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Dario J. Chavez, Eileen A. Kabelka, and José X. Chaparro

Phytophthora capsici causes seedling death, crown and root rot, fruit rot, and foliar blight on squash and pumpkins (Cucurbita spp. L.). A total of 119 C. moschata accessions, from 39 geographic locations throughout the world, and a highly susceptible butternut squash cultivar, Butterbush, were inoculated with a suspension of three highly virulent P. capsici isolates from Florida to identify resistance to crown rot. Mean disease rating (DR) of the C. moschata collection ranged from 1.4 to 5 (0 to 5 scale with 0 resistant and 5 susceptible). Potential resistant and tolerant individuals were identified in the C. moschata collection. A set of 18 PIs from the original screen were rescreened for crown rot resistance. This rescreen produced similar results as the original screen (r = 0.55, P = 0.01). The accessions PI 176531, PI 458740, PI 442266, PI 442262, and PI 634693 were identified with lowest rates of crown infection with a mean DR less than 1.0 and/or individuals with DR = 0. Further selections from these accessions could be made to develop Cucurbita breeding lines and cultivars with resistance to crown rot caused by P. capsici.

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Dennis J. Werner, Michael A. Creller, and José X. Chaparro

Inheritance of the blood-flesh (red-violet mesocarp) trait in peach [Prunus persica (L.) Batsch.] was investigated in S1, S2, F1, F2, F3, BC1P1, and BC1P2 families derived from `Harrow Blood', a clone showing anthocyanin accumulation in fruit about 45-50 days after anthesis. This trait invariably was associated with the red midrib leaf phenotype in `Harrow Blood', an S1 family from `Harrow Blood', and in green leaf F2 progeny derived from `Harrow Blood' × `Rutgers Red Leaf 2n'. A segregation ratio of about 3 blood-flesh : 1 wild-type was observed in the S1 family, but F1 progeny produced only wild-type fruit. Examination of F2 progeny segregating for the blood-flesh and red leaf traits revealed no evidence of epistasis. Based on segregation ratios in F1, F2, F3, BC1P1, and BC1P2 families from this cross, the F1 family from `Contender × (`Harrow Blood' × `Rutgers Red Leaf 2n'), and six additional F1 families from crosses between `Harrow Blood' and green leaf clones with wild-type fruit, we propose that blood-flesh is controlled by one gene, designated bf (blood-flesh). The blood-flesh phenotype was associated with reduced tree height in S1 and F2 progeny derived from `Harrow Blood'. Segregation for leaf blade color deviated significantly (P = 0.05) from the expected 3 red : 1 green ratio in six of the F2 families derived from selfing seven F1 trees from `Harrow Blood' × `Rutgers Red Leaf 2n'.

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Michael A. Creller, Jose X. Chaparro, and Dennis J. Werner

Inheritance of the blood flesh (red-violet mesocarp) trait in peach [Prunus persica (L.) Batsch] was investigated. `Harrow Blood' fruit began accumulation of anthocyanin about 40 days after anthesis. The blood-fleshed trait was associated with the red-veined leaf phenotype in `Harrow Blood' and its self progeny. An approximate segregation ratio of 3:1 (red vein:green vein) was observed in a population generated by selfing `Harrow Blood'. All 112 F1 progeny from a cross of `Harrow Blood' × `Rutgers Red Leaf'-2n produced wild-type fruit. Phenotypic segregation for red leaf:green leaf deviated from the expected 3:1 ratio in two of three F2 families derived from these F1's. More red leaf segregants were observed than expected. Bed-veined, green-leafed progeny comprised about 25% of the green-leafed seedlings in the F2. Examination of fruit on a limited number of F2 segregants revealed the presence of red-leafed, blood-fleshed individual. Preliminary results suggest that the blood trait may be controlled by two loci. The red-vein phenotype was associated with reduced tree height in self progeny of `Harrow Blood'.

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Thomas G. Beckman, Jose X. Chaparro, and Wayne B. Sherman

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Thomas G. Beckman, Jose X. Chaparro, and Wayne B. Sherman

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Jose X. Chaparro, Patrick J. Conner, and Thomas G. Beckman

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Todd W. Wert, Jeffrey G. Williamson, Jose X. Chaparro, E. Paul Miller, and Robert E. Rouse

The effect of climate was observed on the relative frequency of vegetative and floral buds in four low-chill peach cultivars (‘Flordaprince’, ‘Flordaglo’, ‘UFGold’, and ‘TropicBeauty’). The trees were planted in north–central, central, and southwest Florida. The percentage of blind nodes, mixed nodes (nodes with vegetative and floral buds), and nodes with only vegetative buds were determined from three representative shoots per tree at each location. In general, higher percentages of blind nodes were observed in central and southwest Florida and higher percentages of mixed nodes were observed in north–central Florida. ‘TropicBeauty’ tended to have a greater percentage of blind nodes than the other cultivars. Higher temperatures during bud formation most likely contributed to the increased amounts of blind nodes observed in the central and southwest locations and to the reduced amounts of mixed nodes. However, stresses imposed by bacterial spot and hurricanes may have contributed to the higher incidence of blind nodes in 2005. Our results indicate that certain genotypes have a predisposition for the formation of blind nodes. Advanced selections having low chilling requirements and potentially being adapted to a wide diversity of tropical or subtropical climates need to be tested in multiple locations to evaluate blind node formation.

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Todd W. Wert, Jeffrey G. Williamson, José X. Chaparro, E. Paul Miller, and Robert E. Rouse

Fruit shape of four low-chill peach [Prunus persica (L.) Batsch] cultivars was evaluated in north-central, central, and southwest Florida. During 2005, measurements were taken at all locations for cheek diameter, suture diameter, and tip protrusion. A suture deformation index was calculated (suture diameter/cheek diameter) to determine suture deformation. Fruit had more protruding tips and suture deformation was more pronounced at the southwest location than at the north-central or central locations. Overall, ‘TropicBeauty’ had more protruding tips than the other cultivars. It was concluded that warmer temperatures at the southwest location during fruit development affected fruit shape by increasing the incidence of protruding tips and pronounced sutures.

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Gerard W. Krewer, Thomas G. Beckman, Jose X. Chaparro, and Wayne B. Sherman

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Todd W. Wert, Jeffrey G. Williamson, Jose X. Chaparro, E. Paul Miller, and Robert E. Rouse

The effect of climate was observed on fruit quality of four low-chill peach cultivars (Flordaprince, Flordaglo, UFGold, and TropicBeauty). The cultivars were evaluated in three locations (north–central, central, and southwest Florida). Soluble solids content (SSC), titratable acidity (TA), SSC:TA ratio, fruit weight, blush, and fruit development period (FDP) were determined. Longer FDPs were observed at the north–central location than at the southwest location. Fruit development and the expression of quality attributes were affected by location during fruit growth with higher color and SSC and shorter FDP occurring under warmer conditions. Within locations, ‘UFGold’ had the shortest FDP except at the southwest location where its chilling requirement may not have been met. At the central and southwest locations, ‘UFGold’ also tended to have lower TA values and higher SSC;TA ratios than the other cultivars.