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  • Author or Editor: W. R. Okie x
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Two-node stem cuttings of 23- to 79-day-old seedlings of peach [Prunus persica (L.) Batsch] rooted readily under mist in 3 weeks and rooted better than 1-node cuttings. Cuttings from young seedlings rooted well without leaf-trimming or hormone treatments. Rooting of cuttings from lower nodes of older seedlings was improved by an indole-3-butyric acid (IBA) dip. Soil mix (1 soil : 1 peat : 1 vermiculite, by volume), Metro-Mix 300, vermiculite, and peat pellets all allowed adequate rooting in contrast to sand. Slow-release fertilizer improved root growth. Survival rates of 70–95% were obtained using vigorous young stock plants, 2-node cuttings, and soil mix plus Osmocote. Subsequent growth appeared similar to seedling growth.

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Check digit technology is frequently used in commercial applications such as shipping labels and credit cards to flag errors in numbers as they are used. Most systems use modular arithmetic to calculate a check digit from the digits in the identification number. Check digits are little used in horticultural research because the guidelines for implementing them are neither well known nor readily accessible. The USDA–ARS stone fruit breeding program at Byron, Ga., plants thousands of trees annually, which are identified using a 2-digit year prefix followed by a sequential number that identifies the tree location in the rows. Various records are taken over the life of the tree including bloom and fruit characteristics. Selected trees are propagated and tested further. To improve the accuracy of our records we have implemented a system which uses a check number which is calculated from the identification number and then converted to a letter that is added onto the end of the identification number. The check letter is calculated by summing the products of each of the digits in the number multiplied by sequential integers, dividing this sum by 23, and converting the remainder into a letter. Adding a single letter suffix is a small change and does not add much complexity to existing data collection. The types of errors caught by this system are discussed, along with those caught by other common check digit systems. Check digit terminology and theory are also covered.

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The status of plum breeding around the world is reviewed. Two distinct types of plums are grown: Japanese-type shipping plums (mostly diploid hybrids of Prunus salicina Lindl. with other species) such as are grown in California, and hexaploid or “domestica” plums (P. domestica L.), which have a long history in Europe. In recent years there has been a resurgence of plum breeding outside the United States.

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Willow-leaf peaches, reported by Lesley (1957) as a product of inbreeding but also mentioned as far back as 1887 (Hedrick, 1917), are characterized by a narrow leaf shape. We received willow-leaf germplasm from Wayne Sherman (Univ. of Florida, Gainesville), who selected a peach seedling with unusually narrow leaves from a group of seedling rootstocks. His original willow-leaf tree bore very small, poor-quality fruit. In 1983, it was used in breeding at the USDA-ARS breeding program at Byron to develop willow-leaf peaches with improved fruit types. After four generations, current selections are approaching commercial fruit standards in size, color, firmness, and attractiveness. Inheritance studies indicate the character is at least partially dominant and is expressed in some F1 seedlings of crosses with wild-type parents. However, the precise mode of inheritance remains unclear as the ratios do not fit common patterns. Progeny show a range of leaf narrowness, complicating characterization of genotype. The character may be useful in standard-type trees to enhance spray penetration, speed drying of the foliage to reduce disease, improve light penetration and photosynthetic efficiency, and make the fruit more visible to speed picking.

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White-fleshed peaches and nectarines are delicacies that have been enjoyed for centuries around the world. They are native to China and were introduced to the United States in the 1800s. Some white-fleshed peaches and nectarines are highly perishable and bruise easily, but are of very high eating quality. These are perhaps best suited for the local roadside market, where they can be sold and consumed more quickly. Others are much firmer at harvest, have a longer shelf life. and are suitable for long-distance transport to wholesale markets. White-fleshed peaches and nectarines may have some acidity or they may be very low acid with high sugar content (°Brix). Some novel flat (peento or donut) types also exist. Proximity to an urban market with a substantial Asian population is advantageous because Asians, in particular, often prefer the low-acid flavor and are willing to pay premium prices for high quality fruits. In our peach and nectarine cultivar evaluation program at Clemson University, we are currently evaluating 70 cultivars and advanced selections at four different locations in South Carolina. Several of these have been evaluated since 2000 and the “top performers” over the last six seasons by ripening date (earliest to latest) include the following: `Sugar May', `Scarletpearl', `Snowbrite', `Southernpearl', `White Lady', `Sugar Lady', `Summer Sweet', `Sugar Giant', `Stark's Summer Pearl', `Snow King', and `Snow Giant'. In general, most of the white nectarines and the flat/donut peaches and nectarines have serious problems with insect damage and brown rot. Complete details of our peach and nectarine (yellow- and white-flesh) evaluation work in South Carolina since 2000 will be noted by referring to my peach website (http://www.clemson.edu/hort/Peach/index.php).

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