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Sugarcane growers in Hawaii suffer crop damage and sugar losses to rats (Rattus spp.). We conducted tests to evaluate commercial zinc phosphide baits for reducing rat populations in Hawaiian sugarcane fields. During laboratory bioassays, mortality of black rats (R. rattus) and Polynesian rats (R. exulans) was higher (P < 0.05) with KFE Zinc Phosphide Prepared-Rat Bait and Hopkins Zinc Phosphide Pellets than with ZP Rodent Bait AG or Ridall-Zinc Rodent Field and Agricultural Bait. Hopkins Zinc Phosphide Pellets was the most effective (P < 0.05) bait against Norway rats (R. norvegicus), but low mortality with even this bait (70%) indicates the effectiveness of field applications may be variable. Single aerial broadcast applications of HGP Zincphos Oats or Hopkins pellets did not reduce (P > 0.05) the number of rats captured in sugarcane fields. Prebaiting with nontoxic grain according to manufacturers' instructions enhanced (P < 0.05) effectiveness of zinc phosphide oat bait, but not zinc phosphide pelleted bait (P > 0.05). However, substantial numbers of rats remained in all fields, regardless of rodenticide or whether fields were prebaited with nontoxic grain. Absorption of moisture and physical degradation may have reduced rats' acceptance of pellets. A more weather-resistant bait is needed to control rat depredations in wet and humid areas.

In five US states representative of commercial corn production, zinc phosphide baits were deployed for rodent control in corn fields, and subsequent residues were determined in grain, fodder, and forage samples. Results showed that dilutions of the solid zinc phosphide materials with a variety of solids resulted in unacceptably high variation. The most promising carrier was found to be propylene glycol. The method limit of detection was determined to be 7, 10, and 6 ng in ground grain, ground silage, and ground fodder, respectively. Losses of 15.6, 44.8, and 32.1% were found for grain, silage, and fodder, respectively, after storage.

Because laboratory strains of rat (Rattus norwegicus) are most often used to develop rodenticides, it is not known whether aversions to rodenticides are developed similarly by wild and domesticated strains. Thus, we studied and assessed the relative aversions of wild and domesticated rats to food pellets containing the acute rodenticide zinc phosphide under long-term, self-maintenance conditions. Our animals were housed in cages equipped with 2 operant levers by which food pellets could be obtained continuously. Over a 12-hour period, food pellets containing the rodenticide were available from one of the dispensers. Subsequently, untreated pellets were again made available from that dispenser. We repeated these procedures 1 week, 4 weeks, and 34 weeks later. Lever pressing rates, lever preference, and pellet consumption preference indicated that wild and domesticated rats formed a long-lasting aversion to food pellets containing zinc phosphide after only brief exposure to a poisoned food source that usually provided a similar but harmless diet. Wild rats were superior in their ability to discriminate the rodenticide pellets, to redirect their food-seeking behavior to a safe source, and to retain the aversion over a long period. Our data suggest that it would be unwise to assume that rodenticides that do not produce \"poison-shyness\" in domesticated rats will be equally successful on wild rats in the field.

In 1983 zinc phosphide, strychnine with prebait, and strychnine without prebait were applied to black-tailed prairie dog (Cynomys ludovicianus) colonies in west central South Dakota. Short-term (four days later) and long-term (one year later) impacts of the rodenticides on Horned Larks (Eremophila alpestris) and other granivorous birds inhabiting prairie dog colonies were evaluated. Horned Larks and 49 other bird species were observed. Immediate impacts reduced Horned Lark relative densities 66% with strychnine only and 55% with prebaited strychnine. Zing phosphide caused no measurable reduction. Horned Larks showed no long-term direct impacts. Indirect negative impacts occurred through habitat changes following prairie dog control. The granivorous guild showed no short- or long-term effects.

Three rodenticide treatments, zinc phosphide with prebait, strychnine with prebait, and strychnine without prebait, were applied to black-tailed prairie dog (Cynomys ludovicianus) colonies in west central South Dakota. Results were compared immediately posttreatment and for one year after application. Zinc phosphide was the most effective for reducing prairie dog numbers immediately. When burrow activity levels of prairie dogs were initially reduced by 45% with strychnine only, they returned to untreated levels within ten months. When initial reductions were 95% with zinc phosphide, however, the number of active burrows was still reduced 77% in September the following year. Strychnine with prebait treatment showed initial reductions of 83% in burrow activity. Bait consumption by prairie dogs was highest for zinc phosphide.

A rodenticide, zinc phosphide, was applied to remove black-tailed prairie dogs (Cynomys ludovicianus) from 6 ha of a prairie dog colony in southwestern South Dakota. Another adjacent 6 ha was left untreated. The removal experiment was repeated two consecutive years. Contingency table analysis showed that the resultant population was not homogeneous; age classes by sex of the immigrant and resident subpopulations were different (P < 0.01). The ratio of adult females to yearling females was greater among immigrants than among residents (P < 0.03). Female immigrants did not produce young in the treated zone during the year of their arrival. Fewer of these females displayed distended nipples than expected (P < 0.01), indicating that these immigrants did not reproduce during the reproductive season immediately preceding dispersal and suggesting that failure to reproduce may have stimulated dispersal.

In this study, the effects were investigated of salinity, foliar and soil applications of humic substances on the growth and mineral nutrients uptake of Corn (Hagein, Fardy10), and the comparison was carried out of the soil and foliar applications of humic acid treatments at different NaCl levels. Soil organic contents are one of the most important parts that they directly affect the soil fertility and textures with their complex and heterogenous structures although they occupy a minor percentage of the soil weight. Humic acids are an important soil component that can improve nutrient availability and impact on other important chemical, biological, and physical properties of soils. The effects of foliar and soil applications of humic substances on the plant growth and some nutrient elements uptake of Corn (Hagein, Fardy10) grown at various salt concentrations were examined. Sodium chloride was added to the soil to obtain 20 and 60mM saline conditions. Solid humus was applied to the soil one month before planting and liquid humic acids were sprayed on the leaves twice on 20th and 40th day after seedling emergence. The application doses of solid humus were 0, 2 and 4 g/kg and those of liquid humic acids were 0, 0.1 and 0.2%. Salinity negatively affected the growth of corn; it also decreased the dry weight and the uptake of nutrient elements except for Na and Mn. Soil application of humus increased the N uptake of corn while foliar application of humic acids increased the uptake of P, K, Mg,Na,Cu and Zn. Although the effect of interaction between salt and soil humus application was found statistically significant, the interaction effect between salt and foliar humic acids treatment was not found significant. Under salt stress, the first doses of both soil and foliar application of humic substances increased the uptake of nutrients.

Physical, chemical and bacteriological analyses were carried out of water samples from three boreholes located near a landfill, and or soil samples at Akure, Nigeria, to ascertain the effect of the dumpsite on the groundwater and soil quality. The samples from borehole locations with radial distances of 50, 80, and 100 m, respectively, away from the landfill and twelve soil samples collected at distances 0 (dump centre), 10, 20, and 30 m away from the refuse dump were analysed. The parameters determined were the turbidity, temperature, pH, dissolved oxygen (DO), total dissolved solids (TDS), total hardness (TH), total iron, nitrate, nitrite, chloride, calcium and heavy metals like copper, zinc, and lead. Most of these parameters indicated pollution but were below the World Health Organization (WHO) limits for consumption. The pH ranged from 5.7 to 6.8 indicating toxic pollution, the turbidity values were between 1.6 and 6.6 NTU, and the temperature ranged from 26.5°C to 27.5°C. The concentrations of iron, nitrate, nitrite and calcium ranged from 0.9 to 1.4, 30 to 61, 0.7 to 0.9, and 17 to 122 mg/l, respectively. Out of heavy metals, zinc ranged between 3.3 and 5.4 mg/l and lead ranged from 1.1 to 1.2 mg/l. Soil water holding capacity, porosity, pH, organic matter, organic carbon and organic nitrogen ranged from 38 to 54, 44 to 48, 6.9–7.5, 2.44–4.27, 1.42–2.48, and 0.12–0.21%, respectively. Statistical analyses indicated significant differences at 95% level. The results showed that all the boreholes were not strongly polluted but require treatment before use while the soil is absolutely unsuitable for the crop production. Re-designing of sanitary landfills to prevent leachate from getting to the water table, adoption of clean technology for recycling greenhouse gases and a sustainable land management programme for reclamation are recommended.