Geranium Plants Research Articles

Biomass yield, essential oil yield and resource use efficiency in geranium (Pelargonium graveolens L. Her. ex. Ait), intercropped with fodder crops

The objective of this study was to determine the effect of intercropping of fodder crops on growth and yield attributes of the essential oil-yielding multi-harvest aromatic plant geranium (Pelargonium graveolens L. Her. ex. Ait) under field conditions during 2005–2007. In addition aggressivity, land equivalent ratio (LER), area time equivalent ratio (ATER) and land use efficiency % (LUE%) as an index of intercropping advantage were determined to assess the resource use efficiency of intercropping systems. The main crop geranium was intercropped with oat (Avena sativa L.) and berseem or Egyptian clover (Trifolium alexandrum L.) in different combinations. All crops were also grown in pure stands. The study indicated that the growth and yield of geranium was affected at first harvest compared to sole. But the second harvest in different intercropping systems compared to sole did not affect biomass and oil yield of geranium. Intercrops produced bonus yields over and above that of geranium. The resource use efficiency values were higher in intercropping systems over sole geranium. The study clearly showed that geranium-based intercrop treatments might provide the highest total yield as well as resource use efficiency.

Effect of 24-epibrassinolide on growth, photosynthesis, and essential oil content of Pelargonium graveolens (L.) Herit

The effects of 24-epibrassinolide on growth, photosynthesis, chlorophyll content, carbohydrate fractions, and essential oil content of rose scented geranium (Pelargonium graveolens (L.) Herit) were investigated. Foliar application of 24-epibrassinolide at 0.5, 1, and 3 μM concentrations substantially increased the growth. 24-epibrassinolide at all concentrations improved herbage yield as reflected in the increase of foliar biomass. Exogenous application of 24-epibrassinolide increased the rate of photosynthesis. Growth promotion was also associated with increased chlorophyll content and resulted in the accumulation of carbohydrate fractions. At 3-μM concentration, 24-epibrassinolide increased the total content of essential oils. The quantitative analysis of geranium oil from the geranium plant treated with 3-μM concentration revealed an increase in geraniol content and decrease in citronellol content. The present study demonstrates a positive impact of the new group of phytohormones on the performance of geranium plant, a highly valued aromatic plant.

Evaluation of a plant-controlled subsurface drip irrigation system

Limited water resources and losses during irrigation are major concerns of irrigated agriculture. Subsurface drip irrigation (SDI) can be an effective method for improving the irrigation efficiency in agriculture. Further improvements in SDI can be achieved using the negative pressure technique. A laboratory experiment was conducted to compare the performance for growing greenhouse plants of the negative- and zero-pressure techniques in SDI with a hand-watered treatment used as a control. Geranium plants were grown on peat moss, and a porous drip tape was used to supply water and nutrients directly to the plant roots. The irrigation treatments consisted of zero pressure, negative pressure (−0.2 m head), and a hand-watered treatment as a control. The number of leaves, leaf area, and water uptake rate were measured at weekly intervals. The foliage weight, root weight, and root length were measured at the end of the experiment. The leaf area and the number of leaves in the negative pressure treatment were significantly higher than zero pressure, but compared well with the hand-watered plants. The root length and root weight under negative pressure were significantly higher than the zero pressure and hand-watered treatments. An empirical model was developed to estimate geranium leaf area non-destructively using leaf length and width. The leaf length, width, and area were measured using image analysis part of the Arc GIS software. The modelled leaf area compared well with the measured area with a standard error of 9.93% of the mean (correlation coefficient R2 = 0.95). The success of this negative pressure technique appears to be more beneficial for greenhouse production and areas experiencing water shortages since it minimised water and labour requirements.

THE INFLUENCE OF IRRIGATION METHOD ON POT GERANIUM (PELARGONIUM PELTATUM L.) GROWN WITH SALINE WATER

ISHS International Symposium on Strategies Towards Sustainability of Protected Cultivation in Mild Winter Climate THE INFLUENCE OF IRRIGATION METHOD ON POT GERANIUM (PELARGONIUM PELTATUM L.) GROWN WITH SALINE WATER

Effect of Harvesting Treatments and Distillation Methods on the Essential Oil of Lemon Balm and Apple Geranium Plants

The effects of harvesting treatments and / or distillation methods (hydrodistillation, hydro-steam distillation and steam distillation) on the essential oil content and composition of Pelargonium odoratissimum L. and Melissa officinalis L. plants were carried out in a greenhouse at Shanghai Institute of Plant Physiology and Ecology (SIPPE), Shanghai, China, during the years of 2007 and 2008. The highest oil yield of P. odoratissimum L. and M. officinalis L. was obtained by hydrodistillation and the lowest by steam distillation. The essential oil was significantly decreased towards the second harvesting. The main component of P. odoratissimum essential oil extracted by hydrodistillation was methyl eugenol (25.9 % - 30.4 %), while the main component of hydro-steam distilled or steam distilled oil was limonene (30.5 % - 32.4 % for hydro-steam distilled oil and 38.8 % - 49.4 % for steam distilled oil). The most abundant compound of M. officinalis oil extracted by hydrodistillation or hydro- steam distillation was citronellal (36.1 % - 37.8 % for hydrodistillation and 27.3 % - 29.8 % for hydro- steam distillation ), whereas αthe essential oil content and co-terpinene (20.2 % - 21.9 %) was the main component with steam distillation. The oxygenated compounds and hydrocarbon compounds were changed according to the distillation methods and / or harvesting number for both P. odoratissimum and M. officinalis. plants.

Detection of Ralstonia solanacearum in Irrigation Ponds and Aquatic Weeds Associated with the Ponds in North Florida

The discovery of exotic Ralstonia solanacearum biovar 1 strains on geranium in north Florida led to a concern that this strain may have become established. Therefore, we monitored irrigation ponds and potential alternative aquatic weeds from 2002 to 2005 for the presence of this strain. We report that this strain, possibly originating from the Caribbean, has become established in several ponds in Gadsden County, FL. Cladistic taxonomy was used to subclassify the bacterium at the species level into four groups or phylotypes based on multiplex polymerase chain reaction of the internal transcribed spacer (ITS) region. The bacterium was further divided into sequevars by sequencing the endoglucanase gene (egl). The strains were determined to belong to phylotype II/sequevar 4 NPB (nonpathogenic on banana) that was recently reported in Martinique. Partial sequencing of the egl followed by phylogenetic analysis placed the new Caribbean strains in a different clade than the typical Florida endemic strains. Pulsed-field gel electrophoresis (PFGE) revealed different haplotypes upon comparison of the collected pond strains and the Floridian strains. Based on PFGE polymorphism, egl sequencing, and phylogenetic analysis, the Caribbean strains were shown to be identical to the strain isolated from infected geranium plants. Experiments were undertaken to monitor R. solanacearum in irrigation ponds and associated weeds. R. solanacearum was detected in surface-disinfested common aquatic weeds growing in the irrigation ponds, including Hydrocotyle ranunculoides (dollar weed) and Polygonum pennsylvanicum (Pennsylvania smart weed). Both weeds were latently infected and showed no signs of wilt when collected. Two different Hydrocotyle spp. were artificially inoculated with R. solanacearum under greenhouse conditions and both developed symptoms 14 days post inoculation (dpi) and the bacterium was recovered from the tissues 42 dpi. There was a positive correlation between ambient temperature and R. solanacearum populations in irrigation water, as previously shown by other researchers.

Sexual differences in response to simulated herbivory in the gynodioecious herb Geranium sylvaticum

Several factors have been proposed to explain female maintenance in gynodioecious populations. In this study, we propose and test a novel hypothesis: greater tolerance to herbivory through more beneficial interactions with plant fungal mutualists might also help to explain female maintenance. Herbivory limits the amount of carbon and nutrients available for the plants and has been shown to affect mycorrhizal colonization. We hypothesized that simulated herbivory would decrease reproductive output, mycorrhizal colonization intensity, and the phosphorus content relatively more in hermaphrodites, so females would achieve higher advantage over hermaphrodites when under herbivory pressure. We tested it in the field using the gynodioecious plant Geranium sylvaticum. We found that simulated herbivory had a negative effect on the reproductive output in both sexes and that there was a similar reduction in fruit set, seed set, and total seed number in both sexes. Defoliation did not affect any fungal parameter measured, but decreased phosphorus content relatively more in females. The plants had a sex-specific relationship with mycorrhizae, but this was not related to herbivory. Thus, we conclude that females do not gain any specific advantage under defoliation from its symbionts at short-term even though it seems that the plants have sex-specific relationship with their mycorrhizal symbionts.

Changes in leaf water relations, gas exchange, growth and flowering quality in potted geranium plants irrigated with different water regimes

Geranium plants are an important part of urban green areas but suffer from drought, especially when grown in containers with a limited volume of medium. In this experiment, we examined the response of potted geraniums to different irrigation levels. Geranium (Pelargoniumxhortorum L.) seedlings were grown in a growth chamber and exposed to three irrigation treatments, whereby the plants were irrigated to container capacity (control), 60% of the control (moderate deficit irrigation, MDI), or 40% of the control (severe deficit irrigation, SDI). Deficit irrigation was maintained for 2 months, and then all the plants were exposed to a recovery period of 112 month. Exposure to drought induced a decrease in shoot dry weight and leaf area and an increase in the root/shoot ratio. Height and plant width were significantly inhibited by the SDI, while flower color parameters were not affected by deficit treatment. The number of wilting and yellow leaves increased, coinciding with the increase in the number of inflorescences and open flowers. Deficit irrigation led to a leaf water potential of about -0.8MPa at midday, which could have caused an important decrease in stomatal conductance, affecting the photosynthetic rate (Pn). Chlorophyll fluorescence (Fvm) values of 0.80 in all treatments throughout the experiment demonstrate the lack of drought-induced damage to PSII photochemistry. Pressure-volume analysis revealed low osmotic adjustment values of 0.2MPa in the SDI treatment, accompanied by increases in the bulk tissue elastic modulus (epsilon, wall rigidity) and resulting in turgor loss at lower leaf water potential values (-1.38MPa compared with -1.0MPa for the control). Leaf water potential values throughout the experiment below those for Psitlp were not found at any sampling time. By the end of the recovery period, the leaf water potential, stomatal conductance and net photosynthesis had recovered. We infer from these results that moderate deficit irrigation in geranium reduced the consumption of water, while maintaining the good overall quality of plants. However, when SDI was applied, a reduction in the number of flowers per plant was observed.

Integrated Approach for Detection of Nonculturable Cells of Ralstonia solanacearum in Asymptomatic Pelargonium spp. Cuttings

Ralstonia solanacearum (biovar 2, race 3) is a soil and water-borne pathogen that causes serious diseases in several solanaceous hosts. It can also infect geranium plants, posing an important threat to their culture when latently infected cuttings are imported from countries where the pathogen is endemic. R. solanacearum can be present in very low numbers in asymptomatic geranium cuttings, and/or in a particular stressed physiological state that escapes direct isolation on the solid media usually employed. Consequently, an integrated protocol has been developed to analyze asymptomatic geranium cuttings routinely. The first screening tests include isolation and co-operational-polymerase chain reaction (Co-PCR), based on the simultaneous and co-operational action of three primers from 16S rRNA of R. solanacearum. This method was selected as the most sensitive one, able to detect only 1 cell/ml including nonculturable cells. When isolation is negative but Co-PCR is positive, the bioassay in tomato plants is proposed, since stressed bacterial cells or those present in low numbers that do not grow on solid media can be recovered from inoculated tomato plants and retain pathogenicity. This methodology has been demonstrated to be useful and has allowed us to assess the relevance of the physiological status of bacterial cells and its implications in detection. It also reveals the risk of introducing R. solanacearum through asymptomatic geranium material when relying only on bacterial isolation.

Population differentiation for plasticity to light in an annual herb: Adaptation and cost

Phenotypic plasticity allows plants to cope with environmental heterogeneity. Environmental variation among populations may select for differentiation in plasticity. To test this idea, we used the annual plant Geranium carolinianum, which inhabits old fields that are densely vegetated and lack canopy cover and wood margins with tree shade but less neighbor shade. Individuals from three populations of each habitat were planted in natural low and high light environments, and morphological traits important for light acquisition were measured. Old-field plants were more plastic, with greater elongation of petioles and internodes in low light than those from wood margins. This larger shade avoidance response suggests evolution of greater plasticity to neighbor shade than to the tree canopy. Fitness of old-field plants was high across both light environments, whereas fitness of wood-margin plants was reduced in low light. Selection favored longer internodes in low than high light. Finally, plasticity for internode length was negatively associated with fitness in high light, suggesting a cost of plasticity for this trait. Together these results indicate that shade-avoidance plasticity of petiole and internode length is adaptive. However, greater elongation of internode length may be constrained by the cost of plasticity expressed in high light. The evolution of plasticity appears to reflect a balance between its adaptive nature and its cost to fitness.

Twospotted Spider Mite Population Level, Distribution, and Damage on Ivy Geranium in Response to Different Nitrogen and Phosphorus Fertilization Regimes

The influence of plant nutrition on arthropod pests has often been studied by comparing plants provided suboptimal nutrients with those provided sufficient or luxurious nutrients, but such results have limited applicability to commercially produced crops because nitrogen (N) and phosphorus (P) are almost never limiting in greenhouse production. We conducted a series of experiments with ivy geranium, Pelargonium peltatum (L.) L'Hŕ. ex Aiton 'Amethyst 96' to determine the response of twospotted spider mite, Tetranychus urticae Koch (Acarina: Tetranychidae), to six combinations of N (8 or 24 mM) and P (0.32, 0.64, or 1.28 mM) that reflected commercial production practices. All six combinations resulted in saleable plants when plants were free of spider mites, but tissue N and P concentrations among fertilizer combinations were different. On mite-infested plants, no difference in mite numbers or plant damage was found in response to N fertilization rates. Phosphorus had no effect on mite population level until week 8, at which time plants fertilized with 0.64 mM P had slightly more mites than plants fertilized with 0.32 mM. However, overall quality and dry weight of plants fertilized by 0.32 mM P was lower than that of 0.64 and 1.28 mM, which suggests that ivy geranium plants fertilized with the higher P rates may better compensate for mite feeding damage. Positive correlations were found between within-plant distribution of mites and the corresponding tissue N and P concentrations in three foliage strata, suggesting that tissue nutrient content may influence mite selection of feeding sites.

Selection of leaf blight-resistant Pelargonium graveolens plants regenerated from callus resistant to a culture filtrate of Alternaria alternata

A protocol has been established for the induction of disease resistance in callus cultures of rose-scented geranium, Pelargonium graveolens cv. Hemanti against leaf blight disease caused by the fungal pathogen Alternaria alternata. The callus cultures were raised and maintained on semi-solid Murashige and Skoog's (MS) medium supplemented with 10 mg l −1 Kn and 1.0 mg l −1 NAA. The calli were subjected to various concentrations of culture filtrate (0%, 4%, 8%, 12%, 16% and 20%) obtained from A. alternata. Resistant calli were selected and placed on regeneration medium (MS supplemented with 0.5 mg l −1 BAP and 0.1 mg l −1 NAA). The regenerants were confirmed for A. alternata resistance by exposing their leaves to the same concentrations of culture filtrate as used previously. While the parental wild type demonstrated typical susceptibility, the leaves of putative resistant clones remained green and viable in the presence of toxin and regenerated shoots directly on the toxin-free regeneration medium (MS supplemented with 5 mg l −1 Kn and l mg l −1 NAA). The above experiment demonstrated the induction of disease resistance in rose-scented geranium plants at the cellular level. This approach could be successfully exploited in raising new disease-resistant cultivars in geranium against various fungal pathogens.

Directional blue light irradiation triggers epidermal cell elongation of abaxial side resulting in inhibition of leaf epinasty in geranium under red light condition

Plant morphogenesis is strongly affected by light quality. We evaluated the effects of localized blue light irradiation from light-emitting diodes (LED) on the leaf shape of geranium plants, which show epinasty under red light conditions. Geranium ( Pelargonium zonale Ait.) plants with five or six true leaves were transplanted into a growth chamber containing a metal halide lamp (MH) or a red LED panel (R-LED) that irradiated light at an intensity of 100 μmol m −2 s −1. The fifth true leaves were then subjected to localized irradiation from small LED light sources. Under localized irradiation of blue light at a 50 μmol m −2 s −1 intensity level, the leaf epinasty index, was 20% lower than under localized red irradiation. The extent of the inhibition of leaf epinasty by blue LED irradiation depended on the light intensity. Blue light irradiation to the abaxial sides of leaves did not inhibit leaf epinasty under red irradiation. In response to blue light irradiation to the adaxial side of the fifth true leaf, the leaf angle reached 225° by the end of the experiment, which was larger than the angle reached under red irradiation. In fifth true leaves treated with localized blue irradiation for 6 h during the daytime, the leaf epinasty level was higher than with blue light irradiation for 12 h. The length of epidermal cells of the abaxial sides irradiated with blue light was 7–13% longer than under red irradiation in the absence of blue irradiation. These results suggest that in geranium, leaf epinasty is controlled by cell elongation in the abaxial epidermis triggered by blue light irradiation of the adaxial side of the leaf.

Detection of Latent Infections of Ralstonia solanacearum Race 3 Biovar 2 in Geranium.

Ralstonia solanacearum race 3 biovar 2 is a regulated quarantine pathogen that infects solanaceous hosts such as potato as well as geranium, where it causes either bacterial wilt (also known as Southern Wilt) or a symptomless latent infection. Geranium growers and government regulators need reliable detection methods to identify infected plant material before it is exported. We previously found that R. solanacearum-infected geranium plants can shed millions of bacteria in effluent water that flows from pots. We tested a nondestructive sampling method wherein effluent water from infected plants grown under commercial conditions was both dilution plated and filter concentrated for real-time polymerase chain reaction (PCR). Under field conditions in Guatemala, effluent shedding of infected geranium plants was highly variable. Comprehensive growth chamber studies confirmed that latently infected and mildly symptomatic geranium plants often but not invariably shed detectable numbers of bacteria in their effluent. At the peak of bacterial shedding, just under 90% of infected plants shed detectable bacteria whereas, at the lowest point, 44% shed detectable numbers of pathogen cells. Bacterial shedding peaked several weeks after inoculation regardless of whether plants were symptomatic or latently infected. Bacterial stem population sizes did not correlate with either effluent population sizes or disease index rating. Finally, we found that the effluent from geranium plants grown in volcanic rock scoria medium contains inhibitors that reduce the effectiveness of real-time PCR detection methods.

The protective triterpene layer of the desert plant Sarcocaulon Patersonii: A bionic model for innovative PV encapsulation?

The transparent, protective encapsulation (wax) layer of the geranium plant Sarcocaulon Patersonii, living in an extreme desert environment, was investigated with respect to its potential as flexible photovoltaic encapsulation material. Surprisingly, the main component of the wax turned out to be triterpenes, the solid state, thermal, optical, photochemical and protective properties of which are unexplored in technology and partially presented here. The protective action of extracted 200 nm thin triterpene layers on CuInS 2 solar modules was encouraging although chemical extraction may have changed a more favorable natural morphology. Complications arising from the little known chemistry, when interacting with specific microelectronic components, and further need of research are discussed.

Effects of Paecilomyces fumosoroseus and Encarsia formosa on the control of the greenhouse whitefly: preliminary assessment of a compatability study

The effect of separate and combined activity of Paecilomyces fumosoroseus Wize (Brown and Smith) Trinidadian strain T11 and the parasitoid, Encarsia formosa Gahan, was assessed on populations of the greenhouse whitefly, Trialeurodes vaporariorum (Westwood), infesting Phaseolus vulgaris L. (French bean) and Pelargonium x domesticum (regal geranium) plants in replicate experiments. When infested bean and geranium plants were exposed to E. formosa for 2 days, and 4 days later sprayed with P. fumosoroseus blastospores, whitefly percent mortality was 99.5% and 75.5%, 94.6% and 59.4% for experiments 1 and 2, respectively. Treatment of infested bean plants with either E. formosa or P. fumosoroseus resulted in 87.8% and 78.7%, 73.1% and 97.0% whitefly mortality for experiments 1 and 2, respectively, while similar treatment of infested geranium plants resulted in 9.2% and 52.8%, 34.3% and 64.5% whitefly mortality for experiments 1 and 2, respectively. Our results support the use of E. formosa and P. fumosoroseus in combination in Experiment 1 for the treatment of whitefly infested P. vulgaris plants since a significant difference in mortality is observed than when either E. formosa or P. fumosoroseus is applied alone. However, in experiment 2, the combination treatment on P. vulgaris was no more effective than spraying P. fumosoroseus alone. On P. x domesticum plants, only P. fumosoroseus alone is needed for efficient control of the whitefly compared to the combination treatment. The relative timing of parasitoid oviposition and fungal infection are critical in determining the outcome of the interaction and are plant host dependent.

Using Leaf Temperature as a Nondestructive Procedure to Detect Root Rot Stress in Geranium

Diagnosis of incipient disease based on visual symptoms of geraniums (Pelargonium ×hortorum) exposed to water mold pathogens is often difficult, especially when the plants are maintained under optimum growing conditions. Such plants tend to be asymptomatic until late in the infection process when control methods are less effective and the aesthetic value of the finished crop is diminished. To circumvent such a problem and to be able to predict the susceptibility of the plants to infection, we used infrared transducers to measure leaf surface temperature, in addition to other parameters, in geranium plants exposed to a number of soil pathogens that are commonly associated with greenhouse production. Differences in leaf temperature among treatments were noticeable by 2 week after inoculation and were the greatest in week 7. However, visual disease symptoms were not detected until 3 weeks after inoculation. Results of this study suggest that leaf temperature measurements are a versatile, nondestructive way of rapidly determining whether plants are under pathogen stress before visual symptoms develop.

Biologically Active Constituents of a Polyphenol Extract from Geranium sanguineum L. with Anti-Influenza Activity

From the aerial roots of the medicinal plant Geranium sanguineum L. a polyphenol-rich extract with strong anti-influenza activity has been isolated. To investigate its active fractions, the extract was partitioned by solvents with increasing polarity. The n-BuOH fraction contained the majority of the in vitro antiviral activity; the EtOAc fraction was the most effective one in vivo. A bioassay-directed fractionation of the n-BuOH and EtOAc fractions was performed to obtain information about the nature of the chemical components of the plant extract, responsible for the antiviral effect. The individual constituents were identified by spectroscopic methods and comparison with authentic samples and by HPLC. The cell-toxic and virus-inhibitory effects of the fractions and some individual polyphenol compounds, found in Geranium sanguineum L., were studied using the replication of representative influenza viruses in cell cultures. This study showed that the presence of a variety of biologically active compounds as well as the possible synergistic interactions between them seem to be decisive for the overall antiviral effect.

Growth of Geranium Plants in Soilless Media Containing Sphagnum Peat and Anaerobic Digestion-Derived Biosolids

Anaerobic digestion-derived biosolids (ADB) has the potential to become a complete or partial substitute for sphagnum peat in the greenhouse and nursery industry. Bedding plant production being one of the largest segments of the floriculture industry may possess the greatest application for this new organic addendum to soilless media. An experiment was conducted in which geraniums (Pelargonium ×hortorum `Red Elite') were grown in potting mixes formulated with vermiculite and perlite plus various concentrations and combination of anaerobic digestion-derived biosolids (ADB) and sphagnum peat to determine if ADB could be used as a partial or complete replacement for sphagnum peat in soilless horticultural growing media. Plants were grown during June and July 2003–05 in the greenhouse at 75 ± 5 °F and normal light and photoperiod. Plant growth was assessed by measuring the dry weight of stem tissue. Plants were harvested when at least 50% of the total number of plants produced at least one inflorescence. Floriferousness was measured by counting the number of visible inflorescences per plant. Dry weight of plants grown in media containing ADB was greater than those grown in media containing sphagnum peat as the sole organic addendum. Plants grown in media containing ADB were also more floriferous. This study demonstrates that ADB has great potential for use as an organic addendum to horticultural growing media as a partial or complete replacement for sphagnum peat. Use of anaerobic digester-derived biosolids in horticultural growing media is a protected intellectual property and available for license through the WiSys Technology Foundation.

Control of Bacterial Wilt of Geranium with Phosphorous Acid.

Various bactericides were screened for efficacy in protecting geranium plants (Pelargonium hortorum) from Ralstonia solanacearum infection. Many of these bactericides were found to slow the disease progress; however, they were not able to protect the plants from infection and subsequent death. Potassium salts of phosphorous acid were found to be effective in protecting plants from infection when applied as a drench. The active portion of the potassium salts was found to be phosphorous acid (H3PO3). Phosphorous acid was found to inhibit in vitro growth of R. solanacearum. It is thought to be protecting plants from infection by acting as a bacteriostatic compound in the soil. The plants, however, are not protected from aboveground infection on wounded surfaces. Phosphorous acid drenches were shown to protect geranium plants from infection by either race 1 or 3 of R. solanacearum. Other phosphorous-containing products commonly used in the industry, such as phosphorus pentoxide (P2O5) and phosphoric acid (H3PO4), were not able to protect plants from bacterial wilt infection.