late May and Juneperiod which may coincide with heavy rains for several days.
Cercospores (Pseudocercospora punicae)
Photography: KV XavierPseudocercospora punicae It causes a pomegranate tree disease which is very frequent also in periods of rain and high ambient humidity, associated with spots on the leaves or fruits.
On the leaves, symptoms begin as small, dark brown (0.1-0.3 cm) irregularly shaped lesions. These lesions may expand (0.5 to 1.2 cm) and develop a distinctive dark brown margin with gray discoloration.
In some cases, these lesions are large enough to show alternating light and dark gray concentric rings in the center of the lesion.
They often form a greenish halo around the lesions, which becomes very pronounced when the leaves turn yellow from chlorosis.
Only in some cases the leaves age prematurely, leading to severe defoliation of the pomegranate, which usually reduces the productive yield.
Symptoms on pomegranate fruit are identified as small, irregular-looking black lesions that may later coalesce into larger spots.
Injuries caused by Pseudocercospora punicae in fruits they are only superficial, unlike Colletotrichum and other fungal pathogens, which affect the bark and arils.
Leaf and fruit symptoms can vary between different pomegranate varieties.
Stem canker (Neoficoccum parvum Yes Lasiodiplodia theobromae)
Photography: A KCTwo fungi of the Botryosphaeriacea family, Neoficoccum parvum Yes Lasiodiplodia theobromae cause this disease in pomegranate, forming brown sores on pomegranate stems.
Symptoms begin as small brown lesions on new stems. Lesions enlarge and become large, swollen cankers with deep fissures and numerous fruiting bodies one year after infection.
The stems girdle slowly and the tree dies after one or two years. Numerous fruiting bodies become visible on the surface of infected stems.
Fruit rot (Colletotrichum spp. Yes D. punicae)
Photography: A KCFruit rot is a serious pomegranate disease that can cause production loss of more than 80% in some countries.
In addition to fruit rot caused by Colletotrichum spp. Yes D. punicae a third pathogenic fungus, Pilidiella granati is often detected in already rotten fruit.
The surface of the fruit begins to turn brown and the rot progresses to the skin. The fruit begins to decay and abundant black pycnidia become visible on the surface of the fruit as small raised black dots.
Stem blight and leaf spot symptoms may also appear. Leaf spots caused by P. granati they have concentric rings of pycnidia over the lesion. Towards the end of the growing season, fruit infected with P. granatidry and mummify.
Nearly 50% of these mummified fruits fall off, while the rest remain attached to the tree.
Several pathogens are often isolated from these mummified fruits, including Colletotrichum sp., N. parvum, L. theobromae, D. punicae Yes P. granati . These observations reinforce the need to remove all mummified and rotten fruit from orchards during and between seasons to limit the potential spread and transfer of inoculum.
Pomegranate Disease Treatment
Pomegranate in Spain is a secondary crop, so there are not many phytosanitary references authorized to combat this type of disease.
Many of the fungi mentioned above never appear in the life of the pomegranate tree in many dry areas and where long periods of humidity are rarely achieved.
Copper formulations, such as copper oxychloride or copper hydroxide, are effective preventive and curative solutions, in particular for closing and healing pruning wounds and mechanical damage (due to hail for example).