1,395,824 research outputs found
Heart rot of spruce and alder in forests of Latvia
No full textHeart rot causes great decrease in timber quality throughout the world. In the conifer forests of Northern Hemisphere the most significant losses are caused by fungi from the Heterobasidion annosum species complex. The spread of the disease is favored by forest management, as the fungus can use freshly cut stumps as an infection court, and so extend through root contacts to infect neighboring trees.
The country-scale inventory revealed that about 22% of Latvian spruce trees contained heart rot, which extended on average 6.6 m within the tree stem; the most commonly associated fungus being H. parviporum. These facts highlight the need to take actions to reduce the level of inoculum in already infested stands. Stump removal and the planting of resistant tree species are two options for that.
Long-term trials carried out in Scandinavia showed that stump removal could significantly decrease the proportion of infected trees in regenerated stands, although the effectiveness of this procedure may eventually decrease with time. In addition, this method is quite drastic and the adverse influence of continuous stump removal on stand biodiversity and productivity should be taken into consideration. The trail conducted in Finland showed that stump removal had a positive impact on seedlings growth, but influenced negatively mycorrhization and species richness.
The other management method which could be employed is the planting of resistant tree species, especially broadleaved trees. In the work undertaken for this thesis heart rot incidence, associated fungi and decay caused yield losses were studied in Latvian grey (Alnus incana) and black alder (A. glutinosa) stands. Despite the high decay incidence and the number of associated fungal species, no single H. annosum s.l. was found. Also, our data showed that the proportion and size of the heart rot column increased with tree age. These data suggest that a short rotation of fast growing broadleaved trees (not only Alnus, but also species of Populus, Betula, and Salix) could be used for clearing up the Heterobasidion inoculum
Characterization of isolates that cause black rot of crucifers in East Africa
No full textA study was conducted in the East African countries of Kenya, Tanzania and Uganda in the months of July and August 2009 with the objectives of assessing the status of black rot and race structure of Xanthomonas campestris pv. campestris in the three countries. Samples infected with black rot were collected from farmers’ fields mainly from Brassica oleracea crops (broccoli, cabbage, cauliflower and kales). A total of 399 farms were surveyed of which 260 were from Kenya, 91 from Tanzania and 48 from Uganda. Following successful isolations, a total of 249 isolates of the causal agent, Xanthomonas campestris pv. campestris were recovered. Pathogenicity of all isolates was confirmed on B. oleracea susceptible cultivars Copenhagen Market F1 and Wirosa F1. Sixty of the 250 isolates were race-typed using a differential set Brassica spp. Only two races, 1 (Kenya and Tanzania) and 4 (Kenya, Tanzania and Uganda) were observed however, another race (5) was observed from one isolate recovered from a B. rapa sample obtained from Tanzania in 2003. Genomic fingerprinting with repetitive-PCR revealed clusters that did not depict significant correlations between isolates and geographical location, isolates and host adaptation or isolates and race. However, it did demonstrate existence of genetic differences within the East African X. campestris pv. campestris population indicating that it is not a similar clonal population of the same genetic background
Calonectria species associated with cutting rot of Eucalyptus
No full textDecline in the productivity of Eucalyptus hybrid cutting production in the Guangdong Province of China is linked to cutting rot associated with several Calonectria spp. The aim of this study was to identify these fungi using morphological and DNA sequence comparisons. Two previously undescribed Calonectria spp., Ca. pseudoreteaudii sp. nov. and Ca. cerciana sp. nov. were identified together with Ca. pauciramosa. Calonectria pseudoreteaudii resides in the Ca. reteaudii complex and Ca. cerciana is closely related to Ca. morganii. Connected to the discovery of Ca. pseudoreteaudii, species in the Ca. reteaudii complex were re-considered and the group is shown to accommodate two cryptic species. These originate from Australia and are described as Ca. queenslandica sp. nov. and Ca. terrae-reginae sp. nov
A severe outbreak of crown and root rot of tomato caused by Fusarium oxysporum f. sp. radicis-lycopersici in Malta
No full textA severe outbreak of crown and root rot of tomato was observed in greenhouses in Malta in eight locations
during the period November 2004 – February 2005. Besides root and crown symptoms, several plants showed
cankers at the basal part of the stem. Fusarium oxysporum was constantly isolated from these plants. One isolate
from each location was tested for pathogenicity on tomato seedlings. All these isolates caused severe necrotic lesions
of the crown and roots, and stem cankers. It was concluded that F. oxysporum f. sp. radicis-lycopersici (FORL) was
the cause of the outbreak. Incidence ranged from 10 to 50%. Cold weather conditions occurring in Malta during the
late fall and winter of 2004–2005 probably favoured the disease. The use of tomato cultivars or hybrids resistant to
FORL is suggested for winter tomato crops in south Mediterranean areas.peer-reviewe
Brown rot a cause of blossom-blight and fruit-rot
No full textTitle from PDF cover (viewed on October 25, 2017).This archived document is maintained by the State Library of Oregon as part of the Oregon Documents Depository Program. It is for informational purposes and may not be suitable for legal purposes.Mode of access: Internet from the Oregon Government Publications Collection.Text in English
Following basal stem rot in young oil palm plantings
No full textThe PCR primer GanET has previously been shown to be suitable for the specific amplification of DNA from Ganoderma boninense. A DNA extraction and PCR method has been developed that allows for the amplification of the G. boninense DNA from environmental samples of oil palm tissue. The GanET primer reaction was used in conjunction with a palm-sampling programme to investigate the possible infection of young palms through cut frond base surfaces. Ganoderma DNA was detected in frond base material at a greater frequency than would be expected by comparison with current infection levels. Comparisons are made between the height of the frond base infected, the number of frond bases infected, and subsequent development of basal stem rot. The preliminary results suggest that the development of basal stem rot may be more likely to occur when young lower frond bases are infected
Xanthomonas campestris pv. campestris race 1 is the main causal agent of black rot of Brassicas in Southern Mozambique
No full textSevere outbreaks of bacterial black rot caused by Xanthomonas campestris pv. campestris (Xcc) were observed in Brassica production fields of Southern Mozambique. The causal agent of the disease in the Mahotas and Chòkwé districts was identified and characterised. In total, 83 Xanthomonas-like strains were isolated from seed samples and leaves of cabbage and tronchuda cole with typical symptoms of the disease. Forty-six out of the 83 strains were found to be putative Xcc in at least one of the tests used: Classical biochemical assays, enzyme-linked immunosorbent assay (ELISA) with monoclonal antibodies, Biolog identification system, polymerase chain reaction (PCR) with specific primers and pathogenicity tests. The ELISA tests were positive for 43 strains. Biolog identified 43 strains as Xanthomonas, but only 32 as Xcc. PCR tests with primers targeting a fragment of the hrpF gene were positive for all 46 strains tested. Three strains were not pathogenic or weakly pathogenic and all other strains caused typical black rot symptoms in brassicas. Race type differentiation tests revealed the Xcc strains from Mozambique as members of race 1. The prevalence of this pathogenic race of the Xcc pathogen in Mozambique should be considered when black rot resistant cultivars are evaluated or introduced into the production regions of this country
An analysis of key preparedness factors for marketing automation implementation: a case of a selected company
No full textFcStuA from <i>Fusarium culmorum</i> controls wheat foot and root rot in a toxin dispensable manner
No full textFusarium culmorum is one of the most harmful pathogens of durum wheat and is the causal agent of foot and root rot (FRR) disease. F. culmorum produces the mycotoxin deoxynivalenol (DON) that is involved in the pathogenic process. The role of the gene FcStuA, a StuA ortholog protein with an APSES domain sharing 98.5% homology to the FgStuA protein (FGSG10129), was determined by functional characterisation of deletion mutants obtained from two F. culmorum wild-type strains, FcUk99 (a highly pathogenic DON producer) and Fc233B (unable to produce toxin and with a mild pathogenic behavior). The ΔFcStuA mutants originating from both strains showed common phenotypic characters including stunted vegetative growth, loss of hydrophobicity of the mycelium, altered pigmentation, decreased activity of polygalacturonic enzymes and catalases, altered and reduced conidiation, delayed conidial germination patterns and complete loss of pathogenicity towards wheat stem base/root tissue. Glycolytic process efficiency [measured as growth on glucose as sole carbon (C) source] was strongly impaired and growth was partially restored on glutamic acid. Growth on pectin-like sources ranked in between glucose and glutamic acid with the following order (the lowest to the highest growth): beechwood xylan, sugarbeet arabinan, polygalacturonic acid, citrus pectin, apple pectin, potato azogalactan. DON production in the mutants originating from FcUK99 strain was significantly decreased (-95%) in vitro. Moreover, both sets of mutants were unable to colonise non-cereal plant tissues, i.e. apple and tomato fruits and potato tubers. No differences between mutants, ectopic and wild-type strains were observed concerning the level of resistance towards four fungicides belonging to three classes, the demethylase inhibitors epoxiconazole and tebuconzole, the succinate dehydrogenase inhibitor isopyrazam and the cytochrome bc1 inhibitor trifloxystrobin. StuA, given its multiple functions in cell regulation and pathogenicity control, is proposed as a potential target for novel disease management strategies
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