Impact of soil chemistry,nutrient supplements,and fungicides on the health and yield of field-grown processing tomatoes

We report the results of a 3-year study in which we collected and analyzed soil and yield data from experimental plots in six commercial processing tomato fields in Yolo and Solano counties in California. Our objective was to assess the effect of soil chemistry and soil-delivered nutrients and fungicides on tomato plant health and fruit yield at harvest. Marketable yield, leaf necrosis, and fruit loss due to sunburn differed significantly between individual fields, with averages ranging from 81.2–138.5 Mg ha^?1, 32–72% leaf necrosis and 1.9 to 8.8% sunburnt fruit, respectively. Higher-yielding fields showed significantly lower levels of leaf necrosis and sunburn damage and a positive correlation with pre-plant soil parameters such as potassium concentration and cation exchange capacity (CEC). Interestingly, soil amendments of composted poultry manure or other nutrient supplements in low-CEC fields, but not high-CEC fields, resulted in higher fruit yield and less leaf necrosis. While all fields showed symptoms typical of Verticillium wilt and some fields showed symptoms of Fusarium wilt, Fusarium crown and root rot, corky root, and root knot nematode, none of our soil amendments, including chemical and biological fungicides, significantly or consistently reduced incidence or severity of these diseases. We discuss our findings in the context of premature vine decline of tomato, an emerging phenomenon in production fields in the Sacramento Valley, which is characterized by the loss of plant vigor and canopy cover at the onset of fruit ripening and for which causative agent(s) and management options in California remain elusive. (247 words).     

Relationship Between Soil Properties and Nitrogen Mineralization in Undisturbed Soil Cores from California Agroecosystems

Soil nitrogen (N) mineralization rates from different agricultural regions in California were determined and related to soil properties. Undisturbed soil cores were sampled in spring from 57 fields under annual crop rotations and incubated at 25℃ for 10 weeks. Soil properties varied across and within regions, most notably those related to soil organic matter (SOM), with total soil carbon ranging from 6 to 198 g kg^?1. Multivariate linear regression was used to select soil properties that best predicted N mineralization rates. Regression models with a good fit differed between soils with high and low SOM contents, but generally included a measure of SOM quantity, its quality as well as soil texture or mineralogy. Adjusted R² values were 0.95 and 0.60 for high and low SOM soils, respectively. This study has shown that information on soil properties can contribute to better estimates of N mineralization in soils of contrasting characteristics.     

Water Quality and Plankton Communities in Hybrid Catfish (♀ Channel Catfish,Ictalurus punctatus × ♂ Blue Catfish,Ictalurus furcatus) Ponds After Partial Fish Harvest

Twelve 0.4‐ha ponds were stocked with 10,000 hybrid catfish fingerlings in March 2015. Six ponds were partially harvested in August to remove fish larger than ～0.57 kg. All remaining fish were removed in October and November. Partial harvest of faster‐growing fish removed ～26% of the fish initially stocked; feeding rate (and therefore external nutrient loading) was reduced by about the same amount. However, reduced nutrient loading after partial fish harvest had no meaningful effects on water quality, phytoplankton biomass, phytoplankton and zooplankton community structure, or supplemental aeration. Lack of ecosystem change was caused by persistent internal recycling of nutrients added to the system before partial harvest and continued high (albeit reduced) external nutrient loading after partial harvest. Decisions to employ partial fish harvest to manage single‐cropped hybrid catfish ponds should be based on economic considerations and risk reduction rather than the expectation that fish biomass reduction will improve water quality.     

Survey of pesticides used in the control of ectoparasites of farm animals in Ghana

Summary A study to identify the various types of pesticides used on farm animals in Ghana for the control of ectoparasites was conducted in 1989. Eleven organisations involved with pesticide use were questioned. Thirty organised farms and 110 kraals distributed throughout the 10 regions of Ghana were visited.Twenty different pesticides were in use. Of these 45% were organophosphates, 30% were synthetic pyrethroids, 15% were carbamates and 10% organochlorines. The most widely distributed and used pesticide was an organochlorine (lindane), which accounted for 35% of those used on farms and 85% used by herdsmen. The most popular mode of application was by hand dressing. No withdrawal periods before slaughter or sale of milk for consumption were practised.The implications of these findings in the light of possible emergence of pesticide resistance and health hazards are discussed.

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Un Estudio De Pesticidas Utilizados En El Control De Ectoparasitos En Animales De Granja En Gana

Resumen Se realizó un estudio en 1989 para identificar los diferentes tipos de pesticidas utilizados para controlar parásitos externos, en animales de granja en Gana. Se encuestaron 11 organizaciones involucradas en el uso de pesticidas. Se visitaron 30 granjas organizadas y 110 unidades pastoriles, en las 10 regiones ganaderas del país. Veinte pesticidas diferentes estaban en uso. De estos, 40% eran organofosforados, 30% piretroides sintéticos, 15% fueron carbamatos y 10% organoclorinados. El pesticida más usado fue un organoclorinado (lindane), el cual constituyó el 35% de los pesticidas utilizados en las granjas y el 85% de los utilizados por los pastores. El método de aplicación más popular fue a mano. No se tuvo en cuenta período alguno de retiro del pesticida, antes de la matanza para venta de carne, o para la venta de leche. Se discuten las implicaciones de estos hallazgos, en relación a la posible emergencia de resistencia a los pesticidas y a los riesgos para la salud.

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Enquete Sur Les Pesticides Employes Pour La Lutte Contre Les Ectoparasites Des Animaux En Elevage Fermier Au Ghana

Résumé Les auteurs décrivent une étude réalisée en 1989 pour identifier les divers types de pesticides utilisés en élevage fermier dans la lutte contre les ectoparasites du bétail au Ghana. Des questionnaires ont été envoyés à 11 organismes concernés par leur emploi: 30 fermes individualisées et 110 kraals répartis sur 10 régions du Ghana ont été visités. Vingt pesticides de marques différentes ont été utilisés. Parmi eux, 40 p. 100 comportaient des organophosphatés, 30 p. 100 des pyréthrinoides de synthèse, 15 p. 100 des carbamates et 10 p. 100 des organochlorés. Le pesticide le plus largment répandu et utilisé était un organochloré, le lindane, qui représentait 35 p. 100 des pesticides employés dans les fermes et 85 p. 100 chez les éleveurs traditionnels. La technique d'utilisation la plus courante était l'application manuelle. Aucun arrêt avant l'abattage ou la vente du lait pour la consommation n'était pratiqué. Les auteurs discutent les implications de ces résultats, à la lumière d'une possible apparition d'une résistance aux pesticides et des risques encourus pour la santé.

     

Production of Channel Catfish Ictalurus punctatus in Flowing Agricultural Waters in Arizona

Catfish were cultivated in 0.3 m³ site-specific cages built for fish culture in irrigation ditches. Poor growth (239 g ± 4.2) in 1989 was probably due to velocity of water and variability of fish size at stocking. Addition of baffles to the cages and hand grading of fish eliminated these problems in 1990. A power failure near the middle of the 1990 growing season forced the brief move of the fish from the ditch to a pond. Catfish reached an average weight of 465 g in 1990 over roughly the same growing season as in 1990. Before the cages were moved, fish at lower densities had significantly higher growth (588 ± 3, 515 ± 3) than those at higher densities (396 ± 4.6, 334 ± 4). However, at the end of the experiment, growth was not significantly different between densities (P > 0.05). Perhaps stress to fish caused by moving cages obliterated the previous density differences in growth.     

Induced Spawning of Nassau Grouper Epinephelus striatus

Nassau grouper Epinephelus striurus females ovulated 48–51 h after the first of two intramuscular injections of human chorionic gonadotropin given 24 h apart (usually 0.7 IU/gram body weight). Typical spawns contained 400,000–600,000 eggs. With fresh milt and clean water, fertilization rate was 85 and 86%. Survival from fertilization to first feeding for six spawns was 73–94%.