Evaluation of Likelihood of Co-Occurrence of Erwinia amylovora with Mature Fruit of Winter Pear

ABSTRACT Phytosanitary concerns about fire blight prohibit export of U.S.-grown pears to some countries without this disease. To examine these concerns, we evaluated the potential for co-occurrence of Erwinia amylovora with mature, symptomless winter pear fruit by inoculation experiments and by survey of commercial orchards. Immature pear and apple fruit were inoculated in orchards with E. amylovora strain 153N as resuspended lyophilized cells or as ooze from diseased tissues. Regardless of inoculum source, population size of Ea153N on fruit declined by an order of magnitude every 3 to 4 days during the first 2 weeks after inoculation; at 56 days after inoculation, Ea153N was not detected, except on 1 of 450 fruit with 4 colony forming units (CFU). After inoculation of flowers, calyx-end survival of Ea153N on pear and apple fruit declined from high populations at petal fall to a few cells at harvest, with no detection of the pathogen after a 7-week cold storage. Migration of Ea153N into symptomless pear fruit from diseased branches was evaluated by enrichment assay and nested polymerase chain reaction of internal fruit core tissues; these assays failed to detect the pathogen in healthy fruit from diseased trees. At harvest, E. amylovora could not be detected on 5,599 of 5,600 fruit of d'Anjou pear sampled from commercial orchards in major production areas of the Pacific Northwest; one fruit yielded 32 CFU of the pathogen. Postharvest, mature pear fruit contaminated with Ea153N and subsequently wounded required a dose of >10,000 cells at the wound site to allow for persistence of the pathogen through a 7-week-cold storage. We conclude that epiphytic E. amylovora shows similar survival characteristics on both pear and apple fruit, this pathogen is not an endophyte within mature symptomless pear fruit, its presence is exceptionally rare on commercially produced fruit, and that epiphytic survival of E. amylovora through a postharvest chilling period is unlikely given the unrealistically high population size required for persistence.     

Osteomalacia as a result of phosphorus deficiency in beef cattle grazing subtropical native pastures in Uruguay

We investigated 2 outbreaks of osteomalacia as a result of phosphorus (P) deficiency in herds of lactating beef cows grazing subtropical native pastures in Uruguay. Cows exhibited pica, difficulty to stand and walk, rib fractures, and body weight loss even with adequate forage availability. Osteopenia and severe osteomalacia were observed on gross and histologic examination. The concentrations of bicarbonate-extractable P in soil (4.0, 4.1 mg P/kg), total P in pasture (0.9, 1.1 g P/kg), inorganic P in serum (1.0, 0.71 mmol P/L), and P in bone (73 mg P/mL) were all low. Although injectable and mineral salt supplements provided additional P in both outbreaks, these supplementary amounts were insufficient to prevent P deficiency. The P ingested by the cows from the pasture and supplements would have provided 20–55% of their daily P requirements of ~21 g P/d. Osteomalacia occurred in cattle at the 2 ranches as a result of severe P deficiency in the soil and forage, and inadequate P supplementation. Following diagnosis, control of P deficiency in beef cattle requires estimation of the amount of pasture P ingested and provision of sufficient additional supplementary P to meet the animals’ requirements.     

Aerodynamic properties of windbreaks of various designs formed by thinning in central Ukraine

In this article, we investigate the regulation of wind regime by windbreaks of different designs formed by thinning. In particular, we look at the effects of thinning in 52–67 years old oak stands. Based on our results, different windbreaks designs of foliage and aphyllous states influence wind regime of adjacent fields. This research shows that windbreaks of sieve-looking and blown designs with an average optical porosity of 20–25% between the trunks and 5–10% in the crowns have better aerodynamic properties than windbreaks of dense design. The uniformity coefficient of reduction in the airflow ranged between 0.42 and 0.76. There is a clear tendency to decrease wind velocity at a distance of 15H in the leeward side, which has a beneficial effect on agronomic productivity of the surrounding areas. With the transition of windbreaks from full foliage to aphyllous state the optical trunk porosity of plantations increases 1.8–3.0 times, and in crowns—2.5–4.0 times. The windbreaks of blown and sieve-looking designs in the aphyllous state with an average porosity between trunks of 40–50% and in the crowns of 20–30%, regulate more effectively the wind regime in comparison with windbreaks of dense design. According to our findings, the windbreaks of blown design with porosity 40–50% between the trunks and 0–10% in crowns and sieve-looking design have the best ameliorative properties in the region.

     

Long-term field evaluation and large-scale application of a Metarhizium anisopliae strain for controlling major rice pests

Journal of Pest Science - There is increasing concern about the toxic effects of chemical pesticides on human health and the environment. Many alternatives, however, are viewed as impracticable or...     

Large-scale,multi-year,phenology modelling of forest insects in Pinus radiata plantations

Journal of Pest Science - Ecologically and economically harmful wood borers and bark beetles, which have the capacity to expand geographically through the international log trade, require...     

Demand and effect of potassium,magnesium, and calcium chlorides on hemolymph parameters,immune-related gene expression,and growth of Litopenaeus vannamei,Boone (1931) under biofloc technology

The ionic composition of culture water may be a more important limiting factor than the salinity itself and may lead to osmotic stress which may influence growth and survival of shrimp culture. The uptake rate and the effect of magnesium chloride (MgCl₂), calcium chloride (CaCl₂), and potassium chloride (KCl) salts in juveniles of whiteleg shrimp (Litopenaeus vannamei) cultured with biofloc technology (BFT) was evaluated for 62 days in seawater (30 practical salinity unity). Five treatments were analyzed in triplicate: T1; control (water exchange rate of 5% daily), T2; adding CaCl₂?+?MgCl₂?+?KCl, T3; adding MgCl₂?+?KCl, T4; adding CaCl₂?+?KCl, and T5; adding CaCl₂?+?MgCl₂. Mineral salts were added to water and the response of experimental parameters: physicochemical variables of water quality, osmotic pressure, total hemocyte count, glutathione peroxidase gene expression, superoxide dismutase, and zootechnical variables of the shrimp was assessed. The uptake of single chloride salts (CaCl₂, MgCl₂, and KCl) by shrimp varied as a function of the concentrations and the ratio of these three ions. Magnesium deficiencies in the culture medium increased CaCl₂ and KCl uptake without showing gene expression of SOD and GPx. The best survival rate was obtained by adding the three ions (T2) and the control (T1, water exchange of 5%). We concluded that L. vannamei can be maintained by the addition of essential chloride ions in BFT without water replacement.

     

Enzyme treatment for elimination of egg stickiness in tench (Tinca Tinca L.), European catfish (Silurus Glanis L.) and common carp (Cyprinus Carpio L.)

Enzyme treatment to eliminate egg stickiness in tench, European catfish and common carp was compared with standard methodology in an attempt to decrease time consuming under hatchery conditions. Eggs of tench and E. catfish were exposed to an alcalase enzyme MERCK EC 3.4.21.14 (0.6 AU g^?1) solution 3 min after egg fertilization for 2 min. The best enzyme concentration in tench and E. catfish was 10 and 20 ml l^?1 of enzyme, respectively. The eggs of c. carp were successfully destickiness with ALCALASE DX (2.5 AU g^?1) using two concentration of enzyme (2 ml l^?1 and 20 ml l^?1) from 8 to 20 min after fertilization.     

Characteristics of monoclonal antibodies against Piscirickettsia salmonis

A panel of 28 monoclonal antibodies against Piscirickettsia salmonis was produced using a purified fraction of the bacterium. To determine their specificity to the pathogen, the antibodies were assayed by ELISA and indirect immunofluorescence microscopy. Six monoclonal antibodies were selected based on their strong reaction against P. salmonis and absence of cross-reactivity with other common fish pathogens. Western blot analysis showed that the antibodies reacted to several antigens of P. salmonis . Immunofluorescence assays revealed that these antibodies reacted with the same specificity to different isolates of P. salmonis obtained from the south of Chile. This panel of monoclonal antibodies represents an important tool to develop simple, rapid, sensitive and highly specific methods for the detection of the pathogen and diagnosis of the disease.