Abstract
Columns of discolored and decayed wood associated with 42 wounds in silver maple (Acer saccharinum L.) were examined with a pulsed-current resistance meter (Shigometer) prior to dissection. Resistance measurements, expressed as a percentage of control readings, were correlated to depth, cross-sectional areas, and calculated volume of the discolored and decayed wood column. The instrument accurately detected the presence and depth of discolored wood. Relative decay volume could be established in a nondestructive manner.
`Washington Navel', `Biondo Comune', `Tarocco', and `Valencia Late' orange [Citrus sinensis (L.) Obsek] fruit, harvested at various periods of time, were subjected to ultraviolet-C (UV-C) irradiation at 0.5, 1.5, or 3.0 kJ·m-2 doses and then stored at 7 °C and 90% to 95% relative humidity (RH) for 4 weeks plus one additional week at 20 °C and 80% RH. Following UV-C treatment, there was varying amounts of rind browning and necrotic peel damage, depending on cultivar, treatment dose, and harvest date. `Tarocco' fruit were damaged more easily by UV-C treatment than the other cultivars. `Valencia L.' were the most resistant to UV-C irradiation, showing no adverse effects at the lowest dosage and having the lowest percentages of damaged fruit at higher dosages. `Washington Navel' and `Biondo Comune' oranges showed an intermediate susceptibility to UV-C treatment, with negligible differences between these cultivars. The percentage of damaged fruit after irradiation at the higher UV-C dosages decreased in most fruit samples as the season progressed. UV-C irradiation at 0.5 kJ·m-2 effectively reduced decay development compared with nontreated fruit. Irradiation with 1.5 kJ·m-2 was more effective compared with 0.5 kJ·m-2 only in early harvested fruit. In `Washington Navel' and `Biondo Comune' oranges in the later harvests, treatment with 3.0 kJ·m-2 improved decay control further, compared with 0.5 kJ·m-2. Following UV-C treatments the phytoalexins, scoparone and scopoletin, accumulated in flavedo tissue depending on the cultivar, fruit age, and UV-C treatment. Both phytoalexins displayed a similar accumulation pattern, however, the levels of scopoletin were very low compared with scoparone. Concentrations of phytoalexins rose as the irradiation dose increased. No scoparone and scopoletin could be detected in nontreated fruit. The highest concentration of phytoalexins among cultivars was recorded in `Valencia Late' oranges, the lowest in `Tarocco', with similar intermediate accumulations in `Washington Navel' and `Biondo Comune'. In `Washington Navel', `Biondo Comune', and `Tarocco' oranges, the rate of scoparone accumulation was significantly higher in fruit harvested earlier in the season while `Valencia late' oranges exhibited an opposite trend.
increase in toluene removal efficiency was assessed over a 7-d period, the timing of the decline was more precisely illustrated ( Fig. 3 ). The decay in the stimulation response varied depending on the plant species tested. B. maculata declined
). Thus, tree mortality resulting from diseases, wood decay, and insects causes significant economic losses in many different ways. Despite the importance and valuable roles that landscape trees play in the enhancement of our quality of life, urban trees
Abstract
Chlorogenic acid and arbutin reduced spore germination of Penicillium expansum Lk. ex Thom, and mycelial growth of Mucor piriformis Fischer. Arbutin decreased growth of Botrytis cinerea Per ex Fr. However, chlorogenic acid increased both germination and growth of B. cinerea.
containers that are delivered to the supermarket. Any treatment to reduce decay of strawberries would best be done as a preharvest operation to fit the current industrial harvesting and handling practices. Postharvest decay treatments to strawberries would
advantage of the fact that incipient decay lesions caused by the green mold or blue mold pathogens ( Penicillium digitatum or Penicillium italicum , respectively), and other severely damaged areas on the fruit display a bright yellow fluorescence in the
of apple slices. Hexanal has also been used to control postharvest decay in stone fruit incited by Monilinia laxa and Rhizopus stolonifer ( Caccioni et al., 1995 ). Hexanal has other properties in addition to its antimicrobial activity. Aroma
change as a result of respiration and package film gas permeation or achieved actively (active MA) by flushing the package with N 2 before sealing the bags closed ( Kim et al., 2005 ). Lettuce has genetic variation for decay or shelf life (tissue
Table grapes are a nonclimacteric fruit with a low rate of physiological activity ( Peynaud and Ribereau-Gayon, 1971 ) but are subject to serious water loss and decay during postharvest handling ( Nelson, 1985 ). Gray mold caused by the fungus