Greenhouse Screening of the Saprophytic Resident Microflora for Control of Leaf Spots of Wheat (Triticum aestivum)

Ten microorganisms of the epiphytic microflora of wheat leaves in Buenos Aires Province, Argentina, were evaluated under greenhouse conditions as potential biocontrol agents of the pathogensAlternaria triticimaculans, Bipolaris sorokiniana, Drechslera tritici-repentisandSeptoria triticiin two application sequences (prior to or together with the pathogens). The antagonists significantly reduced the expression of the diseases on wheat plants compared with control plants not inoculated with the antagonists. Maximum percentage of reduction of the necrotic lesion area (NLA) (40–55%) ofS. triticiresulted whenCryptococcussp.,Rhodotorula rubraandPenicillium lilacinwnwere sprayed on leaves prior to inoculations with the pathogen.Bacillussp.,Cryptococcussp.,Fusarium moniliformevar.anthophylium,P. lilacinumandR. rubrareduced significantly (34–52%) the NLA ofB. sorokinianain both of the application sequences. The best antagonistic effect againstA. triticimaculanswas shown byAspergillus niger, Bacillussp.,Chaetomium globosum, F. moniliformevar.anthophyliumandNigrospora sphaerica, with a NLA reduction from 21% to 35% in the co-inoculation or in the sequential application. All microorganisms exceptN. sphaericaperformed better than the control againstD. tritici-repentis. The area under disease progress curve (AUDPC) of the pathogens appeared to progress similarly, but at lower values, in treated plants than in untreated controls. The two yeasts and the bacteria decreased AUDPC to 50–55% ofS. triticiandB. sorokinianacompared with the control in both application sequences, whereas the maximum efficacy againstA. triticimaculanswas reached byN. sphaericaandA. nigerfor the sequential application and byF. moniliformevar.anthophyliumfor the co-inoculation. If the parasitism occurs also in nature, application of antagonists for biological control might provide the opportunity to compete with the pathogens and regulate their colonization in wheat leaves

Hongos marinos lignícolas de MAR del plata (provincia de Buenos Aires, Argentina). II

This is the second contribution to the study of lignicolous marine fungi from the coast of Mar del Plata city, Argentina. Twelve species were collected from driftwood, intertidal wood and drift culms found in rocks and sand beaches. Ten species of Ascomycotina are described: Buergenerula spartinae Kohlm. & R. V. Gessner, Chaetosphaeria chaetosa Kohlm., Corollospora maritima Werderm., Halosarpheia trullifera (Kohlm.) E. B. G. Jones, S. T. Moss & Cuomo, H. viscosa (I. Schmidt) Shearer & J. L. Crane ex Kohlm. & Volkm-Kohlm., Halosphaeriopsis mediosetigera (Cribb & J. W. Cribb) T. W. Johnson, Wettsteinina marina (H. Ellis & Everh.) Shoemaker & C. E. Babc., Leptosphaeria oraemaris Linder, Passeriniella obiones (P. Crouan & H. Crouan) K. D. Hyde & Mouzouras, Remispora maritima Linder; one species of Deuteromycotina: Phoma glomerata Wollenw. & Hochapfel and one species of Basidiomycotina: Digitatispora marina Doguet. Seven are new records for Argentina and four of them also for South America

Lignicolous marine fungi from Mar Chiquita coastal lagoon (Buenos Aires province, Argentina). I. Ascomycotina and Dueteromycotina on Spartina densiflora

This is the first contribution to the lignicolous marine fungi from Mar Chiquita coastal lagoon, Argentina. Twelve species were collected from Spartina densiflora Brongn. and drift culms. Nine species of Ascomycotina were found: Chaetomastia typhicola (Karsten) Barr, Didymosphaeria lignomaris Strongman & Miller, Leptosphaeria australiensis (Cribb & Cribb) G.C. Hughes, L. oraemaris Linder, L. pelagica Jones, Passeriniella obiones (Crouan & Crouan) Hyde & Mouzouras, Phaeosphaeria spartinae (Ellis & Everhart) Shoemaker & Babcock, Ph. spartinicola Leuchtmann, Sphaerulina oraemaris Linder. Also, three species of Deuteromycotina were found: Phoma glomerata Wollenw. & Hochapfand, Zalerion maritimum (Linder) Anastasiou and Z. varium Anastasiou. Didymosphaeria lignomaris, L. australiensis, L. pelagica and S. oraemaris are new records for South America

Lignicolous marine fungi of Buenos Aires province (Argentina). IV

Five species of lignicolous marine fungi from the coast of Buenos Aires province (Argentina) are described. Haligena salina Farrant & Jones, Nautosphaeria cristaminuta Jones and Ocostaspora apilongissima Jones, Johnson & Moss, were collected from driftwood and intertidal wood. Cumulospora marina I. Schmidt and Helicascus kanaloanus Kohlmeyer were found growing on Spartina densiflora Brongn. N. cristaminuta is a new record for Argentina, while the remaining ones are new records for South America

Hongos marinos lignícolas de Mar del Plata (Provincia de Buenos Aires, Argentina). I

This is the first contribution to the knowledge of the lignicolous marine fungi from Mar del Plata, Argentina. Ten species were collected from submerged wood panels, intertidal wood and driftwood. Seven species of Ascomycotina are described: Ceriosporopsis caduca E.B.G. Jones & Zainal, C. halima Linder, Halosphaeria appendiculata Linder, Lulworthia medusa (Ellis & Everh.) Cribb & Cribb. f. halima Hughes, Marinospora calyptrata (Kohlm.) A. R. Caval., Remispora quadriremis (Höhnk) Kohlm. and R. stellata Kohlm. and three species of Deuteromycotina: Cirrenalia macrocephala (Kohlm.) Meyers & R.T. Moore, Zalerion maritimum (Linder) Anastasiou and Z. varium Anastasiou. Six are new records for Argentina and three of them are new records for South America

Occurrence and distribution of soil Fusarium species under wheat crop in zero tillage

The presence of Fusarium species in cultivated soils is commonly associated with plant debris and plant roots. Fusarium species are also soil saprophytes. The aim of this study was to examine the occurrence and distribution of soil Fusarium spp. at different soil depths in a zero tillage system after the wheat was harvested. Soil samples were obtained at three depths (0-5 cm, 5-10 cm and 10-20 cm) from five crop rotations: I, conservationist agriculture (wheatsorghum- soybean); II, mixed agriculture/livestock with pastures, without using winter or summer forages (wheatsorghum- soybean-canola-pastures); III, winter agriculture in depth limited soils (wheat-canola-barley-late soybean); IV, mixed with annual forage (wheat-oat/Vicia-sunflower); V, intensive agriculture (wheat-barley-canola, with alternation of soybean or late soybean). One hundred twenty two isolates of Fusarium were obtained and identified as F. equiseti, F. merismoides, F. oxysporum, F. scirpi and F. solani. The most prevalent species was F. oxysporum, which was observed in all sequences and depths. The Tukey�fs test showed that the relative frequency of F. oxysporum under intensive agricultural management was higher than in mixed traditional ones. The first 5 cm of soil showed statistically significant differences (p = 0.05) with respect to 5-10 cm and 10-20 cm depths. The ANOVA test for the relative frequency of the other species as F. equiseti, F. merismoides, F. scirpi and F. solani, did not show statistically significant differences (p . 0.05). We did not find significant differences (p . 0.05) in the effect of crop rotations and depth on Shannon, Simpson indexes and species richness. Therefore we conclude that the different sequences and the sampling depth did not affect the alpha diversity of Fusarium community in this system

Dematiocladium celtidis gen. sp. nov. (Nectriaceae, Hypocreales), a new genus from Celtis leaf litter in Argentina.

A Cylindrocladium-like hyphomycete collected on leaf litter of Celtis tala in Argentina had rDNA sequence data (ITS and LSU) that showed it resides in the Hypocreales, and is a member of the Nectriaceae, closely related to, but distinct from Cylindrocladium. A new genus, Dematiocladium and species, D. celtidis gen. sp. nov. is, therefore, introduced to accommodate this fungus. Based on morphology, it can be distinguished from other conidial hypocrealean genera with hyaline, penicillate conidiophores and cylindrical conidia by lacking stipe extensions and vesicles, and by the presence of brown to dark brown, thick-walled setae