Carob Diseases and Pests
Carob is a tree that has been grown with little care in the Mediterranean basin for centuries and is generally known as "disease and pest resistant". This reputation is largely true; however, this does not mean that the tree does not face any problems. Leaf diseases such as powdery mildew and leaf spot, wood rot in old trees, root rot in some soils, and especially the carob moth, which damages the fruit, are the main issues to be considered in the garden and storage.
In this article, we have compiled the important diseases and pests seen in carob, their symptoms, the conditions under which they stand out, and the general control approaches recommended in scientific sources. The aim is to help the producer recognize the problem early and take the right action by avoiding unnecessary spraying.
Is Carob Really a Durable Tree?
Carob (Ceratonia siliqua L.) is an evergreen legume tree adapted to the hot and dry summers of the Mediterranean climate. In the garden facility feasibility report prepared by the General Directorate of Forestry of the Ministry of Agriculture and Forestry in Turkey, it is stated that carob is a plant that does not have many diseases and pests; it can be grown for many years without spraying in areas with wild populations (OGM, 2020). In the 2024 feasibility report prepared for the Western Mediterranean Development Agency, it is stated that carob is generally considered free from serious insect and disease problems and is not traditionally sprayed (Erbaş, 2024).
International sources draw a similar picture. In an evaluation of Mediterranean fruits, branch worm (Zeuzera pyrina) and carob moth were counted as the main pests of carob; It was stated that the fungal disease caused by Oidium ceratoniae was occasionally seen on leaves and young fruits, and no serious problems were reported in the Mediterranean region (Tous and Ferguson, 1996).
However, the picture is changing. A recent review in Italy highlights that with the exacerbation of climatic events and the increase in international trade, some invasive insects and fungi carried by them are increasingly observed in carob orchards (Castello et al., 2023). Therefore, instead of the "carob does not get sick" approach, the approach of "carob causes few problems, but should be monitored" is more realistic.
Leaf Diseases: Powdery Mildew and Leaf Spots
Powdery mildew (Pseudoidium ceratoniae)
Powdery mildew is considered one of the most important cyclical diseases in carob. The current name of the agent is Pseudoidium ceratoniae; in ancient sources, it is referred to as Oidium ceratoniae. According to the review by Castello et al. (2023), the disease manifests itself as powdery yellowish spots on the upper surface of the leaf and a grayish-white cover on the lower surface that darkens over time. The spots may merge to form corky, web-like areas; young leaves may curl. In fruit infections, the pods may remain spind, reduce in size, and decrease in sugar content. An occupational evaluation in Croatia also stated that fruit deformity may occur in severe infections (Miličević, 2020).
According to the same review, powdery mildew; It is supported by high humidity, a temperature range of about 20–25 °C, periods with little rainfall and medium-high temperatures, and shaded areas within the crown. Direct rain and excessive wetness can prevent infection. Outbreaks in hot and dry conditions can lead to severe leaf fall.
Cercospora leaf spot (Pseudocercospora ceratoniae)
The second important leaf disease is Cercospora leaf spot. It starts with blackish-brown spots 2–3 mm in size along the veins, often surrounded by a yellowish halo; grayish fungal clusters appear on the leaflets. In severe infections, a significant part of the crown may shed leaves. The disease is prominent during periods of frequent rainfall; spores are spread by raindrop splashes and wind (Castello et al., 2023). Miličević (2020) also states that this disease can turn into a blight appearance on the leaf in severe cases.
Other black leaf spots
Alternaria alternata, Pestalotiopsis species, and less frequently, other fungi can also cause leaf spots. Since these spots are very similar to Cercospora symptoms, they are difficult to distinguish by eye in the field; laboratory examination is required for a definitive diagnosis (Castello et al., 2023).
Wood Rots and Cancers
Carob is a long-lived tree and rots are common on the trunk and thick branches in older trees. According to Castello et al. (2023), the most common wood rot agent is Laetiporus sulphureus, which causes brown cube rot. The fungus enters through wounds, pruning cuts, cracks and insect damage; it breaks down cellulose and hemicellulose, browning the wood. Shelf-shaped fruit bodies at the base of the trunk are usually seen between May and November. The review states that the tree has the ability to compartmentalize rot within itself, so scraping off the rotten tissue is not recommended.
Less common white rot (Fomes/Phellinus species), Ganoderma species and Schizophyllum commune were also recorded in carob. Recommended measures for this group are; protection of pruning wounds, not stressing the tree, removal of infected tissues and pruning residues from the garden, and use of healthy saplings. In the review, it is also emphasized that carob is relatively resistant to sap rot and that century-old trees with carved trunks can remain healthy.
Branch cancer and branch desiccation are primarily caused by fungi from the Botryosphaeriaceae family (Diplodia olivarum, etc.); shoots and branches dry down from the point of infection. Although it is stated to be rare in gardens in Italy (Castello et al., 2023), Botryosphaeria cancer originating from Diplodia olivarum is counted as one of the three important diseases in Croatia (Miličević, 2020). This difference indicates that disease pressure can vary by region.
Root and Soil-Borne Diseases
Root rots are problems that manifest themselves in the gradual weakening of the tree and are usually advanced by the time they are noticed. According to the compilation by Castello et al. (2023), Armillaria mellea and Rosellinia necatrix can infect carob roots. The fight is mainly preventive: this includes taking into account the previous crop of the area where the garden is to be established, tillage that aerates the roots and the use of Trichoderma-based products against Armillaria on fruit trees.
Verticillium wilt (Verticillium dahliae) has been reported only once in carob, California. Although it is not currently considered a problem in the Mediterranean, it is considered a potential risk in orchards mixed with olives. In the seedling period, soil-borne agents such as Phytophthora, Pythium, Fusarium, and Rhizoctonia can cause collapsing (root collar rot) (Castello et al., 2023).
At this point, the role of soil conditions is important. Carob does not like soils with high ground water and moisture (OGM, 2020; Erbaş, 2024). Since the risk of root diseases will increase in water-retaining parcels with poor drainage, the choice of garden location is actually the first step in disease management.
Bacterial Diseases
Pseudomonas syringae pv. Bacterial leaf necrosis caused by ciccaronei forms small dead spots, mostly on the upper face of the leaf, surrounded by yellowish halos. Heavy rainfall and high humidity favor the disease; in Sicily it has been reported to appear in spring and stop in summer. The bacterium enters through pores and wounds opened during pruning and harvesting. Recommended measures are to limit injury, use copper preparations when necessary, and remove pruning residues (Castello et al., 2023).
Major Pests
Carob moth (carob moth)
The most important pest of carob is Ectomyelois ceratoniae (Apomyelois ceratoniae in some sources), known as carob moth or carob moth. According to Gugliuzzo et al. (2019), who compiled carob pests in the Mediterranean region, most pests appear occasionally and do not cause serious damage; the exception is this moth, which has many hosts that can attack carob both in the garden and in the warehouse. The larvae feed inside the pod; damage can also occur in the stored product. In Turkey, carob, pomegranate, fig, citrus fruits, walnuts, almonds and many other plants are counted among the hosts of the carob moth, and it is stated that it causes the most damage to pomegranates and navel oranges (TAGEM, Agricultural Control Technical Instructions).
The biology and integrated control of this pest is extensive enough to be the subject of a separate article; suffice it to note here that garden hygiene (collecting and destroying contaminated fruits that fall on the ground and remain on the tree) is the main precaution.
Insects that pierce wood and bark
Gugliuzzo et al. (2019) state that insects that enter bark and wood can cause wilting and drying of branches and trunks. Ambrosia beetles such as Xylosandrus compactus and X. crassiusculus, which have come to the fore in Italy in recent years, are new and worrying members of this group. According to Castello et al. (2023), X. compactus females open galleries in wood tissue and carry fungi that feed the larvae; the insect can also carry fungi that block conduction bundles and cause shoot desiccation, such as Fusarium solani species complex. This insect especially prefers stressed trees. A classic pest, the twigworm (Zeuzera pyrina), can also cause damage to the trunks and branches of young trees (Tous and Ferguson, 1996; Erbaş, 2024).
Other pests
Mealybugs, crustacean lice, mites, and some species of flies and butterflies can be seen in carob; however, they usually occur occasionally and have limited economic importance (Gugliuzzo et al., 2019). Erbaş (2024) also counts black aphids and rodents such as squirrels and rats among the problems that can be encountered in carob. In warehouses, moths and rodents can cause fruit loss (Gugliuzzo et al., 2019).
Rapid Diagnosis Table According to Symptoms
| Observed symptom | Possible cause | The first to be done |
|---|---|---|
| Grayish-white powder under the leaf, yellow spot on top | Powdery mildew | Crown ventilation, cleaning of fallen leaves |
| Small black-brown spots along the vein | Cercospora or other leaf spots | Laboratory diagnosis, removal of leaf residues |
| Shelf-shaped mushroom body at the base of the stem | Wood rot | Avoiding new wounds, protecting the tree from stress |
| Slow and general weakening of the tree | Root rot, drainage problem | Soil and root collar control |
| Sudden drying of the shoot tips, small holes in the branch | Ambrosia beetles, twig borer | Expert inspection, removal of drying branches |
| Hole in the pod, dirt and mesh inside | Carob moth | Collection and disposal of contaminated fruits |
This table is only for direction. In cases where the symptoms are similar to each other, especially in leaf spots, support should be sought from provincial and district directorates of agriculture or plant protection laboratories for a definitive diagnosis.
General Approach to Combat: Cultural Measures First
The basis of the fight against carob is cultural measures. Castello et al. (2023) state that the intervention thresholds for powdery mildew are high and chemical application is often not required; when necessary, they mention sulfur-based fungicides in spring. The general recommendations in the review can be summarized as follows:
- Pruning in a way that ventilates the inside of the crown, reducing humid areas in the shade
- Collecting diseased fallen leaves or burying them in the ground
- Not to cause unnecessary wounds on the tree during pruning and harvesting, to protect large cuts
- Removing pruning residues and drying branches from the garden
- Protecting the tree from stresses such as drought and nutrient deficiencies
- Using saplings from a healthy, reliable source
- If possible, choosing disease-tolerant varieties in the new garden
- Regularly dispose of moth-infected fruits that have fallen on the ground and remain on the tree
Variety selection is also a means of control. In the compilation of Castello et al., it is stated that Rojal, Matalafera, Amele di Bari and Racemosa varieties are defined as resistant to powdery mildew, while Negra, Melera and Saccarata varieties are defined as susceptible. Erbaş (2024) also states that the varieties tested in Spain were susceptible to pests to varying degrees, with some hermit varieties being found to be more susceptible to aphids than female varieties.
If chemical control is to be decided, only plant protection products licensed for the relevant product and pest should be used in our country, and label instructions and pre-harvest waiting periods should be followed. Considering that most of the carob is grown without pesticides, unnecessary applications both increase the cost and weaken the natural production advantage of the product.
Frequently Asked Questions
Should the carob tree be sprayed every year? Sources indicate that carob has not been traditionally sprayed and disease-pest problems are mostly limited. Regular observation and cultural measures are recommended instead of routine spraying.
What is white dust on leaves a sign of? A grayish-white cover on the underside of the leaves usually indicates powdery mildew. Crown ventilation and removal of diseased leaves are the first measures.
Should an old tree with a hollowed-out trunk be cut down? Carob is relatively resistant to sap rot and old trees with hollowed-out trunks can remain healthy. A cutting decision should not be made without evaluating the static safety of the tree by an expert.
What causes worms in carob in storage? The main cause of damage in the warehouse is the carob moth. Separation of contaminated product and warehouse hygiene are basic measures.
Healthy Raw Material with Carob Türkiye
Quality products in carob start from a healthy tree and a properly managed garden. It is possible to preserve the natural advantage of this tree, which can grow with little input, by detecting diseases and pests early and avoiding unnecessary interventions. As Carob Türkiye, we supply carob fruit, broken, flour/powder, seed and extract.
For general information about carob What is Carob? You can read our article, our products Carob Fruit and Our Products You can review it on the pages. For your wholesale and export requests Contact Now You can contact us on our page.
Domestic resources
General Directorate of Forestry, "Carob Garden Facility Project: Feasibility Report and Investor Guide", Republic of Turkey Ministry of Agriculture and Forestry, 2020. I'll take it to Konya.
gov. en/ assets/ upload/ files/ Carob- … Erbaş, S., "Carob Agriculture and Industry Feasibility Report", Western Mediterranean Development Agency, Publication No: 153, 2024. DEVELOPMENT LIBRARY.
gov. en/ assets/ upload/ files/ Keciboy... General Directorate of Agricultural Research and Policies (TAGEM), "Technical Instructions for Agricultural Control, Volume V: Subtropical Plant Pests – Carob moth (Ectomyelois ceratoniae)", Ministry of Agriculture and Forestry. bku.
agriculture. gov. en/ Harmful/ SourceDetail/ 1132 Foreign sources
Castello, I., Polizzi, G., Vitale, A., "Major Pathogens Affecting Carob in the Mediterranean Basin: Current Knowledge and Outlook in Italy", Pathogens, 12(11), 1357, 2023. doi.
org/ 10. 3390/ pathogens12111357 Gugliuzzo, A., Mazzeo, G., Mansour, R., Tropea Garzia, G., "Carob pests in the Mediterranean region: bio-ecology, natural enemies and management options", Phytoparasitica, 47(5), 605–628, 2019. doi.
org/ 10. 1007/ S12600- 019- 00766- 7 Miličević, T., "The most important diseases of carob", Glasnik Zaštite Bilja, 43(5), 64–67, 2020. doi.
org/ 10. 31727/ gzb. 43. 5. 8 Tous, J., Ferguson, L., "Mediterranean Fruits", Progress in New Crops (ed. J. Janick), pp. 416–430, 1996. Growables.
Scientific Resourcesorg/ information/ TropicalFruit/ CarobProgNewCrop. htm
