Comparison of larval thermal maxima between <Emphasis Type="Italic">Fundulus heteroclitus</Emphasis> and <Emphasis Type="Italic">F. grandis</Emphasis>

Fundulus heteroclitus and F. grandis are resident salt marsh fishes that overlap in distribution over a narrow range in northeastern Florida. The objective of the present study was to examine whether the limits of the species’ ranges could be explained by differences in thermal tolerance. Two populations of each species were collected and then spawned in the laboratory, and 9-day-old larvae were used for critical thermal maxima trials. Mean LOE temperatures of larvae ranged from 43.04 to 43.65°C and showed little difference between species. Therefore, differences in high temperatures experienced cannot account for the differences of the distributions of the two species. Condition-specific competition may play a greater role in determining the observed range of the two species.     

Bioavailability of amino acids chelated and glass embedded zinc to rainbow trout, Oncorhynchus mykiss, fingerlings

A 2 × 4 factorial experiment was conducted to determine the bioavailability of zinc (Zn) from amino acids chelated (Zn–Am) and glass embedded Zn (Zn–Gl) as sources for rainbow trout, Oncorhynchus mykiss , fed practical type diets. Two levels of Zn (20 and 40 mg kg⁻¹) were supplemented to the diets using either zinc sulphate (Zn–Sf), zinc methionine (Zn–Mt), Zn–Am or Zn–Gl. Rainbow trout with an average weight of 2 g were fed the experimental diets for 15 weeks. Growth and feed gain ratio (FGR) were not significantly influenced by the dietary Zn content and forms. Alkaline phosphatase (ALP) activity for both levels of Zn–Am was significantly higher than that of Zn–Sf and Zn–Gl at 20 mg supplementation. In another experiment, fish of about 95 g were fed the same experimental diets to determine the absorption of Zn and it was found to be significantly higher from Zn–Am compared with the rest. Retention from Zn–Am at 20 mg was significantly higher than the rest, excluding Zn–Sf. The results suggest that the availability of Zn from Zn–Am might be superior among the sources compared.     

The Effect of Gravity on Root Emergence from Cuttings of Some Tree Species

Poplar shoots trained horizontally and normally growing shootswere used to compare the effect of horizontal and vertical orientationin summer on the subsequent rooting of terminal cuttings; asignificantly greater number of preformed roots emerged fromcuttings of vertical shoots. This difference in rooting abilitymay be due to the lower concentration of indolyl-acetic acidin the upper than in the lower half of horizontal poplar stemsas shown by Leach and Wareing (1967). Decapitation of a seriesof these poplar cuttings (Populus ? robusta Schn.) showed thatwound-root production was influenced by the larger terminalbuds on vertical than on horizontal shoots. From a comparison of horizontal and vertical storage of applerootstock cuttings at 45 ?F in the autumn, 29 per cent moreof the horizontal cuttings than the vertical ones had a basalcallus in the following February. Of these cuttings which madesatisfactory shoot growth (over 5 cm) in the following summer,horizontal cuttings exceeded vertical ones by 80 per cent; aresult which was correlated with root production. In a second experiment with M II apple rootstocks in which cuttingswere both stored and grown at the same angle more roots occurredon cuttings placed horizontally rather than vertically, andthis orientation also induced the rootings of a greater proportionof leafy Worcester Pearmain apple cuttings.     

Severity of Xanthomonas axonopodis leaf blight on eucalypt cuttings under different levels of nutrients

Bacterial leaf blight of eucalypt, caused by Xanthomonas axonopodis, occurs mainly in forest nurseries, but also affects young plants in the field. Avoidance of leaf wetness for long periods of time over the whole nursery and using drip irrigation for clonal hedges are, currently, the most effective measures for controlling bacterial leaf blight on eucalypt. However, as these techniques are very costly, alternative management measures are required. We hypothesized that the management of mineral nutrients could reduce disease severity on eucalypts. To examine this hypothesis, rooted cuttings of Eucalyptus urophylla × E. grandis were irrigated with nutrient solutions containing different concentrations of copper (Cu), boron (Bo), potassium (K), calcium (Ca) and nitrogen (N) before inoculation with X. axonopodis 30 days after starting the nutrient solution treatments. Concentration of K higher than that recommended, commonly used in miniclonal hedges, reduced the severity of bacterial leaf blight. However, disease severity increased with an increasing of N/K ratio. The management of mineral nutrition solution, especially K, has great potential for integrated disease management of X. axonopodis in eucalypt nurseries.     

Tithonia and senna green manures and inorganic fertilizers as phosphorus sources for maize in Western Kenya

Efforts to overcome declining soil fertility on small holder farms in western Kenya must be consistent with the reality of low utilization of inorganic fertilizers. Likewise organic inputs alone cannot supply adequate nutrients. The use of two organic resources, Tithonia diversifolia (tithonia) and Senna spectabilis (senna) leaves, and their combination with inorganic P for improving soil fertility and maize yields was investigated on a P limiting soil in Western Kenya. Treatments included: 1) control, no inputs; 2) 5 t ha⁻¹ (dry matter) tithonia leaves; 3) 5 t ha⁻¹ senna leaves; 4) 5 t ha⁻¹ tithonia leaves + 25 kg P ha⁻¹ as triple superphosphate (TSP); 5) 5 t ha⁻¹ senna leaves + 25 kg P ha⁻¹ (as TSP); and 6) 25 kg P ha⁻¹ of TSP. Maize was used as a test crop. Decomposition and P and N release of tithonia and senna leaves were determined in a litterbag study. Tithonia + TSP applications tripled maize yields compared to the control, senna + TSP and tithonia sole application doubled yields, while senna sole applications did not increase yields substantially. A large residual yield was produced in the tithonia treatments in a subsequent crop. These yield results were consistent with the higher quality and faster release of N and P from the tithonia leaves compared to senna. The tithonia biomass transfer system can improve yields in the short term but has limitations because of the large amount of biomass and the associated labor requirements. This revised version was published online in June 2006 with corrections to the Cover Date.     

Methods of inoculation and evaluation of Erwinia psidii in eucalypt

The dieback and wilting caused by Erwinia psidii are emerging eucalypt diseases that have been observed since 2014 in the south and central‐south regions of Brazil. Field observations have shown variability in disease severity resistance among Eucalyptus spp. clones and species. It is hypothesized that this variability is due to genetic resistance. To confirm this hypothesis, inoculations in genetically distinct eucalypt plants are necessary. However, lack of an inoculation method and disease assessment makes difficult to select resistant genotypes for use in commercial plantations or genetic breeding programmes. Three inoculation methods were tested on eight clones of Eucalyptus spp. Among them, inoculum deposition with bacteria‐impregnated toothpick on the axillary buds was the simplest and most effective, capable to reproduce the disease symptoms observed under conditions of natural infection. We also developed a rating scale for disease assessment. Among eight clones tested, only Clone 1 (Eucalyptus saligna) and Clone 2 (Eucalyptus urophylla) were resistant.     

Erysiphe australiana: the cause of powdery mildew on Lagerstroemia speciosa in Brazil

Powdery mildew symptoms and signs were observed on seedlings of Lagerstroemia speciosa within an ornamental plant nursery in Viçosa, State of Minas Gerais, Brazil. Signs were most prominent as intense mycelial growth and sporulation on the shoots, new branches and leaves, which led to tissue necrosis. Based on morphological characteristics and phylogenetic analyses of ITS and 28S rDNA sequences, the powdery mildew pathogen of L. speciosa was identified as Erysiphe australiana, a well‐known powdery mildew pathogen infecting Lagerstroemia spp. worldwide. To our knowledge, this is the first report of E. australiana causing powdery mildew on L. speciosa in Brazil.     

Taxonomic,geographic, and diversity trends for exotic plant pests in recent biosurveillance articles

Journal of Pest Science - Some plant protection organizations use biosurveillance to identify heightened risks from exotic plant pests or generally inform safeguarding. Biosurveillance programs...