Infection process of Rhizoctonia solani on Solanum tuberosum and effects of granular nematicides

The infection process ofRhizoctonia solani AG-3 was studied on potato sprouts, cv. Bintje, in growth chamber trials at 15 °C. Initially hyphae ofR. solani grew predominantly in the longitudinal direction of the sprouts (runner hyphae). They tended to follow the junctions between epidermis cells as was observed by SEM. The hyphae formed side-branches mainly half-way of the subterranean parts of the sprouts. They branched several times with short swollen cells to form infection cushions. Lesions developed only underneath the infection cushions and were first observed five days after inoculation. The necrotic area was proportional to the area covered with infection cushions on the sprouts. Depth of the lesions could extend up to the vascular bundle. Sprouts were colonized only in healthy tissue in the epidermal layer underneath the infection cushion and in necrotic tissue. A few days after appearance of the lesions,R. solani formed brown, uninfective mycelium on and in the circumference of these lesions.Aldicarb did not influence any part of the infection process. Ethoprophos delayed the emergence of sprouts, but increased the number of sprouts per tuber. As soon as sprouts had emerged, growth was considerably promoted by ethoprophos. Ethoprophos delayed the appearance of lesions and reduced their size. Oxamyl showed the same effects to a smaller extent.As the size of lesions appears to be proportional to the size of the infection cushions, any agents that change the size of the infection cushions, such as pesticides or antagonists, may alter the severity of the disease.Samenvatting Het infectieproces vanRhizoctonia solani AG-3 werd bestudeerd op aardappelspruiten, cv. Bintje, in een klimaatcel bij 15C. Aanvankelijk groeide de schimmel met runnerhyfen voornamelijk in de lengterichting van de spruit. Via SEM kon waargenomen worden, dat de hyfen hierbij vooral over de begrenzingen van de epidermiscellen groeiden. Het mycelium vormde veel zijvertakkingen, bestaande uit iets gezwollen korte cellen, welke voornamelijk halverwege op het ondergrondse deel van de spruit gevormd werden. Een dichte massa van deze cellen vormde een infectiekussentje. Lesies, welke vanaf vijf dagen na inoculatie werden waargenomen, bevonden zich slechts onder spruitoppervlak bezet met infectiekussentjes. De lesiegrootte was recht evenredig met het spruitoppervlak dat bezet was met infectiekussentjes. De diepte van de lesies reikte tot aan de vaatbundels. De spruit werd alleen door de schimmel gekoloniseerd in gezond epidermisweefsel onder het infectiekussentje en in necrotisch weefsel. Enkele dagen na verschijning van lesies vormde R.solani bruin, niet infectieus, mycelium op en rondom de lesies.Aldicarb had geen effect op het infectieproces. Ethoprophos vertraagde de opkomst en verhoogde het aantal tot ontwikkeling gekomen spruiten per knol in gestoomd zand. Direct na opkomst had ethoprophos echter een sterk groeistimulerend effect. Ethoprophos vertraagde de lesievorming en reduceerde de lesiegrootte, vergeleken met onbehandelde planten. Oxamyl vertoonde deze effecten in geringere mate.Daar de lesiegrootte direct gecorreleerd blijkt met de grootte van het infectiekussentje, mag verwacht worden dat elke beïnvloeding van de ontwikkeling van het mycelium van R.solani, bijvoorbeeld door pesticiden of antagonisten, een verandering van de lesiegrootte ten gevolge heeft.     

Can treatment of <Emphasis Type="Italic">Brachiaria decumbens</Emphasis> (signal grass) improve its utilisation in the diet in small ruminants?—a review

Brachiaria decumbens is an extremely productive tropical grass due to its aggressive growth habit and its adaptation to a varied range of soil types and environments. As a result of the vast availability, treated B. decumbens demonstrates as a promising local material that could be utilised as an improved diet for sheep and goats. Despite the fact that the grass significantly increases weight gains in grazing farm animals, there were many reports of general ill-thrift and sporadic outbreaks of photosensitivity in livestock due to the toxic compound of steroidal saponin found in B. decumbens. Ensiling and haymaking were found to be effective in removing toxin and undesirable compounds in the grass. Biological treatments using urea, activated charcoal, polyethylene glycol, and effective microorganisms were found to be useful in anti-nutritional factor deactivation and improving the nutritive values of feedstuffs. Besides, oral administration of phenobarbitone showed some degree of protection in sheep that fed on B. decumbens pasture. In this review, we aim to determine the effect of B. decumbens toxicity and possible treatment methods on the grass to be used as an improved diet for small ruminant.     

Genomic characterization of the first oral avian papillomavirus in a colony of breeding canaries (<Emphasis Type="Italic">Serinus canaria</Emphasis>)

Papillomaviruses are non-enveloped, DNA viruses that infect skin and mucosa of a wide variety of vertebrates, causing neoplasias or simply persisting asymptomatically. Avian papillomaviruses, with six fully sequenced genomes, are the second most studied group after mammalian papillomaviruses. In this study, we describe the first oral avian papillomavirus, detected in the tongue of a dead Yorkshire canary (Serinus canaria) and in oral swabs of the same bird and other two live canaries from an aviary in Madrid, Spain. Its genome is 8,071 bp and presents the canonical papillomavirus architecture with six early (E6, E7, E1, E9, E2, E4) and two late open reading frames (L1 and L2) and a long control region between L1 and E6. This new avian papillomavirus L1 gene shares a 64% pairwise identity with FcPV1 L1, so it has been classified as a new species (ScPV1) within the Ethapapillomavirus genus. Although the canary died after showing breathing problems, there is no evidence that the papillomavirus caused those symptoms so it could be part of the oral microbiota of the birds. Hence, future investigations are needed to evaluate the clinical relevance of the virus.     

Knowledge,attitudes and practices towards <Emphasis Type="Italic">cystic echinococcosis</Emphasis> in livestock among selected pastoral and agro-pastoral communities in Uganda

A cross-sectional study was done from March 2013 to May 2014 to assess knowledge, attitudes, and practices towards cystic echinococcosis (CE) or hydatidosis among selected pastoral and agro-pastoral communities in Uganda. A structured questionnaire was administered to 381 respondents. Multivariate logistic regression analysis was done to find the relationship between knowledge about CE and factors such as age, sex, and level of education across all regions. The odds ratio and confidence interval were used to determine the difference in responses across regions. It was shown that age above 36 years was significantly (p < 0.001) associated with awareness about CE in livestock. Likewise, uneducated (p < 0.0001) and agro-pastoralists (p = 0.01) were significantly less knowledgeable than the educated and pastoralists across all regions. The overall knowledge towards CE in livestock was low 17.8% (95% CI = 14.0–21.6). Dog ownership was high and they never dewormed their freely roaming dogs. Dogs shared water with livestock. In conclusion, knowledge about CE in livestock was low across all regions. Therefore, public health education and formulation of policies towards its control by the relevant stakeholders should be done. Also, the true prevalence of CE in livestock needs to be done so that the magnitude and its public health significance are elucidated.     

Avian predation on wild and cultured sea urchin <Emphasis Type="Italic">Strongylocentrotus intermedius</Emphasis> in a rocky shore habitat

ABSTRACT:   The present study reports the annual variation in consumption of the sea urchin Strongylocentrotus intermedius by avian predators on a rocky shore where the culture of sea urchins has been conducted. Carrion crow and a few gull species were the most abundant avian predators and consumed a large number of sea urchins. Crows consumed mostly natural sea urchins, approximately 36 kg ww/ha per year on the intertidal rocky bench, but the gull species consumed mostly cultured sea urchins, approximately 100 kg ww/ha per year in the culture area. The seasonal variation in the amount of sea urchins consumed by crows was higher than that by the gull species, presumably because of the difference in foraging behavior in association with the seasonal tidal cycle. The natural sea urchins consumed are an allochthonous input from the subtidal to the intertidal habitat, and thus, crow predation may not affect the natural and the cultured populations of the sea urchin. The gull species consumed much of the cultured sea urchin, and thus, may be regarded as an effective predator causing damage to sea urchin culture. The results suggest that further studies are needed to determine why the gull species selectively feed on cultured sea urchins.     

Powdery Mildew Resistance in a Collection of Chinese Barley Varieties

One hundred and forty-seven Chinese barley varieties maintained at the Gene Bank of the National Barley Improvement Centre, Zhejiang, and 84 progenies from these varieties were tested at the seedling stage for their reaction to 32 selected pathotypes of Blumeria graminis f. sp. hordei. Eighteen resistance spectra were identified comprising single or combined resistances from eight known (Ml(Bw), Ml(Ch), Mla7, Mla8, Mla9, Mla13, MlaRu4 and Mlg) and six unknown resistance genes. The most frequent gene was Ml(Bw), which was found in 69 varieties and previously detected in only a few European winter barley varieties. The genes Mla8 and Ml(Ch) were also often present, but other resistance genes were rare. After inoculation, considerably fewer pathogen colonies were observed in ‘Aiganqi’ and one line of ‘Tong5’. Twenty varieties were composed of lines with different resistance genes. China is likely to be a region of origin of the genes Ml(Bw), Mla7, as well as three unknown genes found in original landraces and perhaps another three unknown genes detected in cultivars bred in China. The resistances of varieties from the Zhejiang province and those originating from 11 other Chinese provinces were quite different. Unfortunately, none of the varieties are promising sources of resistance to powdery mildew and China does not seem to be a region suitable for identifying such sources.     

Cation exchange capacity of density fractions from paired conifer/grassland soils

The cation exchange capacity (CEC) of a soil depends on the type and amount of both mineral and organic surfaces. Previous studies that have sought to determine the relative contribution of organic matter to total soil CEC have not addressed differences in soil organic matter (SOM) composition that could lead to differences in CEC. The objectives of this study were (1) to compare the CEC of two distinct SOM pools, the “light fraction (LF)” composed of particulate plant, animal, and microbial debris, and the “heavy fraction (HF)” composed of mineral-bound organic matter; and (2) to examine the effects of differences in aboveground vegetation on CEC. Soil samples were collected from four paired grassland/conifer sites within a single forested area and density fractionated. LF CEC was higher in conifer soils than in grassland soils, but there was no evidence of an effect of vegetation on CEC for the HF or bulk soil. LF CEC (but not HF CEC) correlated well with the C concentration in the fraction. The mean CEC of both fractions (per kg fraction) exceeded that of the bulk soil; thus, when the LF and HF CEC were combined mathematically by weighting values for each fraction in proportion to dry mass, the resulting value was nearly twice the measured CEC of bulk soil. On a whole soil basis, the HF contributed on average 97% of the CEC of the whole soil, although this conclusion must be tempered given the inflation of CEC values by the density fractionation procedure.     

Long-term effect of chemical fertilizer,straw, and manure on labile organic matter fractions in a paddy soil

To assess the effect of long-term fertilization on labile organic matter fractions, we analyzed the C and N mineralization and C and N content in soil, particulate organic matter (POM), light fraction organic matter (LFOM), and microbial biomass. Results showed that fertilizer N decreased or did not affect the C and N amounts in soil fractions, except N mineralization and soil total N. The C and N amounts in soil and its fractions increased with the application of fertilizer PK and rice straw. Generally, there was no significant difference between fertilizer PK and rice straw. Furthermore, application of manure was most effective in maintaining soil organic matter and labile organic matter fractions. Soils treated with manure alone had the highest microbial biomass C and C and N mineralization. A significant correlation was observed between the C content and N content in soil, POM, LFOM, microbial biomass, or the readily mineralized organic matter. The amounts of POM–N, LFOM–N, POM–C, and LFOM–C closely correlated with soil organic C or total N content. Microbial biomass N was closely related to the amounts of POM–N, LFOM–N, POM–C, and LFOM–C, while microbial biomass C was closely related to the amounts of POM–N, POM–C, and soil total N. These results suggested that microbial biomass C and N closely correlated with POM rather than SOM. Carbon mineralization was closely related to the amounts of POM–N, POM–C, microbial biomass C, and soil organic C, but no significant correlation was detected between N mineralization with C or N amounts in soil and its fractions.     

Identification of double/twin bolled and bicolor unit ‘cluster’ in <Emphasis Type="Italic">Gossypium hirsutum</Emphasis> L. cotton

Cultivated tetraploid Gossypium hirsutum L. (Malvaceae) cotton has been characterized as having one flower at a primordia. In a strain (CSH-13) of Gossypium hirsutum cotton, four plants out of 103 had two to three double bolls or twin bolls/plant during 2003–2004 crop season at CICR regional station, Sirsa, Haryana, India. Progeny evaluation in 2004 and 2005 crop seasons indicated that plants raised from seeds harvested from double bolls/twin bolls produced plants bearing double bolls only and plant progeny raised from the seed of single bolls from these mutant plants produced two to three double bolls per plant similar to the parent. Progeny testing revealed that double boll formation is the result of spontaneous mutation and environment does not influence its expression. The mutant is early in maturity by 10–15 days, naked seeded and possesses comparable agronomic characters with normal plants. Another spontaneous mutant of Gossypium hirsutum having more than three appendages originating from primordia.: four bolls one leaf, three bolls one leaf, two bolls two leaves, one boll three leaves were obtained from the population of CISV-13 strain in crop season 2003. These appendage groups have been described as bicolor unit by Clemens Bayer, [Zur Infloreszenzmorphologie der Malvales. Dissertations Botany 212 (1994)] and cluster mutant by Russell and Luther [J Cott Sci 6 (2002) 115]. One to three bolls in a cluster or bicolor unit were observed without formation of seeds and lint. About one-third of the total bolls on the mutant plant were of this type. In progeny testing during 2004 and 2005 crop seasons, this mutant produced plants exclusively with more than three appendages revealing that plants identified in 2003 were due to spontaneous mutation. This mutant was also early and naked seeded. Many of the other characters of the mutant plants were comparable with the wild type plants of the strain. Both the mutants were observed having economic impact due to their better yielding ability as compare to respective parents.