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Bruce W. Wood

There is increasing evidence of substantial pollination related crop losses by pecan [Carya illinoensis (Wangenh.) K. Koch] orchards. These most likely occur in block-type orchards consisting of only one or two cultivars, but can also occur at locations with a great number of different genotypes nearby. Main crop cultivars should generally be within about two rows of pollinizers to ensure cross-pollination. Thus, block widths exceeding about four rows between pollinizers are especially likely to exhibit serious pollination problems. Scattered trees of off-type genotypes are potentially of major importance as backup orchard pollinizers. Tree age/size and spring temperatures influence the characteristics of flower maturity windows and are probably primary factors contributing to pollination-related fruit-set losses in many block-type orchards. Flower maturity tends to be earlier in older/larger trees while warmer springs accelerate catkin development relative to that of pistillate flowers. Because of substantial variability in relative differences associated with initiation and duration of flower maturity windows within either protandrous or protogynous flowering types (i.e., Type I or II), selection of complementary pollinizers should be based on the relatively high resolution 30-class flowering classification system rather than the traditional low resolution 2-class system. Other factors sometime causing pollination related crop losses are either abnormally wet weather or strong dry winds during the pollination period or abnormally warm or cool springs. Pollination problems can be visually detected by noting premature non insect related post pollination fruit drop or diminishing fruit set with increasing distance from pollinator trees or off-type genotypes within the orchard.

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Darby S. Kellum, Manoj K. Shukla, John Mexal, and Sanjit Deb

). To the best of our knowledge, no studies have quantified GHG emissions from irrigated pecan orchards of southern New Mexico. The objectives of this research are 1) to examine the effect of soil moisture, fertilization, climate, and soil texture on N 2

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G.R. Brown, J. Hartman, R. Bessin, T. Jones, and J. Strang

Apple growers would like to use pesticides efficiently and diminish concerns about food safety and pesticide usage. The 1992 Apple IPM Program objectives were: 1) to demonstrate the application of Integrated Pest Management practices in commercial orchards and, 2) to provide the training and support needed to help these growers become self sufficient in IPM practices. Grower training meetings and regular scouting of the orchards were the primary educational methods. End-of-the-season evaluations of past and disease incidence were made. Except for Frogeye Leaf Spot, there were no significant differences in insect pest, disease levels or in fruit quality attributes in IPM versus standard blocks. The IPM blocks had significantly more mite incidence. Growers did produce commercially acceptable crops using IPM based decisions while reducing the average past control cost by $56 par acre. Educational programs did help growers to be more proficient in making IPM based decisions.

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M. Teresa Gómez-Casero, Francisca López-Granados, José M. Peña-Barragán, Montserrat Jurado-Expósito, Luis García-Torres, and Ricardo Fernández-Escobar

mechanized harvesting) to obtain modern olive orchards. They realize that for sustainable production and good net returns, site-specific fertilization based on maps from remote sensing approaches may have potential. Canopy hyperspectral reflectance analysis

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Rhuanito S. Ferrarezi, Arun D. Jani, H. Thomas James III, Cristina Gil, Mark A. Ritenour, and Alan L. Wright

the uncertain future of grapefruit in the Indian River, some grapefruit growers in the region are considering sweet orange as an alternative citrus crop. However, this region is characterized by poorly drained soils, and grapefruit orchards are

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M.L Parker, J. Hull, and R.L. Perry

The root distribution of peach trees [Prunus persica (L.) Batsch cv. Redhaven/Halford] as affected by six orchard floor management treatments was evaluated after 3 years of growth. Two treatments were maintained vegetation-free and four had vegetative covers in the alleyway with a 1.2-m-wide herbicide strip in the tree row. The profile wall method was used to determine root distribution. Trees maintained vegetation-free with herbicide had the most roots. Trees in the vegetation-free plots, maintained with herbicide or cultivation, produced more roots 1.2 m from the tree than trees in the vegetative covers. The number of roots, 1.2 m from the tree, was lowest in the tall fescue treatment. The number of roots were higher in the Kentucky bluegrass (Poa pratensis L.) or alfalfa (Medicago sativa L.) than with tall fescue (Festuca arundinacea, Schreb.).

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Steven A. Weinbaum, R. Scott Johnson, and Theodore M. DeJong

Over-fertilization (i.e., the application of fertilizer nitrogen (N) in excess of the tree or vine capacity to use it for optimum productivity) is associated with high levels of residual nitrate in the soil, which potentially contribute to groundwater and atmospheric pollution as a result of leaching, denitrification, etc. Overfert-ilization also may adversely affect productivity and fruit quality because of both direct (i.e., N) and indirect (i.e., shading) effects on flowering, fruit set, and fruit growth resulting from vegetative vigor. Pathological and physiological disorders as well as susceptibility to disease and insect pests also are influenced by the rate of applied N. Over-fertilization appears to be more serious in orchard crops than in many other crop species. The perennial growth habit of deciduous trees and vines is associated with an increased likelihood of fertilizer N application (and losses) during the dormant period. The large woody biomass increases the difficulty in assessing the kinetics and magnitude of annual N requirement. In mature trees, the N content of the harvested fruit appears to represent a large percentage of annual N uptake. Overfertilization is supported by a) the lack of integration of fertilizer and irrigation management, b) failure to consider nonfertilizer sources of plant-available N in the accounting of fertilizer needs, c) failure to conduct annual diagnosis of the N status, and d) the insensitivity of leaf analysis to over-fertilization. The diversity of orchard sites (with climatic, soil type, and management variables) precludes the general applicability of specific fertilization recommendations. The lack of regulatory and economic penalties encourage excessive application of fertilizer N, and it appears unlikely that the majority of growers will embrace recommended fertilizer management strategies voluntarily.

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C.R. Unrath

High-density apple (Malus domestica) orchard management techniques and productivity were evaluated on an old orchard replant site in North Carolina. Trees were planted at 5 × 10 ft (1.5 × 3.0 m), giving a tree density of 871 trees/acre (2152 trees/ha). Well-branched `Smoothee Golden Delicious' trees on `Mark' rootstock were planted in 1990. Orchard-management factors which increased cumulative yield were supplemental irrigation (+21%), slender spindle training (+19%), preplant tree-hole fumigation (+11%), and fumigation + postplant mefenoxam (Ridomil) collar drench (+17%). Collectively, these factors increased cumulative yield by 55%. Supplemental irrigation was the only treatment to significantly impact fruit quality, increasing average fruit size by 20% over the 11-year study.

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Bruce Wood*, Charles Reilly, and Andrew Nyczepir

Nickel (Ni) is an essential nutrient element for higher plants; although, it has generally been ignored. This is because it appeared that Ni deficiency would not likely occur in field situations. This conclusion is because a) Ni content of nearly all soils is thought to be high enough to satisfy plant requirements, and b) plant Ni requirements were thought to be very low. Thus, plant Ni nutriton has been generally ignored. We report here: 1) the discovery of acute Ni deficiency in field plantings of pecan (Carya illinoinensis); 2) the wide variety of symptoms associated with Ni deficient; 3) soil management conditions that cause Ni deficiency; and 4) potential impact of Ni deficiency on management strategies for crops. Observations indicate that Ni deficiencies are occuring on many woody crops in orchard or nursery situations. Evidence indicates that Ni deficiency is likely a factor in many complex disorders of unknown cause affecting a variety of crops. Ni deficiency problems are likely to become increasing common and severe as a result of contemporary management practices. The information presented identifies a need for greater attention to plant Ni nutrition by practitioners of crop husbandry.

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Michael L. Parker and John R. Meyer

Peach trees (`Biscoe'/Lovell) were planted in March, 1988 in ten different ground cover management systems. The trees were planted at the Sandhills Research Station in Southeastern North Carolina on a Candor sand and Eunola sandy loam. In December, 1991 the trench profile method was used to evaluate root distribution under the six orchard floor management systems of nimblewill, bare ground control, centipedegrass, brome, bahiagrass, and weedy control. Trenches were dug parallel to the tree row 60 cm from the center of the row on both sides of the tree. Grids 1 meter square, sectioned into 10 cm squares, were placed on the profile walls and root distribution (in three size categories) was recorded for 1 meter on each side of the tree in each trench. Root numbers were greatly reduced under the vegetative covers that provided the greatest suppression of vegetative tree growth. Total root densities under the trees in the vegetative covers were ranked into three size categories which were correlated with the amount of vegetative tree growth.