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Trees were pruned by removing 1, 2, or 3 leader limbs per year or not pruned from 1975 through 1993. Cuts were made flush with another limb below 9 m from the ground. Pruning induced trees to respond like younger trees. Pruning increased leaf N, P, Mg, Mn, Fe, Zn, vigor, color intensity, terminal growth, nut size, and nuts per terminal. Kernel grade was reduced slightly by pruning. Yield was reduced by two or three pruning cuts per year, but not by one cut. Pruned trees were lower, more spreading, and more efficient to spray. Removal of one leader per year satisfactorily held the tree within the 21.3 × 21.3 m spacing without reducing yield. The lower height of pruned trees should decrease loss from high winds. All pruned trees survived a hurricane and a small tornado, while many unpruned trees in the area were blown down.
Abstract
Dikegulac, when applied in the fall of a dry year, did not enhance shuck dehiscence of pecan (Carya illinoensis (Wang.) K. Koch but did promote increased numbers of new shoots on young trees the next spring.
Abstract
Leaflet mineral concentration of normal and mouse-eared leaflets differed for different cultivars of pecan (Carya illinoensis (Wang.) K. Koch). Normal ‘Schley’ leaflets were higher in Mg, Cu, Cr and Pb than mouse-eared leaflets. Normal ‘Desirable’ leaflets were lower in Cr, Pb and Cd than mouse-eared leaflets. Normal ‘Mohawk’ leaflets were higher in Mn, Cu, Al, Cr, Pb, and Cd than mouse-eared leaflets. Normal ‘Wichita’ leaflets were lower in Ca, Mg, Zn, Cr and Pb than mouseeared leaflets. Normal ‘Mohawk’ leaflets had a higher Zn/Fe ratio and normal ‘Wichita’ had a lower Zn/Fe ratio than mouse-eared leaflets.
Pecan [Carya illinoensis (Wangenh.) C. Koch] tree height was gradually reduced by removing one, two, or three limbs per year at a height <9 m. Pruning improved tree vigor and color, increased trunk circumference, terminal shoot growth, nut size, and leaf N, P, and Mg, but reduced leaf K and percentage of fancy grade kernels relative to unpruned trees. Yield was not influenced by selective limb pruning.
Nitrogen was applied at 112 kg·ha-1 to mature 'Stuart' pecan (Carya illinoinensis (Wangenh.) C. Koch] trees, but the radii of the application were limited to 4.6, 6.1, 7.6, or 9.1 m. Yield, nut size, percentage of kernel, tree growth, and appearance were not affected by concentrating the N application. Leaf N was highest for the largest N application radius, but all treatments supplied abundant N. Concentrating N reduced soil pH and occasionally P, K, and Ca in the 0–15 or 15–30 cm soil layers, but all three soil nutrients and Mg were medium to high after 19 years of treatments.
Abstract
Gibberellic acid (GA) and benzylamino purine (BA) induce many growth and fruiting responses in plants (Davies, 1986; Elkner and Coston, 1986; Forshey, 1982; Green, 1980; Jones, 1973; Unrath, 1974). This study was conducted to determine some vegetative, flowering, and yield responses of pecan trees to low rates of BA and GA.
Eleven `Desirable' pecan trees with yield data for 22 to 47 years were selected from a database with data from three orchards. Cumulative yield were computed for each tree. Cumulative data was transformed using LOG10. Quadratic or cubic regression curves were fit for each tree and for all in a single analysis. In most cases, variances were not homogeneous among the 11 trees. Using the regression coefficients for each tree, an average of the five was made and appropriate standard errors were computed. Number of cases where homogeneity of variances were found increased. Younger trees benefiting from better orchard management had different variances than older trees moving across changing managements. LOG10-transformation tended to decrease variation, but variances were still heterogeneous.