Rot Disease Research Articles

Large-scale IPM validation in Basmati rice (Oryza sativa) in Western Uttar Pradesh, India

Pusa Basmati 1121, a high-yielding aromatic rice (Oryza sativa L.) variety released by ICAR-IARI in 2005, became widely popular among farmers of Punjab, Western Uttar Pradesh and Haryana in India due to higher yield and good price in the market. But, soon after its release, the variety was severely affected by bakanae foot rot disease (Fusarium fujikuroi). The ICAR-National Research Centre for Integrated Pest Management (NCIPM) synthesized an integrated pest management (IPM) module and validated it in large-scale at Bambawad village (District Gautam Budh Nagar, UP) in farmers’ participatory mode during 2010-14. The trial was initiated on 40 ha in 2010, which was gradually increased to 80, 120, 200 and 286 ha during 2011, 2012, 2013 and 2014, respectively. The IPM module involved green manuring, seed treatment with carbendazim, seedling root dipping in Pseudomonas fluorescens, pest monitoring and need-based application of bioagents/ pesticides. Implementation of the module resulted in a significant reduction in the incidence of bakanae ranging from 0.05±0.01 to 10.18±4.05% in IPM fields against 1.22±0.27 to 46.5±6.30% in Farmers’ practices (FP). Brown plant hopper (Nilaparvata lugens) population (average of the season) remained 7.74, 9.55, 1.22, 4.32 and 0.49 nymphs and adults/hill in IPM against 31.13, 14.16, 1.36, 7.24 and 0.82 in FP fields during 2010, 2011, 2012, 2013 and 2014, respectively. Regular pest monitoring and ETL-based application of pesticides in IPM helped in conservation of spider population in IPM as compared to FP with very low application of chemical pesticides, i.e. 103.2 g a.i./ha in IPM against 1214.4 g a.i./ha in FP. Analysis of rice grain samples for pesticide residue indicated carbendazim below detectable level. IPM trial also resulted in higher yield (36.01 q/ha in IPM against 26.24 q/ha in FP) and benefit- cost ratio (3.80 in IPM and 2.56 in FP) as compared to FP (Average of five years).

Genetic alteration of UDP-rhamnose metabolism in Botrytis cinerea leads to the accumulation of UDP-KDG that adversely affects development and pathogenicity.

Botrytis cinerea is a model plant-pathogenic fungus that causes grey mould and rot diseases in a wide range of agriculturally important crops. A previous study has identified two enzymes and corresponding genes (bcdh, bcer) that are involved in the biochemical transformation of uridine diphosphate (UDP)-glucose, the major fungal wall nucleotide sugar precursor, to UDP-rhamnose. We report here that deletion of bcdh, the first biosynthetic gene in the metabolic pathway, or of bcer, the second gene in the pathway, abolishes the production of rhamnose-containing glycans in these mutant strains. Deletion of bcdh or double deletion of both bcdh and bcer has no apparent effect on fungal development or pathogenicity. Interestingly, deletion of the bcer gene alone adversely affects fungal development, giving rise to altered hyphal growth and morphology, as well as reduced sporulation, sclerotia production and virulence. Treatments with wall stressors suggest the alteration of cell wall integrity. Analysis of nucleotide sugars reveals the accumulation of the UDP-rhamnose pathway intermediate UDP-4-keto-6-deoxy-glucose (UDP-KDG) in hyphae of the Δbcer strain. UDP-KDG could not be detected in hyphae of the wild-type strain, indicating fast conversion to UDP-rhamnose by the BcEr enzyme. The correlation between high UDP-KDG and modified cell wall and developmental defects raises the possibility that high levels of UDP-KDG result in deleterious effects on cell wall composition, and hence on virulence. This is the first report demonstrating that the accumulation of a minor nucleotide sugar intermediate has such a profound and adverse effect on a fungus. The ability to identify molecules that inhibit Er (also known as NRS/ER) enzymes or mimic UDP-KDG may lead to the development of new antifungal drugs.

Transcriptome- Assisted Label-Free Quantitative Proteomics Analysis Reveals Novel Insights into Piper nigrum-Phytophthora capsici Phytopathosystem.

Black pepper (Piper nigrum L.), a tropical spice crop of global acclaim, is susceptible to Phytophthora capsici, an oomycete pathogen which causes the highly destructive foot rot disease. A systematic understanding of this phytopathosystem has not been possible owing to lack of genome or proteome information. In this study, we explain an integrated transcriptome-assisted label-free quantitative proteomics pipeline to study the basal immune components of black pepper when challenged with P. capsici. We report a global identification of 532 novel leaf proteins from black pepper, of which 518 proteins were functionally annotated using BLAST2GO tool. A label-free quantitation of the protein datasets revealed 194 proteins common to diseased and control protein datasets of which 22 proteins showed significant up-regulation and 134 showed significant down-regulation. Ninety-three proteins were identified exclusively on P. capsici infected leaf tissues and 245 were expressed only in mock (control) infected samples. In-depth analysis of our data gives novel insights into the regulatory pathways of black pepper which are compromised during the infection. Differential down-regulation was observed in a number of critical pathways like carbon fixation in photosynthetic organism, cyano-amino acid metabolism, fructose, and mannose metabolism, glutathione metabolism, and phenylpropanoid biosynthesis. The proteomics results were validated with real-time qRT-PCR analysis. We were also able to identify the complete coding sequences for all the proteins of which few selected genes were cloned and sequence characterized for further confirmation. Our study is the first report of a quantitative proteomics dataset in black pepper which provides convincing evidence on the effectiveness of a transcriptome-based label-free proteomics approach for elucidating the host response to biotic stress in a non-model spice crop like P. nigrum, for which genome information is unavailable. Our dataset will serve as a useful resource for future studies in this plant. Data are available via ProteomeXchange with identifier PXD003887.

Selection pressure effects on the proportion and movement of resistance alleles introgressed from wheat in Aegilops cylindrica

SummaryIn winter wheat in the USA, Aegilops cylindrica is one of the most troublesome weeds, while the pathogen Oculimacula spp. causes foot rot disease. Imazamox‐resistant (IR) and foot rot‐resistant (FR) wheat cultivars represent effective tools to control the weed and prevent disease infection. However, resistance allele (RA) movement between wheat and A. cylindrica facilitates the introgression process under herbicide and disease selection pressure. Field experiments using IR and FR A. cylindrica plants intermixed with susceptible plants were conducted to measure the proportion of the RAs in the progeny and RA movement with and without herbicide and disease selection. Yield components of A. cylindrica plants were determined across treatments. The herbicide RA proportion in the progeny was greater when plants were treated with the herbicide imazamox in both years. Disease RA proportion was greater with disease occurrence only in one year. Herbicide RA movement from resistant to susceptible plants was greater with herbicide than without it only in one year. Plants carrying the RAs had greater total spikelet weight and 1000‐spikelet weight compared with susceptible plants with or without selection. However, susceptible plants produced more spikelets than the resistant ones in the absence of selection. If plants within an A. cylindrica population acquire the herbicide RA, its proportion will increase each generation under selection. These findings contribute to the understanding of crop allele introgression into related species and the evolution of increased weediness, with weed management implications.

Current status of wilt/root rot diseases in major chickpea growing areas of Ethiopia

Wilt/root rot diseases are a major chickpea production constraint in Ethiopia causing yield losses by reducing the number of plants. To determine the current status of disease incidence and distribution, surveys were conducted in the 2013/2014 and 2014/2015 cropping seasons in major chickpea growing zones of Ethiopia. Despite recent efforts in dissemination of improved varieties, low to high incidence of 0.0–83.4, 0.0–27.6, 1.3–19.8 and 0.0–16.3% and 1.0–81.9, 0.0–25.5, 3.0–13.9 and 1.0–21.5% in East Gojjam, Southwest Shewa, North Shewa and West Shewa in 2013/2014 and 2014/2015, respectively. Therefore, integrated pest management strategies should be developed and availed to farmers.

Incidence of Bakanae disease of basmati rice in south-western part of Punjab and its management

Basmati rice is an important cash crop of India, being recognized at international level for its quality and aroma. Bakanae/foot rot disease is becoming a limiting factor in its cultivation in southwestern parts of Punjab. A survey was conducted during Kharif 2014 in different blocks of Sri Muktsar Sahib District of Punjab to acquaint with the factor affecting disease incidence. Disease was recorded in all the basmati growing fields and up to 10 per cent incidence was recorded on different aromatic rice cultivars. Pusa Basmati 1401 was observed more susceptible followed by Pusa Basmati 1121 and Pusa Basmati 1509.Basmati crop raised at recommended period showed lower disease incidence than early transplanted crop. Higher disease incidence was observed in fields where seed was purchased from private seed companies than seed from State Agricultural University. The recommended technology to manage this disease i.e. seed soaking in pesticides solution containing carbendazim 50 WP @ 0.2 per cent + Streptocycline 0.01 per cent (one g) for 12 hrs followed by seedling root dip in carbendazim 50 WP (0.2%) for 6 hrs was demonstrated at selected farmers’ field during Kharif 2015. The results showed that seed treatment with carbendazim @ 2.0 g/kg alone (farmers’ practice) was not effective. The disease incidence in demonstrated plots was less as compared to farmers’ practice. The grain yield and net returns were also higher in demonstrated plots. How to view point the article : Sandhu, Gurmail Singh and Dhaliwal, N.S. (2016). Incidence of Bakanae disease of basmati rice in south-western part of Punjab and its management. Internat. J. Plant Protec., 9(1) : 353-357.

Development of an in planta infection system for the early detection of Ganoderma spp. in oil palm

Basal stem rot (BSR) disease caused by the white rot fungus, Ganoderma spp. is a serious threat to the growth and production of oil palm (Elaeis guineensis Jacq.). Traditional in planta infection technique using inoculated rubber wood block can be inaccurate and time-consuming. In this study, a new in planta infection system was developed to detect early symptoms of BSR in young oil palm. One month old clones of oil palm plantlets were artificially infected with pathogenic fungal inoculum (G. boninense GBLS isolate) at three levels of treatments (control, T1; wounded but not infected, T2; wounded and infected, T3) for a period of 8 days. Significant declines in leaf chlorophyll content (from 32.59 to 12.60 SPAD), increases in disease severity index (DSI) values (from 5.56 to 70.37 %) and increased amounts of GBLS DNA (from 0.2 to 116.1 ng μl-1) were progressively detected in T3 as compared to the T1 and T2 plantlets. The internal stem tissues of T3 plantlets were observed to deteriorate gradually from Day 2 post inoculation (DPI) and were severely colonized and damaged by 8 DPI. The potential defence mechanism of total phenolic content peaked on 6 DPI (3.7 mg g-1) in T3 plantlets and reduced thereafter. The data obtained is consistent with BSR symptoms reported in mature oil palm and is indicative of the reproducibility and reliability of an in planta infection system as an effective approach to detect early BSR symptoms in oil palm.

Management of Soft Rot (Pythiumspp.) and Wilt (Ralstonia solanacearum) of Ginger (Zingiber officinale) in Andamans

Five isolates of Trichoderma and one isolate of Pseudomonas fluorescens were evaluated against Pythium and Ralstonia solanacearum in vitro and in vivo with different combinations with some chemical fungicides and neem cake. The results indicated that all isolates of Trichoderma, lone isolates of Pseudomonas fluorescens and fungicides alone significantly inhibited both pathogens in vitro. The biocontrol agent, Trichoderma spp and isolate of Pseudomonas fluorescens were comparable to each other in their ability to inhibit both the pathogens. The combination of cultural practices, chemical pesticides at low concentration, biocontrol agents with optimum population (cfu/g) along with neem cake have been found most effective in reducing the disease incidence of both soft rot and wilt of ginger and corresponding yield increase in the year 2008–09 and 2009–10. Furthermore, seed + soil application of biofungicides and chemical fungicides resulted into lowest incidences of soft rot and wilt diseases, highest rhizosphere population of biocontrol agents at all the dates observed and highest yield of ginger.

Development of improvedCitrusrootstocks through hybridization

Citrus rootstocks have pronounced effect on scion vigour and size, yield, fruit size and juice quality. Citrus rootstock improvement is challenging because so many traits are to be packaged into a single successful rootstock. Rough lemon (Citrus jambhiri Lush.) is the most commonly used rootstock for Nagpur mandarin (Citrus reticulata Blanco), but it is susceptible to Phytophthora (root and foot rot) diseases and citrus nematode. To combine the vigour and high yielding qualities of rough lemon with the resistance of trifoliate orange (Poncirus trifoliata L.) and Troyer citrange (Citrus sinensis x Poncirus trifoliata) for Phytophthora and citrus nematode, a hybridization programme was carried out during 1990–91 and 1991–92. The hybrid seedlings were evaluated for vegetative and reproductive characteristics up to 2005–06. Segregation for different characteristics was observed in the F1 itself. For a rootstock to be successful, it should have faster growth in the nursery and the hybrids 2.6 (rough lemon x Troyer citrange) and 3.1 (rough lemon x trifoliate orange) were vigorously growing in the nursery. Bud take was quite good in all the rootstock hybrids. The hybrids so developed (2.6 and 3.1) will broaden the genetic base of our citrus industry once they are tested for biotic and abiotic stress tolerance/resistance. Further, the hybrids 2.6 and 3.1 are similar to rough lemon in all aspects and have very few trifoliate leaves (0.01%). They are performing well in the field and nursery and their growth is at par with rough lemon. In the development of these hybrids, the germplasm of trifoliate orange and Troyer citrange would play an important role in future breeding programmes for the improvement of citrus rootstocks. The hybrids developed are further being screened for their tolerance/resistance to Phytophthora spp. and citrus nematode and they are also being evaluated for testing the performance of Nagpur mandarin budded on them.

Phytoalexins stimulation in the infected Sesamum indicum L. with fungus Macrophomina phaseolina (Tassi) Goid (Rot Disease)

Plants respond to a wide variety of pathogen attack. They show the local response in originally attacked plant organ and systemic response in unaffected plant parts with the de novo production of phytochemical compounds. Phenolics (polyphenols) play an important role in the defense mechanism of the plants. So, this study was carried out to analyze the metabolic modifications in Sesame plant after the infection with the pathogen (Macrophomina phaseolina) by estimating the levels of polyphenol in 7 days and 14 days old Sesame plants. The polyphenol contents in infected plants are considerably exceeded in contrast to control plants. This in vivo study of M. phaseolina infection reveals the differences of resistance levels in Sesame against the pathogen. The obtained results give important information concerning the plant-pathogen interactions, in the defense response for Sesame improvement programs seeking the adaptation to the diverse range of fungal attack along with adverse environmental factors.International Journal of Environment Vol.4(4) 2015: 1-18

ALTERNARIA ALTERNATA CAUSING FRUIT ROT AND LEAF SPOT ON LOQUAT IN IRAN

A fruit rot and leaf spot disease of loquat (Eriobotrya japonica) was observed in May 2013 in the Sari city of Mazandaran province (Iran) on nearly 40% of the trees planted for arboretum. Tissue fragments from surface-sterilized (75% ethanol for 1 min, and 1% sodium hypochlorite for 3 min) fruits and leaves were excised and transferred to potato dextrose agar (PDA). White fungal colonies were obtained which turned grayish-black due to abundant sporulation. Pale to light brown obpyriform conidia with a beak, showing one to seven transverse and up to three longitudinal septa, measuring 10-45 x 7-22.5 μm, were produced in long chains. Conidiophores were straight, septate, and measured 35-100 × 2-5 μm. These morphological traits conform to those of Alternaria alternata (Simmons, 2007). Leaves and fruits of 12 healthy loquat plants were inoculated by spraying to runoff a spore suspension (105 conidia/ml sterilized water) from three fungal isolates, while an equal number of control plants were atomized with sterile water. After one week, characteristic symptoms resembling those observed in the field developed on all inoculated plants; control plants were symptomless. The pathogen was re-isolated from all inoculated plants. Genomic DNA from a single-spored isolate was extracted and the major allergen of A. alternata (Alt α 1) regions was amplified and sequenced using primers Alt-for and Alt-rev (Hong et al., 2005). BLASTn analysis of a 478 bp sequence (GenBank accession No. KJ396786) showed 100% homology with A. alternata (AF288160). A. alternata is reported to infect over 48 different plants in Iran (Ershad, 2009), to which loquat can now be added.

Triple Strain Cocktail Reduces Soft Rot and Black Leg Diseases in Potatoes

Triple Strain Cocktail Reduces Soft Rot and Black Leg Diseases in Potatoes

IN VITRO SELECTION ON FUSARIC ACID OF Vanilla planifolia PLANTLETS FOR OBTAINING A CULTIVAR, WHICH RESISTANT TO Fusarium oxysporum f. sp. vanillae

<p>The most production constrain on Vanilla planifolia Andrews plantation recently has been caused by foot rot disease that later influence in decreasing the yield product. This disease is caused by Fusarium oxysporum f. sp. vanillae (Fov). So far, the disease has not been successfully prohibited although some experiments had been conducted. The use of foot rot resistant cultivar has been introduced, which expected has high yield as one alternative method for controlling this disease. A resistant vanilla plantlet to Fov has been initiated by in vitro selection on MS medium containing fusaric acid (FA) on selective concentration. The purpose of research were to study and determine: 1) The proper combination of 2,4-D and NAA for callus initiation and shoot development from shoot tip explants, along with proper concentration of BAP for shoots initiation from nodal explants; 2) The FA concentration of plantlet selection tolerant to steady growth; 3) The proper concentration of FA for in vitro selection for suppressing the Fov. Results showed that: 1) the proper concentration of both combination between 2,4-D and NAA is about 2,0 mg/L and 10 mg/L respectively for callus initiation and shoot development from shoot tip explants; also the BA concentration is 1,0 mg/L for shoot initiation from a nodal explants; 2) the FA tolerant concentration for plantlet selection with vanilla steady growth is between 90 ppm-110 ppm; 3) the 110 ppm of FA was effective for suppressing the Fov compared to 90 ppm and 100 ppm respectively. </p><p><strong>Keywords</strong>: Vanilla planifolia Andrews, the vanilla foot rot disease, Fusarium oxysporum f.sp. vanillae, in vitro, fusaric acid</p>

ANATOMICAL CHARACTERIZATION OF SELECTED PLANLET Vanilla planifolia Andrews. ON FUSARIC ACID, RESISTANT TO Fusarium oxysporum f. sp. vanillae

<p>Vanilla is one of the important agricultural export commodity of Indonesia. The vanilla from Indonesia is well known for it high levels of vanillin content,which is about 2,75%. Until recently, the most hazardous disease of vanilla is foot rot infection caused by Fusarium oxysporum f. sp.vanillae (Fov). One alternative way to control the foot rot disease is by using cultivars which resistant to its pathogen. Selected plantlets have been induced by using fusaric acid on the in vitro medium. The goal of this research is to characterize the anatomical point of few especially on leaves, pseudo bulb and root with respect of resistant to Fov. Moreover, it is also addressed to determine the different characters of the phenotype vanilla plantlet whichare total of phenol, peroxydases enzyme activity, the thickness of lignin, and the chlorophyll content. The data on this research were recorded, compiled and categorized as descriptive qualitative and quantitative information. Theresult showed significant increase in chlorophyll a, chlorophyll b, and also the total of chlorophyll. The overall in line correlated with the increasing FA concentration. The total chlorophyll at 90 ppm FA could increased about 1,2 times, while at 100 ppm and 110 ppm FA could enhanced about 1,4 to 1,5 times compared to control. Anatomical characters between vanilla control, infected fov, and resistant to fov, were showed clearly at the stele part especially at xylem as the main function for transporting water from root to the leaf, which formed thyllose. Phenol total at about 4,39 % in control, increased to 5,34% in 90 ppm, and followed by 5,52 % in 100 ppm and 5,87 % at 110 ppm. Peroxidases enzyme activity at FA 90 ppm produced about 0,25 U/mg/min, and at 100 ppm FA on 0,34 U/mg/min, while at FA 110 ppm generated 0.36 U/mg/min compared to control, at 0,12 U/mg/min. The thickness of lignin tracheid in the treatment of 90 ppm was at about 14,59 ìm; 100 ppm 18,16 ìm; and 110 ppm 19,39 ìm compared to controls 10,28 ìm. In conclusion over all showed that FA induced plantlet vanilla inin vitro medium resulted in change of phenotype compare to control, which also affect its anatomy structure, especially on lignification and thyllose formation at surrounding tracheids, which could be use as marker for defend mechanism of plant to Fov.</p><p><br /><strong>Keywords</strong>: Fusarium oxysporum f. sp.Vanillae, peroxydases enzyme, anatomical characters.</p>

POLA AGIHAN DAN INTENSITAS PENYAKIT BUSUK PANGKAL BATANG LADA DI PROVINSI SULAWESI TENGGARA

The success of foot rot disease control is largely dependent on information data of pepper cultivation conditions, distribution pattern of the disease, and the magnitude of the intensity of the disease. This study aimed to determine the condition of pepper cultivation, distribution pattern of pepper foot rot disease, the development of disease symptoms, and intensity of pepper foot rot disease in Southeast Sulawesi. Data cultivation conditions, distribution of the disease, progression of symptoms, and the intensity of the disease were obtained by means of surveys in pepper plantations and interviews with pepper farmers. The results showed that the pepper plantations in Southeast Sulawesi were cultivated on flat to hilly topography, and the cultivation method was very conventional but herbicide use was very intensive. The development of wilt symptoms on pepper plants was very quick in dry weather but slow in the wet. Pepper foot rot disease has patch distribution. The highest intensity of the pepper foot rot disease was in less weedy plantations with intensive use of herbicides. The intensity of the pepper foot rot disease in Southeast Sulawesi was 61,2% with the spread in each district namely South Konawe at 53,8%, Konawe at 63,7% and Kolaka by 61,2%.

Deoxynivalenol-producing ability of Fusarium culmorum strains and their impact on infecting barley in Algeria.

The cereal-pathogenic Fusarium culmorum (W.G. Smith), causal agent of various blights and rot diseases, is considered as a chronic fungus of economic concern worldwide including North African countries such as Algeria. This pathogen produces a wide range of mycotoxins, amongst which the type B-trichothecene deoxynivalenol (DON). In addition to its acute and chronic side effects in livestock and humans, DON is believed to play a determinant role in the pathogenesis toward Triticeae. However, regardless its significant occurrence and impact, little is known about trichothecenes-producing ability of F. culmorum infecting cereals in Algeria. The PCR assay based on Tri genes of 12 F. culmorum strains (designated Fc1-Fc12), which were recovered from several cropping areas of North Algeria, revealed their trichothecenes-producing ability with 3-AcDON genotype. The molecular prediction was confirmed by HPLC analysis. All strains were able to produce the toxin at detectable levels. Strains Fc1 and Fc12 were the highest producers of this mycotoxin with 220 and 230 µg g(-1), respectively. The evaluation of pathogenic ability of strains through a barley infesting experiment exhibited the significant disease impact of most strains. Significant correlation between the DON-producing ability of strains and the increase in both disease severity (r = 0.88, P = 0.05) and disease occurrence (r = 0.70, P = 0.05) was observed. Chemotyping of F. culmorum isolates and evaluation of their pathogenic ability are reported for the first time for isolates from Algeria, and highlights the important potential of F. culmorum to contaminate cultivated cereal with DON trichothecenes.

EPIDEMI PENYAKIT BUSUK PANGKAL BATANG LADA PADA KONDISI LINGKUNGAN YANG BERVARIASI

Foot rot disease epidemic on black pepper in variety of environmental conditions. The foot rot disease on black pepper caused by Phytophthora capsici Leonian, is often destructive to farmers of black pepper. This research aims to study the infection rate and the pattern of development of the black pepper foot rot disease in various condition of the environment. The research was conducted in the areas of black pepper cultivation in the Ultisol and Entisol soils. In each location plots were set with few (<25%) and abundant (>75%) weeds. Variable observed was disease incidence. The data were used to analyze model of development of the black pepper foot rot disease and infection rate. Results of the research showed that the model of development of the black pepper foot rot disease was not affected by soil type, but the type of soil affected the infection rate. At the pepper plantation with abundance of weeds, the disease development followes Gompertz model. At the plantation with few weeds, however the disease developed in a logistic model. The rate of disease infection on the black pepper plant with abundant weeds lower compared with those with few weeds.

Induce Systemic Resistance against Root Rot and Wilt Diseases in Fodder Beet (Beta vulgaris L. var. rapacea Koch.) by Using Potassium Salts

Rhizoctonia solani, Fusarium solani, F. oxysporum F. equiseti and F. semitectum were found to be associated with root rot and wilt symptoms of fodder beet plants collected from different fields in New Valley governorate, Egypt. All the obtained isolates were able to attack fodder beet plants (cv. Starmon) causing damping-off and root rot/wilt diseases. R. solani isolate FB1, F. solani isolate FB7 and F. oxysporum isolate FB11 were the more virulent ones in the pathogenicity tests. The efficacy of 4 different potassium salts for controlling damping-off, root rot and wilt diseases in fodder beet were evaluated in vitro and in vivo. In vitro studies, all the tested potassium salts were significantly suppressed growth of the pathogenic fungi at different concentrations. KHCO3 showed superior higher inhibitory effect on redial growth of the tested pathogenic fungi especially at higher concentration (20 mM). Under green house and field conditions, all potassium salts significantly reduced damping-off and root rot/wilt severity and increased survival of plants. The reduction in damping-off and root rot/wilt increased with increasing of potassium salts concentration except potassium sulfate (K2SO4), while concentration 10 mM was more effective for reducing damping-off and root rot/wilt severity than 20 mM. K2SiO3 followed by K2HPO4 recorded highly protection against damping-off and root rot/wilt severity more than the other tested potassium salts. Under field conditions, all these potassium salts at different concentrations significantly submitted to various growth and yield parameters viz. root length, root diameters, fresh and dry weights compared with control during growing seasons 2013-14 and 2014-15. While, % dry maters was no significant in both growing seasons. The applied treatment K2SiO3 achieved the highest increase in all the mentioned parameters over the other entire three potassium salts during both growing seasons. In physiological studies, activity of defense-related enzymes, including peroxidase (PO), polyphenol oxidase (PPO), phenylalanine ammonia lyase (PAL), and tyrosine ammonia lyase (TAL) and total phenols content were increased in inoculated plants with R. solani, F. solani, and F. oxysporum individually and treated with potassium salts compared with untreated plants. K2SiO3 at 20 mM showed the highest level of all oxidative enzymes activity and total phenols content followed by K2HPO4 and K2SO4 at 20 mM. Whereas, the least enzymes activity was recorded with KHCO3 at 10 mM. These results suggested that these chemicals may be play an important role in controlling the fodder beet damping-off, root rot and wilt diseases; through they have induction of systemic resistance in fodder beet plants.

EFFECT OF INARCHED, TWO-ROOTSTOCK TREES, ON DEVELOPMENT, YIELD AND DISEASE RESISTANCE OF 'VALENCIA' ORANGE

Susceptibility to sudden death, blight and foot rot diseases, and to nematodes, has not prevented Rangpur lime from still being the most used citrus rootstock in Brazil due to its drought resistance, adaptability to poor soils, and productivity. Historically, inarching trees on susceptible rootstocks with others resistant conferred tree resistance against root and trunk diseases. Experiments were established in 2005 and 2007 to compare ‘Valencia’ trees propagated on (1) Rangpur lime, (2) Swingle citrumelo, or (3) inarched using these two rootstocks. Inarched trees had the same height as those on Rangpur lime alone and both types were taller than trees on Swingle citrumelo alone in the 5th year of the orchard. Trees grafted on Swingle tended to yield less fruit than those grafted on Rangpur lime in the first 2 to 4 crops, while inarched trees tended to yield intermediate to larger crops. Fruit quality of inarched trees tended to be intermediate or similar to that of the best quality inducing rootstock. Swingle rootstock totally protected inarched trees from foot rot in the first 7 years of the orchard while trees on Rangpur alone had 1.5% to 2% disease incidence. Therefore, inarching can be used to take advantage of the complementary qualities of known rootstocks regarding disease resistance, tree height, productivity, and fruit quality.

First morphogenetic identification of Fusarium solani isolated from orange fruit in Egypt

Losses due to post harvest decay may occur at any time during post harvest handling, from harvest to consumption affecting the produce quality and quantity. Accurate identification of the pathogen causing post harvest disease is essential to the selection of an appropriate disease control approach. Nine isolates of Fusarium recovered from orange fruit were identified as Fusarium solani. The fungus is involved with fruit decay. The obtained cultures were purified and grown on potato-dextrose agar (PDA), malt yeastagar (MYA), and Czapek's nutrient media (CNM) under light for identification. A pathogenicity test was carried out to fullfil Koch'spostulates. The pathogen could only enter ripe orange fruit through wounds and cracks causing the rot disease. The identification of the fungal isolates was confirmed to be F. solani by DNA sequencing, which was 99 to 100% homologous to those deposited in the Gen-Bank. The identity of nine fungal isolates was confirmed to be F.solani by DNA sequencing of the internal transcribed spacer (ITS) rDNA region (GenBank Accession Nos. DQ486874 to DQ486881 and KC758879). To our knowledge, this is the first morphogenetic identification of F. solani isolated from orange fruit in Egypt.