Fire blight, caused by the bacterium Erwinia amylovora (Burrill) Winslow et al., is one of the most destructive diseases of plants in the Rosaceae subfamily Maloideae. Artificial inoculations, using E. amylovora strain E2002a, were conducted to determine levels of resistance to fire blight among taxa of flowering pears (Pyrus L. spp.) and quince (Chaenomeles Lindl. spp.). The level of resistance was measured as the length of the fire blight lesion as a percentage of overall shoot length. Considerable variation in resistance was observed among both pears and quince. Pyrus ussuriensis Maxim. `Prairie Gem' was highly resistant with a lesion length of 1% of the total shoot length. Pyrus calleryana Decne. `Bradford' was intermediate with a 50% lesion length while P. calleryana `Chanticleer' was significantly more resistant with a lesion length of 31%. Nine pear taxa were highly susceptible and did not differ significantly from 100% disease severity (total shoot death). Chaenomeles speciosa (Sweet) Nak. `Contorta' was highly resistant with a lesion length of 15%. Six quince taxa, including C. × superba (Frahm) Rehd. `Cameo', `Texas Scarlet', and `Jet Trail' were highly susceptible while nine other taxa showed intermediate resistance.
Andrew C. Bell, Thomas G. Ranney, Thomas A. Eaker, and Turner B. Sutton
Douglas H. Marin, Sylvia M. Blankenship, Turner B. Sutton, and William H. Swallow
Mature green `Grande Naine' bananas (Musa AAA) were harvested 13 weeks after flowering in June and Sept. 1993 and Feb. and Mar. 1994 and were sent air freight to Raleigh, N.C. Fruit were held under 1) storage (36 days at 14 C and 80% to 90% relative humidity) or 2) ripening (8 days storage, followed by ethylene treatment on day 8 and subsequent storage at 17 °C and 80% to 90% relative humidity). Despite of similar grade and age, length of the preclimacteric phase (green life) was different between fruit harvested at different times of the year. Fruit harvested in February and March had a longer green life than those harvested in June and September. Rate of respiration best described changes that occurred during the postharvest life of bananas; however, variables such as pulp pH and soluble solids could be commercially useful measures. Once gassed with ethylene, ripening rates were similar between all four lots of fruit, indicating that seasonal variation probably doesn't contribute much to variability seen during ripening. Hand position in the bunch did not have a large influence on variability during ripening or storage.