Identification and pathogenicity of<Emphasis Type="Italic">Fusarium</Emphasis> spp. from stem bases of winter wheat in Erzurum,Turkey

Four-hundred-sixty-eightFusarium andFusarium-like isolates were obtained from crowns and subcrown internodes of winter wheat grown in Erzurum, Turkey. Of these isolates, 34.8% wereFusarium acuminatum, 32.3% wereF. equiseti, 16.9% wereF. oxysporum, 15.0% wereMicrodochium nivale (formerlyFusarium nivale), 0.6% wereF. tabacinum and 0.4% wereF. solani. In pathogenicity tests on wheat, the highest disease severity was caused by isolates ofM. nivale, whereas isolates ofF. acuminatum, F. equiseti, F. oxysporum andF. solani were slightly virulent; isolates ofF. tabacinum were nonpathogenic. This is the first report ofM. nivale andF. tabacinum from wheat in Turkey. http://www.phytoparasitica.org posting Jan. 29, 2003.     

Inhibition of in vitro growth of <Emphasis Type="Italic">Rhizoctonia solani</Emphasis> by liquid residue derived from steam-treated grass clippings

The effects of liquid residue derived from grass clipping after steam-treatment on the in vitro growth of Rhizoctonia solani SN-1, AG-4 were evaluated to verify the antifungal activities of the residue. The liquid residue inhibited R. solani growth, with increasing inhibition with higher concentrations and lower pH. Test of individual organic acids (acetic, formic and propionic acids) present in the residue indicate that the inhibitory effect may be attributed to the organic acids, and the effect of the organic acids seems to depend on pH, especially at lower concentrations.     

Effect of label and sublabel rates of metam sodium in combination with<Emphasis Type="Italic">Trichoderma hamatum,T. harzianum,T. virens,T. viride</Emphasis> on survival and growth of<Emphasis Type="Italic">Rhizoctonia solani</Emphasis>

This work was undertaken to determine the effects ofTrichoderma spp. combined with label and sublabel rates of metam sodium on survival ofRhizoctonia solani in soil. Soils were infested with wheat bran preparations ofTrichoderma hamatum Tri-4,T. harzianum Th-58,T. virens Gl-3, andT. viride Ts-1-R3. Soil was also infested with sterile beet seeds that were colonized withR. solani. Beet seeds were later recovered, plated onto water agar plus antibiotics, and the growth ofR. solani was recorded. Preliminary experiments showed thatT. hamatum andT. virens reduced survival and saprophytic activity ofR. solani when the biocontrol fungi were incorporated into soil at 1.5% (w:w) or greater. Based on these data, biocontrol fungi in subsequent experiments were incorporated into soil at 2%. Metam sodium at label rate killed all biocontrol fungi andR. solani. At 1:2 and 1:5 dilutions, metam sodium reduced survival ofR. solani and allTrichoderma spp. When biocontrol fungi plus the label rate of metam sodium and 1:5, 1:10, 1:50 or 1:100 dilutions of the label rate were tested together, there were no interactions between any biocontrol agent and the fumigant with respect to colony diameter, reflecting that allTrichoderma isolates tested reacted similarly to increasing concentrations of metam sodium. At the label rate of metam sodium, allTrichoderma spp. significantly reduced colony diameter, but not growth rate, ofR. solani from beet seed. For the levels of metam sodium tested in combination withTrichoderma, it does not appear feasible to use a reduced rate of metam sodium to controlR. solani. However, the combination ofTrichoderma with metam sodium does reduce growth ofR. solani in comparison with that provided by metam sodium at the label rate. http://www.phytoparasitica.org posting Feb. 11, 2004.     

<Emphasis Type="Italic">Trichoderma harzianum</Emphasis> elicits defence response genes in roots of potato plantlets challenged by <Emphasis Type="Italic">Rhizoctonia solani</Emphasis>

Biological control of Rhizoctonia solani with Trichoderma harzianum has been demonstrated in several studies. However, none have reported the dynamics of expression of defence response genes. Here we investigated the expression of these genes in potato roots challenged by R. solani in the presence/absence of T. harzianum Rifai MUCL 29707. Analysis of gene expression revealed an induction of PR1 at 168 h post-inoculation (hpi) and PAL at 96 hpi in the plants inoculated with T. harzianum Rifai MUCL 29707, an induction of PR1, PR2 and PAL at 48 hpi in the plants inoculated with R. solani and an induction of Lox at 24 hpi and PR1, PR2, PAL and GST1 at 72 hpi in the plants inoculated with both organisms. These results suggest that in the presence of T. harzianum Rifai MUCL 29707, the expression of Lox and GST1 genes are primed in potato plantlets infected with R. solani at an early stage of infection. Mycothèque de l’Université catholique de Louvain of S. Cranenbrouck's affiliation is part of the Belgian Coordinated Collections of Micro-organisms (BCCM).     

Tachinidae parasitoids of<Emphasis Type="Italic">Traumatocampa ispartaensis</Emphasis> from Turkey

Tachinid parasitoids ofTraumatocampa ispartaensis Doğanlar & Avcı (Lepidoptera, Thaumetopoeidae), which was found to be a new species, were collected from the cedar forests around Isparta-Kapıdağ. The species found wereBlondelia nigripes (Fall.),Compsilura concinnata (Meig.),Pales processioneae (Ratz.),Phryxe caudata (Rond.),Exorista segregata (Rond.) andCarcelia iliaca (Ratz.). Within the six species of Tachinidae,B. nigripes was the most common one, parasitizing up to 4.6% ofT. ispartaensis pupae. http://www.phytoparasitica.org     

Comparison of sequences for the internal transcribed spacer region in <Emphasis Type="Italic">Rhizoctonia solani</Emphasis> AG 1-ID and other subgroups of AG 1

The rDNA-ITS sequence of Rhizoctonia solani AG 1-ID was determined and compared to those of R. solani AG 1-IA, AG 1-IB, and AG 1-IC. The similarity of the isolates from each AG 1 subgroup was almost identical (99%–100%), whereas it was lower between subgroups (91%–95%) than within subgroups. Phylogenetic analysis indicated that isolates of AG 1-ID and other subgroups were separately clustered. Isolates of R. solani AG 1 were clearly separated from R. solani AG 2-1, AG 4, and binucleate Rhizoctonia AG-Bb and AG-K. These results showed that analysis of the rDNA-ITS sequence is an optimal criterion for differentiating R. solani AG 1-ID from other subgroups of R. solani AG 1.     

Phylogenetic analysis of <Emphasis Type="Italic">Rhizoctonia solani</Emphasis> subgroups associated with web blight symptoms on common bean based on ITS-5.8S rDNA

Sixty-eight Rhizoctonia solani isolates (31 AG-1, 37 of AG-2-2) associated with web blight (WB) of common bean, Phaseolus vulgaris, were examined for sequence variations in the ITS-5.8S rDNA region. The isolates were collected in bean-growing lowland and mountainous regions in Central and South America. Sequences of these isolates were aligned with other known R. solani sequences from the NCBI GenBank and distance and parsimony analysis were used to obtain phylogenetic trees. WB isolates of AG-1 formed two clades separated from known AG-1 subgroups. WB isolates of AG-2-2 formed one clade separated from known AG-2-2 subgroups. Other isolates belonged to AG-1 IA and AG-1 IB. Based on phylogenetic analysis, we confirmed that at least five genetically different subgroups incite WB of common beans. Three new subgroups of R. solani have been identified and designated as AG-1 IE, AG-1 IF and AG-2-2 WB. DNA sequences of these isolates provided needed information to design taxon-specific primers that can be employed in ecological/epidemiological studies and seed health tests.     

Note: Tachinid parasitoids of<Emphasis Type="Italic">Ancyrosoma leucogrammes</Emphasis> and notes on parasitization rates of<Emphasis Type="Italic">Clytiomya dupuisi</Emphasis>

The study deals with the tachinid parasitoids ofAncyrosoma leucogrammes (Gmelin) (Heteroptera: Pentatomidae):Clytiomya dupuisi Kugler,Clytiomya sola (Rondani) andGymnosoma clavatum (Rohdendorf) (Diptera: Tachinidae). All species are recorded for the first time as parasitoids ofA. leucogrammes, andC. dupuisi was reared for the first time from a host. The parasitization rates ofC. dupuisi on adults ofA. leucogrammes varied from 7% to 9% between 1994 and 1999.C. sola andG. clavatum were reared in only small numbers. http://www.phytoparasitica.org posting July 10, 2003.     

A fungistatic chromene from<Emphasis Type="Italic">Ageratum conyzoides</Emphasis>

Ageratum conyzoides L. is an annual herb in the tropics and subtropics whose extracts are known to possess pharmacological and biocidal activity. We report on the bioactivity of a secondary metabolite (a chromene) isolated from the shoots ofA. conyzoides against some plant pathogenic fungi. Organic solvent extracts from the shoots were tested for antifungal activity against the plant pathogenic fungiRhizoctonia solani, Sclerotium rolfsii, Botryodiplodia theobromae, Phomopsis theae andFusarium species growingin vitro on potato dextrose agar medium. The cruden-hexane extract completely inhibited the growth ofR. solani andS. rolfsii. Then-hexane extract was chromatographed over a column of silica gel followed by activity-guided fractionation to give an antifungal principle. Structure elucidation by detailed analysis of¹H,¹³C NMR and mass spectroscopy identified the active compound as precocene II. The growth ofR. solani andS. rolfsii was completely inhibited by precocene II at a concentration of 80–100 ppm. The sclerotia ofR. solani andS. rolfsii were also completely suppressed by 150 ppm of precocene II. Sub-culture of these inhibited fungi onto precocene II-free medium restored growth of the fungus, indicating that precocene II is fungistatic. Crude or refined extracts fromA. conyzoides offer the possibility of biocontrol of plant pathogenic fungi. http://www.phytoparasitica.org posting Feb. 11, 2004.     

Population structure of the rice sheath blight pathogen <Emphasis Type="Italic">Rhizoctonia solani</Emphasis> AG-1 IA from India

The population structure of Rhizoctonia solani AG-1 IA causing rice sheath blight from India was evaluated for 96 isolates using seven RFLP loci. Nineteen of the isolates did not hybridise to R. solani AG-1 IA RFLP probes and rDNA analyses subsequently confirmed that they were either Ceratobasidium oryzae-sativae isolates or another Rhizoctonia sp. The population structure of the remaining 77 R. solani AG-1 IA Indian isolates was similar to that of a previously characterized Texas population. Clonal dispersal of R. solani AG-1 IA in India was moderate within fields and no clones were shared among field populations. Low levels of population subdivision and small genetic distances among populations were consistent with high levels of gene flow. Frequent sexual reproduction was indicated by the fact that most populations were in Hardy–Weinberg equilibrium (HWE). The two loci (R68 and R111) that deviated significantly from HWE showed an excess of heterozygosity. Although Texas and Indian populations were geographically very distant, they exhibited only moderate population subdivision, with an F_ST value of 0.193.     

Inhibition of germination of<Emphasis Type="Italic">Orobanche ramosa</Emphasis> seeds by<Emphasis Type="Italic">Fusarium</Emphasis> toxins

Eighteen toxins produced byFusarium species were tested at different concentrations onOrobanche ramosa seeds to evaluate their effectiveness in inhibiting germination. Many of the toxins were active at the highest concentration used. Seven of them,viz. fusarenon X, nivalenol, deoxynivalenol, T-2 toxin, HT-2 toxin, diacetoxyscirpenol and neosolaniol, were highly active at 10μM, causing 100% inhibition of germination. Many of them were still active when assayed at a concentration ten times lower, with T-2, HT-2, nivalenol, neosolaniol and diacetoxyscirpenol still able to cause total inhibition; the last mentioned was very active also at 0.1μM, causing more than 90% inhibition. The results show that the use of toxic secondary metabolites could represent a useful alternative strategy in the management of parasitic weeds, by interfering with the induced germination process, and that fungal culture extracts could be an interesting source of new compounds acting as natural and original herbicides. http://www.phytoparasitica.org posting Sept. 18, 2002.     

Intraspecific Evolution of <Emphasis Type="Italic">Rhizoctonia solani</Emphasis> AG-1 IA Associated with Soybean and Rice in Brazil based on Polymorphisms at the ITS-5.8S rDNA Operon

Rhizoctonia solani AG-1 IA causes leaf blight on soybean and rice. Despite the fact that R. solani AG-1 IA is a major pathogen affecting soybean and rice in Brazil and elsewhere in the world, little information is available on its genetic diversity and evolution. This study was an attempt to reveal the origin, and the patterns of movement and amplification of epidemiologically significant genotypes of R. solani AG-1 IA from soybean and rice in Brazil. For inferring intraspecific evolution of R. solani AG-1 IA sampled from soybean and rice, networks of ITS-5.8S rDNA sequencing haplotypes were built using the statistical parsimony algorithm from Clement et al. (2000) Molecular Ecology 9: 1657–1660. Higher haplotype diversity (Nei M 1987, Molecular Evolutionary Genetics Columbia University Press, New york: 512p.) was observed for the Brazilian soybean sample of R. solani AG-1 IA (0.827) in comparison with the rest of the world sample (0.431). Within the south-central American clade (3-2), four haplotypes of R. solani AG-1 IA from Mato Grosso, one from Tocantins, one from Maranhão, and one from Cuba occupied the tips of the network, indicating recent origin. The putative ancestral haplotypes had probably originated either from Mato Grosso or Maranhão States. While 16 distinct haplotypes were found in a sample of 32 soybean isolates of the pathogen, the entire rice sample (n=20) was represented by a single haplotype (haplotype 5), with a worldwide distribution. The results from nested-cladistic analysis indicated restricted gene flow with isolation by distance (or restricted dispersal by distance in nonsexual species) for the south-central American clade (3-2), mainly composed by soybean haplotypes.     

Insecticidal activity of crude seed extracts of<Emphasis Type="Italic">Annona</Emphasis> spp.,<Emphasis Type="Italic">Lansium domesticum</Emphasis> and<Emphasis Type="Italic">Sandoricum koetjape</Emphasis> against lepidopteran larvae

Crude ethanolic seed extracts ofAnnona muricata, A. squamosa (Annonaceae),Lansium domesticum andSandoricum koetjape (Meliaceae) collected from different locations and years in Maluku, Indonesia, were screened for inhibition of larval growth against the polyphagous lepidopteranSpodoptera litura (Noctuidae). Extracts ofA. squamosa were significantly more active (20-fold) than those ofA. muricata. A. squamosa collected from Namlea yielded the extracts with the greatest inhibitory activity. There were significant differences among locations for bothA. squamosa andA. muricata but not forL. domesticum andS. koetjape. Extracts ofA. squamosa, collected from Namlea, inhibited larval growth in a dose-dependent manner, with a dietary EC₅₀ (effective concentration to inhibit growth by 50% relative to controls) of 191.7 ppm fresh weight. Extracts ofA. squamosa collected from individual trees in Namlea also varied in growth inhibitory effect againstS. litura andTrichoplusia ni larvae. This species is a candidate for development of a botanical insecticide for local use in Indonesia. http://www.phytoparasitica.org posting Dec. 1, 2003.     

Note: Life history of<Emphasis Type="Italic">Lixus bardanae</Emphasis> on curly dock (<Emphasis Type="Italic">Rumex crispus</Emphasis>) in Turkey

The biology ofLixus bardanae (F.) (Coleoptera: Curculionidae) on curly dock (Rumex crispus L.) in northeastern Anatolia (Bayburt, Erzurum and Kars Provinces), Turkey, was studied during the years 2000 and 2001.L. bardanae completes one generation in a year, overwintering as an adult. It feeds on leaves of the host plant. Females lay eggs individually into stems and the young larvae create galleries in stems while feeding. Pupation occurs inside stems in cells fashioned from frass. In late September, adults move into soil and overwinter in an upright position around the roots of the host plant. Infestation levels were found to range between 34% and 84%. Two parasitoids,Exeristes roborator F. andEndromopoda phragmitidis Perve (Hymenoptera: Ichneumonidae), were reared fromL. bardanae. http://www.phytoparasitica.org posting Dec. 21, 2003.     

内蒙古马铃薯黑痣病菌融合群的测定与分析

为明确内蒙古马铃薯黑痣病菌融合群的组成及其致病力,从内蒙古13个县（旗）分离得到109株黑痣病菌,采用载玻片配对法和土壤接种法分别测定其融合群及致病力。结果表明,109株黑痣病菌中共存在8个融合群及亚群,分别为AG1-IB、AG2-1、AG3、AG4-HG-Ⅱ、AG4-HG-Ⅲ、AG5、AG9及AG-A。其中84株菌株为AG3,占77.06%;AG4-HG-Ⅱ和AG5分别为8株和6株,占7.34%和5.50%;其余5个融合群各不超过5株,所占比例均在5.00%以下。在84株AG3融合群中,从薯块分离得到52株,茎表分离得到32株;其它7个融合群共25株菌株均分离自茎表。除AG-A无致病能力外,其它融合群均可致病,AG3致病力最强,AG4和AG5次之,AG2-1、AG9和AG1-IB最弱。表明内蒙古马铃薯黑痣病菌具有丰富的多样性,但其优势融合群仍为AG3。     

Infection of<Emphasis Type="Italic">Ceratitis capitata</Emphasis> by two species of the<Emphasis Type="Italic">Entomophthora muscae</Emphasis> species complex (Zygomycetes: Entomophthorales) in the field

Adult Mediterranean fruit flies (Ceratitis capitata), collected in the field, were infected with entomophthoralean fungi. The fungi sporulated poorly on the cadavers, and resting spores, rhizoids and cystidia were not observed. Measurements of conidia and nuclei and counts of nuclei per conidium from different specimens suggest that the causative agents wereEntomophthora muscae sensu stricto andEntomophthora schizophorae, species recently separated from theEntomophthora muscae species complex. This is the first report ofC. capitata as a host for entomopathogenic fungi. http://www.phytoparasitica.org posting Jan. 29, 2003.     

Genetic diversity,anastomosis groups and virulence of <Emphasis Type="Italic">Rhizoctonia</Emphasis> spp. from strawberry

Virulent Rhizoctonia spp. isolated from strawberry in Israel belonged to anastomosis groups (AG) of: binucleate Rhizoctonia (BNR) AG-A, AG-G, AG-K and AG-F, and to multinucleate Rhizoctonia (MNR) AG 4 subgroup HG-I. In addition, a soil isolate of AG 4 subgroup HG-III was also found to be virulent on strawberry. None of the Israeli isolates obtained in the present study belonged to BNR AG-I, or other MNR AGs. In the cluster analysis of rDNA-ITS sequences, all of the isolate sequences consistently clustered according to their known AGs and subgroups. One AG-F cluster included sequences of 10 strawberry isolates, while another AG-F cluster included sequences of two isolates submitted to GenBank. Additional work is needed to determine whether the isolates of these two clusters may belong to different AG-F subgroups. The current virulence bioassay used for Rhizoctonia spp. isolates on strawberry is based on inoculation of stolon-derived daughter plants with the isolates and estimation of the reduction in plant biomass, rather than on specific distinct disease severity symptoms. The duration of this test is relatively long (ca. 5 weeks or more) and the availability of daughter plants from runners is naturally limited to a certain season. Among the possible alternative methods evaluated in the present study (inoculation of fruits or seedlings developed from germinated strawberry seeds), the method based on seedlings was best. This method has a potential to replace the currently used stolon-daughter plant inoculation bioassay for testing virulence of strawberry root pathogens. This is the first report indicating that Rhizoctonia spp. isolates that belong to AG-F, AG-K, AG 4 HG-I and AG 4 HG-III are virulent to strawberry.     

<Emphasis Type="Italic">Cucumber mosaic virus</Emphasis> isolated from Amazon lily (<Emphasis Type="Italic">Eucharis grandiflora</Emphasis>)

Cucumber mosaic virus (CMV) was isolated from a mosaic diseased plant of Eucharis grandiflora. The virus caused mosaic symptoms on leaves and slight distortion of flower petals in E. grandiflora by either mechanical or aphid inoculation. The virus was identified as a strain of CMV subgroup I from its biological and serological characteristics.     

Diverse <Emphasis Type="Italic">Fusarium solani</Emphasis> isolates colonise agricultural environments in Ethiopia

Fusarium solani is a fungal pathogen that infects many different genera of plants. It represents one of the two Fusarium spp. commonly isolated from agricultural soils and plant tissues in Ethiopia. To determine the diversity of F. solani in Ethiopia, we studied 43 isolates using Amplified Fragment Length Polymorphism (AFLP) and nucleotide sequences of the Translation Elongation Factor 1α (TEF-1α) and β-tubulin genes. TEF-1α sequences from GenBank, representing previously described species and clades of the F. solani-Haematonectria haematococca complex, were also included for comparative purposes. Phylogenetic analyses of the TEF-1α data separated the isolates into three groups corresponding with the three previously described clades (Clades 1–3) for this fungus. The Ethiopian isolates aggregated into one group corresponding to Clade 3. TEF-1α, β-tubulin and AFLPs further separated the Ethiopian isolates into a number of clusters and apparently novel phylogenetic lineages. Although the biological and ecological significance of these lineages and clusters is unclear, our data show that the Ethiopian agricultural environment is rich in species and lineages of the F. solani-H. haematococca complex.