Genetic interaction of the pillar (PI) and weeping (WE) growth habit genotypes was investigated in peach [Prunus persica (L.) Batsch]. Data from F2, BC1P1, and BC1P2 families showed that PI (brbr) was epistatic to the expression of WE (plpl). A unique growth habit not previously described in peach, and referred to as arching (AR), was recovered in the F2 family. Arching trees showed an upright phenotype similar to Brbr heterozygotes, but had a distinct curvature in the developing shoots. Progeny testing of AR trees revealed their genotype is Brbrplpl.
Dennis J. Werner and Jose X. Chaparro
Daniel R. Cooley, Terry A. Tattar, and Julianne T. Schieffer
Oxytetracycline microinjection was assessed in four Massachusetts peach [Prunus persica (L.) Batsch] orchards where many trees were infected with X-disease. The injections significantly alleviated symptoms in all but the most severely diseased trees in the first year following treatment. This improvement was observed, to a lesser degree, the second season after treatment. Injection wounds did not callus and some damage to wood was observed around them, but after 2 years, there was no indication that injection wounds resulted in significant tree damage. Microinjection capsules offer an effective and more efficient injection treatment than existing methods.
Genevieve Pelletier and C.S. Tan
A time domain reflectometry (TDR) technique was used to measure water in the soil profile to derive wetting patterns of drip and microjet irrigation systems in a peach [Prunus persica (L.) Batsch] orchard. A distinct cone shape of >50% available soil water (ASW) extending from the emitter down to a depth of >45 cm was observed in the drip system. The 50% ASW zone in the microjet system was an elongated semicircle from the soil's surface down to a depth of 35 cm. TDR can be used successfully to determine wetting patterns of various irrigation systems to develop better irrigation scheduling.
W.R. Okie and D.J. Werner
Spring frosts often kill all or a portion of the flowers on peach [Prunus persica (L.) Batsch] trees in the southeastern United States. Increased flower bud density increases the likelihood of sufficient flowers surviving to produce a crop. The effect of environment on flower bud density (buds/node) was studied using two locations over 3 years. Bud density of 25 peach and nectarine varieties grown in completely randomized designs was measured in Georgia and North Carolina. Genotypic variability was greater than location or year effects. Varieties selected for high bud density at one location can be expected to have high densities at other locations with similar chilling.
W.V. Welker and D.M. Glenn
Peach [Prunus persica (L.) Batsch] trees were planted in killed sod developed from five different grasses. Tree growth was evaluated within the killed-sod treatments, as well as between killed-sod and bare soil treatments. Canopy width, tree height, and trunk cross-sectional area were all greater in the killed-sod treatments than in the bare soil treatments. All five grasses tested were acceptable for developing a killed-sod mulch. Chemical names used: N-(phosphonomethyl) glycine (glyphosate); N1(3,4-dichlorophenyl)-N,N-dimethylurea (diuron); 5-chloro-3-(1-1-dimethylethyl)-6-methyl-2,4(1H,3H)-pyrimidinedione (terbacil).
T.M. Gradziel and W. Beres
A single seedling exhibiting a semidwarf growth habit was found in an open-pollinated clingstone peach [Prunus persica (L.) Batsch] population. The growth habit was upright and open, with short, spur-like lateral branching. Tree size was about half that of its siblings as a result of shorter internodes. The total number of nodes on first-order branches was not significantly different from that on standard-sized trees. The semidwarf growth habit remained stable after vegetative propagation. Segregation in sexual progeny showed the trait to be highly heritable.
Michael Maurer, Thomas DeWitt, and Gary Ritenour
Mature 7-year-old `Raycrest' peach trees (Prunus persica [L.] Batsch) were treated at prebloom and late postbloom with foliar sprays of lactidichlor ethyl at 0, 25, 50, 75 and 100 mg·liter-1. A trunk girdled treatment was also included. Lactidichlor ethyl treatments had no effect on fruit set, fruit size and maturity. Girdling trees 30 days postbloom increased fruit size and enhanced maturity, but had no effect on fruit set. These results suggest that fruit size and maturity are enhanced by girdling.
D.M. Glenn, T. Tworkoski, R. Scorza, and S.S. Miller
The lack of dwarfing rootstocks for peach has led to cultural and genetic approaches that reduce tree size and vegetative growth to establish high-density plantings. The objectives of the study were to evaluate the interactions of pruning strategies, groundcover management, tree densities, and peach (Prunus persica) architecture combined in eight peach production systems on components of yield and economic value. The use of sod management reduced pruning time and costs, but the reduction of crop load reduced net return. High-density plantings in large vegetation-free areas (VFAs) had greater economic return than low-density plantings.
Danielle R. Ellis and Gregory L. Reighard.
Trees of `Redhaven' peach [Prunus persica (L.) Batsch] budded to `Lovell', `Bailey', and `Nemaguard' rootstocks were grown with bahiagrass or cultivated orchard middles. Terminal shoots were collected once a month through the dormant season. `Redhaven' on `Lovell' had significantly higher levels of sucrose, sorbitol, total soluble sugars, starch and total non-structural carbohydrates than `Redhaven' on `Nemaguard'. However, there were no significant differences in any carbohydrate fraction between `Redhaven' on `Bailey' and the other rootstocks. Orchard floor management system had no significant effect on carbohydrate levels.
Loong S. Chang, Amy Iezzoni, and Gerald Adams
Heritability and the genetic and environmental variance components of resistance to the canker-causing pathogen Leucostoma persoorrii were estimated in a population of diverse peach (Prunus persica L.)-genotypes. Disease resistance was measured as the length of necrotic tissue, i.e., canker length, following artificial inoculation in the field. Genetic and environmental variations were partitioned as variance components of the linear statistical model. Heritability was estimated by regressing average performance of seedlings on performance of their maternal parent. The genetic variance was highly significant, and the heritability for canker necrotic length was relatively high (0.72), suggesting that it should be possible to select L. persoonii -resistant individuals within the population.