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French prunes growing on marianna 2624 (P. cerasifera × P. munsonianna; M 2624), myrobalan seedling and 29C (P. cerasifera; MS and M 29C, respectively) were planted in 1981 on a clay type soil, and evaluated for growth and yield components over a 10 year period. Thirty replicate trees per treatment were pruned and grown under uniform irrigation and fertility regimes. There were no tree size differences among rootstocks after 10 years growth even though initial and seasonal trunk cross sectional area differences were observed. Trees on MS rootstock were highest yielding in the initial 2 years of fruiting, but cumulative yields were not different as a function of rootstock. More rootstock suckers were counted on M 2624 than myrobalan rootstocks. Excavations revealed that trees on MS had a deeper root distribution. No statistical differences were observed with regard to fruit size and fresh to dry fruit weight ratios.

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Commercially available cultivars of tomato Solanum lycopersicum L. were field-tested for resistance to Tomato spotted wilt virus (TSWV) over a 5-year period (from 2006 to 2010) at the Coastal Plain Experiment Station at Tifton, GA. Selected cultivars were transplanted each year into staked, black plastic mulch beds on drip irrigation in the spring of each year when the incidence of Tomato spotted wilt (TSW) tended to be highest. The presence of TSWV was confirmed by double antibody sandwich (DAS) enzyme-linked immunosorbent assay (ELISA). Also, the presence of thrips vectors was monitored using beat-cup sampling of foliage and flower samples. Tomato cultivars with the Sw-5 resistance gene provided high levels of control of TSW expression over all 5 years. However, these genotypes had no apparent effect on the thrips vectors, western flower thrips, Frankliniella occidentalis (Pergande), and tobacco thrips, Frankliniella fusca (Hinds), that transmit TSWV. Overall, the top 15 commercial tomato cultivars based on consistent TSW resistance and ranked from highest marketable fruit yield were: ‘Tycoon’, ‘Tous 91’, ‘Talladega’, ‘Red Defender’, ‘BHN 444’, ‘Nico’, ‘Carson’, ‘BHN 685 (Roma type)’, ‘Picus’, ‘Redline’, ‘Tribute’, ‘Quincy’, ‘BHN 640’, ‘BHN 602’, and ‘Top Gun’.

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Prune (Prunus domestica) producers have an increased incentive to produce larger fruit. Potassium is thought to be critical in prune production and the fruit utilize large amounts of K. Growers have been fertilizing heavily with K to maximize fruit size. We conducted a survey of 16 `French' prune orchards in 1998 and 1999 growing seasons. Low (≈1.0% mid-July) leaf K concentration is associated with leaf chlorosis, early leaf drop and shoot dieback, with symptoms pronounced in the upper canopy, particularly with heavy cropping. The survey orchards were chosen to represent a range of leaf K within and among orchards, and among counties. At harvest, fruit drying ratio, dry yield per tree, and dried fruit size were determined in order to develop relationships between fruit quality and yield, and leaf K over the growing season. To date we have determined the following: 1) spring (May 1998 and April–May 1999) leaf K concentration is correlated with mid-summer (mid-July 1998) and early summer (late June 1999) leaf K concentration, respectively; 2) mid-April to mid-May leaf K concentration is being maintained by growers due to thinning and fertilizing, and to light cropping in 1998, at adequate to above adequate levels (2%) that increase through the growing season; 3) no beneficial relationship between fruit size, drying ratio or dry yield has been found with spring or summer (June or mid-July) leaf K concentration above 2%, either when evaluating all surveyed orchards together or as individual orchards.

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Abstract

‘Horizon’, a small shoot-mass tomato (Lycopersicon esculentum Mill) cultivar, and ‘Sunny’, a large shoot-mass cultivar were planted at 30.5-, 61-, and 91-cm within-row spacings at five locations in Florida during Spring 1985 to determine if yields differed between these cultivars and among plant densities. Marketable weight and number of fruit per plant, mean fruit size (g/fruit), and shoot weight increased linearly with an increase in within-row spacing. Marketable weight of fruit/ha decreased linearly with wider within-row spacings. Responses of both cultivars to within-row spacing were similar for each measured trait, except for marketable fruit number per plant. A larger increase in marketable number of fruit per plant occurred between 61- and 91-cm within-row spacings for ‘Sunny’ than for ‘Horizon’. Fruit : shoot ratio (w/w) was not influenced by within-row spacings or cultivars. Each measure variable differed among locations. These results suggest that ‘Sunny’, with a larger inherent shoot growth, sufficiently compensated for smaller shoot growth when grown at higher plant densities to maintain marketable fruit yields comparable to ‘Horizon’.

Open Access

Bell pepper (Capsicum annuum L.) cultivars were grown in nine Florida environments to evaluate phenotypic stability of marketable fruit yield (t-ha-') and mean fruit size (g/fruit). A stable cultivar excelled for a particular trait when grown in either favorable or unfavorable environments. A stable cultivar for a given trait was defined as one with an individual mean greater than the grand mean (mean of all cultivars) (x > X), a regression coefficient (b1) ≤ 1 (individual genotypic mean regressed against environmental means), nonsignificant deviation mean squares from regression (S2d), coefficient of linear determination (R2) > 0.50, and coefficient of variation (cv) < the pooled cv. `Ssupersweet 860', `Whopper Improved', and `Ranger' were stable for mean marketable fruit weights and fruit size, and `Ssupersweet 860' and `Whopper Improved' were stable for mean fruit size. Bell pepper cultivars were differentiated for phenotypic stability of yield and fruit size or adaptability to diverse environments. Therefore, through stability analyses, bell pepper plant breeders can identify cultivars or select advanced breeding lines that express adaptability for fruit yields or size to diverse environmental conditions or cultural practices.

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Mini watermelons are the size of cantaloupes and weigh 1.5 to 3 kg (4 to 8 lbs). Melons of 18 selections were grown in replicated trials in North Carolina, South Carolina, and north and south Florida. Melons were harvested when ripe, and samples of heart and locule tissue were frozen and sent to Lane, Okla. A total of 960 samples, representing 6-12 melons per selection per location, were analyzed for total lycopene content using colorimeter and spectrophotometer methods. Subsamples of `Mohican', `Hazera 6007', `Vanessa', `Petite Treat', and `Precious Petite' were analyzed by HPLC for carotenoid profiles. Total lycopene content ranged from 52 to 108 μg·g-1, depending on variety. Selections were grouped into two levels of lycopene content. The varieties Precious Petite, Petite Perfection, Betsy, Bonny, Petite Treat, Valdoria, Vanessa, Hazera 5133 and 5138, RWT 8149, 8155, 8162 had 60 to 79 μg·g-1 lycopene and the varieties Hazera 6007, 5123, 5109, 5177, Mohican, and Extazy had 80 to 100 μg·g-1. Melons harvested from the Florida locations had more total lycopene than those from North and South Carolina. `Precious Petite' had more β-carotene as a percentage of total carotenoids than other varieties tested. These results indicate that lycopene content is affected primarily by germplasm and also by environment.

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Tomato (Lycopersicon esculentum Mill.) was grown with drip irrigation on an Arredondo fine sand and on an Orangeburg fine sandy loam to evaluate the effect of N and K time of application on petiole sap, leaf-N and -K concentrations, fruit yield, and to determine N and K sufficiency ranges in leaf tissue. On the sandy soil, N—K at 196-112 kg·ha-1 were applied 0%, 40%, or 100% preplant with the remainder applied in 6 or 12 equal or in variable applications in 12 weeks. With the variable application rate, most nutrients were applied between weeks 5 and 10 after transplanting. On the sandy loam soil that tested high in K, only N (196 kg·ha-1) was applied as above. Petiole sap K concentration declined during the season, but was not greatly affected by treatment. Petiole NO3-N concentrations decreased during the season from 1100 to 200 mg·L-1, and the decrease was greater with preplant N treatments. On the sandy soil, marketable fruit yields were lowest with 100% preplant, intermediate with 100% drip applied (no preplant N), and highest with 40% preplant and 60% drip applied. With 100% drip applied, yields were higher with 12 even applications than with either six even weekly applications or with 12 variable N and K applications. With 40% preplant, timing of application had little effect on yield. On the sandy loam soil in 1993, yields were highest with 100% preplant, intermediate with 40% preplant and 60% drip applied, and lowest with all N drip applied. In 1994 when excessive rains occurred, yields were similar with all preplant and with split N applications. Petiole N concentration was correlated with tomato yield, especially at 10 weeks after transplanting. The best correlation between sap-N and total yields occurred between 4 and 6 weeks at Gainesville and between 4 and 10 weeks at Quincy.

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Abstract

Ten fresh-market tomato (Lycopersicon esculentum Mill.) genotypes were evaluated for stability of fruit firmness, citric acid, soluble solids, β-carotene and ascorbic acid concentrations, sugar : acid ratio, color, N content, and dry weight when grown in nine environments. Linear relationships between the genotype means for a given trait and the mean for the trait in each environment were used as an indicator of stability. A stable genotype for a given trait was considered to possess a regression coefficient (b1) ⩽ a coefficient of linear determination (r2) > 0.50, a genotype mean above the grand mean (mean of all genotypes), and a nonsignificant deviation from regression mean square (S2d). Using these criteria, stability in the nine environments was shown by the fruits of the various cultivars as follows: ‘Flora-Dade’, ‘FTE-12’, and D76I27 for firmness; ‘Castlehy 1035’ and ‘Sunny’ for citric acid; ‘Walter’ for soluble solids concentration; ‘FTE-12’ for ascorbic acid concentration; ‘Hayslip’, ‘Walter’, and ‘Burgis’ for sugar : acid ratio; ‘FTE-12’ and ‘Hayslip’ for β-carotene concentration: ‘Flora-Dade’ and 827115-IBK for color a/b; ‘Castlehy 1035’ and ‘Hayslip’ for dry weight; and ‘Walter’ for N content. Stable genotypes are less sensitive to environmental changes and are more adapted to favorable and unfavorable conditions than unstable genotypes. No genotype was found to be stable for every fruit quality trait in the nine environments. Stability of fruit quality characteristics should be considered in tomato breeding programs to develop genotypes adapted to diverse environmental and management conditions.

Open Access

Studies were conducted at three locations in Florida to evaluate the effects of kasugamycin alone, in alternation, or as a tank-mix partner with copper bactericides and other fungicides against bacterial spot of tomato. In greenhouse trials, kasugamycin, formulated as Kasumin® 2L, reduced bacterial spot severity by up to 37.5% compared with a non-treated control. Little advantage in disease control was observed by mixing kasugamycin with other fungicides. Kasugamycin was assessed in six field trials. In the four field trials that tested kasugamycin alone, it was as effective as the standard copper + mancozeb treatment for the control of bacterial spot. In four trials, no benefit was observed in applying kasugamycin as a mixture with copper + mancozeb, and only one of three trials did alternating kasugamycin with copper + mancozeb improve bacterial spot control over either the copper + mancozeb standard or kasugamycin alone. Although kasugamycin was effective for the control of bacterial spot in greenhouse and field trials, rapid development of resistance in field populations of X. perforans may shorten the effective use of this antibiotic.

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