Copper Sprays—Effects on Apple Fruit Typiness and Market Color Grades

Late dormant copper (Cu) sprays and mid-summer foliar Cu sprays are being promoted within the Washington apple industry as a means to enhance fruit typiness and red skin color, respectively. While there appears to be theoretical bases for these practices, they have not been tested for horticultural significance. Differential late dormant spray treatments of Cu hydroxide (the Cu source most commonly recommended by agricultural consultants) were imposed in two `Delicious' orchards. Flower cluster Cu was positively related to Cu rate, but the sprays had no effect on leaf Cu or on six fruit typiness variables. Differential mid-summer spray treatments of water, Cu sulfate, and Cu oxysulfate solutions were imposed in three `Delicious' orchards and one `Fuji' orchard. The Cu sprays increased leaf Cu, but had no effect on market color grade measured using a commercial color sorter. The results appear to reflect Cu physicochemistry and timing of application. These preliminary results call into question the utility of the Cu sprays for improving apple fruit quality characteristics when trees show no visual signs of Cu deficiency. They do suggest some alternative ways to manage Cu nutrition in deciduous tree fruit orchards.

Planting-hole Amendments Modify Growth and Fruiting of Apples on Replant Sites

The effects of various nonfumigant planting-hole treatments on growth and yield of apple (Malus domestics Borkh.) trees were measured during the first 3 years after planting. Eight orchards diagnosed as having a replant problem were monitored. First-year shoot growth, the number of blossoms in the second year (inmost orchards), and first-year trunk cross-sectional area increment (TCAI) in 50% of test orchards were increased by monoammonium phosphate (MAP) fertilizer+ peat, MAP+ mancozeb, or MAP + peat + a bacterial antagonist. By the end of year 3, TCAI generally was not affected by treatments, but treatments resulted in more blossoms by the third season in two of seven orchards that blossomed in the second season. Cumulative yield after 3 years increased significantly in only three orchards, with the best treatment, MAP+ peat, resulting in cost recovery in only one orchard. Inadequate K or Cu nutrition may have reduced growth in some of the orchards, which were characterized by a wide range in yields, independent of planting-hole treatment.

A SURVEY OF MATERNAL COPPER STATUS AND FETAL TISSUE COPPER CONCENTRATIONS IN SASKATCHEWAN BOVINE

Copper (Cu) status of cattle raised in different soil zones of Saskatchewan was examined with emphasis on the relation between liver Cu concentration in pregnant cows, stage of pregnancy and fetal liver Cu status. Whole fetuses and livers from adult animals were obtained during routine slaughter operation at a local packing plant. Twenty percent of steers, 54% of pregnant cows, 52% of heifers and 77% of nonpregnant cows had liver Cu levels less than 25 mg kg−1 dry matter (DM). Hypocuprosis was most marked in cattle originating from northern regions of Saskatchewan. Fetal liver Cu concentration depended on the dam liver Cu concentration and on stage of pregnancy and could be represented as: Fetal liver Cu concentration (mg kg−1 DM) = 217.5 + 0.023 [(age of fetus (days) × dam liver Cu concentraiton (mg kg−1 DM)]. During gestation the level of Cu progressively increased in the fetal liver and decreased in maternal liver. Liver Cu levels of fetuses from dams with liver Cu greater than 25 mg kg−1 DM were higher (P < 0.05) than those in fetuses from dams with liver Cu levels lower than 25 mg kg−1 DM. Dam liver Cu status did not influence fetal liver, kidney, heart and brain weights or the Cu concentration of fetal kidney, heart or brain. The magnitude of hypocuprosis in cattle in Saskatchewan is extensive and emphasizes the importance of adequate Cu nutrition in pregnant cattle with respect to maintaining acceptable fetal Cu status. Key words: Copper deficiency, Saskatchewan, soil zones, cattle, pregnancy, fetus

THE EFFECT OF SULPHUR ON MANGANESE AND COPPER NUTRITION OF CANOLA

A growth chamber experiment was conducted to assess the Mn and Cu nutrition of canola (Brassica napus L. 'Westar') and whether S nutrition has an impact on the Mn and Cu nutrition of this crop. Three rates of Mn (0, 25, and 50 mg kg−1), three of Cu (0, 5, and 10 mg kg−1) and three rates of S (10, 20, and 30 mg kg−1) were applied in all combinations to canola grown on an organic soil. High Mn:Cu ratios (> 15) led to Cu deficiency, which, at 10 and 20 mg S kg−1, was alleviated by Cu additions. The Mn-induced Cu deficiency was self-corrected at the 30 mg S kg−1 application rate. This was attributed to the alleviation of a Cu × Mo antagonistic effect through addition of S. Key words: Canola, available soil Mn and Cu, Mn × Cu × S interaction, S × Mo interaction, Cu × Mo interaction

Distribution and availability of copper fractions to wheat from some loess derived alkaline calcareous soils

Copper has been identified as a deficient micronutrient in many alkaline calcareous soils of Pakistan (Kausar et al. 1979; Anon. 1986b). Copper extracted with DTPA from several soils of Pakistan correlated significantly with organic matter and free CaCO3 content (Kausar et al. 1979). Both soil organic matter and CaCO3 content have been reported by Viets (1962) to be among several other factors that affect Cu solubility and hence the Cu nutrition of plants. Working with temperate acid soils, several investigators (McLaren & Crawford, 1973; Shuman, 1979) have recently used different extractants and indicator plants to characterize the chemical pools which appear to control plant available Cu. Shuman (1979) separated various soil fractions and determined their Zn, Cu and Mn content. However, the distribution of Cu among various fractions in alkaline calcareous soils of arid regions has received little attention. The object of the present study was to investigate the relationship between the Cu content of wheat, and native soil Cu and applied Cu. The contribution of Cu in various soil fractions towards plant uptake and that extracted by different reagents was also ascertained.

2.1 The Nutritional Basis for Trace Element Deficiencies in Ruminant Livestock

The role of trace element deficiencies in the causation of clinical diseases is often questioned because of the poor correlations which are found between the trace element status of the animal or its diet and the incidence of disease. The most striking example is that relating to the copper (Cu) nutrition of sheep, in which concentrate diets containing 8 mg Cu/kg DM can cause poisoning (Hogan, Money and Blayney, 1968) while pastures containing twice as much Cu can cause a deficiency disease (swayback) to develop (Allcroft and Lewis, 1957; Alloway, 1973). Unidentified stress factors are often invoked to explain such anomalies. However, the poor relationships between nutritional status and disease incidence reflect the inadequacies of past methods of assessing the extent that a trace element is absorbed from the diet and its functional activity in the animal and the fact that requirements vary during an animal's life. The object of this paper is to re-emphasize the nutritional component of trace element disorders by looking at the quantitative and functional basis of trace element requirements, the factors which predispose animals to deficiencies and how these might be countered.