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E. W. Neuendorff and K. P. Patten

Rabbiteye blueberry flower buds are initiated and differentiated on three distinct wood types - spring growth on old weak growth, spring growth on vigorous 1-year-old shoots, or postharvest late summer/fall growth. Flower buds on spring growth are usually formed and visible by July, while buds formed on postharvest growth flushes appear in late summer and early fall. To evaluate the influence of wood type on cold damage, shoots of `Tifblue' and `Delite' were tagged by season of growth. Following a -10°C freeze in Feb. flower buds on shoots from each growth flush were examined for dead ovaries. Flower buds surviving the freeze were evaluated following a -2° late frost in Mar. Influence of wood type on floral bud and fruit development was determined. All fruit were removed from 5 shoots of each wood type on 2 harvest dates corresponding to early and midseason harvests. Floral buds formed on fall growth were more freeze and frost tolerant than those initiated on spring growth at similar stages of bud development. `Tifblue' was more cold tolerant than `Delite'. Floral buds formed on both spring wood types were earlier to develop than buds formed on fall wood. There were no differences in ripening patterns and quality of fruit removed from spring - new and fall wood. Fruit formed on spring - old wood were later maturing and smaller sized for both harvests than spring-new or fall wood. Postharvest pruning to encourage fall growth may be a cultural means of frost avoidance.

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Bala Rathinasabapathi, James Ferguson, and Mark Gal

Shredded and chipped wood mulches are used for weed suppression in perennial fruit crops, in urban landscapes, and occasionally in vegetable crops. Wood chip mulches with weed-suppressing allelochemicals may be more effective for weed control, especially under sustainable and organic production systems, than mulches without such properties. The objective of this study was to test for the presence of water-soluble allelochemicals in wood chips derived from tree species, often found in wood resource recovery operations in the southeastern US. Presence of allelochemicals in water eluates of woodchips and leaves was evaluated in a lettuce bioassay. Eluates of wood chips from red maple (Acer rubrum L.), swamp chestnut oak (Quercus michauxii Nutt.), red cedar (Juniperus silicicola L.H. Bailey), neem (Azadirachta indica A. Juss.), and magnolia (Magnolia grandiflora L.) highly inhibited germinating lettuce seeds, as assessed by inhibition of hypocotyl and radicle growth. The effects of wood chip eluates from these five species were more than that found for eluates from wood chips of black walnut (Juglans nigra L.,) a species previously identified to have weed-suppressing allelochemicals. Tests on red cedar, red maple, and neem showed that water-soluble allelochemicals were present not only in the wood but also in the leaves. In greenhouse trials, red cedar wood chip mulch significantly inhibited the growth of florida beggarweed (Desmodium tortuosum DC.), compared to the gravel-mulched and no-mulch controls.

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Patricia S. Holloway

Five woody ornamentals Rosa rugosa, Cotoneaster acutifolia, Malus baccata, Picea glauca and Pinus contorta var. latifolia, were grown for 4 seasons mulched with one of five treatments: 2.5 cm or 5 cm of crushed basaltic quarry stone, 5 cm or 10 cm of quaking aspen wood chips, and an unmulched control. Maximum soil temperatures at the 10 cm depth on the wood chip plots were decreased by as much as 8°C over control plots, and soil moisture was increased. Stone mulch plots showed a slight increase in both temperature and moisture. Soil minimum temperatures were lower on the wood chip plots than the other treatments early in the season, but were slightly higher in September. Soil pH and available N, P and K did not differ among mulch treatments. Weed growth was suppressed by all mulch treatments but was best controlled on the wood chip plots followed by the 5 cm stone plots. Plant growth for all species except Rosa rugosa was greatest on the stone mulch plots. Roses growing on the stone mulch plots and the control were subject to significant dieback from winter injury and did not show any difference in total growth after 4 years when compared with the wood chip plots. Plants grown on the wood chip plots exhibited varying degrees of nitrogen deficiency which may be related to reduced nutrient uptake in cooler soils or to a significant amount of rooting in the mulch-soil interface.

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Patricia S. Holloway

Five woody ornamentals Rosa rugosa, Cotoneaster acutifolia, Malus baccata, Picea glauca and Pinus contorta var. latifolia, were grown for 4 seasons mulched with one of five treatments: 2.5 cm or 5 cm of crushed basaltic quarry stone, 5 cm or 10 cm of quaking aspen wood chips, and an unmulched control. Maximum soil temperatures at the 10 cm depth on the wood chip plots were decreased by as much as 8°C over control plots, and soil moisture was increased. Stone mulch plots showed a slight increase in both temperature and moisture. Soil minimum temperatures were lower on the wood chip plots than the other treatments early in the season, but were slightly higher in September. Soil pH and available N, P and K did not differ among mulch treatments. Weed growth was suppressed by all mulch treatments but was best controlled on the wood chip plots followed by the 5 cm stone plots. Plant growth for all species except Rosa rugosa was greatest on the stone mulch plots. Roses growing on the stone mulch plots and the control were subject to significant dieback from winter injury and did not show any difference in total growth after 4 years when compared with the wood chip plots. Plants grown on the wood chip plots exhibited varying degrees of nitrogen deficiency which may be related to reduced nutrient uptake in cooler soils or to a significant amount of rooting in the mulch-soil interface.

Open access

Mary Bauer, C. E. Chaplin, G. W. Schneider, B. J. Barfield, and G. M. White

Abstract

‘Redhaven’ peaches (Prunus persica L. Batsch) were sprinkled from the end of rest, January 22, 1975, until the time check trees reached full bloom, April 18, 1975. Sprinkling delayed bloom by 15 days. Energy models predicted bloom one day before it occurred in the check trees. Wood temperatures were lowered as much as 6.5°C in sprinkled trees, but no significant difference in wood cold hardiness was observed. Sprinkled fruit buds were more cold hardy than non-sprinkled fruit buds until early March. Non-sprinkled buds were more cold hardy than sprinkled fruit buds in late March. Sprinkling reduced the number of viable buds/m by late March. Analyses of total and reducing sugars and protein showed no significant difference.

Open access

G. D. Blanpied and G. H. Oberly

Abstract

Analyses were made of Ca and Mg in a consecution of annual rings of 3 mature ‘McIntosh’ apple (Malus domestica Borkh.) orchard blocks in New York (acid rain region) and also 3 mature ‘McIntosh’ blocks in British Columbia (arid-irrigated region) in an attempt to assess the long range effects of acid rain on Ca levels in apple trees. Differences in patterns of Ca and Mg deposition in the wood did not appear to be caused by acid rain.

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Dennis Werner, Michael L. Parker, and Elisabeth Wheeler

Peach tree short life (PTSL), a major disease complex impacting peach culture in the southeastern United States for decades, accounts for millions of dollars of losses annually. In spite of the overwhelming amount of research that has been conducted on PTSL, many uncertainties still exist regarding the factors involved in the syndrome and the true cause of tree death. As a consequence, we examined the wood structure and anatomy of 6-year-old peach trees, some showing the initial visible symptoms of PTSL, and others that appeared unaffected and healthy. Very dramatic differences in wood anatomy were observed between healthy and stricken trees. Stricken trees showed a total lack of vessel formation in some earlywood zones, a decrease in vessel formation in latewood, and a marked increase in ray parenchyma cells. Healthy trees showed normal vessel and ray formation. Preliminary results indicate that in some way PTSL may be associated with increased gum production in the xylem and decreased earlywood vessel production, thereby significantly reducing water conduction, leading to tree death. Results of studies currently in progress to further investigate this hypothesis will also be presented.

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Danny L. Barney

During freezing studies of `Concord' grape (Vitis labrusca L.), bud viability significantly affected callus formation, adventitious root initiation, and root dry weight during regrowth assays conducted to assess freezing injury. Applying exogenous 1- H -indole-3-acetic acid (IAA) partially offset bud loss and stimulated root initiation. Further tests demonstrated that buds were less cold hardy than internode woody tissues in dormant `Concord' canes. Because of cold-hardiness differences between buds and wood and because bud viability affects callus formation, root initiation, and root dry weight, regrowth assays do not seem to be sensitive indicators of freezing injury in grape woody tissues. Regrowth assays, however, seem to be reliable indicators of overall viability for frozen `Concord' grape cuttings.

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Curt R. Rom and Jason McAfee*

`Apache' blackberry planted in 3-m plots spaced at 0.6 m between plants were maintained either with or without waste municipal wood chip mulch and grown for 5 years. Plots received similar weed control, pest management, and irrigation. All plots were annually hedged at 1.35-m height twice during midsummer to encourage branching. Fruit were harvested beginning in the second season after a season of establishment. Annual yield in the mulched plots was 15% greater, average fruit size was 4% larger, and cumulative yield was 9% greater in the mulched plots compared to nonmulched control plots. In two seasons, average berry soluble solids content of fruit from mulched plots was slightly, but not significantly higher. Annual primocane number was 33% greater, floricane number 41% greater, floricane dry weight after harvest was 15% greater, and average plant height before summer pruning was 24% taller in mulched plots compared to nonmulched plots. Mulch significantly reduced weeds within the plots.

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M.A. Woodard, B.C. Bearce, S. Cluskey, and E.C. Townsend

`Inca Yellow' marigolds (Tagetes erects L.) were planted in polyethylene bags containing coal bottom ash (CBA), pine wood peelings (PWP), a mixture of 1 CBA: 1 PWP (v/v), and loose Grodan rockwool (RW) and grown in a circulating nutriculture system. Three fertigation frequencies of 12, 6, or 4 cycles per 12-hour light period were set with a duration of 5 minutes each. Flower diameters of marigolds grown in CBA, PWP, and CBA-PWP exceeded flower diameters of RW-grown marigolds, and days from planting to harvest were less in CBA and CBA-PWP than in the other two media. There was no interaction between medium and fertigation frequency. Foliar analysis showed no significant differences in plant elemental composition among root media or fertigation frequencies. Postharvest PWP water extracts contained higher P levels than extracts of other media, and CBA-PWP water extracts contained higher K, Ca, and Mg. In the CBA-PWP mixture, decomposition products from PWP may have increased P volubility and solubilized the K, Ca,-and Mg-in CBA.