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891.
Laboratory evaluation of the insect growth regulator lufenuron againstHelicoverpa armigera on cotton
An insect growth regulator (IGR), lufenuron (Match 5EC), was tested for its toxicity toHelicoverpa armigera on cotton. Potency of the IGR against the larval stage of the pest was demonstrated with respect to larval instars; the LC90 values of 1st, 2nd, 3rd, 4th and 5th instar larvae were 5.63, 7.89, 8.03, 11.39 and 14.76 mg a.i.l
−1, respectively. However, different larval instars did not differ significantly with respect to LC50 and LC10. IGR-treated larvae had swollen heads and were significantly smaller (1.5–2.3 mm) than the untreated control (2.9 mm). Larval
weight was significantly reduced from 190 mg in the control to 50–70 mg in the lufenuron treatment. IGR treatment in the larval
stage significantly affected both pupal length and pupal weight. Pupal duration of the test insect was significantly extended
by IGR treatment. Pupal deformities, including an inability to shed the last larval skin and formation of larval-pupal intermediates,
occurred following treatment. A significant reduction in adult emergence was recorded. In addition, abnormalities in the form
of development of cavities in the forewings of adult were evident. A significant decline in fecundity was noted in the studies.
http://www.phytoparasitica.org posting Feb. 3, 2003. 相似文献
892.
Marlene Cordero Pedro L. Ramos Lester Hernández Ana I. Fernández Ana L. Echemendía Rudy Peral Gloria González Daniel García Surey Valdés Ana Estévez Keren Hernández 《Phytoparasitica》2003,31(5):478-489
The presence of a begomovirus in potato plants with yellow mottle symptoms was determined for the first time in Cuba. The
incidence of typical begomovirus-like symptoms in potato plants in some regions of Havana province (Güira de Melena, San José
de las Lajas, Güines and Boyeros) during the growing seasons from 1992 to 1998 was in general low. However, in some cultivars
belonging to the National Program for Potato Genetic Improvement, the incidence reached 100%. Yield losses, determined in
1992 and 1994, ranged as high as 19% to 56.33% depending on the cultivar. Characterization of the causal agent was done by
light microscopy, host range (graft and mechanical transmission), DNA hybridizations, polymerase chain reaction, and restriction
fragment length polymorphism analysis. Nucleotide sequence of the amplified fragments revealed the presence ofTomato mottle Taino virus. The virus was transmittedvia tubers and has been detected in mixed infections withPotato virus X and withPotato leaf roll virus.
http://www.phytoparasitica.org posting Oct. 20, 2003. The first two authors contributed equally to this work. 相似文献
893.
Resistance to paraquat has been studied in detail in many weed species for more than a decade, with the precise mechanism of resistance still unclear. Several studies have indicated that reduced movement of the herbicide to the site of action in the chloroplast is at least partly responsible for endowing resistance. Although paraquat translocation studies have been performed in the past it has been rare for these studies to have been conducted on whole plants in the light, despite early observations which clearly showed that paraquat translocation is minimal unless treated plants are exposed to light. This study has addressed this issue in Arctotheca calendula by tracing the movement of 14C-paraquat in resistant and susceptible plants in both the dark and light. Differences in paraquat translocation between the resistant and susceptible biotypes of A. calendula were only observed when treated plants were exposed to light. It was observed that paraquat translocation was significantly reduced in the resistant compared to the susceptible biotype when plants were exposed to light but not in the dark. It is postulated that paraquat translocation is dependent on light mediated damage. As paraquat-induced damage is less severe in paraquat resistant plants, overall paraquat translocation is reduced in the resistant biotype. 相似文献
894.
S.K. Raj R. Singh S.K. Pandey B.P. Singh 《European journal of plant pathology / European Foundation for Plant Pathology》2003,109(5):467-470
Natural occurrence of a geminivirus causing severe leaf curl disease on sunn hemp (Crotalaria juncea) was recorded in India. The association of a geminivirus with the disease was demonstrated by whitefly transmission tests and polymerase chain reaction (PCR) amplification of DNA fragments of expected sizes with three pairs of degenerate geminivirus primers. The PCR-amplified viral DNA fragments were further characterized by Southern hybridization with a geminivirus probe consisting of the cloned coat protein (CP) gene of Indian tomato leaf curl virus (ITLCV). Restriction fragment length polymorphism analysis of a PCR-amplified CP fragment revealed that the geminivirus from sunn hemp was different than ITLCV. 相似文献
895.
A. Sid Ahmed M. Ezziyyani C. Pérez Sánchez M.E. Candela 《European journal of plant pathology / European Foundation for Plant Pathology》2003,109(6):633-637
Two bacterial isolates and one strain of Trichoderma harzianum were tested alone and in combination with chitin for efficacy in control of root rot disease caused by Phytophthora capsici and Rhizoctonia solani in pepper plants under greenhouse conditions. These bacteria (Bacillus subtilis HS93 and B. licheniformis LS674) were isolated from repeatedly washed roots of pepper plants. In in vitro assays, HS93, LS674 and T. harzianum were antagonistic against P. capsici and R. solani and produced high levels of chitinase. Seed treatment and root drenching with bacterial suspensions of HS93 with 0.5% chitin was more effective against Phytophthora and Rhizoctonia root rot than addition of the organisms without chitin. LS674 and T. harzianum reduced Rhizoctonia but not Phytophthora root rot. In two greenhouse tests, seed treatment and root drenching with HS93 amended with chitin enhanced its biocontrol activity against P. capsici but not on R. solani. The effects of LS674 and T. harzianum against R. solani were significantly enhanced when they were used as suspensions with 0.5% chitin for root drenching, but this had no effect on P. capsici. In both greenhouse experiments, the use of 0.5% chitin alone for root drenching reduced Rhizoctonia root rot. Reduction of root rot disease was accompanied by increased yield. These results show that the antagonistic activity of HS93, LS674 and T. harzianum may be stimulated by chitin resulting in significant improvements in their effectiveness against pathogens. 相似文献
896.
Diversity of the coat protein-coding region among Ilarvirus isolates infecting hop in Australia 总被引:1,自引:0,他引:1
D. R. Crowle S. J. Pethybridge G. W. Leggett L. J. Sherriff C. R. Wilson † 《Plant pathology》2003,52(5):655-662
Coat protein (CP) sequences of 17 Ilarvirus isolates were obtained from hops at three farms in Tasmania, Australia. Phylogenetic analysis of these sequences and additional database sequences indicated several Apple mosaic virus (ApMV) isolate clusters distinct from Prunus necrotic ringspot virus (PNRSV): one containing isolates from apple; one containing a single isolate from almond; a third containing Australian hop isolates of the 'apple' serotype and a German isolate of unknown origin; and a fourth containing Australian hop isolates of the 'intermediate' serotype. Isolates from hop, pear and prune from the Czech Republic either formed a fifth grouping, or were divergent members of the 'intermediate' serotype group. Deduced amino acid (aa) residue differences between the coat proteins of the two hop isolate serotype groups were highlighted as possible regions of serological differentiation. No evidence for coinfection of plants with both serotypes was found. Tests of ApMV-infected hop buds using the Shirofugen flowering cherry assay revealed a possible differentiation of the two strains based on hypersensitivity. Because of serological similarities to PNRSV, these viruses have commonly been reported as strains of PNRSV. However, this study shows ilarviruses from Australian hops are strains of ApMV, but distinct from those infecting Malus spp. 相似文献
897.
S. Mansoor I. Amin S. Iram M. Hussain Y. Zafar K. A. Malik R. W. Briddon 《Plant pathology》2003,52(6):784-784
898.
899.
900.
A. Laarif S. Fattouch W. Essid N. Marzouki H. Ben Salah M. H. Ben Hammouda 《EPPO Bulletin》2003,33(2):335-338
In Tunisia, Phthorimaea operculella is an important pest in traditional, unrefrigerated potato stores. An integrated control approach including the use of biological control agents and specifically insect viruses is being developed. From this perspective, we carried out a screening and an evaluation of local Phthorimaea operculella granulosis virus naturally present in Tunisian pest populations. On the basis of symptomatology, P. operculella larvae were collected from different regions (North, Cap Bon, Sahel). Indirect ELISA using a serum raised against the purified Tunisian isolate of the virus was used to establish the geographical distribution of the virus. Comparison of the two approaches showed that symptomatology is not so virus-specific, as morphologically healthy insects were sometimes ELISA-positive. The serological technique therefore gives better detection of the virus. 相似文献