Tolmiea menziesii plants are recognized as being Fe inefficient plants. Under intense production practices, Fe related chlorosis develops rapidly resulting in a loss of production. Tissue levels of Fe have not been determined for chlorotic or nonchlorotic plants. A study was undertaken to determine leaf Fe concentration of chlorotic and nonchlorotic Tolmiea menziesii plants and to establish a tentative minimum critical foliar Fe level.
Tank mixing Uran (0.5% by weight) with ZnSO4 increased leaflet Zn concentration compared to ZnSO4 alone in pecan [Carya illinoensis (Wang) K. Koch]. Zinc nitrate was more efficient than ZnSO4 in increasing leaflet Zn concentration especially if tank mixed with Uran (0.5%). Zn concentration of spray solutions can be reduced by 1/8 to ¼ of the current recommended rate of Zn at 86 g/100 liters of water as ZnSO4. Use of the lowest rate of Zn(NO3)2, 10.8 g/100 liters of water + Uran, increased yield and income over the recommended rate of ZnSO4.
Nutrient spray residue can be removed from leaflets of pecan (Carya illinoensis (Wang.) K. Koch for nutrient absorption measurement. The residue can be removed by washing the leaflets in 0.1% Alconox, rinsed in running tap water followed by a 7 liter 1% HCl rinse and three separate 7 liter demineralized distilled water baths. The elimination of some of the solutions resulted in erroneously high results in adsorption of the nutrients. Young leaflets absorbed more zinc than did the old leaflets. Nutrient sprayed pecan leaflets washed in 0.1% Alconox, rinsed in running tap water, 7 liters 1% HCl, and three separate 7 liter demineralized distilled water baths prior to tissue analysis gave more consistent and reliable data than leaflets washed by any other method. This leaf washing procedure does not remove biologically significant amounts of any of the elements analyzed.
Nutrient concentration of azalea (Rhododendron sp.), juniper (Juniperus sp.), crapemyrtle (Lagerstroemia indica L.), and camellia (Camellia sp.) did not differ between leaves dried in microwave or conventional ovens.
Five rates of ZnSO4 and 3 rates of S were applied in March 1966 in a single application to pecan trees (Carya illinoensis (Wang) K. Koch) in a factorial experiment. A rate of ZnSO4 in excess of about 20 kg/tree would be required to reach June 1966 leaflet Zn concentration in excess of the minimum optimum range of 60 ppm. No 1966 treatment resulted in leaflet Zn concentration in excess of 60 ppm in June 1967 or 1968. Significant Zn and S interaction was detected in September 1966 and 1967 leaflet Zn concentrations. There was a direct relationship between application rates of ZnSO4 and S on leaflet Zn concentration in September 1966 and 1967.
Staminate and pistillate flower maturity of 80 cultivars of young (<15 years old) pecan [Carya illinoinensis (Wangenh.) K. Koch] trees are presented. These patterns show that pollination and receptivity windows within the flowering season can be divided into very early, early, mid, late, and very late season protandrous (Type I) and protogynous (Type II) types. This system therefore provides a seasonally based 30-class Type I and Type II alternative to the standard two-class Type I and Type II system, thus offering enhanced resolution of flowering intervals and an improved means of selecting cultivars to ensure cross-pollination of yard and orchard trees. Scott-Knott cluster analysis of budbreak, nut ripening date, and date of autumn leaf drop segregated cultivars into one of several categories.