Fruit size in wild olives: implications for avian seed dispersal

1. The response of frugivorous birds to an enlargement of fruit size, and the consequences for both birds and plants, are analysed for the interaction between avian seed dispersers and olives ( Olea europaea) .
2. The enlargement of fruit size promotes a shift in frugivorous birds' feeding behaviour, from swallowing fruits whole to pecking pieces of pulp. The relative frequency of olive consumption using each feeding behaviour was assessed by combining field data on frequency of appearance of olive pulp and seeds with data from laboratory trials.
3. Sardinian Warblers ( Sylvia melanocephala ) and European Robins ( Erithacus rubecula ) were mainly peckers both on cultivated and wild olives. Blackcaps ( Sylvia atricapilla ) consumed wild olives mainly by swallowing but consumed cultivated olives (larger than the wild ones) primarily by pecking. Song Thrushes ( Turdus philomelos ) were primarily swallowers of both types of fruits.
4. Laboratory trials with Song Thrushes, Blackcaps and European Robins showed that: (a) all were able to peck fruits; (b) fruit size determined a shift from swallowing to pecking, as pecking frequency increased with the enlargement of the fruit size; (c) all the species had an increased fruit handling failure rate when trying to swallow increasingly large fruits; and (d) from the birds' perspective, small shifts in fruit size may have important consequences on fruit profitability.
5. Pecking on olives turns the mutualistic fruit–frugivore interaction into a fruit-pulp predator interaction, thus arising a conflict between the plant and frugivorous birds.
6. This study shows that heavy dependence on fruit is not always simply related to seed dispersal. The same frugivorous bird species can act as a seed disperser or a pulp predator for the same plant species. The threshold between these roles is highly influenced by the ratio gape size/fruit size.     

The Fate of 1,2-14C-(Chloroethyl) Phosphonic Acid (Ethephon) in Olive (Olea europea)

The translocation and metabolism of ethephon at pH 7.0 and its effect on abscission of olive fruit, were studied in attached and detached fruits. In detached olives, the lowest fruit removal force values were achieved when the fruits were treated at their proximal cavity and kept under humid conditions. Following application of ¹⁴C-ethephon to the proximal cavity 63% of the label was absorbed within 4 h; evolution of ¹⁴C-ethylene proceeded at a slow rate, mainly from ¹⁴C-ethephon remaining on the olive surface, totaling 37% of the applied ethephon in 20 days. ¹⁴C-ethephon disappeared rapidly after its application to olive on the tree. More ¹⁴C-ethephon could be extracted from olives on the trees after distal application than after proximal application. Since the response of detached olives to treatments with ethephon was similar to that of attached olives in regard to fruit removal force reduction, the former can be used for the study of many aspects of ethephon and ethylene metabolism in olives. In our study no ethephon metabolites other than ¹⁴C-ethylene could be detected after ¹⁴C-ethephon application to attached or detached olive fruits.     

Centennial olive trees as a reservoir of genetic diversity

Background and Aims

Genetic characterization and phylogenetic analysis of the oldest trees could be a powerful tool both for germplasm collection and for understanding the earliest origins of clonally propagated fruit crops. The olive tree (Olea europaea L.) is a suitable model to study the origin of cultivars due to its long lifespan, resulting in the existence of both centennial and millennial trees across the Mediterranean Basin.

Methods

The genetic identity and diversity as well as the phylogenetic relationships among the oldest wild and cultivated olives of southern Spain were evaluated by analysing simple sequence repeat markers. Samples from both the canopy and the roots of each tree were analysed to distinguish which trees were self-rooted and which were grafted. The ancient olives were also put into chronological order to infer the antiquity of traditional olive cultivars.

Key Results

Only 9·6 % out of 104 a priori cultivated ancient genotypes matched current olive cultivars. The percentage of unidentified genotypes was higher among the oldest olives, which could be because they belong to ancient unknown cultivars or because of possible intra-cultivar variability. Comparing the observed patterns of genetic variation made it possible to distinguish which trees were grafted onto putative wild olives.

Conclusions

This study of ancient olives has been fruitful both for germplasm collection and for enlarging our knowledge about olive domestication. The findings suggest that grafting pre-existing wild olives with olive cultivars was linked to the beginnings of olive growing. Additionally, the low number of genotypes identified in current cultivars points out that the ancient olives from southern Spain constitute a priceless reservoir of genetic diversity.     

Damage evaluation of Rhynchites cribripennis (Col., Attelabidae) in olive fruits

Rhynchites cribripennis is a pest of olives widely distributed in the Mediterranean region. The adults drill holes in the flesh of olives, resulting in fruit drop. Although earlier studies reported high damage levels, its damage potential has not been specifically investigated. In the current study, the damage potential of this weevil was evaluated with regard to its density. Olive shoots were enclosed in muslin cages, along with two or four adult weevils, during the initial phase of the olive fruit development. In each cage, the shoots bore 357 fruits, on average. The percentage of fruits dropped and the damage level on the fruits were recorded at about 1‐month intervals. At harvest, the fruits that remained on the shoots were individually weighed to evaluate the damage as regards fruit weight. The results showed that R. cribripennis can cause a significant damage because of fruit drop (54 ± 6%, 38 ± 4% and 16 ± 2% in the cages with 4, 2 and 0 adults, respectively). The damage was more severe in fruits within the first month after their formation. A single feeding hole was shown to cause the drop of small fruits. The high percentage of dropped fruits caused a significant decrease in the weight of the olives at harvest among treatments. These results show that R. cribripennis can cause serious damage to olive production and offer useful information for quantifying its damage potential and developing a more rationale control strategy for this pest.     

Relation of fruit color,elongation, hardness,and volume to the infestation of olive cultivars by the olive fruit fly,Bactrocera oleae

The susceptibility of olive cultivars to the olive fruit fly, Bactrocera oleae (Rossi) (Diptera: Tephritidae), has seldom been studied. This article examines factors associated with olive fruit fly infestation of 16 commonly planted Sicilian olive cultivars. Total infestation data were simultaneously correlated with categorical and quantitative factors using ordinal logistic regression. When all factors were included in the analysis, year, sampling date, cultivar, and fruit color were highly significant, but the quantitative factors fruit volume, fruit elongation, and fruit hardness were not. When the analysis was repeated excluding cultivar, all quantitative factors were significant, and elongation and volume were highly significant. Spherical, large, and hard fruit seemed to be preferred by B. oleae over fruit that are elongate, small, and soft. Therefore, fruit color, elongation, volume, and hardness provide useful information regarding the susceptibility of cultivars. In both organic and conventional olive cultivation, information about olive cultivar susceptibility to olive fruit fly will help orchard managers to produce quality oil and table olives while reducing treatments for olive fruit fly control.     

Quarantine strategies for olive fruit fly (Diptera: Tephritidae): low-temperature storage, brine, and host relations

A dose-response relationship was not observed in olive fruit fly, Bactrocera oleae (Gmelin), larvae exposed to acetic acid concentrations (0-2.5%) used in commercial brine solutions to cure olives. Immersion in a 1% acetic acid brine solution impeded emergence of the immature stages. A 1-wk exposure of olives infested with olive fruit fly larvae to low-temperature storage as a postharvest treatment at 0-1 degree C resulted in 8% survival of the population, and exposures of 2 through 5 wk further reduced pupal and adult emergence to <1.0%. One- to 2-wk exposures at 2-3 degrees C resulted in a significant decrease in survival from 20 to 3%, respectively, and longer durations of 3-5 wk reduced survival to <1.0%. Mean daily fruit pulp temperatures in olives in the top, middle, and bottom of plastic bins stored at 2-3 degrees C decreased by 5-8 degrees C from the first to the second day. Lowest temperatures were observed in the top, and highest temperatures were observed in the middle layer of fruit, which attained a mean temperature of 3.8 degrees C on day 5. Laboratory choice tests showed that olive fruit fly oviposited at a higher rate in late season Mission olives that were green than in fruit that were in the red blush maturity stage in tests with 1- and 3-4-d exposure periods, and an increase in duration of exposure was related to an increase in the total number of ovipositional sites. Higher percentages of olive fruit fly third instars, pupae, and adults were reared from green fruit than from fruit in the red blush stage after a 1-d exposure to oviposition. Manzanillo olives were more attractive for oviposition by olive fruit fly than Mission olives, and significantly more third instars, pupae, and adults developed in Manzanillo fruit than in Mission fruit in the red blush stage. These differences were related to the better quality and higher flesh content of the Manzanillo versus Mission olives used in the tests.     

Effect of Crossbreeding on the Chemical Composition and Biological Characteristics of Tunisian New Olive Progenies

Olive fruit characteristics (weight, pulp/stone ratio, and oil and moisture content) and the iodine value (IV) of 31 new olive progenies (Olea europaea L.) were determined. To evaluate the effect of the genetic variability on these parameters, the new olive progenies, obtained through cross‐pollination between Tunisian and Mediterranean olive cultivars, were planted in a selected grove guaranteeing the homogeneity of the pedologic and climatic conditions. A strong genetic effect and significant differences between genotypes were obtained for the IV and the fruit characteristics evaluated. Discriminant analysis was used to classify the new progenies as distinct from each other, based on their IV, and their pulp and stone weight. An almost full discrimination of the olives from different genotypes was only achieved when the fruit characteristics (pulp and stone weight) and the IV data were analyzed together.     

Physiological, biochemical and molecular changes occurring during olive development and ripening

Since ancient times the olive tree (Olea europaea), an evergreen drought- and moderately salt-tolerant species, has been cultivated for its oil and fruit in the Mediterranean basin. Olive is unique among the commercial important oil crops for many reasons. Today, it ranks sixth in the world's production of vegetable oils. Due to its nutritional quality, olive oil has a high commercial value compared with most other plant oils. Olive oil has a well-balanced composition of fatty acids, with small amounts of palmitate, and it is highly enriched in the moneonic acid oleate. This makes it both fairly stable against auto-oxidation and suitable for human health. Nevertheless, it is the presence of minor components, in particular phenolics, contributing for oil's high oxidative stability, color and flavor, that makes olive oil unique among other oils. Moreover, as a result of their demonstrated roles in the prevention of cancer and cardiovascular diseases, olive phenolics have gained much attention during the past years. Also unique to virgin olive oil is its characteristic aroma. This results from the formation of volatile compounds, namely, aldehydes and alcohols of six carbon atoms, which is triggered when olives are crushed during the process of oil extraction. The biochemistry of the olive tree is also singular. O. europaea is one of the few species able to synthesize both polyols (mannitol) and oligosaccharides (raffinose and stachyose) as the final products of the photosynthetic CO(2) fixation in the leaf. These carbohydrates, together with sucrose, can be exported from leaves to fruits to fulfill cellular metabolic requirements and act as precursors to oil synthesis. Additionally, developing olives contain active chloroplasts capable of fixing CO(2) and thus contributing to the carbon economy of the fruit. The overall quality of table olives and olive oil is influenced by the fruit ripening stage. Olive fruit ripening is a combination of physiological and biochemical changes influenced by several environmental and cultural conditions, even if most events are under strict genetic control.     

Genetic diversity and relationships of wild and cultivated olives in Turkey

In the present study, we proposed to determine the genetic diversity and relationships between local cultivars and wild olive trees from three important olive-growing regions, i.e., Marmara, Aegean, and Mediterranean, of Turkey. This is the first known large-scale molecular study to investigate the relationships between local cultivars and wild olives from the eastern Mediterranean basin. Two hundred and four oleaster trees and 27 cultivars were sampled to represent molecular diversity. We used 11 simple sequence repeat and 13 sequence-related amplified polymorphism markers to assess genetic variations and inter-relationships among the samples. The results of the analysis showed differences in the levels of allelic composition and heterozygosity between cultivated and wild olive trees. The observation of a high proportion of a certain wild-type genetic background in the cultivars may indicate the former use of local wild trees in olive domestication in Turkey, a possible autochthonal origin of cultivars. “Gemlik” was found to be the most common olive cultivar in the Marmara region and most of the wild olive samples from this region may be feral forms derived from cultivar seed spreading. The information obtained from this study can help to assist the management of an olive collection and sheds some light on the origin of Turkish olive cultivars.     

Demethyloleuropein and beta-glucosidase activity in olive fruits

Demethyloleuropein plays a major role in the defense mechanism of olive fruits. To understand how this molecule is metabolized during different stages of maturation of olive fruits, a biomolecular approach to identify the demethyloleuropein chemistry was employed. The beta-glucosidase activity in crude extracts was assayed spectrophotometrically using the chromogenic substrate p-nitrophenyl-beta-D-glucopyranoside. Demethyloleuropein was extracted and identified by HPLC-MS from both infected and uninfected olive fruits at different physiological stages. The release of more functionally relevant dialdehydes in uninfected fruits was investigated using ESIMS/ MS. In fruits harvested in October, the activity of beta-glucosidase was significantly enhanced in uninfected fruits when compared to the infected fruits. Quantitative differences in the demethyloleuropein content from uninfected fruits showed the highest values (5.09 mg/g) in October, whereas lower levels (4.44 mg/g) were found in infected fruits. The results demonstrated that demethyloleuropein derivatives could be influenced by beta-glucosidase activity to improve the quality of the olive products with the best dialdehyde nutraceutical content.     

Microsatellite marker-based identification and genetic relationships of olive cultivars from the Extremadura region of Spain

Seventy-seven olive accessions corresponding to 25 cultivars from the Extremadura region of Spain were studied using four microsatellite or SSR markers in order to fingerprint them, and evaluate genetic similarity and relationships between local and introduced olive cultivars. The number of alleles per locus ranged from 4 to 8, with a mean of 6.25 alleles per primer pair (a total of 25 alleles). The observed heterozygosity ranged from 0.58 to 0.95, while the expected heterozygosity varied between 0.68 and 0.83. The polymorphism information content values ranged from 0.63 to 0.79. The mean polymorphism information content value of 0.70 for the SSR loci provided sufficient discriminating ability to evaluate the genetic diversity among the cultivars. The SSR data allowed unequivocal identification of all the cultivars; a combination of three SSR markers was sufficient to discriminate all 25 olive cultivars. A dendrogram was prepared, using the unweighted pair-group method with arithmetic mean clustering algorithm; it depicted the pattern of relationships between the cultivars. Most of the local cultivars grouped according to their geographic origin. No clear clustering trends were observed when the morphological traits of fruit endocarps or fruit use of cultivars were employed as analysis criteria. We conclude that there is a high level of variability among local olive cultivars from the Extremadura region at both the morphological and molecular levels; these data should be useful for identifying and distinguishing local germplasm.     

Influence of the geographical locations on the agronomical and technological potentialities of the olive tree (Olea europaea L.) in Tunisia

This study aims at characterization four cultivars of the olive trees, Chétoui, Chemlali, Gerboui, and Cha?bi, cultivated in three different geographical locations, from pomological and technological points of view. The pomological characters of the fruit are influenced by the geographical location. Each individual of the same cultivar expresses different pomological characters. We have noted a significant fluctuation of the flush percentage in three Cha?bi individuals according to their geographical site; it varies from 49.06 to 82.19%. The three Gerboui individuals showed a significant variability of the fruit weight (from 1.13 to 3.17 g). Fluctuations of olive oil contents were also observed. Several fatty acid compositions showed some variation. The oleic and linoleic acid contents varied among individuals from Chétoui and Cha?bi. Moreover, the individuals of the cultivar Chemlali showed a variation of their content in palmitic and palmitoleic acids. Indeed, each individual of a cultivar showed its own potentialities, which are reflected by its pomological and technological characters. According to their geographical location, individuals from a given cultivar displayed diverse potentialities.     

Variation in antioxidant activity and phenolic content in different organs of two Tunisian cultivars of Olea europaea L.

This paper reports a comparative study based on the antioxidant compounds, total phenol content and antioxidant activities of leaves, stems and fruits from the main Tunisian cultivars, ‘chetoui’ and ‘chemchali’, grown in two different locations, north and south of Tunisia. The repartition of olive phenolic compounds was organ dependant. Therefore, the HPLC analysis indicated that the olive organs from the northern cultivar had the highest level of hydroxybenzoic acids, hydroxycinnamic acids and flavonoid class; which were less in the southern cultivar. Principal component analysis of the phenolic compounds showed discrimination between methanol extracts of the organs olive. Significant differences (p < 0.05) in the levels of phenols, orthodiphenols and flavonoids were found between cultivars and between organs. Antioxidant activities of the methanolic extract from aerial parts of the two studied cultivars were evaluated using 2,2-diphenyl-1-picrylhydrazyl and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) assays. In all tests, methanolic extracts of different olive parts showed higher antioxidant activity. These results can be used to discriminate and to characterize the ‘chetoui’ and ‘chemchali’ aerial parts.     

Developmental events in differentiating floral buds of four olive (Olea europaea L.) cultivars during late winter to early spring

The olive tree (Olea europaea L.) is a very important evergreen fruit tree because of the high interest of olive oil and table olives in the human diet. Differentiation of olive floral buds during winter is strictly related to flowering during spring and finally to fruit production during autumn–winter. In order to determine which are the developmental events in differentiating olive floral buds we studied in four olive cultivars “Amfissis”, “Kalamon”, “Manzanillo” and “Chalkidikis” the anatomical progress of the ontogeny using median longitudinal sections of floral buds (cutting odd nodes), in weekly intervals from early February (initiation of differentiation) to mid-April (one week after floral bud burst) keeping the cultivars under the same environmental conditions. At the same time, we determined the changes in their water extractable proteins, as an index of the meristematic activity. At the beginning of differentiation, floral buds consisted of the apical and one pair of developed (odd) axillary meristems which were covered with the corresponding bracts. Floral buds showed a slow gradual enlargement in all cultivars. The sequence of the developmental events (initiation of intense mitotic activity in the apical and the first axillary meristems, initiation of mitotic activity in the second axillary meristem, development of the third pair of bracts (except from cv. Chalkidikis), appearance of mitotic activity in the third axillary meristem, swelling of apical and axillary meristems and appearance of primordial whorls) are presented comparatively. All cultivars showed similar ontogenetic trends but there were temporal differences in the initiation, the progress and the completion of the process. Cv. Amfissis initiated differentiation one week later compared to the other cultivars, also delaying the development of the second and the third axillary meristems. On the other hand, cvs. Kalamon and Chalkidikis delayed one week to complete the process when compared to cvs. Amfissis and Manzanillo.     

自交可育甜荞、金苦荞、米苦荞不同品系总黄酮、粗蛋白及其蛋白组分含量研究北大核心CSCD

为探究荞麦新品种的营养保健价值,该文对自交可育甜荞、金苦荞、米苦荞共56个不同品系荞麦种子的粗蛋白、总黄酮、蛋白组分含量及其果实性状的变异进行了研究。结果表明:(1)甜荞、金苦荞、米苦荞种子中粗蛋白含量平均值分别为13.19%、15.44%、11.75%,总黄酮含量平均值分别为0.14%、2.50%、2.09%,清蛋白含量的平均值分别为5.22%、6.13%、4.56%,球蛋白含量的平均值分别为1.29%、1.15%、0.91%,醇溶蛋白含量的平均值分别为0.42%、0.58%、0.55%,谷蛋白含量的平均值分别为2.66%、3.36%、2.80%,三种荞麦的蛋白组分均符合清蛋白>谷蛋白>球蛋白>醇溶蛋白。(2)果实性状中,甜荞果实千粒重、果实面积、果实直径的变异系数最大,米苦荞果实周长、果实长宽比、果实长、果实宽和50 mL容重的变异系数最大。(3)相关分析表明甜荞种子粗蛋白含量与果实长宽比、果实长,金苦荞种子粗蛋白含量与果实周长、果实长,米苦荞种子粗蛋白含量与果实宽、总黄酮含量与果实面积、果实宽、果实直径、50 mL容重的相关性均达到了显著或极显著水平。(4)该研究筛选出甜荞(1808-166贵甜2号优系)、金苦荞(多苦74、多苦78)、米苦荞(1906-136黑米荞麦、43-2)等高蛋白含量或高黄酮含量的荞麦品系。该研究结果对荞麦优良品种的选育和荞麦新产品的开发具有一定指导意义。     

Morphological traits and RAPD markers for characterization and identification of minor Spanish olive cultivars from the Extremadura region

A total of 91 wild olive accessions and 31 olive cultivars growing in the Extremadura region of central-western Spain were analyzed using morphological traits and RAPD markers. We focused on three main and 16 minor Spanish olive cultivars that are recognized as native or local to the Extremadura region. The five arbitrary 10-mer primers tested on the olive cultivars gave 67 polymorphic bands, representing 91% of the total amplification products. The number of bands per primer ranged from 9 to 18, whereas the number of polymorphic bands ranged from 8 to 17. All the cultivars could be identified by a combination of three primers (OPF-6, OPA-8, and OPK-16); four cultivar-specific markers were detected. The minor local "Jariego" and "Tempranillo" cultivars showed the most distal similarities. The resulting dendrogram, using the unweighted pair-group method with arithmetic mean clustering algorithm, depicted the pattern of relationships between the local Extremadura cultivars and the cultivars from geographically connected regions. This analysis showed a correlation between most of the minor local cultivars and the geographical origin; there was no apparent clustering according to morphological traits or fruit use of olive cultivars when these parameters were used as analysis criteria.     

Structure of genetic diversity in <Emphasis Type="Italic">Olea europaea</Emphasis> L. cultivars from central Italy

The olive is considered one of the most important fruit crops of the Mediterranean basin where it shows a wide range of variability, with about 2,000 cultivars. Italy, with about 500 cultivars, plays a fundamental role. The ability to discriminate olive cultivars and estimate genetic variability are important factors in better management of genetic resources and in helping to understand how genetic diversity is partitioned among cultivars. The two main objectives of the present investigation were to evaluate the identity of cultivars grown in Abruzzo region, central Italy, and to study their genetic structure. We applied amplified fragment length polymorphism (AFLP) methodology on 84 genotypes belonging to the most relevant and oldest varieties cultivated in Abruzzo and on six unknown genotypes. The information content of data was evaluated using the Marker Ratio index and the Polymorphic Index Content. Moreover, STRUCTURE software was used to investigate the genetic population structure. The analysis enabled us to clearly distinguish eight cultivars within seven clusters. Additionally, one cluster was found to have various minor cultivars and showed a relatively high level of diversity. The partitioning of genetic diversity showed that the largest amount of molecular variance was within groups. Our data suggest that both sexual and clonal propagation have played an important role in the evolution of olive cultivars. In our hypothesis, some ancestral population spread in central Italy with a relevant role of seed propagation, followed by a selection of superior clones from which more traditional varieties originated. In a few cases, hybridization should be taken into consideration to explain the diffusion of recently developed cultivars.     

Genetic diversity of Brazilian and introduced olive germplasms based on microsatellite markers

Olive trees have been grown since the beginning of civilization, and the consumption of olives and olive products is increasing worldwide, due to their health benefits and organoleptic qualities. To meet the growing market for olives, commercial cultivation of this species is expanding from traditional areas to new regions. Although the Brazilian olive industry has just begun to be established, breeding programs are already developing cultivars that are more adapted to local conditions. We used 12 microsatellite markers to evaluate 60 olive accessions, including several cultivars that were developed in Brazil. The analyses identified 72 distinct alleles; the largest number of alleles per locus were at the markers GAPU 101 and GAPU 71B, which contained 10 and 9 alleles, respectively. The largest allelic diversity and polymorphic information contents were also found at the GAPU 101 and GAPU 71B markers, with values of 0.8399/0.8203 and 0.8117/0.7863, respectively. Additionally, the 12 microsatellite markers generated a cumulative identity probability of 1.51 x 10(-10), indicating a high level of accuracy of accession identification. The set of markers that we used allowed the identification of 52 of the 60 olive genotypes, in addition to the recognition of several varietal synonyms. The components of a two-dimensional principal coordinate analysis explained 48.6% of the total genetic variation. The results obtained from the microsatellite markers showed a substantial degree of genetic diversity in the olive tree accessions used in Brazil.     

Detection of latent infections caused by Colletotrichum sp. in olive fruit

Aims

To set up a practical method to detect latent infections of Colletotrichum sp., the causal agent of olive anthracnose, on olives before the onset of disease symptoms.

Methods and Results

Freezing, sodium hydroxide (NaOH), ethanol and ethylene treatments were evaluated to detect latent infections on inoculated and naturally infected olive fruit by Colletotrichum sp. as non‐hazardous alternatives to paraquat. Treatments were conducted using fruit of cultivars Arbequina and Hojiblanca. The disease incidence and T₅₀ were calculated. Dipping in NaOH 0·05% solution and the paraquat method were the most effective treatments on both inoculated and naturally infected fruit, although the value of T₅₀ was lower for the NaOH method than for the paraquat method in one of the experiments. Subsequently, the dipping time in NaOH 0·05% was evaluated. Longer dipping times in NaOH 0·05% were better than shorter ones in cultivar Arbequina, with 72 h being the most effective in cultivar Hojiblanca.

Conclusions

NaOH solution is a practical method to detect latent infections of Colletotrichum sp. on immature olive fruit.

Significance and Impact of the Study

This study is relevant because we set up a viable, non‐hazardous alternative to paraquat to detect latent infections of Colletotrichum sp. using NaOH. The use of NaOH is a simple and eco‐friendly tool that allows the determination of the level of latent infections by Colletotrichum in olives. Therefore, our method will be useful in decision‐making processes for disease management before the appearance of the first visible symptoms.