Showing papers on "Rhizoctonia solani published in 1979"

Control of rhizoctonia solani on cotton seedlings with Pseudomonas fluorescens and with an antibiotic produced by the bacterium.

Abstract: HOWELL, C. R., and R. D. STIPANOVIC. 1979. Control of Rhizoctonia solani on cotton seedlings with Pseudomonasfluorescens and with an antibiotic produced by the bacterium. Phytopathology 69:480-482. A strain of Pseudomonasfluorescens antagonistic to Rhizoctonia solani Alternaria sp., and Verticillium dahliae. A Fusarium sp. was only partially was isolated from the rhizosphere of cotton seedlings. An antibiotic inhibited and Pythium ultimum was unaffected. Treating cottonseed with strongly inhibitory to R. solani was isolated from P. fluorescens cultures P. fluorescens or pyrrolnitrin at time of planting in R. solani-infested soil and identified as pyrrolnitrin (3-chloro-4-[2'-nitro-3'-chlorophenyl]increased seedling survival from 30 to 79% and from 13 to 70%, respectively. pyrrole). The antibiotic also inhibited growth of other fungi associated with Pyrrolnitrin persisted for up to 30 days in moist 'nonsterile soil with no the cotton seedling disease complex including: Thielaviopsis basicola, measurable loss in activity. Additional key words: seed treatment, biological control. Fluorescent pseudomonads appear frequently among isolates portion was extracted twice with 100-ml volumes of ethyl ether. from plant rhizospheres (11) and often comprise an important The ether extracts were combined and taken to dryness in vacuo. component of the bacterial population (8,12). Pseudomonas spp. The residue was dissolved in chloroform at a concentration 1OOX were ineffective for control of damping-off by Rhizoctonia solani that in the original culture volume, and l-ml samples were streaked and Pythium spp. in nonsterile soil (3). However, Pseudomonas on thin-layer plates coated with silica gel 7GF. The plates were spp. have been used successfully to protect carnation cuttings developed in cyclohexane/chloroform/diethylamine (50:40:10, against Fusarium roseum f. sp. cerealis (9), potato seedpieces v/v) and observed under long and shortwave UV light to detect against certain pathogenic bacteria and fungi (4), and soybean fluorescing and adsorbing bands. Bands and blank areas were seedlings against Phytopthora megasperma var. sojae (13). scraped separately from the plates and eluted with acetone. In our work on seedling diseases of cotton we have isolated Acetone eluates diluted 1:10 with sterile water were assayed for fluorescent pseudomonads from the seedling rhizosphere and activity against R. solani by placing 100-/t1 aliquots in 7 mm report here: the isolation and identification of a fluorescent diameter wells cut in PDA plates inoculated simultaneously on the pseudomonad antagonistic to R. solani; the isolation and surface with agar plugs of the fungus. After 2 days of incubation the identification of an antibiotic produced by the isolate; and the plates were examined for mycelium-free zones around the wells. efficacy of that isolate or its antibiotic as a seed treatment to The eluate that contained active material again was streaked on prevent damping-off of cotton seedlings by R. solani. silica gel 7GF plates and developed with chloroform and the procedure for locating bands and detecting zones with antibiotic MATERIALS AND METHODS activity then was repeated. The eluate from the band showing inhibitory activity was concentrated in hot cyclohexane, and the Isolation and identification of an antagonistic bacterium from antibiotic was crystallized from it after cooling. Mass and NMR rhizosphere soil. Dilutions (10-6 and l0 , w/v) of rhizosphere soil spectra of the purified crystaline antibiotic were made and from 7-day-old cotton seedlings were spread in 0. l-ml samples on compared with standard spectra for authentic pyrrolnitrin plates of medium 523 in agar (7). Plates were incubated at 24 C for 4 obtained from the Fujisawa Pharmaceutical Co., Osaka, Japan. days then inoculated on the surface with PDA plugs of R. solani Antifungal spectrum of the antibiotic. Purified antibiotic (strain W-18 from cotton). After 3 days of incubation at 24 C the dissolved in 10% aqueous acetone was diluted to 25 vg/ml with plates were examined for bacterial colonies antagonistic to the sterile water. The solution then was assayed (by the methods growth of R. solani. Colonies with putative antibiotic activity were described previously for the chromatogram eluates) against the isolated and challenged with the fungus after 3 days. The most following fungi that have been associated with cotton seedling active isolate, a fluorescent pseudomonad, was subjected to diseases: Thielaviopsis basicola, Alternaria sp., Vertici/lium standard staining (10) and physiological tests (I), and identified to dahliae, Fusarium sp., and Pythium ultimum. species according to Bergey's manual (2). Efficacy of cottonseed treatment with bacterial cultures or Isolation and identification of an antibiotic from the antibiotic to control damping-off. Nonsterile soil containing 33 g of antagonistic bacterium. Plates containing medium 523 in agar were R. solani inoculum per 9 kg of soil was prepared and its level of spread with a bacterial suspension, incubated for 10 days at 24 C, infestation was determined according to methods described cut into 1-cm squares, and extracted with 200 ml of 80% aqueous previously (5). Dilutions of purified antibiotic in acetone were acetone for each 10 plates of culture medium. The extracts were prepared at 0, 20, 40, 60, 80, 100,200, and 400 pg/ml. One-milliliter filtered through cheesecloth and centrifuged at 12,000 g for 10 min samples were added to 0.2-g lots of diatomaceous earth carrier, and to remove particulate matter. The supernatant fluids were the acetone was removed in vacuo. Each of the 0.2-g samples then combined and condensed in vacuo at 40 C. Five grams of NaC1 was mixed with methyl cellulose, and coated onto 30 cottonseed per were added to each 100 ml of the aqueous concentrate and each sample, and assayed for optimum protective effect against R. solani This article is in the public domain and not copyrightable. It may be freely by the soil tube method described previously (5). reprinted with customary crediting of the source. The American PhytopathCottonseed treated with 200 /Ag/ml antibiotic were planted in ological Society, 1979. lots of 30 seed per flat in R. solani-infested or noninfested

Hyperparasites of Rhizoctonia solani in Dutch potato fields

Abstract: Gliocladium roseum was found to be the most common and probably the most effective mycoparasite in potato fields in the northern parts of the Netherlands. It is able to parasitize and kill living hyphae at temperatures of 12°C and higher. Sclerotia ofR. solani are often infected and killed by this fungus under suitable conditions, i.e. at temperatures of 16°C and more. Killing of sclerotia by other antagonistic organisms was also observed. It is also shown by not parasitic fungi and is caused by toxins produced by the antagonist.

The post-harvest fruit rots of tomato (Lycopersicum esculentum) in Nigeria.

Abstract: A survey of the post-harvest fruit rot diseases of tomato was conducted in five states of Nigeria During severe infections, the diseases could cause 25% loss at harvest and 34% loss of the remaining product in transit, storage and market stalls; thus giving an overall loss of about 50% of the product Two types of rots, soft and dry were recognised The soft rot was found to account for about 85% and the dry rot about 15% of the overall loss Erwinia carotovora, Rhizopus oryzae, R stolonifer, Fusarium equiseti, F nivale and F oxysporum were established as the soft rot pathogens; while Aspergillus aculeatus, A flavus, Cladosporium tenuissimum, Corynespora cassiicola, Curvularia lunata, Penicillium expansum P multicolor and Rhizoctonia solani were established as the dry rot pathogens of tomato fruits in Nigeria

Specificity in Vitamin Requirement among Anastomosis Groups of Rhizoctonia solani Kühn

Abstract: The influence of vitamins on the growth of hyphal anastomosis groups of Rhizoctonia solani Kuhn, AG-1 (IA, sasakii type), AG-1 (IB, web-blight type), AG-2-1 (winter crop type), AG-2-2 (IIIB, rush type), AG-2-2 (IV, root rot type), AG-3 (potato type), AG-4 (praticola type), and AG-5, were studied. All isolates of AG-2-2 (IIIB), AG-2-2 (IV), and AG-5 barely grew in the medium without thiamine hydrochloride, and showed 10∼20-fold growth at 10-5M thiamine, i.e. these groups are thiamine auxotrophic. The stimulating effect of thiamine was slight at 10-10M and obvious at 10-9M, and the mycelial dry weights at 10-8 or 10-7M were almost the same at 10-5M. The need for thiamine is a specific character of the group, not of the isolate. Most of AG-2-1, AG-2-2 (IIIB), AG-2-2 (IV) and AG-5 isolates had their growth somewhat stimulated with 10-5M of calcium pantothenate, but were not auxotrophic. There were two isolates of AG-2-1 that might be Ca-pantothenate auxotrophic. Some isolates had stimulated their growth with biotin, folic acid, p-aminobenzoic acid, inositol, nicotinic acid, pyridoxine hydrochloride, and riboflavin, but were not auxotrophic. The need for these vitamins is a character of the isolate, not of the group.

Seed-borne Pathogenic Fungi and Bacteria of Cowpea in Northern Nigeria

Abstract: Fungal and bacterial flora of cowpea seeds in northern Nigeria were studied in agar plates and in plates containing moistened filter paper. Seeds were surface-sterilised with either sodium hypochlorite solution or mercuric chloride solution. About 90 fungal species, the vast majority of which were non-pathogens, were detected on seeds obtained from markets and from fields affected by various diseases. Cowpea pathogens detected on seeds from markets included Ascochyta sp., Colletotrichum lindemuthianum. C. truncatum, Rhizoctonia solani (Thanatephorus cucumeris), Fusarium oxysporum, F. solani, Macrophomina phaseolina, Septoria vignae and Corticium rolfsii. Except for Ascochyta sp., C. lindemuthianum and Fusarium oxysporum, all the above fungi were isolated from seeds from field plots which also yielded three other pathogens, namely Colletotrichum capsici, Cercospora canescens and Xanthomonas vignicola. Seed-plant transmission was established for all pathogens, except C. canescens, detected on seeds...

Hyphal parasitism and chlamydospore formation by Fusarium oxysporum on Rhizoctonia solani

Abstract: Hyphal parasitic behaviour of Fusarium oxysporum on Rhizoctonia solani and consecutive changes during this phenomenon have been investigated and studied. The hyphal parasitism was very commonly recorded between the test fungi. During the course of parasitism coiling, penetration, lysis and formation of chlamydospores by F. oxysporum on R. solani were observed. R. solani is a new host record for the mycoparasite F. oxysporum.

Influences of the Rhizoctonia disease on production of the Russet Burbank potato

Abstract: Pentachloronitrobenzene (PCNB) treatment (20 lb/A – 22.4 kg/ha) showed significant reduction ofRhizoctonia (Rhizoctonia solani Kuhn) symptoms on potato. The PCNB treatment increased the number of non-girdled stolons as compared to untreated plots by 50, 34, and 30% at respective seedpiece spacings of 6, 9, and 12 in (15, 23, and 30 cm). Numbers of non-girdled stolons in PCNB-treated plots at 9- and 12-in spacing did not differ significantly from those in untreated plots at 6-in spacing.

Superiority of a soil debris isolation method over a beet seed colonization method for assay of Rhizoctonia solani at high soil inoculum densities.

Abstract: A quantitative soil debris isolation method (all debris from known weight of soil plated) and a garden beet seed saprophytic colonization method were compared over a 1-year period for assaying Rhizoctonia solani populations. Four fields of different soil textures were selected. Within each field four areas of healthy and four areas of diseased (rhizoctonia root and crown rot) sugarbeets were sampled bimonthly from August 1976 until June 1977. The maximum numbers of R. solani colonies obtained by the debris method were 2 per gram of soil in areas of healthy beets, and 11 per gram of soil in areas of diseased sugarbeets. At such high inoculum densities the beet seed colonization method underestimated R. solani populations, because the inoculum per unit of soil exceeded the numbers of beet seeds per unit of soil available for colonization. Modifications of the beet seed method did not significantly alter results of colonization assays. Ranked correlation comparisons of assay methods yielded r = 0.81 for all ...

Influence of soil texture on survival and saprophytic activity of Rhizoctonia solani in soils.

Abstract: Survival of Rhizoctonia solani in precolonized tablebeet seed was greater in a light-textured sandy loam (SL 1) than in a heavy-textured silty clay loam (SiCL). Reduction in survival as well as competitive saprophytic activity of the pathogen resulted when clays (kaolinite and montmorillonite) were added to SL to prepare soils of heavier texture. Survival and activity of R. solani, however, were not increased when sand was added to SiCL (suppressive to R. solani survival) to make this soil lighter in texture. In natural soils of different textures, activity of R. solani was maintained longer in two light-textured sandy loam soils than in a light-textured loamy sand or loam. During investigation of soil chemical and biological influences on R. solani survival, high K2O content in soil was significantly correlated with low saprophytic activity of the pathogen. In all instances where soil microbial activity as determined by a dehydrogenase assay was high, low saprophytic activity was found. Since high microbial activity or K2O content in soil were not associated with any particular soil type, biological or chemical factors may be more important than soil texture in influencing survival and activity of R. solani in soil.

Soil populations of Rhizoctonia solani from areas of healthy and diseased beets within four sugarbeet fields differing in soil texture

Abstract: Both debris isolation and beet seed colonization methods were used to ascertain Rhizoctonia solani populations in areas of healthy (AH) and rhizoctonia crown rot diseased (DA) sugarbeets within four fields differing in soil texture over a 1-year period (August 1976 to July 1977). Inoculum densities were initially (August–October) higher in DA than in AH, but declined over the winter to levels similar to AH by June. As ascertained by the debris isolation method, AH populations remained low (mostly < 30 colonies/50 g soil) throughout the year. High (90–422 colonies/50 g soil) DA inoculum densities were apparently sustained by active parasitism. Seasonal R. solani populations were postulated to consist of groupings of propagules differing in capacities for survival. Inoculum densities in AH and DA were similar in June indicating that factors other than inoculum density per se may initiate DA within beet fields. Soil textural differences did not adversely affect R. solani populations. Assays based on debris i...

La pourriture des faines causfée par Rhizoctonia solani Kühn: Incidence de cette maladie après les fainées de 1974 et 1976. Traitement curatif des faines en vue de la conservation

Abstract: Rot of beechnuts caused by Rhizoctonia solani Kuhn. Disease incidence after the 1974 and 1976 mast years. Curative seed treatment before storage. Rot of beechnuts by Rhizoctonia solani Kuhn, occurred throughout French beech forests after the masts of 1974 and 1976. The site conditions and the climatic conditions of November and December determine the incidence of disease which is notably reduced by soil cultivation before the mast. Thermotherapy - 24 hours at 36–38°C at 100 % relative humidity - was shown to be a curative treatment of seeds before storage.

Presence of Rhizoctonia solani in native callitris pine soils and its implications for future potato growing

Abstract: Radial growth was measured daily, twice on each plate, for 21 days or until the colony reached the edge of the petri d ish . The experiment was conducted twice . The anastomosis grouping of each isolate was tested by opposing isolates of known anastomosis groups with the potato isolates on sterile cellophane resting on 2% water agar (1). Results are summarised in Table 1. There was no geographic grouping of temperature tolerances; isolates from Coleambally grew no faster at 30°C than those from Glen Innes . The apparently faster growth at 5°C of Guyra and Glen Innes isolates (cool Tablelands) compared with isolates from warmer soils of Coleambally were not statistically significant due to var iation in growth rate among isolates from the same region. 25°C was the optimum growth temperature for all isolates. Four Coleambally isolates, two from Orange, three from Guyra and three from Crookwell did not grow at 30°C. There was no growth at 5°C in two isolates from Guyra and one from Glen Innes indicating lack of cold tolerance in these isolates. All isolates except one from Coleambally belonged to anastomosis group 3. The remaining isolate did not anastomose with any of the standard groups. It would appear that isolates of R. so/ani from irrigated sands have not adapted in terms of growth rate to high soil temperatures which prevail in sandhill soils over the summer months. In a potato crop, soil temperatures at seed depth (10 em) usually rise above 30°C for at least 8 hr each day from mid November to late February and only fall below 20°C following irrigation. At depths of 5 em or less soil temperatures generally exceed screen temperatures by 5-15°C for about the same period of time and dry soil surface temperatures of 60°C at sowing are often recorded (Logan. unpublished data). Differences in disease expression in Tableland soils and irrigated sands are not explained by adaptation to high temperatures per se. Sandhill soils are very low in organic matter content and have a low level of microbial activity. Absence of vigorous microbial competition may allow the fungus to infect stolon tissue more readily than in heavy soils with higher organic matter levels , or alternatively host physiology is sufficiently disturbed by high temperatures as to lower the plants \"resistance\" to infection.

Rhizoctonia solani, a seed-borne pathogen of French bean in Malaysia.

Abstract: A study on some aspects of the biology, pathogenicity and control of Rhizcotonia solani Kuhn (the imperfect state of Thanatephorus cucumaris (Frank) Donk was undertaken using an isolate from infected French bean seed. The fungus was found to be seed-borne on both the imported and some local varieties of French bean. The rate of growth of the fungus varied with temperature and the medium used. Malt extract agar gave poor growth and lima bean agar supported the best growth of the fungus at 28°C. The fungus infects the aerial parts of the French bean plant. The strain was found to have a wide host range. An in vitro study to test the efficacy of fungicides against Rhizoctonia showed that pentachloronitrobenzene at 50 ppm gave a good control.