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- Author or Editor: J.W. Daniell x
- HortScience x
Abstract
Rooted twig cuttings of ‘Jefferson’ peach [Prunus persica (L.) Batsch] infected or noninfected with phony peach disease were divided into nonphony, medium phony, and severe phony based on symptoms and on Fastidious, gram-negative, xylemlimited bacteria (PPXLB) counts. During the dormant season, the rooted plants were subjected to cold treatments of -11.7°, -14.4°, -17.9°, -20.0°, and -21.6°C in cold chambers. Plants with higher PPXLB counts exhibited more cold injury than plants with lower counts.
Abstract
Twenty-seven cultivars of peach [Prunus persica (L.) Batsch] and 4 seedling clones were evaluated over a 3 year period for susceptibility to gummosis disease caused by Botryosphaeria dothidea (Moug. ex Fr.) ces. & de Not. ‘Harbrite’ was highly resistant while ‘Pekin’, ‘Harmony’, ‘Redskin’, ‘Harken’ and ‘White English’, a seedling clone, exhibited some degree of resistance. All other cultivars were susceptible.
Abstract
A device was designed to permit accurate and rapid measurement of the abscission or removal force of peaches when used with a mechanical force gauge. To handle fruit of different sizes, small and large units were constructed. A detail drawing of the two units is shown. This instrument was used to study the physiology of abscission, chemicals for thinning, and chemicals for uniform ripening of peaches for mechanical harvesting as related to the removal force.
Abstract
Softwood cuttings taken from phony peach disease-infected and uninfected trees of ‘Jefferson’ peach [Prunus persica (L.) Batsch] produced 80% or more well-rooted cuttings with no significant difference (5% level) between phony and non-phony cuttings.
Abstract
‘Woodroof’ pecan [Carya illinoensis (Wang) K. Koch] has been released to provide a disease-resistant, very good quality cultivar for home orchards in the southeastern United States where scab [Fusicladium effusum (Wint.)] is a major disease. Within the past 20 years, scab has greatly reduced pecan yields in home plantings in the southeast where the small number of trees does not justify expensive disease-control equipment (3, 5).
Abstract
‘Spalding’ pear (Pyrus sp. Nak) has been released to provide a good quality pear cultivar for home planting in the Piedmont area of the southeast where fire blight is a major problem.
Abstract
Nondestructive studies of plant root systems are limited to hydroponic and glass-wall-type growing systems, which are expensive and limit the ways to observe and measure root structures. The following system was adapted from agronomic studies as a convenient, cost-efficient, and sensitive method of monitoring root growth of horticultural crops.
Abstract
Application of 960 ppm (2-chIoroethyl)methylbis(phenylmethoxy)silane (CGA-15281) substantially inhibited carbon transport into young fruit of peach [Prunus persica (L.) Batsch] 4 to 5 days before visual symptoms of senescence occurred. Carbon transport was unaffected 4.25 hours after treatment, but was greatly reduced after 24 hours. Reduced carbon transport continued through 144 hours following CGA-15281 application.
Two field experiments were conducted to assess peach (Prurus persica L.) cultivar susceptibility to the three Botryosphaeria spp. that cause peach tree fungal gummosis. Inoculated trees were evaluated for disease severity by rating gum exudation, vascular discoloration, and fungal colonization. Each severity measurement yielded a different rank ordering of cultivars for susceptibility. However, in a greenhouse study, these same measurements gave consistent rankings for aggressiveness of the fungal species on `Blake'. Despite large differences in disease severity in the greenhouse study, none of the severity measures were correlated with tree growth after inoculation. The only factor significantly correlated with growth rate of the trees after inoculation was growth rate before inoculation.
Abstract
Dormant cuttings of muscadine grape, Vitis rotundifolia Michx., rooted best early in the dormant season, although root quality was poor and the percentage rooting was low. Large-diameter cuttings rooted better than small-diameter cuttings. A high percentage of cuttings with aerial roots produced additional root growth. Medium heating was necessary for root formation. No significant rooting response was observed with indolebutyric acid (IBA), (2-chloroethyl) phosphonic acid (ethephon), precallousing, sucrose treatments, or with mallet cuttings.