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Vitalization is a process whereby senescence is retarded and refrigerated storage can be extended. The process involves hyperhydration of plant materials with selected aqueous solution, thereby flooding interstitial spaces and vascular tissues. Microscopic examination revealed increased size of interstitial spaces and expansion and increased roundness to cells. No disruption of tissues was detected. Turgidity was measured with an Instron Universal Testing Machine equipped with a Kramer Shear Cell. Color was measured with a Minolta color difference meter. Leaves were evaluated for color and turgidity changes during storage. Vitalized leaves did not change significantly in color or turgidity during a 10-week storage period. Untreated leaves lost turgidity and yellowed in storage.
White drupelet disorder (WDD) in blackberry (Rubus subgenus Rubus) is an abiotic condition resulting from a cultivar and environment interaction. Although high temperatures and light intensities have been implicated, little is known why this disorder manifests. Other factors, such as overall plant stress, may be contributing influences. In this study, three treatments were applied to examine whether the addition of nitrogen (N) can reduce WDD on ‘Sweetie Pie’ erect blackberry over three seasons. An initial 50 lb/acre (56.0 kg⋅ha–1) N was applied to all plots at budbreak. Two additional N application treatments of 100 kg⋅ha–1 were applied at one time (1×) or five, 20-kg⋅ha–1 applications (5×), spaced 1 week apart for 5 weeks starting at bloom. One control treatment of no additional N (0×) was also included. Berries were harvested and weighed as a total, then berries with white drupelets were separated out and weighed. The two values were divided to create a proportion and were then multiplied by 100 to determine the percentage. Nitrogen application decreased the percentage of white drupelet berries from 13.0% (control) to 10.0% (one additional application) and 9.1% (five additional applications). WDD for the 0× treatment correlated negatively to maximum high daytime temperatures during May (r = –0.58, P = 0.03) over the three seasons. Occurrence of white drupelets by treatments 0×, 1×, and 5× correlated significantly with the cumulative number of rainfall events (r = 0.49, 0.47, and 0.46, respectively). Leaf chlorophyll index and photosynthesis measurements were unaffected by treatment. Although it is likely that multiple factors are involved in the development of white drupelets, additional N may reduce the problem.
Abstract
Five rates of ZnSO4 and 3 rates of S were applied in March 1966 in a single application to pecan trees (Carya illinoensis (Wang) K. Koch) in a factorial experiment. A rate of ZnSO4 in excess of about 20 kg/tree would be required to reach June 1966 leaflet Zn concentration in excess of the minimum optimum range of 60 ppm. No 1966 treatment resulted in leaflet Zn concentration in excess of 60 ppm in June 1967 or 1968. Significant Zn and S interaction was detected in September 1966 and 1967 leaflet Zn concentrations. There was a direct relationship between application rates of ZnSO4 and S on leaflet Zn concentration in September 1966 and 1967.
Resistant cultivars are a promising disease control method for eastern filbert blight, which is devastating hazelnut production in Oregon. In 1990, two studies were begun to evaluate the relative resistance of European hazelnut (Coyhls avellana) genotypes to the causal fungus, Anisogramma anomala. A randomized block design of 40 genotypes was planted using inoculated trees planted in the borders as the disease source. The first- and second-year disease incidence (percent) were compared to the published disease incidence (percent) based on exposing potted trees of 44 genotypes to high doses of inoculum. Disease incidence was significantly correlated between the two studies in 1991 (r =0.41, P = 0.02) and in 1992 (r =0.64, P = 0.001; rs = 0.35, 0.025 < P < 0.050). Three genotypes, however, showed no disease in the field, but they had disease in >70% of the potted tree study. A plot of disease incidence in the field planting indicates that the inoculum was present throughout the blocks.