Diseases of the gladiolus: I. Control of hard rot, due to Septoria gladioli Passer., by fungicidal treatment of the corms

Losses from hard rot, measured by an arbitrary disease index, were reduced by treating the dehusked corms before planting with mercuric chloride (with or without the addition of 10% hydrochloric acid), mercurous chloride (calomel), three proprietary mercury compounds (Aretan, Uspulun and Ceresan) and one proprietary non-mercury compound (Folosan). Calomel was the least effective. All the treatments were relatively less effective when corms with definite lesions were treated.
The weight of clean corms produced per old corm planted (weight index) was usually increased by all the fungicides tried, but calomel and Ceresan were less satisfactory than the others.
Mercuric chloride (3 hr. steep in a 0.1% solution) was not rendered more effective by the addition of hydrochloric acid nor by a preliminary dip in methylated spirits to facilitate wetting, while the addition of a proprietary wetting compound (Agral) was definitely harmful to the corms and usually less effective than mercuric chloride alone. Increase in time of steeping or concentration of mercuric chloride was not beneficial and was sometimes harmful. Reduction in time of steeping to 1 hr. gave promising results.
Treatment in November had some advantages over treatment in March.
All the mercury compounds tended to delay flowering, this being most marked in the presence of the wetting compound. Stunted foliage and poor quality flowers resulted from the use of Ceresan.     

Diseases of the gladiolus; note on the incidence and control of scab disease Bacterium marginatum McCull

Stocks of imported gladioli which originally contained a proportion of scabbed corms showed very little carry-over of the disease during the eight growing seasons 1938-45. Carry-over was greatest on ground where gladioli had been planted for several successive years.
The incidence of the disease was greatest in the hot summer of 1940.
Treatment with mercurial fungicides just before planting time gave good control. Two non-mercurial fungicidal dusts were less effective.     

Outbreak of otitis media caused by Burkholderia gladioli infection in immunocompromised mice

An athymic nude mouse with severe head tilt due to otitis media was identified. Within weeks of identification of this first case, immune-deficient mice of various genotypes from the same facility were similarly affected, and cases from other facilities were found within two months. Culture of ear exudate specimens from affected mice yielded bacteria that were initially identified as Burkholderia cepacia, a plant pathogen considered an important opportunistic pathogen in persons with cystic fibrosis or chronic granulomatous disease. Several of these isolates, however, were subsequently identified as B. gladioli on the basis of results of biochemical analysis and a species-specific polymerase chain reaction (PCR) assay. Genotyping analysis revealed clonality among the isolates, indicating a shared strain among affected mice. A 16S rDNA-based PCR assay specific for the genera Burkholderia and Ralstonia, and a selective culture medium were used in efforts to characterize the epidemiology of this outbreak. In addition to culture of specimens from the oropharyngeal cavity of affected mice, samples were obtained from the environment, feces, sipper tubes, drinking water, and soiled bedding from cages of affected individuals. Burkholderia gladioli was most consistently detected in oropharyngeal swab specimens from affected mice. The PCR assay was equivalent to selective culture in identifying mice in the carrier state that did not have clinical signs of infection. However, neither detection method had sufficient sensitivity to reliably identify all carrier mice, causing the organism to persist at low levels unless entire colonies of immune-deficient mice were removed. The organism was highly resistant to antibiotic therapy. The source and epidemiology of this organism remain unknown. This epizootic serves as an important reminder that immunocompromised rodent colonies may harbor important human opportunistic pathogens.     

Copper nanoparticles: Green synthesis and managing fruit rot disease of chilli caused by Colletotrichum capsici

The present study was focused on synthesis and characterization of copper nanoparticles to evaluate their efficacy against fruit rot pathogen of chilli crop. The green synthesis of nanoparticles was carried out by using extracts of Eucalyptus and Mint leaves. The synthesis of copper nanoparticles was confirmed by XRD, PSA, SEM and TEM. The average size of these particles synthesized by Eucalyptus leaf extract (CuNP-E) ranged from 10 to 130 nm, while as size of Mint leaf extract synthesized particles (CuNP-M) ranged from 23 to 39 nm, thus confirming their nano size. These green synthesized copper nanoparticles were evaluated against Colletotrichum capsici where Carbendazim 50 WP @ 500 ppm and copper oxychloride 50 WP @ 2500 ppm served as standard checks. The mycelia inhibition of Colletotrichum capsici caused by copper nanoparticles was studied on PDA medium. CuNP-M @ 1000 ppm showed highest mycelial inhibition of 99.78% followed by 93.75% at 500 ppm and CuNP-E @ 1000 ppm compared to standard fungicides, carbendazim 50 WP @ 500 ppm (72.82%), and copper oxychloride 50 WP @ 2500 ppm (85.85%). The CuNP-M @ 500 ppm were significantly superior to carbendazim 50 WP @ 500 ppm and copper oxychloride 50 WP @ 2500 ppm, but was statistically at par with CuNP-E @ 1000 ppm. This shows effectiveness of much lower concentration of copper nanoparticles compared to conventional fungicides. In detached fruit method, nanoparticles applied before inoculation of pathogen showed better results with regard to incubation period, lesion number and lesion size than after inoculation of pathogen. The present study reveals a simple, convenient, non-toxic and cost-efficient technique for the synthesis of nanoparticles and their effectiveness against Colletotrichum capsici. CuNP-M first time synthesized and evaluated against Colletotrichum capsici performed better than CuNP-E.     

Influence of bio-inoculants on the control of root rot and wilt disease of pyrethrum caused by Rhizoctonia solani

The effect of four bio-inoculants namely, Glomus aggregatum, Streptomyces sp., Bacillus subtilis and Trichoderma harzianum and a fungicide, Ridomil-mancozeb was evaluated on the biomass production and control of root rot and wilt disease under glasshouse conditions. Results showed that 21-day- prior inoculation with G. aggregatum was most effective where none of the treated plants produced disease symptoms and interestingly their growth was increased by 39.4%. The colonisation by G. aggregatum (>80%) also increased P concentration in shoot. While, similar treatment with Streptomyces sp., B. subtilis, T. harzianum and Ridomil-mancozeb individually failed to produce any significant effect over Rhizoctonia solani inoculated control, where all inoculated plant died, prematurely. The simultaneous and 3-day-post treatments of G. aggregatum were non-effective but simultaneous treatment with Streptomyces sp. produced 70% disease control, while B. subtilis and T. harzianum individually provided 50% control. Their effects were either better or at par when compared with the simultaneous treatment of Ridomil-mancozeb. In 3-day-post treatment, Streptomyces, B. subtilis and Ridomil-mancozeb individually provided 50% disease control, whereas T. harzianum was least effective as it could protect only 25% plants against infection. The results reveals that 15 days prior treatment of G. aggregatum can significantly controls the root rot and wilt disease of pyrethrum. Further, treatment of Streptomyces can also serve the next effective post infection control method.     

Biological control of Sclerotinia disease by Aspergillus sp. on oilseed rape in the field

Sclerotinia sclerotiorum causes serious yield losses to many crops worldwide. Aspergillus sp. Asp-4, previously shown to inhibit germination of sclerotia of S. sclerotiorum in vitro and in the field, was evaluated in field trials for suppression of this pathogen on oilseed rape. Spray application of Asp-4 to the soil prior to sowing rice in a rice–oilseed rape rotation resulted in a significant reduction in incidence of Sclerotinia stem rot on oilseed rape compared with the non-treated control in two field trials. This application of Asp-4 also resulted in a significant reduction in germination of sclerotia relative to the non-treated control in these field trials, suggesting that this reduction in sclerotial germination led to disease control. Microscopic examination demonstrated that Asp-4 could effectively colonise external and internal portions of sclerotia of S. sclerotiorum in vitro. Incubation of Asp-4 with sterile sclerotial material induced production of β-glucanase and chitinase activities by this isolate; β-glucanase and chitinase being potentially capable of degrading the glucan and chitin polymeric components of sclerotia. Incubation of Asp-4 with sterile sclerotial material also resulted in a significant reduction in dry weight of this sclerotial material relative to the non-treated control in 96?h in vitro experiments. Experiments reported here indicate that Aspergillus sp. Asp-4 has promise as a biological control agent for S. sclerotiorum on oilseed rape. Experiments reported here suggest that disease control results from inhibition of germination of sclerotial resting structures due to mycoparasitic colonisation by Asp-4.     

Identification and validation of QTL for Sclerotinia midstalk rot resistance in sunflower by selective genotyping

Midstalk rot, caused by Sclerotinia sclerotiorum (Lib.) de Bary, is an important cause of yield loss in sunflower (Helianthus annuus L.). Objectives of this study were to: (1) estimate the number, genomic positions and genetic effects of quantitative trait loci (QTL) for resistance to midstalk rot in line TUB-5-3234, derived from an interspecific cross; (2) determine congruency of QTL between this line and other sources of resistance; and (3) make inferences about the efficiency of selective genotyping (SG) in detecting QTL conferring midstalk rot resistance in sunflower. Phenotypic data for three resistance (stem lesion, leaf lesion and speed of fungal growth) and two morphological (leaf length and leaf length with petiole) traits were obtained from 434 F₃ families from cross CM625 (susceptible) × TUB-5-3234 (resistant) under artificial infection in field experiments across two environments. The SG was applied by choosing the 60 most resistant and the 60 most susceptible F₃ families for stem lesion. For genotyping of the respective F₂ plants, 78 simple sequence repeat markers were used. Genotypic variances were highly significant for all traits. Heritabilities and genotypic correlations between resistance traits were moderate to high. Three to four putative QTL were detected for each resistance trait explaining between 40.8% and 72.7% of the genotypic variance ( ). Two QTL for stem lesion showed large genetic effects and corroborated earlier findings from the cross NDBLOS_sel (resistant) × CM625 (susceptible). Our results suggest that SG can be efficiently used for QTL detection and the analysis of congruency for resistance genes across populations.     

Efficacy of potent antagonistic yeast Wickerhamiella versatilis against soft rot disease of potato caused by Pectobacterium carotovorum subsp. carotovorum

Abstract

In this study, an antagonistic yeast isolate, Wickerhamiella versatilis was considered as a promising biocontrol agent against Pectobacterium carotovorum subsp. Carotovorum (Pcc) the causal agent of soft rot disease of potato. Antagonistic yeast inhibited the growth of Pcc in vitro, and reducing the soft rot severity of infected potato tubers (cv. Diamant) under greenhouse conditions. Consequently, cellulase and pectinase hydrolytic activities in infected potato tubers with yeast?+?Pcc were decreased compared with infected tubers with Pcc. The histological characterization of treated potato tubers with antagonistic yeast W. versatilis using scanning electron microscope showed the accumulation of extracellular substances that may induce plant resistant and protects potato tubers from hydrolysis and damages. This study may introduce the possibility of using the antagonistic yeast isolate, as a biocontrol agent against soft rot of potato tubers.     

Diseases caused by defects of mitochondrial carriers: a review

A strikingly large number of mitochondrial DNA (mtDNA) mutations have been found to be the cause of respiratory chain and oxidative phosphorylation defects. These mitochondrial disorders were the first to be investigated after the small mtDNA had been sequenced in the 80s. Only recently numerous diseases resulting from mutations in nuclear genes encoding mitochondrial proteins have been characterized. Among these, nine are caused by defects of mitochondrial carriers, a family of nuclear-coded proteins that shuttle a variety of metabolites across the mitochondrial membrane. Mutations of mitochondrial carrier genes involved in mitochondrial functions other than oxidative phosphorylation are responsible for carnitine/acylcarnitine carrier deficiency, HHH syndrome, aspartate/glutamate isoform 2 deficiency, Amish microcephaly, and neonatal myoclonic epilepsy; these disorders are characterized by specific metabolic dysfunctions, depending on the physiological role of the affected carrier in intermediary metabolism. Defects of mitochondrial carriers that supply mitochondria with the substrates of oxidative phosphorylation, inorganic phosphate and ADP, are responsible for diseases characterized by defective energy production. Herein, all the mitochondrial carrier-associated diseases known to date are reviewed for the first time. Particular emphasis is given to the molecular basis and pathogenetic mechanism of these inherited disorders.     

The interaction between mushroom strains and fungicides in the control of dry bubble disease caused by Verticilliumfungicola

Five fungicides were compared for control of Verticilliumfungicola on six strains of the cultivated mushroom. The strains showed considerable differences both in their sensitivity to the fungicides and their susceptibility to infection. These factors complicated comparison of the fungicides, but benodanil was less effective than chlorothalonil against V. fungicola.     

Incidence and identification of Cassava tuber rot caused by Phytophthora palmivora

The occurrence of Cassava tuber rot in regions of Kolli hills, Kollam, and Kottayam of South India, causes major economic loss up to 70% in Cassava production. The disease tuber is characterised by brown watery lesions with foul smell, making it unfit for further use. The sporangia of the pathogen were oval and ellipsoid with a short pedicle. Identification of the isolate from these regions was also confirmed by ribosomal internal transcribed spacer (ITS) of rDNA region. The pathogen was highly aggressive when pathogenicity was tested. Based on morphological, pathogenicity and ITS sequences, the pathogen was identified as Phytophthora palmivora. Development of integrated disease management practices is essential to combat the disease. This is the first report recording the spread of Cassava tuber rot disease in regions of Kolli hills of Tamil Nadu and Kollam and Kottayam, of Kerala.     

Effect of soil temperature on root rot of rough lemon caused by Fusarium solani

Rough lemon seedlings were root dip-inoculated in Fries liquid cultures of two Fusarium solani isolates, one from California and one from Florida. Plants were potted and placed in soil temperature tanks at 15, 21, 27, and 33 C. Plant height, trunk diameter, and fresh weight of inoculated plants significantly differed from the control at 15 and 21 C. Plant height was the only growth parameter significantly affected by inoculation at 27 and 33 C. Height of plants inoculated with the California isolate was significantly less than the control at 27 but not at 33 C. Height of plants inoculated with the Florida isolate did not differ from the controls at 27 and 33 C. Significantly more root rot occurred on inoculated plants at 15 and 21 C, but not at 27 and 33 C. Formerly at the University of Florida, IFAS, Agricultural Research and Education Center, P.O. Box 1088, Lake Alfred, FL 33850, USA     

Decreased incidence of disease caused by Sclerotinia sclerotiorum and improved plant vigor of oilseed rape with Bacillus subtilis Tu-100

Sclerotinia sclerotiorum causes serious yield losses in oilseed crops worldwide. Bacillus subtilis Tu-100 significantly reduced (P≤0.05) the incidence of disease caused by S. sclerotiorum on oilseed rape at harvest in two trials conducted in fields artificially infested with this pathogen. Mean plant dry weight was significantly greater (P≤0.05) and mean plant length was significantly greater (P≤0.07) at the seven-true-leaf stage with the Tu-100 treatment than with the control. Mean seed yield per 120 plants at harvest was significantly greater (P≤0.05) in the second field trial with treatments containing isolate Tu-100. B. subtilis Tu-100 also promoted the growth of hydroponically grown oilseed rape. Plants were approximately 15% greater in dry weight (P≤0.0001) and 6% greater in length (P≤0.0025) when grown in the presence of isolate Tu-100 in Hoagland’s solution, compared with the noninoculated control. In gnotobiotic studies, the lacZ-tagged strain B. subtilis Tu-100(pUC18) was detected within all roots of oilseed rape. Isolate Tu-100 did not persist in the ectorhizosphere of oilseed rape. Populations of this isolate decreased from 8.5×10⁸ colony-forming units (CFU) per seed to approximately 10² CFU in the plant ectorhizosphere within 30 days of sowing in autoclaved soil.     

The occurrence of sclerotium rot on Momordica charantia caused by Sclerotium rolfsii in Korea

Sclerotium rolfsii is one of the most destructive pathogens and thought to affect a broad range of plant hosts. In July 2014, an occurrence of sclerotium rot was observed on bitter melon (Momordica charantia L.) in Jinju, South Korea. The rot symptoms were most developed on stems and fruit near the soil line, and infected bitter melon plants withered and eventually died. White mycelial mats with numerous sclerotia were produced on diseased stems and fruit near the soil surface. Based on the morphological characteristics, pathogenicity tests, and DNA sequencing and phylogenetic analysis of the internal transcribed spacer (ITS) ribosomal RNA (rRNA) gene region, the causal fungus was identified as S. rolfsii Saccardo. This is the first report of sclerotium rot caused by S. rolfsii on bitter melon in Korea. The recent occurrence of sclerotium rot on bitter melon poses a potential threat to its production in Korea.     

The impact of current research on the treatment of infestations by the dry rot fungus Serpula lacrymans

There have been a number of advances in the understanding of the physiology of the dry rot fungus, Serpula lacrymans, in the last decade. Specifically, studies on the natural origins of the fungus, morphogenesis, toxicant tolerance, environmental sensitivity, nitrogen metabolism, utilization of non-woody materials and biological control have all contributed to this understanding and each is discussed in relation to potential control strategies for the future. In addition, molecular studies involving detection, monitoring of speciation and the heat shock response of Serpula lacrymans have provided new insights into an organism which is uniquely destructive in the built environment.