Rot Infection Research Articles

Antibacterial activity of carob (Ceratonia siliqua L.) extracts against phytopathogenic bacteria Pectobacterium atrosepticum

Acetone and ethanol extracts of carob (Ceratonia siliqua L.) leaf and pods were evaluated for their in vitro inhibitory ability against the pectinolytic Gram negative Pectobacterium atrosepticum (Pca, CFBP-5384) bacteria, the causal agent of potato soft rot. Potato (Solanum tuberosum, var nicola) tuber rot tissues obtained after 5 day bacterial inoculation was analyzed by LC–MS and GC–MS to study Pca pathogenicity. Trans/cis N-feruloylputrescine was identified in potato tuber after 5-day inoculation with Pca in a dark moist chamber. Although glycoalkoloid (α-chaconine and α-solanine) production increased due to Pca soft rot infection, it was not a resistance-determining factor. Many secondary metabolites were identified including the phytoalexins solavetivone and fatty acids responsible for plant defence responses. Acetone extract of carob leaf (FCA) exhibited the strongest inhibitory effect (IC50 = 1.5 mg/ml) and displayed synergistic antimicrobial effect in the presence of infected potato tuber extract (Pdt-Pca extract) against Pca. This synergy could be used in an integrated control program against potato soft rot pathogens, thereby reducing chemical treatments.

Evaluating unsupervised and supervised image classification methods for mapping cotton root rot

Cotton root rot, caused by the soilborne fungus Phymatotrichopsis omnivora, is one of the most destructive plant diseases occurring throughout the southwestern United States. This disease has plagued the cotton industry for over a century, but effective practices for its control are still lacking. Recent research has shown that a commercial fungicide, flutriafol, has potential for the control of cotton root rot. To effectively and economically control this disease, it is necessary to identify infected areas within fields so that site-specific technology can be used to apply fungicide only to the infected areas. The objectives of this study were to evaluate unsupervised classification applied to multispectral imagery, unsupervised classification applied to the normalized difference vegetation index (NDVI)and six supervised classification techniques, including minimum distance, Mahalanobis distance, maximum likelihood and spectral angle mapper (SAM), neural net and support vector machine (SVM),for mapping cotton root rot from airborne multispectral imagery. Two cotton fields with a history of root rot infection in Texas, USA were selected for this study. Airborne imagery with blue, green, red and near-infrared bands was taken from the fields shortly before harvest when infected areas were fully expressed in 2011. The four-band images were classified into infected and non-infected zones using the eight classification methods. Classification agreement index values for infected area estimation between any two methods ranged from 0.90 to 1.00 for both fields, indicating a high degree of agreement among the eight methods. Accuracy assessment showed that all eight methods accurately identified root rot-infected areas with overall accuracy values from 94.0 to 96.5 % for Field 1 and 93.0 to 95.0 % for Field 2. All eight methods appear to be equally effective and accurate for detection of cotton root rot for site-specific management of this disease, though the NDVI-based classification, minimum distance and SAM can be easily implemented without the need for complex image processing capability. These methods can be used by cotton producers and crop consultants to develop prescription maps for effective and economical control of cotton root rot.

First Report of Branch Rot of Lonicera japonica Caused by Sclerotium delphinii in China.

Honeysuckle flower (Lonicera japonica Thunb.) is a perennial, traditional Chinese medicine plant, widely cultivated in China. In early June 2013, heavy branch rot infection was observed on L. japonica in an approximately 10,000-m2 field in Linyi, Shandong, China. The disease incidence was 30 to 40%. Early symptoms appeared as small, elliptoid, pale brown lesions on the branches. Lesions expanded into 50 to 100 mm long and 3 to 7 mm wide, brown, elongated spots. The upper branches wilted after the lesions expanded around the stems. A fungus was consistently isolated from stem lesions on potato dextrose agar (PDA) that was morphologically similar to S. delphinii, with white mycelium, round to irregularly shaped reddish-brown sclerotia that were 2 to 4 mm diameter (2). The identity of the fungus was confirmed by DNA sequencing of the internal transcribed spacer (ITS) region (GenBank Accession No. KJ145328), which was 99% homologous to those of other S. delphinii isolates (JN241578 and AB075314) (1). Pathogenicity tests were conducted with three 2-year-old seedlings grown in 20-cm-diameter pots at 25 to 30°C during experiments in greenhouse. Ten branches from the three plants pricked by needle were inoculated with a mycelial plug (0.4 cm diameter) harvested from the periphery of a 4-day-old colony. An equal number of branches pricked by needle serving as controls were mock-inoculated with plugs of PDA medium. Inoculated branches were covered with plastic bags for 24 h to maintain high relative humidity and incubated at about 25°C. Plugs were removed 48 h after inoculation. After 3 days, nine inoculated branches showed symptoms identical to those observed in the field under natural conditions, whereas controls remained symptom-free. Re-isolation of the fungus from lesions on inoculated branches confirmed that the causal agent was S. delphinii. Pathogenicity tests were repeated three times by the same methods with the same results. To our knowledge, this is the first report of S. delphinii infecting Lonicera japonica in China.

Apple ring rot-responsive putative microRNAs revealed by high-throughput sequencing in Malus × domestica Borkh.

MicroRNAs (miRNAs) are small non-coding RNAs, which silence target mRNA via cleavage or translational inhibition to function in regulating gene expression. MiRNAs act as important regulators of plant development and stress response. For understanding the role of miRNAs responsive to apple ring rot stress, we identified disease-responsive miRNAs using high-throughput sequencing in Malus × domestica Borkh.. Four small RNA libraries were constructed from two control strains in M. domestica, crabapple (CKHu) and Fuji Naga-fu No. 6 (CKFu), and two disease stress strains, crabapple (DSHu) and Fuji Naga-fu No. 6 (DSFu). A total of 59 miRNA families were identified and five miRNAs might be responsive to apple ring rot infection and validated via qRT-PCR. Furthermore, we predicted 76 target genes which were regulated by conserved miRNAs potentially. Our study demonstrated that miRNAs was responsive to apple ring rot infection and may have important implications on apple disease resistance.

English

Contamination of potato with soft rotting enterobacteria belonging to the Pectobacterium and Dickeya genera is one of the biggest problems in potato production. Calcium plays an important role in minimising the severity and incidence of potato tuber soft rot in storage. This review gives a detailed assessment of the epidemiology of the pathogens and how calcium affects potato tuber soft rot in storage. Key words: Potato, soft rot, calcium, Pectobacterium, Dickeya.

Antifungal Activity of Plant Products for the Management of Fruit Rot Infection in Chillies

Antifungal Activity of Plant Products for the Management of Fruit Rot Infection in Chillies

Monitoring Cotton Root Rot Progression within a Growing Season Using Airborne Multispectral Imagery

Cotton root rot, caused by the fungus Phymatotrichopsis omnivora, is a serious and destructive disease affecting cotton production in the southwestern United States. Accurate delineation of cotton root rot infections is important for cost-effective management of the disease. The objective of this study was to use airborne multispectral imagery for monitoring the progression of root rot infections within cotton fields during a growing season. A number of cotton fields near Edroy and San Angelo, Texas were selected for this study. Airborne multispectral digital imagery with blue, green, red and near-infrared bands was taken from these fields two to four times during the 2010 growing season. The imagery for two fields from each of the two locations was georeferenced and classified into two to twenty spectral classes using unsupervised classification techniques. The optimal number of spectral classes was determined based on the average transformed divergence for each classification and the spectral classes were then grouped into root rot-infected and non-infected zones. The infected areas within each field were determined for each imaging date and compared among the different dates. Both airborne imagery and ground observations showed that cotton root rot expanded in different patterns and at different rates over the growing season. Toward the end of the growing season, the percentage of root rot-infected areas increased to 13.2% and 26.8% in the two fields in Edroy, and to 37.8% and 50.6% in the two fields in San Angelo. The results from this study will be useful for the understanding of the progression of the disease and for the development of site-specific treatment plans for the disease.

Формирование урожая и фитосанитарное состояние озимой тритикале в зависимости от приемов управления посевами

The yield composition peculiarities of winter triticale were studied, depending on the application rate and the use of fungicides. The differences in the development of root rot and leaf fungal infections of triticale were revealed, when sown with different seeding rates. The positive effect of the use of fungicides on the yield of winter triticale confirmed. Optimum seeding rate for Nemchinovskiy 56 variety was 5 million seeds per hectare. An effect of seeding rates and fungicide treatment on disease development and productivity of winter triticale determined by vegetation conditions of crop. In optimal conditions for overwintering and development of plants in spring and summer the advantage had the higher seeding rates, whereas in the more arid conditions of maximum values for yield were at a rate of 4.0 million seed per hectare. The maximum value of the biological efficacy of fungicide against leaf fungal infections was at higher seeding rates. The minimum development of septoria spot of leaf on the background without using fungicides was at higher seeding rates (5 and 6 million seeds per hectare), the minimum values of rhynchosporium disease were at sowing norm of 4.0 million per hectare. The maximum value of the biological efficacy against both fungal infections has been at the application of the fungicide in the version with a seeding rate of 6.0 million seeds per hectare. An effect of seeding rates and fungicide treatment on disease development and productivity of winter triticale is determined by vegetation conditions. Having optimal conditions for overwintering and development of plants in spring and summer, we had the advantage of higher seeding rates, whereas in the more arid conditions the maximum values of yield were at a seeding rate of 4.0 million seeds per hectare. The maximum value of the biological efficacy of fungicide against leaf fungal infections was at higher seeding rates.

Bio-Efficacy of Microbial Infused Rice Straw Compost on Plant Growth Promotion and Induction of Disease Resistance in Chili

ABSTRACT Microbial fortified organic amendment in chili cultivation may affect plant development and disease suppression. Microbial infused rice straw compost, commercial rice straw compost, and fungicide Benomyl for chili (Capsicum annum L.) cultivation and control of Sclerotium foot rot were studied under glass house condition. Chili seed cv. Kulai were sown in the Sclerotium rolfsii infested and non-infested soil. After two weeks, five healthy seedlings were transplanted into planting bags. Growth performance and development of disease symptoms associated with S. rolfsii foot rot infection were assessed. Applying microbial infused rice straw compost increased seed germination and plant growth, and suppressed development of foot rot compared to using commercial rice straw compost and the Benomyl. A higher disease reduction (84.6%) occurred with 15 Mg · ha−1 microbial infused rice straw compost (62.7%), followed by Benomyl (53.8%), and 15 Mg · ha−1 commercial rice straw compost (46.2%). Application of microbial infused rice straw compost at 15 Mg · ha−1 yielded optimum seed germination and seedling establishment, plant growth, and disease suppression. Microbial infused rice straw compost is a good alternative to chemical fungicide in controlling Sclerotial disease in chili.

Soybean Seed Phenolics, Sugars, and Minerals Are Altered by Charcoal Rot Infection in MG III Soybean Cultivars

Soybean seed is a major source of phytochemical compounds that impact human health nutrition and livestock meal. Charcoal rot is a disease caused by the fungus Macrophomina phaseolina (Tassi) Goid, and thought to infect the plants through roots by a toxin-mediated mechanism, resulting in yield loss and poor seed quality, especially under drought conditions. Limited information is available on the effect of charcoal rot on seed phytochemical compounds and mineral nutrition in soybean. Therefore, the objective of this research was to investigate the effect of charcoal rot infection on seed phenol, seed coat lignin, isoflavones, and minerals using susceptible (S) (DK 3964) and moderately resistant (MR) (AG 3905) maturity group (MG)III soybean cultivars to charcoal rot. A two-year field experiment was conducted, and infested soil with charcoal rot (infested soil conditions, INF) or control (non-infested soil conditions, NINF) was used. The results showed that the moderately resistant genotype had higher concentrations of seed phenolics, total isoflavones, and seed coat lignin under infested and non-infested conditions and under irrigated or non-irrigated conditions compared with the susceptible genotype. The same general trend was found for seed K, Ca, P, Mn, Zn, B, and Cu concentrations in the moderately resistant genotype compared with the susceptible genotype. Our research demonstrated that these seed phytochemical constituents may explain the differences between susceptible and moderately resistant cultivars and may play an important role in the resistance to charcoal rot.

Seed Treatment with Live or Dead Fusarium verticillioides Equivalently Reduces the Severity of Subsequent Stalk Rot

AbstractFusarium verticillioides is a widely distributed fungus that can associate with maize as a deleterious pathogen and an advantageous endophyte. Here, we show that seed treatment with live F. verticillioides enhances maize resistance to secondary stalk rot infection and further demonstrate that dead F. verticillioides is sufficient to equivalently reduce F. verticillioides biomass. Seed treatment with live or dead F. verticillioides primes maize plants, and upon subsequent stalk infection, terpenoid phytoalexins accumulate faster than control‐treated plants. Seed treatment did not constitutively activate plant defences nor did it impact plant growth. These results suggest that seed treatment with dead F. verticillioides can be used as a ‘vaccination’ method to decrease the severity of stalk rot and potentially pathogen infection throughout the plant.

Eco-friendly methods to control infection of Botrytis cinerea during propagation of grapevines

Grey mould (Botrytis cinerea Pers.) is a pathogenic fungus which causes damage to the production of grapevine nursery plant materials especially on the stored canes or on graftings during the callusing period. The conditions, increased temperature and humidity, are ideal for the pathogen during the pre-forcing stage and in the storage Botrytis cinerea can easily infect the outbursting buds as large amounts of grapevine canes are stored in a relatively small place. The fungicide-based management is general in the prevention of gray rot infection but the palette of authorised chemical compounds is narrowed year by year due to the regulations of the European Union. Our aim is to develop an eco-friendly method which combines the use of natural materials with techniques used in organic farming. Effect of the ultraviolet-c light on the Botrytis cinerea was studied. The development characteristics of the pathogen were examined under daylight and dark conditions and experiments were set up with cow’s milk and acetic acid. UV-C light destroyed the developed conidia, however, the radiation stimulates the development of immature propagules. Larger quantities of conidiophores and conidia were formed in daylight compared to culture in the dark, while different conditions did not signifi cantly change the mycelial growth characteristics. The developed bacteria prevented the spread of pathogen mycelia during the test with cow’s milk in Petri dishes, although the smooth development of propagules that occurred did not change the vitality of the fungal colony. Furthermore the growth of Botrytis cinerea fungus mycelia was strongly inhibited by acetic acid.

Functional Variation of Ascorbate Peroxidase in Black Pepper (Piper nigrum) Varieties during Infection of Phytophthora capsici

Activity of ascorbate peroxidase was determined in black pepper (Piper nigrum) infected by Phytophthora capsici causing foot rot disease in varieties of Shakthi and Panniyur. The pathogen Phytophthora capsici was inoculated under in vitro conditions to the healthy plants of Shakthi and Panniyur. The black pepper plants of Shakthi variety at post inoculated phase showed a progressive increase in ascorbate peroxidase (APX) activity and the inoculated plants remain healthy without showing the symptoms of foot rot indicating the role of APX in inducing tolerance during pathogenesis. Meanwhile a gradual depletion of ascorbate peroxidase activity was observed in the inoculated plants of Panniyur, exhibiting the susceptible nature with all critical symptoms of foot rot infection. The activity of APX in both varieties was also checked qualitatively by native gel electrophoresis. Histological variations at cellular level during infection was examined by scanning electron microscope (SEM). An analytical comparison was done between the APX activity and scavenging of H2O2 in the varieties during infection.

Disease warning models for brown rot fungi of fruit crops

In this review, disease warning models for brown rot fungi, including Monilinia fructigena, M. laxa and M. fructicola, were summarized. Few studies have been made to relate epidemiology and disease warning in brown rot infection caused by M. fructicola and M. laxa in order to predict infections or develop decision support models for fungicide applications during the growing season. More recently a disease warning model and a decision support system were also performed for M. fructigena for organic apple orchards. This review gives an overview on some details of the above disease warning models and decision support system.

Postharvest grape infection ofBotrytis cinereaand its interactions with other moulds under withering conditions to produce noble-rotten grapes

To investigate the interactions between Botrytis cinerea and other moulds during grape withering and postharvest infection to obtain noble-rotten grapes. Strains of Botrytis cinerea, Penicillium expansum, Penicillium crustosum, Aspergillus niger, Fusarium verticilloides and Alternaria alternata, isolated from naturally withered grapes and identified by molecular tools, were used to infect Garganega and Corvina grapes. Individually sterilized berries were infected by a single inoculation of each strain or a simultaneous inoculation of B. cinerea together with one of each of the other moulds. Withering kinetics, glycerol, gluconic acid, total polyphenols, total anthocyanins and laccase activity greatly varied among each strain and also in respect to untreated berries. Successful noble rot settlement was ascertained by an additional infection assay carried out on nonsterilized berries. The suitability of inducing noble rot infection during grape withering and the improvement of the health of noble-rotten grapes have been demonstrated. This study provides insights on the effects of mould interactions on withered grape quality. Implementing noble rot induction by postharvest infection in winery drying fruit rooms to standardize the level of grape botrytization is encouraged.

Zdrowotność jęczmienia jarego uprawianego w systemie konwencjonalnym i ekologicznym z uwzględnieniem konwersji

Spring barley was grown in 2004–2006 on the experimental plots in Bałcyny. The average root rot infection index remained at a similar level and significant differences were modified by crop rotation selection. Symptoms of leaf blotch, net blotch and powdery mildew were recorded on barley leaves. Pyrenophora teres and Rhynchosporium secalis infected cereal leaves more frequently in the conventional system than in the organic system. Conversion period was inhibited influence the intensification of barley leaf dieases. Evaluation of steam base revealed higher severity of fusarium foot rot and eyespot infection in the conventional farming system than in the organic. Fusarium fungi were the largest group of isolates, and destructive pathogen Cochliobolus sativus colonized barley that derived from the organic farming tenfold more frequently, and Aureobasidium and Microdochium were isolated with higher frequency from the barley grown in the conventional system. Jęczmień jary uprawiano w latach 2004–2006 na poletkach doświadczalnych w Bałcynach. Średni indeks porażenia korzeni kształtował się na zbliżonym poziomie, a istotne różnice były modyfikowane doborem płodozmianu. Na liściach jęczmienia odnotowano symptomy rynchosporiozy, plamistości siatkowej oraz mączniaka prawdziwego zbóż i traw. Pyrenophora teres i Rhynchosporium secalis częściej atakowały liście w systemie konwencjonalnym niż ekologicznym. Okres konwersji działał inhibicyjnie na nasilenie chorób liści jęczmienia. Na podstawie źdźbła stwierdzono wyższe nasilenie fuzaryjnej zgorzeli podstawy źdźbła oraz łamliwości źdźbła zbóż i traw w konwencjonalnej uprawie jęczmienia w porównaniu do ekologicznej. Najliczniejszą grupą izolatów były grzyby rodzaju Fusarium, zaś groźny patogen jęczmienia Cochliobolus sativus dziesięciokrotnie częściej zasiedlał jęczmień pochodzący z uprawy ekologicznej, a grzyby rodzaju Aureobasidium i Microdochium z wyższą frekwencją wyosobniano z jęczmienia uprawianego w systemie konwencjonalnym.

Zdrowotność pszenżyta ozimego w warunkach przestawiania produkcji konwencjonalnej na ekologiczną

Winter triticale cultivar Witon was grown in 2004–2006 on the experimental plots in Bałcyny (NE Poland). The first two years of conducting the experiment referred to a period of converting the conventional production system to organic. Organic crop production started in 2006. The results of the experiment, showed that the average root rot infection index was higher in the organic farming system (22.4%) than in the conventional system (17.4%), in contrast to the data on the severity of stem base diseases, eyespot and fusarium foot rot (17.9, 31.8% and 30.7, 35.8% in the organic and conventional systems, respectively). Fungicides used in the conventional farming system effectively reduced the development of cereal leaf pathogens. The symptoms of infection caused by Puccinia recondita were recorded only in the organic farming system (35.0%). The severity of tan spot of cereals reached 94.0% in the organic system, and only 6.0% in the conventional system. Pszenżyto ozime odmiany Witon uprawiano w latach 2004–2006 na poletkach doświadczalnych w Bałcynach. Dwa lata badań (2004, 2005) stanowiły okres przestawiania produkcji na uprawę metodami ekologicznymi, a kolejny, zgodnie z obowiązującym rozporządzeniem był już uprawą w systemie ekologicznym. Średni indeks porażenia korzeni w okresie badań był wyższy w ekologicznym systemie gospodarowania (22,4%) niż w konwencjonalnym (17,4%). Odwrotnie przedstawiało się nasilenie chorób podstawy źdźbła – łamliwości źdźbła zbóż i fuzaryjnej zgorzeli podstawy źdźbła (odpowiednio 17,9 i 31,8% oraz 30,7 i 35,8% w systemie ekologicznym i konwencjonalnym). Użyte fungicydy w systemie konwencjonalnym skutecznie hamowały rozwój patogenów aparatu asymilacyjnego. Objawy powodowane przez Puccinia recondita odnotowano jedynie w systemie ekologicznym – 35,0%. Nasilenie objawów brunatnej plamistości liści w systemie ekologicznym wynosiło 94,0%, a w konwencjonalnym jedynie 6,0%.

Susceptibility to Apple Ring Rot Infection of Apple Branches of Different Ages and Preventive Effect of Fungicides on Wart Bark Formation

Susceptibility to Apple Ring Rot Infection of Apple Branches of Different Ages and Preventive Effect of Fungicides on Wart Bark Formation

Efficacy of Pseudomonas aeruginosa and other biocontrol agents in the control of root rot infection in cotton

Seed dressing with <em>Pseudomonas aeruginosa, Paecilomyces lilacinus and Trichoderma koningii</em> significantly (p<0,05) reduced infection of <em>Macrophomina phaseolina, Rhizoctonia solani</em> and <em>Fusarium solani</em> on cotton roots in pot experiments and in field. Combined use of P.aeruginosa strain CMG63 with <em>T.koningii</em> produced greater plant height and fresh weight of shoot in field as compared to CMG52 which showed better results in pot experiments.

Chemical Control and Economics of Phomopsis Blight and Fruit Rot of Brinjal in the Eastern Ghat Highland Zone of Odisha

A field trial was conducted during 2011 and 2012 for management of phomopsis blight and fruit rot of brinjal caused by Phomopsis vexans by seed treatment with carboxin 37.5% + thiram 37.5% (Vitavax power) @ 2 g/kg and foliar application of copper oxychloride (Blitox-50) @ 0.3%.The disease and economic parameters as well as yield were compared with that of untreated farmers’ field. It was revealed that the plant protection chemicals increased the seed germination by 21.18% and reduced seedling mortality, seedling blight and fruit rot infection by 90.25, 74.51 and 65.9%, respectively. The improved germination and reduced disease infections helped to sustain 40.28% higher brinjal yield with a net higher return of Rs. 26513 per ha.