Search Results

You are looking at 21 - 30 of 73 items for

  • Author or Editor: Michael W. Smith x
Clear All Modify Search

Legume ground covers in pecan orchards can reduce nitrogen inputs and increase beneficial insects. Preliminary data indicate that certain legumes can supply over 100 kg·ha-1 N. Additionally, certain legumes have high aphid populations which attract beneficial insects. When aphid populations on the legumes crash, beneficial insects seek alternative food sources in the pecan trees, thus reducing the necessity for pesticide applications. Preliminary studies suggest that a mixture of 'Dixie' crimson clover and hairy vetch produces high populations of beneficial insects and over 100 kg·ha-1 N. Treatments were established at four pecan orchard sites in Oklahoma, each with 5 ha of a crimson clover/vetch mixture and 5 ha of native grass sod. Additions of 0-200 kg·ha-1 N were added to the sod plots but no supplemental N was added to the legume plots. Nitrogen and biomass production by the legumes, and leaf N concentration of pecans were determined. In addition, both aphid and beneficial insect populations were monitored in the legume and grass treatments, and in the pecan trees. Results will be discussed in the presentation.

Free access

Patch budding is a common propagation technique for pecan (Carya illinoinensis) commonly used in the central and western United States, but seldom used in the southeastern United States. Success rates vary, but 75% is normally an acceptable survival rate. Selected budwood and rootstock treatments were evaluated to improve budding success. Additional studies were conducted to evaluate bud forcing techniques that would leave the rootstock intact, allowing a second bud to be inserted if the first patch bud failed. Girdling exceptionally vigorous shoots at the base used for budwood improved success, but neither tip pruning shoots used for budwood or rootstock affected patch bud survival. Patch budding was more successful using budwood from 1-year-old branches than from current season shoots, a finding that greatly extends the window available for propagation using patch buds. The age of rootstock wood at the budding site did not affect patch bud survival. Girdling the rootstock immediately above the dormant patch bud was less effective than top removal for forcing the patch bud in the spring. Application of a lanolin paste of 0% to 5% 2,3,5-triodobenzoic acid (TIBA) or 0.02% 6-benzylaminopurine (BAP) to a girdle immediately above the patch bud was positively related to the percentage of patch buds forcing when tree tops were left intact. The combination of girdling, 5% TIBA, and 0.02% BAP resulted in 76% of the buds forcing compared with 73% forced using top removal. This approach damages trees less and enables a second chance for patch budding on a stronger tree.

Full access

Typical damage, cleanup, and recovery from four ice storms beginning in Dec. 2000, with the latest in Dec. 2007, are reported for pecan (Carya illinoinensis). Damage levels were amplified as radial ice accretion increased. Cultivar affected the amount of damage incurred. Trees less than 15 ft tall typically had the least damage. Trees 15 to 30 ft tall incurred as much or more damage than larger trees and cleanup costs were greater. Production potential was directly related to canopy loss during the first growing season. The time to recover full production potential varied with the severity of canopy loss. Cleanup costs depended upon the amount of canopy damage incurred, tree spacing, tree size, and the amount of pruning needed to remove hanging and damaged limbs from the tree.

Free access

Abstract

Juvenile cuttings of pecan (Carya illinoensis (Wang) K. Koch) produced more roots and a larger percentage of rooted cuttings than adult cuttings when treated with a 0.5, 1, or 2% solution of indolebutyгic acid (IBA) in February, 1 or 2% IBA in June, and 0.5 or 1% IBA in August. Juvenile cuttings treated with a 1% IBA solution produced significantly more roots than treatment with 0, 0.5%, or 2% IBA when cuttings were taken during February, June, or August. The percentage of juvenile cuttings rooting was greater with February, June, and August than April, October, and December collections.

Open Access

A study was conducted to compare a single nitrogen application in March (125 kg N/ha) vs. a split application in March (75 kg N/ha) and October (50 kg N/ha) on 15-year-old `Maramec'. After one season, N application time did not affect return bloom. A split N application increased trunk wood Kjeldahl-N but decreased Kjeldahl-N in the current season's reproductive shoots and 1-year-old branches compared to a single application in March. Kjeldahl-N concentration was not affected by treatment in current season's vegetative shoots, trunk bark or roots. Nitrate-N concentration was not affected by treatment in any tissue sampled. Between the first week of October and the first killing frost in November, Kjeldahl-N increased 29% in current season's shoots, 21% in trunk bark, 32% in roots >1 cm in diameter, and 15% in roots <1 cm in diameter but decreased 42% in trunk wood and 5% in 1-year-old branches. Roots <1 cm in diameter accumulated more nitrate-N than other tissues during November.

Free access

March vs. October N applications in factorial combination with two P rates were evaluated on two pecan [Carya illinoinensis (Wangenh.) C. Koch] cultivars. Leaf N concentrations were not affected by N application time. However, yield of `Hayes' was increased during 4 of 7 years and cumulative yield was increased 37% when N was applied during October compared to March. Yield of `Patrick' and individual nut weight and kernel percentage of `Hayes' and `Patrick' were not affected by N application time. Phosphorus application increased leaf P concentration 5 of 7 years during the study. Shoot growth, yield, individual nut weight, and kernel percentage were not affected by P application.

Free access

Abstract

Nitrogen and K were applied to 26-year-old ‘Western’ pecan [Carya illinoensis (Wangenh.) C. Koch] trees at 0, 56, 112, or 224 kg ha−1, and 0, 93, or 186 kg ha−1, respectively, for 6 consecutive years (1978–1983). There was a positive relationship between N rate and leaf N concentration and shoot growth. The number of new shoots per 1-year-old shoot was increased by N application. Yield was greater using 56, 112, or 224 kg N ha−1 than no N. Nitrogen rate was negatively related to leaf K concentration and curvilinearly related to leaf Mn concentration, but did not affect leaf Ca or Mg. Leaf P and Zn concentrations were reduced during some years by N application. Potassium application increased leaf K concentration in 1980, 1982, and 1983, but did not affect leaf K concentration in other years. Surface applied K moved to the 30–45 cm depth by 1980 and to the 45–60 cm depth by 1982. Potassium rate was positively related to leaf Mn concentration, but not leaf N, P, Ca, Mg, or Fe concentration. Annual yield was increased by K rate only in 1979, but cumulative yield was positively related to K rate.

Open Access

Effective nitrogen (N) management promotes consistent and abundant pecan [Carya illinoinensis (Wangenh.) C. Koch] production while minimizing waste. Recovery and partitioning characteristics of N potentially affects N management decisions; for this reason, we report certain N characteristics exhibited by trees in a bearing ‘Pawnee’ orchard. Nitrogen was applied prebudbreak (PBB) as a single 10 Mar. application at 1.689 g·cm−2 cross-sectional trunk area or a split application in Mar. (70%) followed by a midsummer application during rapid fruit development (RFD) on 28 July (30%) (i.e., PBB + RFD) using 15N-enriched fertilizer. Recovery of N by trees the first year was 7.2% from the PBB application and 11% from the RFD portion of the split application. Nitrogen application was 210% larger at PBB (Mar.) than at RFD (July), resulting in 118% more N absorbed. At harvest in November, fruit contained 41% and 36% of total N recovered during the first year from the PBB and RFD treatments, respectively. About 3% of the total fruit N was derived from fertilizer (NDF) absorption during the current year. Recovery was 12% for the PBB treatment and 19% for the RFD treatment by the end of the second growing season, with 93% more N absorbed from the PBB application. Nitrogen recovered from the PBB application increased ≈50% while trees were dormant, but there was little change in N recovery when applied during RFD. During the year of application, NDF was similar in shuck, shell, and kernel tissue when 15N-enriched fertilizer was applied PBB. When applied at RFD, more NDF was in the kernel than the shuck and shell, indicating rapid absorption and transport to the fruit, especially to the developing kernel. In both treatments, most fruit N was derived from tree storage reserves. In the second year, NDF was highest in shucks and lowest in kernels for the PBB application; thus, N enrichment from the previous year was being depleted. In contrast, NDF was higher in kernels than shucks and shells when 15N-enriched fertilizer was applied during RFD the previous year, indicating that N applied during RFD the previous July was being absorbed in the latter part of the subsequent growing season. This study demonstrates that pecan trees maintained with adequate N nutrition derived the majority of N used for annual parts from stored N pools, although applied N was also rapidly absorbed and transported to N sinks. Dependence on endogenous N pools explains why pecans usually require at least 2 years to respond when N is withheld from well-managed trees. These results emphasize the importance of maintaining an annual N fertility program for current and future production.

Free access

Abstract

Greenhouse experiments using seedling pecan trees [Carya illinoensis (Wan-genh.) C. Koch] compared rates and repeated applications of K2SO4, K2SO4 vs. KNO3, and Ν adjuvants in combination with K2SO4 or KNO3. Leaf and stem Κ concentrations increased linearly with rates to 87.1 g/liter K2SO4 applied 5 times at 14-day intervals. Phytotoxicity was negligible to 10.9 g/liter K2SO4. Plants receiving individual applications of KNO3 or K2SO4 at 9.8 g K/liter 2 times at 14-day intervals had 92% and 53% more Κ than the control, respectively. KNO3 at 25.3 g/liter or K2SO4 at 21.8 g/liter, in combinations with urea and/or NH4NO3 at 6.25, 12.50, and 25.00 g/liter, increased leaf Κ concentration significantly and the increase was consistently greater using KNO3 than K2SO4. Both urea and NH4NO3 applied with either KNO3 or K2SO4 increased leaf Κ concentrations. Negligible phytotoxicity occurred when urea or NH4NO3 was applied at 6.25 g/liter with K2SO4 or KNO3.

Open Access

Abstract

Thirty-six-day-old ‘Dodd’ pecan seedlings [Carya illinoensis (Wangenh) C. Koch] were flooded for 31 days or not flooded in factorial combinations with 0, 215, or 430 g P per m3 of media. Flooding decreased leaf number, leaf area, leaf and root dry weight, and induced stomatal closure. Flooding also reduced leaf, trunk, and root K, Ca, Mg, Zn, Fe, and Mn concentrations. Nitrogen was lower in the leaves and trunk of flooded trees, but higher in the roots of flooded trees than unflooded trees. Flooding decreased the leaf P concentration, but did not affect the P concentration in the roots. Phosphorus application increased leaf P concentration in unflooded trees, but not flooded trees.

Open Access