No abstract

Silverleaf whitefly (SLW) (Bemisia argentifolii Bellows and Perring) feeding was associated with development of tomato irregular ripening (TIR) symptoms. `Micro-Tom', `Florida Basket', `Florida Lanai', and `Florida Petite' dwarf cherry tomatoes (Lycopersicon esculentum Mill.) were infested with adult SLW to observe oviposition preference, plant tolerance, and TIR symptom development in two experiments. There was no oviposition preference among the cultivars in either of the trials. TIR fruit symptoms were expressed as longitudinal red streaks with yellow, green, pink, or red blotches externally and white tissue internally. External TIR symptoms at the pink stage of ripening ranged from 32% (`Micro-Tom') to 82% (`Florida Basket') in Expt. 1 and 44% (`Micro-Tom') to 93% (`Florida Petite') in Expt. 2. In Expt. 1, external TIR symptoms disappeared from 18% (`Florida Lanai') to 37% (`Micro-Tom') and, in Expt. 2, 16% (`Micro-Tom') to 39% (`Florida Basket') of the fruit during ripening. SLW-infested plants exhibited 82% (`Florida Lanai') to 99% (`Florida Basket') and 76% (`Micro-Tom') to 90% (`Florida Petite') of fruit with internal white tissue regardless of external symptoms in Expts. 1 and 2, respectively. Tomatoes with severe TIR symptoms rarely ripened to full red. Postharvest characteristics of ripening SLW-infested and control fruit were evaluated (Expts. 3 and 4). Generally, the SLW-infested fruit were lighter in color than the control fruit. The control fruit developed normal red color while the SLW-infested fruit developed a blotchy, streaky color that was overall more of an orange-red. SLW-infested fruit were firmer than the control fruit in both experiments. Ethylene production was higher in SLW-infested fruit. While the total soluble solids contents were not significantly different between the treatments, the SLW-infested fruit were more acidic than the control fruit. Each cultivar was susceptible to oviposition by SLW and induction of TIR symptoms. However, TIR symptom expression differed among the cultivars. Despite higher ethylene levels, the ripening process in the SLW-infested fruit appeared slower or may have been inhibited by factors induced by the SLW compared with the control fruit, which ripened normally.

External and internal tomato irregular ripening (TIR) symptoms were associated with the feeding of silverleaf whitefly (SLW), Bemisia argentifolii Bellows and Perring. Four experiments consisting of various soil drench applications of GA 3 (100 ppm) and cycocel (CCC, an inhibitor of GA biosynthesis; 1,000 and 2,000 ppm) were applied to dwarf cherry tomato cv. Florida Petite in the presence and absence of SLW in an attempt to mimic the disorders induced by the SLW. The application of GA 3 induced external and internal TIR symptoms similar to the SLW-induced disorder. Minimal TIRlike symptoms also occurred in the control and CCC treatments. Internal TIR symptoms in GA 3 , GA 3 plus SLW, and GA 3 plus CCC treatments ranged from 66% to 97% throughout the experiments. The incidence of external TIR symptoms was highest in the GA 3 plus SLW treatment compared with the other treatments. CCC reduced the incidence of external TIR symptoms induced by GA 3 or GA 3 plus SLW treatments. However, CCCtreated plants also attracted more oviposition and higher populations of SLW and consequently induced a greater incidence of TIR symptoms than SLW treatment alone. Furthermore, although low SLW populations may be associated with low external TIR symptoms, internal TIR symptoms almost always remained high in infested plants. The results suggest that the TIR disorder in dwarf cherry tomato which is induced by the SLW may be a gibberellin-regulated disorder.

External and internal tomato irregular ripening (TIR) symptoms have been associated with the feeding of silverleaf whitefly (SLW), Bemisia argentifolii Bellows and Perring. Soil drench application of gibberellic acid (GA3) (100 ppm, Trial 1 and 2) and cycocel (CCC) (2000 ppm, Trial 1; 1000 ppm, Trial 2) were applied to dwarf cherry tomato (Lycopersicon esculentum) in the presence and absence of SLW to mimic the TIR disorder induced by the SLW. Application of GA3 induced external and internal TIR symptoms similar to the SLW-induced disorder in `Florida Petite'. There were essentially no TIR symptoms in fruit treated with CCC, an inhibitor of GA biosynthesis. In Trial 1, internal white tissue in GA3, SLW, and CCC treatments was expressed in 97%, 95%, and 4% of the total fruit, respectively. Incidence of external TIR symptom was highest (56%) in the GA3 plus SLW treatment. In Trial 2, GA3 application in the presence (83%) or absence (85%) of SLW resulted in the highest incidence of fruit with internal white tissue. External TIR symptoms induced by GA3 in the presence and absence of SLW were reduced with CCC application. These results suggest that the TIR disorder in tomato is induced by the SLW may be a GA3-regulated disorder.