This study aimed to investigate whether different doses of specific phenolic acids (chlorogenic acid, caffeic acid, ferulic acid, gallic acid, protocatechuic acid,
-hydroxybenzoic acid, syringic ...acid, vanillic acid, and
-coumaric acid), alone or in combination, can inhibit the early growth of the common ragweed (
L., Asterales: Asteraceae). A seed bioassay was performed in Petri dishes and placed in a climate chamber to assess the effects of five dose levels of phenolic acids to radicle and shoot length, as well seedling biomass of
. The lowest dose of phenolic acid corresponded to the natural phenolic acid concentration previously reported in dry plant tissue samples from Brassicaceae cover crop plants. Results show that the inhibition of the early growth of
depends strongly on phenolic acid. Across different treatments, high doses of phenolic acids significantly shortened shoots and radicles, as well as reduced seedling biomass. Treating seeds with ferulic acid alone, vanillic acid alone,
-hydroxybenzoic acid alone, or a mixture of all phenolic acids significantly reduced all early growth parameters. The estimated effective dose for the 50% inhibition (ED
) of radicle growth in
seedlings was 368.39 ± 59.85 × 10
mol with ferulic acid, 135.41 ± 17.65 × 10
mol with
-coumaric acid, 810.36 ± 134.15 × 10
mol with
-hydroxybenzoic acid, and 160.11 ± 12.30 × 10
mol with the combination of all phenolic acids.
Plant pathogenic bacteria pose a significant threat to olive cultivation, leading to substantial economic losses and reduced yield. The efficacy of antimicrobial agents against these pathogens is of ...great interest for sustainable disease management strategies. As such, the management of olive knot disease is one of the major challenges in olive protection. In the presented study, through a series of in vitro assays, we investigated the antimicrobial effect of six essential oils (EOs) and their most concentrated constituents against causative agent of olive knot disease—Pseudomonas savastanoi pv. savastanoi, highlighting the high potential of Origanum compactum EO and its constituent carvacrol. Carvacrol exhibited the highest potential for practical application, demonstrating membrane disruption as its mechanism of action even at the lowest concentration. The bactericidal effect of antimicrobials was confirmed in a time–kill assay, where concentrations of MIC, 2× MIC, and 4× MIC were evaluated. Some of the applied treatments resulted in inhibition equal or higher than copper-based treatment. Additionally, we assessed the phytotoxicity of carvacrol by foliar application on olive cv. Leccino. The appearance of phytotoxic injuries majorly occurred on the young leaves of olive plants, with the highest proportion of damaged canopy observed when the 2× MIC concentration was applied. Due to its great efficiency against P. savastanoi pv. savastanoi in vitro, these findings highlight the potential of carvacrol as a molecule of interest for the development of environmentally friendly biopesticides. This study also contributes to the advancement of disease management practices in olive cultivation, leading to enhanced crop protection.
Plant pathogens pose a significant threat to agricultural productivity and food security worldwide. The use of traditional chemical pesticides for plant disease management raises concerns due to the ...emergence of pesticide resistance and their potential adverse effects on human health and the environment. As a result, there is a growing interest in exploring alternative approaches for plant disease control. This review provides an overview of the antimicrobial potential of some plant-derived compounds, including essential oils, plant extracts, wastes and their major constituents, against plant pathogenic bacteria. The antimicrobial activity is attributed to the diverse chemical composition of these plant-derived compounds and their ability to target multiple cellular processes in pathogens’ cells. Furthermore, the review explores the use of some antagonistic bacteria and fungi as control tools. These beneficial microorganisms have shown promising results in suppressing the growth of plant pathogens through various mechanisms such as competition, antibiosis and induced systemic resistance. This review discusses the advantages and limitations of using plant-derived compounds and antagonistic microorganisms for plant disease management. Moreover, it highlights the need for further research to optimize their efficacy, develop sustainable formulations and evaluate their performance under field conditions.
Herbicides are the most commonly used means of controlling the growth of Ambrosia artemisiifolia L. Their constant use has led to the development of resistant populations. They can be evaluated by ...studying seed germination and the corresponding grown plants, but A. artemisiifolia exhibits seed dormancy, preventing germination and delaying research. Here, we developed a simple and rapid method to stimulate germination of freshly collected or stored A. artemisiifolia seeds. The germination of A. artemisiifolia freshly collected/stored seeds was evaluated after storage, stratification, and chemical treatments (ethephon, gibberellic acid (GA3), thiourea, KNO3). Ethephon or ethephon + GA3 improved freshly collected seed germination by 88 and 95%, respectively, and germination of stored seeds by 78 and 80%, respectively. In addition, placing the seeds of A. artemisiifolia in ethephon, GA3, ethephon + GA3, or thiourea solutions caused the freshly collected seeds to germinate faster than stored seeds or nontreated seeds. In contrast, the conditioning of seeds in these solutions favored germination of stored seeds, especially when ethephon + GA3 or GA3 was used. Imbibition of the freshly collected A. artemisiifolia seeds in a mixture of ethephon and GA3 can effectively overcome primary dormancy when rapid experimental results are needed. For seeds requiring prolonged storage, conditioning in ethephon, GA3, or thiourea solutions may be applied to promote germination.
Strains of
pv.
(
), isolated from infected olive trees (
L.) in three European countries (Croatia, Slovenia and Portugal) were identified and characterised according to their colony morphology, ...physiological and biochemical features. According to the LOPAT scheme, 38.6% of
isolates were grouped in the Ib cluster. The Portuguese
strains were fully consistent with the typical LOPAT profile for this bacterium. Conversely, most Slovenian
strains showed delayed oxidase activity, whilst Croatian
strains did not produce any fluorescent pigment when grown in vitro. For
molecular identification, both end-point and real-time PCR were used, as well as MALDI-TOF, which was additionally used for proteomic analysis and the subsequent species identification of a number of strains that showed deviations from expected LOPAT results.
was confirmed as a causal agent of olive knot disease in 46.6% of olive orchards screened. Overall, these data suggests a possible correlation of certain
features with the geographical origin and the ecological niche of
isolates.
Bakteriozni rak masline je bolest uzrokovana bakterijom Pseudomonas savastanoi pv. savastanoi (Pss). Pss je vrsta koja pripada kompleksu vrsta Pseudomonas syringae. Mehanizam zaraze s Pss uključuje ...sintezu dvaju hormona rasta – auksina i citokinina, koji uzrokuju pojavu hipertrofiranog tkiva, odnosno nekontrolirane i ubrzane diobe stanica na različitim biljnim organima masline (Olea europaea L.). Prisutnost bakterioznog raka masline zabilježena je u gotovo svim maslinarskim regijama u svijetu. Tijekom dvije godine (2021. i 2022.) obavljeno je terensko istraživanje i uzorkovanje zaraženog biljnog materijala kako bi se utvrdila prisutnost ovog patogena i na području hrvatskog dijela istarskog poluotoka. Ukupno 102 uzorka sakupljena su s 22 različite sorte u 45 maslinika. Prisutnost patogena određena je molekularnom metodom Real - time PCR u 32 (30 %) uzorka. Najveći udio pozitivnih uzoraka činile su sorte Leccino i Frantoio, koje su ujedno bile najzastupljenije sorte u istraživanim maslinicima. Veći tumori na simptomatičnim stablima masline utvrđeni su u sjevernim dijelovima Istre.
Olive knot disease is caused by bacterium Pseudomonas savastanoi pv. savastanoi (Pss). The bacterium Pss belongs to the Pseudomonas syringae species complex. The mechanism of action used by Pss to establish an infection involves synthesis of two types of growth hormones - auxins and cytokinins. This mechanism leads to uncontrolled and accelerated cell division in different plant organs of olive tree (Olea europaea L.), which cause the appearance of hypertrophic tissue, known as knots. The presence of bacterial olive knot disease is recorded in almost all olive-growing regions in the world. In this research, a field survey and sampling of symtomatic plant material was carried out during 2021 and 2022 with aims to determine the distribution of olive knot disease in the Croatian part of the Istrian peninsula. Totally 102 samples were collected from 22 various olive varieties in 45 orchards. The bacterium Pss was identified using the Real-time PCR method in 32 (30%) of tested samples. The highest number of positive samples was recorded from susceptible Leccino and Frantoio varieties, which were the most widely grown varieties in sampled orchards in Istria. The formation of larger tumours on symptomatic olive trees was observed in olive orchards located in more northern regions of surveyed area.
Plant pathogenic bacteria pose a significant threat to olive cultivation, leading to substantial economic losses and reduced yield. The efficacy of antimicrobial agents against these pathogens is of ...great interest for sustainable disease management strategies. As such, the management of olive knot disease is one of the major challenges in olive protection. In the presented study, through a series of in vitro assays, we investigated the antimicrobial effect of six essential oils (EOs) and their most concentrated constituents against causative agent of olive knot disease—Pseudomonas savastanoi pv. savastanoi, highlighting the high potential of Origanum compactum EO and its constituent carvacrol. Carvacrol exhibited the highest potential for practical application, demonstrating membrane disruption as its mechanism of action even at the lowest concentration. The bactericidal effect of antimicrobials was confirmed in a time–kill assay, where concentrations of MIC, 2× MIC, and 4× MIC were evaluated. Some of the applied treatments resulted in inhibition equal or higher than copper-based treatment. Additionally, we assessed the phytotoxicity of carvacrol by foliar application on olive cv. Leccino. The appearance of phytotoxic injuries majorly occurred on the young leaves of olive plants, with the highest proportion of damaged canopy observed when the 2× MIC concentration was applied. Due to its great efficiency against P. savastanoi pv. savastanoi in vitro, these findings highlight the potential of carvacrol as a molecule of interest for the development of environmentally friendly biopesticides. This study also contributes to the advancement of disease management practices in olive cultivation, leading to enhanced crop protection.
Poljska ljubica (Viola arvensis Murr.) jednogodišnja je vrsta koja zakorovljuje usjeve gustog sklopa te nasade bobičastog voća i povrćarskih kultura. Potječe s prostora Euroazije, a zbog svojstva ...adaptibilnosti proširila se i na ostale kontinente. Često je moguća zamjena s vrstom V. tricolor L. (maćuhica) od koje se razlikuje po boji cvjetova i obliku gornjih listova. Razmnožavanje V. arvensis generativno je. U laboratorijskim uvjetima najveća klijavost ostvaruje se pri temperaturi od 15 °C u trajanju od 8 sati te pri temperaturi od 5 °C u trajanju od 16 sati. Preferira pjeskovita tla reakcije od blago kisele do lužnate. Tolerantna je na zasjenjivanje i sušu. Prezimljuje u formi rozete, a visinom biljka može dosegnuti prosječno 30 cm. Zbog niskog habitusa izravne štete uzrokovane korovnom vrstom V. arvensis nisu toliko značajne koliko neizravne koje se javljaju nakon žetve usjeva kada biljno tkivo zahvaćeno pri žetvi usjeva može utjecati na povećanje vlage sjemena usjeva. V. arvensis vrsta je koja se prilagodila utjecaju čovjeka te se uspješno razvija na obrađivanim tlima. Forma rozete smatra se tolerantnom prema primjeni herbicida te je zbog toga otporna na primjenu kemijskih mjera suzbijanja.
Olive knot disease, caused by the bacterium Pseudomonas savastanoi pv. savastanoi, causes great damage in olive orchards. While control measures of P. savastanoi pv. savastanoi in olive orchards ...primarily rely on pruning and copper-based treatments, the use of antibiotics as bactericidal preparations in agriculture is limited and highly restricted. However, plants are naturally endowed with protective molecules, such as phenolic compounds, which defend them against herbivores, insects, and microorganisms. This research aimed to test the virulence of five strains of P. savastanoi pv. savastanoi isolated from different growing regions and olive varieties, and to examine whether there is a difference in plant susceptibility based on the variety. An additional goal was to test the antimicrobial activity of olive mill wastewater, known for its high content of phenolic compounds, and aqueous garlic hydrolysate, as well as to compare them with a commercial copper-based product, pure hydroxytyrosol, and a standard antibiotic as references. Analysis of knot characteristics showed variations in the virulence of the P. savastanoi pv. savastanoi strains, with the highest virulence being observed for the strain I7L and the lowest virulence for the strain B45C-PR. The olive cultivar Rosinjola displayed higher susceptibility compared to Frantoio, Buža, and Leccino, while cv. Istarska bjelica exhibited the least susceptibility compared to the other investigated olive cultivars. In an attempt to explore alternative solutions for disease control, in vitro tests revealed that the phenol HTyr, GE, and the wastewater with the highest total phenolic content (cv. Istarska bjelica) possess the highest antibacterial activity. This supports the role of polyphenols in host defense, aligning with previous field observations of lower susceptibility of cv. Istarska bjelica to olive knot disease. These findings highlight the complex nature of olive knot interactions with bacterial strains and olive cultivars, simultaneously accentuating and underscoring the importance of considering the host’s defenses as well as bacterial virulence in disease management strategies.
