Journal of Plant Diseases and Protection

Ratti, C.; Rubies-Autonell, C.; Maccaferri, M.; Stefanelli, S.; Sanguineti, M.; Vallega, V.

doi: 10.1007/BF03356171pmid: N/A

One-hundred and eleven cultivars of durum wheat (Triticum durum Desf.) representative of a large portion of the genetic diversity present in the world’s improved durum wheat gene pool were grown two seasons in a field with natural inoculum sources of soil-borne cereal mosaic virus (SBCMV) near Bologna (Italy). The materials were evaluated for resistance on the basis of symptom severity expression and Sbcmv concentration in leaves according to Das (double antibody sandwich) ELISA. Among the cultivars screened, two-year overall means ranged from 0.1 to 3.2 for symptom severity (on a 0 to 4 scale) and from 0.036 to 1.702 for ELISA absorbance values. Thirty-five cultivars showed relatively low ELISA values and very mild symptoms in both seasons. These relatively more resistant entries included cultivar Edmore and twelve of its derivatives, independently bred in Canada, France, Italy and the U.S. Twenty-one entries consistently gave ELISA values and symptom scores higher than that of cultivar Grazia, the susceptible control. Because of their extreme reactions to Sbcmv and wide adaptability, a number of the cultivars tested should prove useful for investigating the existence of pathotypes within SBCMV, and of diverse cultivar responses in regard to Furoviruses until recently considered as belonging to the same species, namely soil-borne wheat mosaic virus (SBWMV) and Chinese wheat mosaic virus (CWMV).

Koch, E.; Weil, B.; Wächter, R.; Wohlleben, S.; Spiess, H.; Krauthausen, H.

doi: 10.1007/BF03356172pmid: N/A

The aim of this study was to further characterise the activity as seed treatments of five actinomycete and four Trichoderma strains that in a previous screening under controlled conditions had shown promising activity against Tilletia tritici. The strains were evaluated under controlled conditions for activity against Fusarium culmorum and Fusarium spp./Septoria nodorum on wheat, and Drechslera graminea and D. teres on barley, and some of them were tested for control of T. tritici in the field. Eleven microbial and four non-microbial, commercially available alternative products, most of them developed and marketed for other uses than seed treatment, were also included in the study, mainly to determine their activity against T. tritici. In the experiments under controlled conditions the strains of Trichoderma failed to reduce seedling infection by the pathogens stated above, and the two strains tested against T. tritici in the field did not protect against bunt. These results indicate that the tested Trichoderma strains are no candidates for further development. None of the actinomycetes reduced net blotch (D. teres), but the strains Fzb 53 and W 490 had a significant reducing effect on barley leaf stripe (D. graminea) and seedling blight of wheat caused by F. culmorum and, in case of Fzb 53, also on Fusarium spp./S. nodorum. In a year with conditions favouring the development of bunt, Fzb 53 and W 490 had also activity against T. tritici in the field. For Fzb 53 it could be shown that the level of bunt control depended on resistance of the respective variety, but overall the activity of Fzb 53 against bunt was insufficient in that year. Of the commercial B. subtilis products evaluated against T. tritici, Fzb 24 and Serenade showed activity under controlled conditions, but not in the field. Fzb 24 and Serenade had also some activity against D. teres but not against F. culmorum. Serenade was also effective against D. graminea. In two replicated field experiments, the highest level of bunt control (82 and 94% efficacy) was obtained with the seed treatment product Tillecur. In four experiments under controlled conditions, Tillecur showed also consistent activity (mean: 78% efficacy) against barley leaf stripe. Results obtained with all other commercial products either gave no indication for T. tritici activity at the rates tested, or bunt control in the field was low or inconsistent.

Dumalasová, V.; Bartoš, P.

doi: 10.1007/BF03356173pmid: N/A

The resistance of 90 European commercial winter wheat cultivars and advanced lines was tested after inoculation with common bunt. Out of it 27 cultivars/lines showed bunt incidence below 25% at least in one trial. The results obtained were compared with results published by other authors. Cultivars described as resistant were mostly resistant also in our trials. Of the cultivars registered in the Czech Republic cv. Globus proved to be highly resistant (bunt incidence 0–0.9%) followed by cv. Bill (bunt incidence 0.1–10.4%). Cultivar Tommi of similar pedigree as cv. Globus was highly resistant, too. The resistance of 21 North American and two European cultivars, sources of bunt resistance, was validated. The bunt incidence on 31 wheat cultivars tested in 2004 and 2005 was compared. Similar in both years was the ranking of the most resistant cultivars Globus and Bill. Cultivars Batis, Clever and Caphorn were very susceptible in both years; the ranking of medium resistant/susceptible cultivars varied. In all trials except in 1995 a mixture of Tilletia tritici and T. laevis was used for seed inoculation. In 1995 considerable differences in bunt incidence on several cultivars after separate inoculation with Tilletia tritici and T. laevis were found suggesting differences in virulence of the two bunt species in the trial.

Zamponi, L.; Michelozzi, M.; Capretti, P.

doi: 10.1007/BF03356174pmid: N/A

The inhibitory effects of the monoterpenes (−)-α-pinene, (−)-β-pinene, δ-3-carene and myrcene, in both the contact and the volatile phase, on Heterobasidion spp., Leptographium wingfieldii and Leptographium serpens were studied in vitro. Inhibition was usually greater when the monoterpenes were in contact with the fungi than when the fungi were exposed to the monoterpene vapours. Myrcene was the most strongly inhibiting compound for H. annosum s.l., followed by δ-3-carene; the Leptographium spp. were inhibited most strongly by δ-3-carene. Exposure to the monoterpenes reduced conidiogenesis in H. abietinum. After exposure of the fungi to the monoterpenes was discontinued, there were in general no residual effects on fungal growth, apart from Leptographium spp. that had been exposed to δ-3-carene.

Trdan, S.; Vidrih, M.; Valic, N.

doi: 10.1007/BF03356175pmid: N/A

Four entomopathogenic nematode species (Steinernema fel-tiae, Steinernema carpocapsae, Heterorhabditis bacteriophora, and Heterorhabditis megidis) were tested in a laboratory bioassay with the aim of studying their efficacy in control of the adults of two stored grain pests, Sitophilus granarius and Oryzaephilus surinamensis. Activity of the biological agents studied was determined at three different concentrations (500, 1000, and 2000 infective juveniles [IJs] per adult) and temperatures (15, 20, and 25°C). The granary weevil mortality rate was higher than the mortality rate of the saw-toothed grain beetle. Heterorhabditis megidis proved to be the least efficient in control of both pests, while no significant differences were recorded between any of the other three nematode species. The experiment demonstrated that the entomopathogenic nematodes were most efficient in the control of S. granarius at 20°C (LC50 after 7-day exposure 803–1195 IJs/adult) and 25°C (LC50 505–1175 IJs/adult). A satisfactory level in control of the pest O. surinamensis was reached at 20°C (LC50 921–1335 IJs/adult). The concentration of the suspension used in our experiment was shown to be a less important factor affecting the biological activity of nematodes against the adults of both stored grain pests. Though the use of entomopathogenic nematodes for control of the tested pests is not possible at the present time, it may be possible to combine this approach with some other (biotechnical) methods in the future.

Tomanović, Ž.; Kavallieratos, N.; Starý, P.; Petrovic-Obradović, O.; Tomanović, S.; Jovanović, S.

doi: 10.1007/BF03356176pmid: N/A

Aphid and aphid parasitoid associations on willows (Salix spp.) and poplars (Populus spp.) in southeastern Europe are reviewed. In total 13 aphid parasitoid species were reared from aphids on these plants. The specific parasitoid complex of Acyrthosiphon cf. malvae (Mosley) on Salix retusa and the aphids and parasitoids composition on willows and poplars are discussed. The most frequently sampled and the most abundant parasitoid species in poplar aphid-aphid parasitoid associations was Adialytus salicaphis Fitch. Furthermore, Lysiphlebus confusus Tremblay & Eady was the most abundant species collected on willow-feeding aphids, whereas A. salicaphis, Euaphidius cingulatus (Ruthe) and Binodoxys heraclei (Haliday) were the most frequently sampled parasitoid species on willows. Trophic connections between aphids and parasitoids associated with willow agroecosystems are also discussed. A key for the identification of aphid parasitoids associated with aphids on willows and poplars in southeastern Europe is provided.

Thungrabeab, M.; Blaeser, P.; Sengonca, C.

doi: 10.1007/BF03356177pmid: N/A

The current study is focusing on the effect of temperature and host plant on the efficacy of different entomopathogenic fungi from Thailand against western flower thrips, Frankliniella occidentalis (Pergande) and onion thrips, Thrips tabaci Linde-man (Thysanoptera: Thripidae). The results showed that the efficacy of five entomopathogenic fungi, i.e. two isolates of Beauveria bassiana (Balsamo) Vuillemin (Bb. 4591 and Bb. 5335), two isolates of Metarhizium anisopliae var. anisopliae (Metsch) Sorokin (Ma. 6079 and Ma. 7965) as well as one isolate of Paecilomyces fumosoroseus (Wize) Brown & Smith (Pfu. 5338) varied depending on the temperature and the fungal isolate in both thrips species. The Lc50 values decreased with increasing temperature. All fungal isolates showed a significantly higher efficacy against both thrips species at 25 and 30°C than at 16°C. Among five isolates, B. bassiana Bb. 5335 and M. anisopliae Ma. 7965 were superior in terms of efficacy against both thrips species within a broader range of temperature. The effect of host plants on the efficacy of B. bassiana (Bb. 5335) and M. anisopliae (Ma. 7965) was tested against first instar larvae of F. occidentalis and T. tabaci. The results revealed that the efficacy of these two fungi against F. occidentalis and T. tabaci varied with to the host plant, whether on crop or on ornamental plants. Both thrips species reared on bean, cucumber, leek and swan river daisy were highly susceptible to fungal infection but significantly less susceptible when reared on cotton and saintpaulia.

Tzortzakakis, E.; Bletsos, F.; Avgelis, A.

doi: 10.1007/BF03356178pmid: N/A

Twenty-two Solanum accessions used as rootstocks were evaluated for their resistance towards the root-knot nematodes Meloidogyne javanica and M. incognita and three tobamoviruses (Tmv, ToMV and Pmmv). Five out of seven S. gilo accessions, namely Rnl 300/328, Rnl 304/337, Rnl 308/347, Rnl 297/323 and Rnl 307/346, were resistant or immune against all viruses while others within S. aethiopicum group kumba, S. linnaeanum, S. macrocarpon and S. dasyphyllum were susceptible. Furthermore, variability of plants within the same accession being either susceptible or resistant/immune to viruses was recorded in others. Both nematode species produced galls and egg masses on all tested plants.

doi: 10.1007/BF03356179pmid: N/A