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- Author or Editor: John E. Fucik x
Grapefruit is weighed in air and water using the suspended weighing hook on the bottom of a top loading balance. Weight and volume of a fruit of any shape can be accurately determined in less than a minute.
Uniform samples of Texas grapefruit, harvested in December, January, February, and March, were run through five Rio Grande Valley packingsheds, then stored for 30 days at 65C and 80% RH. The tests were done in 1987, 1988, and 1989 (December only). Data evaluated were degreening effectiveness, water loss, spoilage, and juice analysis. There were no degreening differences between sheds. Analyses of the parameters of time in storage × water loss regressions for sheds and harvest dates showed fruit harvested in the warmer months tended to have the higher percentage of water loss. Water loss differences between sheds was inconsistent, varying with month and season. The correlation between average fruit weight and percentage of water loss was very inconsistent. Harvest date rather than sheds had the most influence on spoilage. While the variations in the physical characteristics and chemical treatments of each packing line probably underlay the packingshed × harvest date interaction for water loss, no simple cause and effect hypothesis involving all these factors could be constructed.
To meet the Federal Crop Insurance's need to estimate the fruit crop on young citrus trees with no bearing history and partial fruit loss, the relationships between tree age, trunk and canopy size, and yields were studied. Pertinent data taken over many years from 1- to 7-year-old trees were analyzed using SAS regression procedures. The correlations for tree age × trunk diameter and truck diameter × canopy size were highly significant with R2 > 0.80. Although its R2 was only 0.20, the canopy size × yield correlation provided an acceptable estimate of the potential yields of grapefruit trees ≤6 years of age. The effect of 20% to 80% leaf loss on subsequent yields was determined in a field experiment, and the results included with a training guide on estimating leaf loss. The whole program was designed to provide a method by which insurance adjusters with little previous citrus experience could estimate postfreeze yield losses.
The harvest of Rio Red grapefruit (Citrus paradisi Macf.) was “intercepted” at three stages: 1) unpicked fruit, 2) picked and carried to pallet box trailer, and 3) picked, carried, dumped in the pallet box and transported to the packing shed. Three harvesters picked fruit from four canopy locations on two trees each. At each intercept, half the fruit was dipped into a spore solution of green mold (Penicillium digitatum) and half left nontreated as controls. Intercept 1 fruit was dipped and left unpicked on the tree. After 10 days incubation, the rate of green mold infection and its location on the fruit was determined. Tests were run in May 1995 and Feb. and Apr. 1996. The rate of infection increased with each intercept, and treated fruit had 15 times the infection rate of the controls. The highest infection rate, 1.3%, occurred in May 1995 followed by Feb. (0.8%), and April (0.5%). Most infection sites appeared above and below the fruit's equator, rather than on its top or bottom exclusively. There were no effects associated with harvesters or the location of the fruit in the canopy.
Water extracts of cocklebur,CBX (Xanthium spinosa L.) and velvetleaf,VLX (Abutilon theophrasti Medic.) shoots and Mexican ash,AshX (Fraxinus Berlandieriana A.DC.) roots were added to 9 month-old sour orange Citrus aurantium L.) seedlings(SOs) in water culture. Final extract concentrations represented either 50 or 12.5 g. of plant material liter-1 of culture solution, i.e. 1/20 or 1/80 dilutions. Leaf water potential(ψ); stomatal conductance(gs);transpiration(T) and growth responses were measured for 13 days. After 1 day, SOs in AshX and CBX had lower ψ than controls. After 11 days SOs in CBX had higher ψ than the others. ψ responded similarly to both extract concs.. Thru day 5, AshX decreased gs vs. the controls and VLX. By day 11, gs of SOs in AshX was less than for VLX but not the others. On days 1 and 5, gs for VLX at 1/20 was lower than controls but at 1/80, gs's were the highest of all treatments. These results supported by the T rates, growth responses and others findings suggest AshX and VLX induce water stress by reducing water absorption and/or transport in addition to possibly disrupting normal root/shoot communications
Advertisers endow Texas grapefruit with perennial, uniform excellence, yet prices reflect quality variation in the packed product. This study attempts to determine which packinghouse operations, if any, contribute to this variation. Sixty marked `Ruby Red' grapefruit were run through each of 5 Rio Grande Valley packingsheds. Sample runs were made in Dec., Jan., Feb., and Mar. for two seasons. Within-sample variation was reduced by picking outside canopy fruit from the same 20 trees. After packingshed treatment, weekly water loss was determined over 30 days storage at 22 C. and 70% R.H. Then fruit juice and peel were evaluated. Water losses varying from 6-8% appeared related more to initial differences between sheds than to rate of loss in storage. Water loss was greatest for March-and lowest for January-harvested fruit with Dec. and Feb. intermediate. Packingsheds had no effect on fruit spoilage. While some differences between juice (e.g., %) and peel (e.g., strength) characteristics were associated with water loss, season and harvest date caused the greatest variation.
Glyphosate [41% a.i. isopropylamine salt of N-(phosphonomethyl) glycine] at 0, 50, 75, 100, 150, and 200 mg·liter-1 was sprayed on mature lemon and tangerine trees to control a heavy infestation of eastern dodder (Cuscuta monogyna Vahl.). All concentrations completely eliminated the weed from the tree canopies. At the higher concentrations, the herbicide appeared to slightly reduce leaf size, cause some minor fruit deformation, and increase the number of abnormal shoots.