ABSTRACT.- Diseases caused by crop residue-dependent pathogens have increased during the last decades in Uruguayan agriculture systems, in particular Pyrenophora tritici-repentis and Cochliobolus sativus. Consequently, we searched for the presence of fungal antagonists for these pathogens, particularly Trichoderma. Seven species of Trichoderma inhabiting soils and crop residues were identified. Strains of all identified species had high in vitro antagonistic activity against both pathogens. These results confirm the presence of Trichoderma spp.

ABSTRACT.- Penicillium expansum is an important pathogen of cold-stored fruit, currently controlled by chemical fungicides. In this work chitosan combined with the biocontrol yeast Debaryomyces hansenii F9D was tested as a safer alternative for its control on cold-stored apples and pears. When medium molecular weight chitosan was applied on fruit a reduction of rot incidence of 62% and 53% was achieved in apples and pears. respectively. When chitosan was combined with the yeast, disease reduction was 76% and 90%.

ABSTRACT.- Dieback and canker disease caused by species of Botryosphaeriales affect the productivity of pome fruit orchards. In this study, we evaluated the efficacy of fungicides and biofungicide for controlling canker and dieback diseases in apple and pear using in vitro and field trials. Isolates of Diplodia seriata, D. mutila, and Dothiorella omnivora from apple, and of D. seriata and Aplosporella aquifolii from pear were used.

ABSTRACT.- Soybean is the main agricultural crop in Uruguay. One of the diseases with the greatest damage potential is Asian soybean rust, with estimated grain yield losses up 80% in the region. Throughout history, different authors have stated the importance of genetic resistance as a fundamental tool to decrease the adverse effects of phytopathogens, leading to agriculture sustainability. The objective of this work was to introduce rust resistance genes into elite lines of INIA's soybean breeding program and to evaluate the enhanced resistance.

ABSTRACT.- Fusarium head blight (FHB) is a destructive disease of cereal grains caused by several Fusarium species, of which Fusarium graminearum is considered the primary causal agent. In this work 586 pure cultures of Fusarium spp. were obtained from infected grains, of which 64.9% belonged to the Fusarium graminearum species complex. 96.4% of those isolates had 15-acetyldeoxynivalenol genotype and the rest exhibited Nivalenol genotype. The second most predominant species was F. poae (19.1%) followed by F. avenaceum (8.2%) and F. tricinctum (4.6%).

ABSTRACT.- This study aimed to describe morphological and histological characteristics of ovaries of two genetic groups of guinea pigs from Latin America. Ovaries from 20 improved and 20 native guinea pigs were collected after slaughtering. One ovary from each animal was weighed, measured, counted for visible follicles on the ovarian surface, and used for subsequent oocyte collection by the slicing method. Contralateral ovaries were used to prepare histological sections and quantify follicles.

Diverse practices related to livestock intensification often have a deep impact on grassland diversity. Moreover, alternative degraded states that are hardly reversible can be observed, resulting in low-diversity communities, dominated by invasive alien species. Therefore, the need arises to understand aboveground vegetation dynamics in these communities, and the potential of the seed bank to revert this degradation.

Legume overseeding along with P fertilization is a common practice used in natural temperate and subtropical grasslands to increase forage production. This practice has been evaluated at experimental plots but not at the paddocks level of commercial farms. The latter are realistic evaluation units to generate knowledge for livestock management. In this study, the enhanced vegetation index (EVI), a proxy of forage production, was used to evaluate the effect of this practice on grazed paddocks in Uruguay.

ABSTRACT.- Brown rot, caused by Monilinia spp., is the main stone fruit disease. Major efforts to detect sources of resistance are being applied by several breeding programs worldwide. The main objective of this study was to seek sources of brown rot resistance, as well as to study the segregation, estimate the heritability, verify the possible existence of the maternal effect, and estimate the genetic advances.

ABSTRACT.- The major surface protein 1a (MSP1a) gene has been used to characterize Anaplasma marginale genetic diversity. This pathogen causes significant productivity and economic losses to the cattle industry. The objective of the present study was to report the first characterization of A. marginale genetic diversity in Uruguay based on MSP1a genotypes and their putative relationship with Rhipicephalus microplus. This cross-sectional study was conducted between 2016 and 2020.