The effect of nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) on nitrifying organism populations under <i>in vitro</i>conditions

The application of nitrification inhibitors is a technique to reduce the nitrate concentration on leachates that delay ammonium oxidation by reducing the activity of ammonium oxidizing bacteria in soils. Two experiments were carried out in order to estimate the influence of DMPP on the population of ammonium oxidization bacteria under in vitro conditions. In both experiments, three treatments were established. The treatments were the following: a) ammonium oxidization bacteria established in a growing media without fertilizers, b) ammonium oxidization bacteria established in a growing media with Urea, and c) ammonium oxidization bacteria established in a growing media with DMPP. Results obtained showed that the population of the ammonia oxidizing bacteria diminished in the DMPP treatment as compared with the urea and control treatments. In conclusion, DMMP influences on ammonium oxidization bacteria activity being a useful tool in fertilizers strategies to reduce the contamination by nitrates in groundwater.

Detection of Antibody in Dogs with Blastomycosis Using <i>Blastomyces dermatitidis</i>Yeast Phase Lysate Antigens

The objective of our study was to compare two B. dermatitidis yeast phase lysate antigens [ERC-2, dog Wisconsin;85, soil Georgia, ATCC 56,920] for detecting antibody in 38 serum specimens [pre-treatment, 30-day, and 60-day post treatment] from dogs with diagnosed blastomycosis. The mean absorbance values obtained with the two antigens (N = 38) were ERC-2 = 2.359 and 85 = 2.189. The mean absorbance values when the sera were divided into the three treatment groups were as follows pre-treatment: Isolate ERC-2 had an absorbance value of 2.418;Isolate 85 had an absorbance value of 2.688, 30-day post treatment: ERC-2 had an absorbance value of 2.452;85 had an absorbance value of 2.303 and 60-day post treatment: ERC-2 had an absorbance value of 2.150;85 had an absorbance value of 2.073 with the mean absorbance values of all treatment groups were ERC-2: 2.229 and 85: 2.141. This study indicates the potential for further evaluations of the two lysate antigens with regard to antibody detection in dog sera with the ERC-2 reagent slightly more reactive than the 85 lysate antigen.

<i>Cladosporium</i>: Causal agent of scab in purple passion fruit or gulupa (<i>Passiflora edulis</i>Sims.)

The Scab of purple passion fruit or gulupa (Passiflora edulis Sims.) is a serious disease, affecting all aerial organs of the plant, but also to reducing the visual quality of the fruits, which reduces export production. To determine the primary causal agent of disease in Colombia, associated microorganisms were isolated from scab lesions on stems, leaves, flowers and fruits, recovering in PDA. Obtaining Cladosporium, Colletotrichum and Botrytis. Cladosporium had the highest frequency of fungal isolates. 15 strains were evaluated for their pathogenicity on fruits and leaves of gulupa in laboratory and greenhouse conditions. 9 strains caused symptom expression at 95% humidity and 17°C - 20°C, validating Cladosporium as causal agent of gulupa scab. For those pathogenic strains, were determinate incubation and latency periodsin leaves (7 - 11 and 8 - 12 DPI) and fruits (6 - 10 and 8 - 12 DPI) revealing differences or virulence levels in the pathogen populations.

Potyvirus Affecting Uchuva(Physalis peruviana L.)in Centro Agropecuario Marengo,Colombia

Fruit production and especially fresh tropical fruit trade, has an important relevance on world economy. Refining knowledge on virus diseases affecting tropical fruits is required to improve the understanding of these diseases, their dynamics and consequently, the ability to manage them. In this paper, samples of “uchuva” plants (Physalis peruviana L.) obtained from Centro Agropecuario Marengo (CAM) Municipality of Mosquera, Cundinamarca region of Colombia were analyzed after expressing symptoms of leaf chlorosis, leaf malformation, mosaic patterns and dwarfing. Electron microscopy revealed the presence of two different viral particles congruent with Potyvirus and Tobamovirus genus morphology. The presence of Potyvirus affecting the P. peruviana L. culture was confirmed in the samples analyzed by means of electronic microscopy images and serology. Similarly, the existence of viral particles with coherent characteristics of a putative Tobamovirus was observed. However, its presence could not be confirmed by means of serological tests. Nevertheless, its incidence should not be neglected. The mechanism of Potyvirus disease transmission in P. peruviana L. remains unknown, as well as the vectors associated with this disease. Therefore, complementary work and research should be considered. In addition to serology and electron microscopy, the use of indicator plants for diagnosis is suggested. Finally, a complete molecular characterization of the Potyvirus is recommended for a better understanding of the characteristics of its association with P. peruviana L.