Search Results

You are looking at 1 - 9 of 9 items for :

  • Author or Editor: Dean R. Evert x
  • HortScience x
Clear All Modify Search
Author:

Armothin® thinned `Sentinel' fruit on peach trees (Prunus persica L.) in 1993. Thinning increased as Armothin® rate in the single spray increased from 1.5X, to 3.0% to 6.0% (v:v) and as the percentage of open blossoms increased from 30% to 61%. The 1.5 % rate of Armothin® thinned significantly only on the third date, and the 6.0% rate overthinned slightly on the third date. Minor discoloration developed on the expanding leaves of a few of trees but disappeared in a few days. No leaf abscission occurred on treated trees and tree growth was normal. Variability between trees treated alike probably reflects the variability in bloom when sprayed. According to Akzo, Armothin® prevents pollination by reacting with the surface of the receptive stigma. Spraying after full bloom should selectively prevent fertilization of the last blossoms to open without destroying the fertilized fruit. This possibility will be tested in 1994. Armothin®, which is a contact thinner, seems to avoid the problems associated with thinners that act as growth regulators and with nonselective caustic thinners. Because of its low phytotoxicity and wide range of effective rates, Armothin® has great potential as a chemical thinner.

Free access
Author:

Abstract

Center-pivot irrigation during two radiation frosts in Mar. 1986 increased the temperature and reduced fruit injury in a wedge-shaped sector of a 6-year-old ‘Rio Grande’ peach [Prunus persica (L.) Batsch.] orchard. Irrigation increased temperatures under the pivot as much as 5°C during the –5.3° frost on 2 Mar. and 3° during the –2.8° frost on 23 Mar. The percentage of live fruit on 3 Mar. ranged from 35% on nonirrigated trees adjacent to the irrigated sector to 67% on trees in the middle of the irrigated sector (P < 0.01). The percentage of live fruit after the less severe frost on 23 Mar. ranged from 80% to 95% in the same locations (P > 0.05). The weight of fruit thinned on 21 Apr. was 18.2 kg for trees in the middle of the irrigated sector, 2.1 kg for trees along an edge of the irrigated sector, and 9.5 kg for nonirrigated trees adjacent to the irrigated sector (P < 0.05); therefore, injury likely was greater along the edge of the irrigated sector.

Open Access
Author:

Abstract

Weight and flesh firmness of peach fruit [Prunus persica (L.) Batsch ‘Junegold’] were measured at harvest from phony-infected and noninfected trees. Regression equations showed that fruit from phony-infected trees had an average increase in weight of 0.95 g to 1.03 g per newton decrease in flesh firmness at harvest, significantly less than the 1.69 g to 2.90 g increase per newton decrease for normal trees (P = 0.05). Internal moisture stress caused by xylem blockage in phony-infected trees may explain the changed flrmness/weight relationship during final swell.

Open Access

More peach [Prunus persica (L.) Batsch.] trees survived when planted in killed bahiagrass (Paspalum notatum Flugge `Paraguayan-22') sod growing between previous orchard tree rows (98%) than when planted in previous tree sites (81%) or in previous tree rows, but halfway between previous tree sites (79%). The previous orchard was removed Nov. 1986, and new trees were planted Feb. 1987. Surviving trees in the killed sod grew better than trees at the other two sites. Tilling the sites before planting did not affect nematode populations or tree survival and growth. Soaking the tree roots in a fenamiphos solution (1 g·liter-1) for 20 minutes before planting resulted in 79% tree survival vs. 93% survival for the nonsoaked trees. Fenamiphos sprayed under the trees at a rate of 11.2 kg·ha-1 during the spring and fall of the planting year did not change nematode populations, tree survival, or tree growth. The fenamiphos sprays reduced the increase in trunk cross-sectional area by 3 cm2 for trees in the sod. Other than leaf Zn concentration, which was low, concentrations of the elements were within the sufficiency range for Georgia for all treatments. Trees planted in the killed sod had an increased leaf K concentration and decreased leaf Mg concentration when compared with trees planted in the rows. Chemical name used: ethyl 3-methyl-4-(methylthio)phenyl (1-methylethyl)phosphoramidate (fenamiphos).

Free access

Abstract

Horticulturalists frequently use the analysis of variance (F-test) to determine treatment differences. Many simple non-parametric tests, which require fewer assumptions, are also available. This note presents an example of the modified Friedman test as an alternative analysis for ranked data from a randomized complete-block design.

Open Access

Abstract

The xylem water potential of leaves of peach [Prunus persica (L.) Batsch] was lower for trees with moderate to high counts of the phony peach disease organism in roots during the day in September and October (P = 0.1%), after bloom in March (P = 3%), and before harvest in May (P = 1%). No significant differences occurred for predawn measurements on any date, during periods of rapid shoot growth in June, and for measurements made on terminal twigs in January. Experimental results suggest that the phony disease organism invades and clogs the new xylem each year. The internal water stress that results when the tree transpires produces the fruit and shoot symptoms known as phony disease of peach.

Open Access

Two peach cultivars (Flordaking & Junegold) were planted in wheel-spoke design under a center pivot irrigation system. Main plots were sprays (Blast, Cheek, & Piggy-back) and cultivars. Sub-plots were training systems (Inside, Outside, & Standard). Sub-sub-plots were tree areas. Four rows were planted with two Inside rows and two Outside rows. Middle two rows of the standard plots were harvested. Intra-row spacing increased the further they were from the center. All trees harvested in 1990, standard plots were harvested every year, and Inside/Outside were harvested in alternate years. Most sources of variation in the model failed to be homogeneous among the 3 years. Since the number of trees harvested each year varied, all mean comparisons were done using the unequal N - unequal variance t-test.

Free access

Abstract

Forsythia mandschurica Uyeki, F. ovata Nakai, and F. × intermedia Zab. ‘Lynwood’ flower buds were frozen from 0 to –35°C during January to mid-April 1978, then forced under intermittent mist. In field and laboratory tests, ‘Lynwood’ flower buds were significantly less hardy than those of F. mandschurica or F. ovata. The hardiness of the latter 2 species was not significantly different throughout the test period. In May, 50 to 60% of F. mandschurica and F. ovata flower buds bloomed; 5% of the ‘Lynwood’ bloomed. Regression equations at 20% flower bud survival indicated that during mid-winter F. mandschurica survived temperatures 3.6° colder than did F. ovata.

Open Access

Abstract

Pesticides were applied to ‘Rio Grande’ peach [Prunus persica (L.) Batsch] trees at recommended rates from bloom to harvest using three sprinkler configurations on a center pivot and an air-blast sprayer. Fruit scab infection rates with a patented sprinkler configuration (Piggy-back) that has spray nozzles mounted on a lower truss rod of the center pivot were equivalent on 12 and 23 June 1987 to those with the air-blast sprayer. Scab infection rates for standard impact-nozzles and for a deflector nozzle configuration were equivalent to each other, and tended to be lower than the infection rate for the unsprayed fruit, but higher than the rate for the air-blast sprayer or piggy-back configuration. Brown rot, bacterial spot, and insect catfacing (the other fruit defects observed at harvest) were independent of the method of pesticide application. It may be feasible to chemigate peach orchards with center-pivot irrigation systems.

Open Access