Shaded Fruit Research Articles

Fruit load and canopy shading affect leaf characteristics and net gas exchange of 'Spring' navel orange trees.

Five-year-old 'Spring' navel (Citrus sinensis (L.) Osbeck) orange trees were completely defruited, 50% defruited or left fully laden to study effects of fruit load on concentrations of nitrogen (N) and carbohydrate, net assimilation of CO2 (Ac) and stomatal conductance (gs) of mature leaves on clear winter days just before fruit harvest. Leaves on defruited trees were larger, had higher starch concentrations and greater leaf dry mass per area (LDMa) than leaves on fruited trees. Both Ac and gs were more than 40% lower in sunlit leaves on defruited trees than in sunlit leaves on trees with fruit. Leaves immediately adjacent to fruit were smaller, had lower leaf nitrogen and carbohydrate concentrations, lower LDMa and lower Ac than leaves on non-fruiting branches of the same trees. Removing half the crop increased individual fruit mass, but reduced fruit color development. Half the trees were shaded with 50% shade cloth for 4 months before harvest to determine the effects of lower leaf temperature (Tl) and leaf-to-air vapor pressure difference on leaf responses. On relatively warm days when sunlit Tl > 25 degrees C, shade increased Ac and gs, but had no effect on the ratio of internal to ambient CO2 (Ci/Ca) concentration in leaves, implying that high mesophyll temperatures in sunlit leaves were more important than gs in limiting Ac. Sunlit leaves were more photoinhibited than shaded leaves on cooler days when Tl < 25 degrees C. Shade decreased total soluble sugar concentrations in leaves, but had no effect on leaf starch concentrations. Shading had no effects on canopy volume, yield or fruit size, but shaded fruit developed better external color than sun-exposed fruit. Overall, the presence of a normal fruit crop resulted in lower foliar carbohydrate concentrations and higher Ac compared with defruited trees, except on warm days when Ac was reduced by high leaf temperatures.

Internal quality of ‘Valencia’ orange fruit as influenced by tree fruit position and winter girdling

During the 1999 season the internal quality of ‘Valencia Late’ orange was investigated with regard to fruit position and exposure in the canopy and the effects of winter girdling of branches. Fruit at shoulder height from northern and southern exposed positions were sampled during maturation. Fruit from eastern and western exposed positions were sampled on the crown while shaded fruit were sampled from bottom, inner canopy positions. Fruit from exposed canopy positions generally had higher soluble solids concentrations (SSC) although no real differences were found for kg SSC t−1. Girdling of branches late in the season did not improve SSC. Quadratic trends were best fitted to the data in this study indicating an increase of SSC over the season, peaking and then decreasing.

Causal Factors of "Kohansho" Disorder in 'Kiyomi' Tangor Fruit

The causes of the occurrence of Kohansho, a physiological disorder of 'Kiyomi' tangor ['Miyagawa wase' ( Citrus unshiu Marc.) × 'Trovita' orange (Citrus sinensis Osbeck)] fruit were investigated to establish effective preventive measures. The disorder appeared mainly on the fruit surface exposed to sunlight that was over 10°C warmer than the shaded side which was slightly affected. On a clear day, the transpiration rate of sun-exposed fruit was three-fold faster and at night it was only 25% as rapid as that of shaded fruit. Hence, greater water loss of sun-exposed parts is closely associated with the disorder. No significant differences were found in the mineral contents between the sun-exposed and shaded parts, although starch and total sugars were slightly higher in the flavedo of sun-exposed parts. The affected parts had a little greater a* value and more carotenoids than had the normal rind. Shaded fruit had an uneven surface under which the oil-glands protruded, whereas sun-exposed surface had smooth part between round shaped oil-glands.

Diurnal changes in non-structural carbohydrates in leaves, phloem exudate and fruit in ‘Braeburn’ apple

Diurnal changes in carbohydrates in leaves, phloem exudate and within fruitwere determined in apple trees grown under high, low or no crop load. Inleaves, diurnal patterns of carbohydrate concentrations were most distinct inhigh-cropping trees and least so in non-cropping trees. In phloem exudate,sorbitol comprised about 65–70% of sugars and sucrose30&amp;ndash;35%, with clear diurnal patterns in the amounts. Phloemexudates from stalks of sun and shade fruit were similar. Fruit carbohydratesshowed little diurnal variation. Crude fruit extracts showed little differencein sucrose synthase (SS, EC 2.4.1.13) activity between crop loads, whilesucrose phosphate synthase (SPS, EC 2.4.1.14) activity in high-cropping treespeaked at night and in low-cropping trees in the morning. SPS activity inshade fruit from high-cropping trees was only half of that in sun fruit (atmidday). Results indicate that the greater weight of individual fruit from lowcrop loads is primarily due to greater supply from the source, rather thanhigher metabolic activity in the sink, compared to fruit from high crop loads.In contrast, fruit size differences in sun and shade fruit of high-croppingtrees appear to be due to differences in sink metabolism rather than supplyfrom the source.

Direct Sunlight Influences Postharvest Temperature Responses and Ripening of Five Avocado Cultivars

Effect of direct sunlight on the postharvest behavior of five avocado (Persea americana Mill.) cultivars (Ettinger, Fuerte, Hass, Horshim and Pinkerton) was examined. Probes placed 6 to 7 mm under the peel showed that the temperature an the side exposed to the sun could be as much as 15 to 20 °C higher than the temperature of shade fruit, while the nonexposed side of the fruit was ≈5 °C higher than the shade fruit. With the exception of `Ettinger', sun fruit, and especially the exposed side, were found to be most tolerant to postharvest 50 and 55 °C hot water treatments. Similarly, storage of fruit at 0 °C for between 3 to 6 weeks caused severe chilling injury to shade fruit, with less effect on sun fruit. Furthermore, there was little or no damage on the exposed side of the sun fruit. During postharvest ripening at 20 °C, sun fruit showed a delay of between 2 to 5 days in their ethylene peak compared with shade fruit. The exposed side of the sun fruit was generally firmer than the nonexposed side, and the average firmness was higher than that of shade fruit. Activities of polygalacturonase and cellulase were similar in shade and sun fruit of similar firmness. After inoculation with Colletotrichum gloeosporioides (Penz.) Penz@sacc., the appearance of lesions on sun fruit occurred 2 to 3 days after shade fruit. Levels of heat-shock proteins were examined using western blotting with antibodies for Class I and II cytoplasmic heat-shock proteins. Class I reacted with proteins from the exposed side of sun fruit and Class II with proteins from both sides of sun fruit. Thus, it is clear that preharvest exposure of fruit to the sun can result in a wide range of postharvest responses.

Predicting transpiration of shaded and non-shaded tomato fruits under greenhouse environments

Fruit water balance is determined by entry of sap through xylem and phloem, and losses due to back-flow from fruits to other organs, and to transpiration. The latter, which may vary according to growing and climatic conditions, plays a significant role in fruit water balance. To better understand and predict tomato fruit transpiration, measurements of the transpiration rate of shaded and nonshaded fruits were carried out under a wide range of climatic conditions in two greenhouse compartments with different levels of air vapour pressure deficit (VPD air). Linear models relating transpiration and either air VPD (VPD air) or fruit-to-air VPD (VPD fr-air) were proposed and their parameters were identified. The best fit was always obtained when using the explicative variable VPD fr-air. The model using VPD air as variable fits moderately well in the case of shaded fruits, but is not adequate for non-shaded fruits. Values of cuticular conductance, g c deduced from our measurements appeared to depend (i) on the growth-VPD regime and (ii) on the prevailing values of VPD fr-air. Our results suggest that, as for leaf transpiration, VPD between the evaporating surface and the air is the variable that drives the fruit transpiration rate, and that more realistic models could be based on the hypothesis of a variation of g c vs.VPD.

Preharvest exposure to the sun influences postharvest responses of ‘Hass’ avocado fruit

‘Hass’ avocados (Persea americana Mill.) exposed to direct sunlight (sun fruit) had diurnal temperature cycles with flesh tissue reaching as high as 43°C under ambient temperatures of 15–25°C. The response of sun and shaded fruit to postharvest treatments differed significantly. External damage from hot water treatments of 50°C for up to 10 min, was lower in sun fruit, particularly on the exposed side of the fruit. Similarly, while shaded fruit had high levels of external chilling injury when stored at 0.5°C for up to 28 days, the exposed side of the fruit was undamaged. Leakage of electrolytes from skin tissue from the exposed side of sun fruit did not increase during storage, while that from shaded fruit increased by about 60%. In addition, for fruit ripened without storage, sun fruit took longer to ripen than shade fruit. Changes in heat shock protein (hsp) gene expression and specific protein bands reflected the diurnal temperature cycle, with up-regulation of hsp mRNA and synthesis of specific proteins at flesh temperatures >30°C. Thus, exposure of fruit to the sun results in high skin and flesh temperatures, and consequently reduced incidence of postharvest heat and chilling injuries. These beneficial effects are similar to those found following postharvest heat treatments.

Fruit and spur leaf growth and quality as influenced by low irradiance levels in pear

The effects of shading on spur leaf and fruit growth and quality of Pyrus communis L. cv. `Bartlett' were evaluated in the High Valley region of Argentina. The trees were trained to palmette leader and fruit load was low. Treatments were application of shade using a 80% saran shade cloth, applied at two stages of fruit development: 2 October–3 December 1996 (14 days after full bloom (DAFB) to 76 DAFB, Stage I) and 3 December 1996–23 January 1997 (76–128 DAFB, Stage II). Meteorological data were continuously monitored. Shading during Stage I decreased area per spur leaf, specific leaf mass and fruit diameter by 16.70%, 20.88% and 10.80%, respectively, at 76 DAFB. There was no significant treatment effect on final fruit size, although shaded fruits tended to be smaller. Microscopic examinations showed contrasting anatomical features in leaves that were exposed to different light regimes. Induction of early fruit drop by cloth-covering individual branches during Stage I was also demonstrated here. Shading during Stage II yielded significantly ( P≤0.05) smaller fruits as compared to control and light reduction did not affect fruit firmness and soluble solids concentration. It was concluded that early shading reduced spur vigor and fruit load, whereas late shading diminished fruit size. These results suggest some goals of pruning and training for optimizing yield, by efficiently converting captured sunlight into fruit.

Effects of solar radiation on grape (Vitis vinifera L.) composition and dried fruit colour

SummaryMost sun-exposed fruit (Vitis vinifera L.) produced dark brown berries with low L-values, whereas most dried berries from shade fruit were acceptable in lightness although some had a green tinge. Fruit shaded by the natural vine canopy or exposed to direct solar radiation had similar drying ratios. However, berry weights were significantly higher in the shade than in the sun for both cultivars. The difference in berry weight between the two positions was less pronounced in the heat affected year. Solar radiation changed the composition of fresh berries and the colour of the dried fruit. The soluble-solid concentration was higher in fresh fruit exposed to direct solar radiation than in fruit grown in shaded conditions within the canopy. In the heat affected year the berries from both positions had the same soluble-solid concentrations, possibly due to dehydration of the fruit. No significant difference was found between the pH of sun fruit and shade fruit, but the titratable acidity was higher in shade fruit. Malate and tartrate concentrations in berry skin and the polyphenol oxidase activities had carotenoid concentrations in whole fresh berries were not significantly different for sun and shade fruit. Total phenol concentrations in berry skin were higher in sun fruit and chlorophyll concentrations in whole, fresh berries were higher in shade fruit.

リンゴ「北斗」の有袋栽培が貯蔵中の陽向面果皮褐変障害の発生と揮発成分に及ぼす影響

The apple cv. Hokuto is very susceptible to a new skin-browning disorder called stain during storage. To study the cause of 'Hokuto' stain, young fruits were individually covered with commercial double paper bags from early June to late September. These shaded fruits were harvested in late October and stored at 0°C for up to six months. Incidence of stain between bagged and unbagged (control) fruits during storage at 0°C was recorded and volatiles in their skins were determined by gas chromatography-mass spectrometry and gas chromatography. There was less stain in bagged fruit than in unbagged ones. The same 50 volatiles were identified in the skin of bagged and unbagged fruits during storage. Differences in content of volatile compounds in the skin of bagged fruit were compared to those in unbagged fruit, noting the compositions whose contents were smaller in the skin of bagged fruit than those in unbagged ones. The difference in content of trans-2-hexenal was the greatest among the volatiles, followed by 2-methyl-butan-1-ol, n-hexanal, n-propanol, trans-3-hexenol, n-hexyl propionate and n-amyl acetate, in that order. No difference was found in (E, E)-α-farnesene whose oxidation products are believed to cause superficial scald. Exposure of healthy 'Hokuto' apples to seven volatiles and farnesene (mixed isomers) at 20°C for 20 hours showed that both trans-2-hexenal and n-hexanal induced stain-like injury at the lowest concentration, followed by n-amyl acetate, n-hexyl propionate and 2-methyl-butan-1-ol, in that order. No symptoms of stain appeared on fruits exposed to n-propanol, trans-3-hexenol and farnesene. Comparison in stain-like injury between C6-aldehydes and its C6-alcohols i.e. trans-2-hexenal and trans-2-hexenol, n-hexanal and n-hexanol, revealed that the injury was greater in C6-aldehyde than in its respective C6-alcohol. Application of linolenic and linoleic acids, respective precursors of trans-2-hexenal and n-hexanal, on 'Hokuto' apple skin at 0°C for four days induced stain-like injury in both unsaturated acids. The injury was greater in linolenic acid than in linoleic acid. However, the degree of the injury decreased remarkably in nitrogen gas. Results suggest that shading of the apples by double paper bags reduces concentration of trans-2-hexenal characteristically and that the shading is related to metabolism of linolenic acid to trans-2-hexenal, which were used in these experiments to induce stain-like injury to 'Hokuto' apples.

Effect of Shade on Pear Fruit Growth and Quality

This investigation was undertaken to determine the response of pear fruit growth and quality to shade imposed during development. Whole branches of mature `Bartlett' trees on P. communis L. growing at the Experimental Farm on a sandy loam soil were covered with a 20% transmission black, neutral-density shadecloth from 43 days after full bloom (DFB) to 138 DFB, during the 1995–96 growing season. Two comparable branches on each of five uniform trees were selected for good exposure and one branch of each pair was shaded. Fruit diameters were measured at 2-weekly intervals. Pulp pressure and soluble solids concentration (SSC) were measured at harvest time on 31 Jan. Specific leaf mass (SLM) also was recorded (leaf dry mass was obtained by drying discs at 80°C). Relative fruit growth rates were initially similar between light regimes, becoming lower for the shaded fruit at the subsequent measurements. Light exposure induced a 8.76% increase in final fruit diameter (66.40 mm); this increment would appear to depend on carbohydrate availability, since highly significant differences at P ≤ 0.01 emerged in the spur SLM of the exposed and covered branches (7.68 vs. 5.79 mg·cm–2, respectively). SCC was similar for the two light environments, while flesh firmness was 8.80% higher in the shaded fruit. Our results indicate that solar radiation deprival had clearly detrimental effects on fruit growth and maturity, and they provide a basis for improving pruning and training practices in the future.

Estimating the photosynthetic contribution of developing peach (Prunus persica) fruits to their growth and maintenance carbohydrate requirements

CO2 exchange rates (CO2 evolution) of late‐maturing cv. Cal Red peaches, exposed to different photon flux densities, were simulated from 24 days after flowering (DAF) until harvest by using light and temperature response curves measured on attached fruits in the field at biweekly intervals. The daily patterns of dark respiration rates per unit dry weight indicated their dependence on temperatures. Fruit CO2 exchange rates in light were also affected by photosynthetic photon flux densities. Daily photosynthetic rates per unit dry weight and per fruit were significantly lower in shaded fruits receiving 7% of the full daily sunlight compared to fruits exposed to 35% sunlight. However, the difference in photosynthetic rates in peach fruits receiving 21 and 35% of total daily sunlight was small. Within the last 4 weeks before harvest, weekly carbohydrate requirements for the production of dry matter rose rapidly in cv. Cal Red peaches and were related to high carbohydrate accumulations, especially of sucrose, in the peach mesocarp. Weekly photosynthetic contribution of late‐maturing cv. Cal Red peaches to these carbohydrate accumulations increased up to 115 DAF. A decline in photosynthetic contributions between 115 DAF and harvest was related to decreasing photosynthetic activities in association with declining chlorophyll contents. Photosynthesis of late‐maturing cv. Cal Red peaches provided 3–9% of the weekly fruit carbohydrate requirements early in the season and 8–15% in the midseason depending on fruit exposure to light. Photosynthesis of mature fruits contributed 3–5% of the total fruit carbohydrate requirements. Since fruit photosynthetic rates approach saturation at a photosynthetic photon flux density of about 600 μmol m2 s−2, the difference in weekly photosynthetic contributions was small between exposed and partially exposed (35 and 21% sunlight, respectively) peach fruits. However, a shaded fruit (7% sunlight) supplied significantly less of its weekly carbohydrate requirements through photosynthesis compared to exposed fruits. During the growing period of 24 DAF until harvest, dry matter accumulation of latematuring cv. Cal Red peaches accounted for 78% of the total carbohydrate requirements and 22% was used in respiration. Fruit photosynthesis of shaded peach fruit, partially exposed fruit and exposed fruit (receiving 7. 21 and 35% of full sunlight over the day, respectively) contributed 5. 8 and 9%, respectively, of the total growth and maintenance carbohydrate requirements during the growing season.

Influence of Cluster Exposure and Winemaking Processes on Monoterpenes and Wine Olfactory Evaluation of Golden Muscat

Effects of cluster exposure and winemaking treatments on free- and potential-volatile terpenes (FVT, PVT), total soluble solids (TSS), titratable acidity (TA), phenols, pH, color, and potassium were studied. Canopies of Golden Muscat grape vines were manipulated by shoot positioning and basal leaf removal at fruit set to create shaded and exposed cluster conditions. Winemaking treatments included: control, four-hour skin contact prior to press, freeze concentration of must, and addition of β-glucosidase after fermentation. At harvest, exposed fruit had higher PVT levels in the pulp and skin fractions, and shaded grapes had lower FVT levels in the skin and pulp fractions. Accumulation of FVT and PVT differed between exposed and shaded fruit and between skin and pulp fractions. Exposed fruit contained more phenols and TSS and less TA than shaded fruit, and these differences remained in the wines. Wines made from exposed fruit contained greater FVT and PVT than wines from shaded fruit. Addition of β-glucosidase increased FVT. Other winemaking treatments had inconsistent effects on PVT and FVT levels.

INFLUENCE OF CANOPY POSITION ON CHR0MATICITY OF PEACH FRUIT.

The objective of this study was to determine the difference in color development between exposed and shaded fruit of `Loring' and `Raritan Rose' peach (Prunus persica L. Batsch). Chromaticity values (L* a* b*) were measured with a Minolta CR-200b colorimeter on 10 tagged fruit on each of 3 trees of each cultivar. Five fruit were fully exposed to sunlight and 5 were shaded. Measurements were made on each fruit from July 17, 1991 through harvest. Differences in the a*/b* ratio between shaded and exposed fruit were observed at the first sampling date and increased towards maturation; shaded fruit approached a*/b* values similar to exposed fruit at a significantly later time. Shading reduced relative fruit color development more in `Loring' than in `Raritan Rose'.

DIFFERENCES IN FRUIT COLOR CHANGE WITH MATURITY AND GROWING LOCATION IN `SENSATION' AND `MAX RED' BARTLETT PEARS

Fruit color of `Sensation' and `Max' Red Bartlett pears was analyzed once at mid-season and three times during later stages of fruit maturity with a Minolta CR-200b portable colorimeter. Color measurements were taken on sun-exposed and shaded fruit surfaces in three different growing locations in Oregon. Color change is nearly constant over time during fruit maturation. Both cultivars gained red and yellow on sun-exposed fruit surfaces, and lost red but gained yellow on shaded surfaces. `Sensation' gained red on sun-exposed surfaces to a greater extent than did `Max' at all locations. `Max' gained more yellow and lost more red on shaded surfaces than did `Sensation'. Differences between cultivars and locations were greater on shaded than on sun-exposed fruit surfaces. Greatest gain in both red and yellow on sun-exposed surfaces was associated with the warmest growing location. Visually perceived color change with maturity appears to be due both to loss of red on shaded surfaces and gain of yellow on all surfaces.

FRUIT QUALITY DEVELOPMENT OF `GRANNY SMITH' APPLES IN RESPONSE TO TREE CANOPY LIGHT MICROCLIMATE.

A preliminary study suggested light distribution (400-700nm) did not change from terminal bud set (July) to harvest (9/9/88). Therefore, limbs of 5-year-old trees were shaded the last 90 days of the season in 1988 and 7-year-old trees were shaded the last 60 days in 1989 with 30, 63, 95% or no shadecloth. Medium (63%) and heavy (95%) shade decreased fruit weight both years. Fruit soluble solids (SSC) decreased with increasing shade in 1988 but not in 1989 until after 60 days of storage. Fruit peel chlorophyll (chl) declined with time for all treatments. Apples from full sun and heavy shade treatments had the lowest chl and visually appeared the lightest. Evidence from both years suggested there was an optimal light level between 37-70% full sun for maximum fruit color and chl. Link of 7-year-old trees were shaded at intervals, light all season, mid-season and late season. Fruit weight and firmness were not affected by time of shading. SSC was liner for mid-season shaded fruit. Chl was highest for late season shaded fruit but differences evaporated by 90 days of storage.

FRUIT QUALITY DEVELOPMENT OF `GRANNY SMITH' APPLES IN RESPONSE TO TREE CANOPY LIGHT MICROCLIMATE.

A preliminary study suggested light distribution (400-700nm) did not change from terminal bud set (July) to harvest (9/9/88). Therefore, limbs of 5-year-old trees were shaded the last 90 days of the season in 1988 and 7-year-old trees were shaded the last 60 days in 1989 with 30, 63, 95% or no shadecloth. Medium (63%) and heavy (95%) shade decreased fruit weight both years. Fruit soluble solids (SSC) decreased with increasing shade in 1988 but not in 1989 until after 60 days of storage. Fruit peel chlorophyll (chl) declined with time for all treatments. Apples from full sun and heavy shade treatments had the lowest chl and visually appeared the lightest. Evidence from both years suggested there was an optimal light level between 37-70% full sun for maximum fruit color and chl. Link of 7-year-old trees were shaded at intervals, light all season, mid-season and late season. Fruit weight and firmness were not affected by time of shading. SSC was liner for mid-season shaded fruit. Chl was highest for late season shaded fruit but differences evaporated by 90 days of storage.

Developmental changes in ‘Valencia’ orange fruit epicuticular wax in relation to fruit position on the tree

Seasonal changes in orange fruit cultivar ‘Valencia’ ( Citrus sinensis (L.) Osbeck) epicuticular wax quantity and ultrastructure were examined in relation to fruit position on the tree. Total wax accumulated per fruit and per unit fruit surface area declined in very young fruit and then increased during growth and development, regardless of fruit exposure. Fruit from the northeast (NE) quadrant of the tree had amounts of wax similar to fruit from the southwest (SW) quadrant until late in the season, when the latter had a significantly greater quantity. The wax of very young fruit was smooth and amorphous. During fruit development, ‘crusty’ plates and upright platelets were obvious, and subsequently the surface appeared amorphous. The change back to an amorphous surface occurred earlier on exposed than on shaded fruit surfaces; in fact, crystalline wax never completely disappeared from the shaded side of fruit from the NE quadrant. Rindstaining, a peel disorder, was more severe on exposed surfaces and, among exposed surfaces, it was more severe in situations where the crystalline-to-amorphous transition was more advanced.

The Effects of Sun Exposure on the Phenolic Content of Cabernet Sauvignon Berries During Development

The phenolic composition of Cabernet Sauvignon grape berries was monitored throughout the growing season from anthesis to maturity in clusters exposed to sunlight and clusters growing in natural canopy shade. Analyses included total soluble phenols, anthocyanins, and polymerized phenols. Significant differences were found between sun-exposed and shaded fruit in soluble phenol content per berry and in both anthocyanin concentration and total content per berry preharvest. There were no significant differences at harvest, however. Total soluble phenols increased until véraison, then decreased from véraison to harvest. The percentage of polymerized phenols decreased during early berry growth, then increased from véraison to harvest.

Citrus Rust Mite Control (CRM), 1984

Abstract Treatments were assigned to 3 x 5 (15-tree) plots in a randomized block design replicated 4 times in both tests. Three sample trees were selected from each 15-tree plot. Each plot was separated from adjacent plots by 2 trees within the row and 3 rows between treatments. Sprays were applied with 250 gal per acre using an FMC 4000CP airblast sprayer driven at 1.5 mph. In Test 1, MK 936 at 10.7 oz was tank mixed with 1 gal 7N oil in 250 gal water/acre and applied to treatment 3 only. The remaining treatments consisted of the miticide only and all treatments were applied on 1 Jun. On 24 Jul, MK 936 at 5.35 oz was tank mixed with 1 gal 7N oil and 6 lb tribasic copper sulphate in 250 gal water/acre and applied to treatment 2 only. On 7 Aug, 6 lb tribasic copper sulphate in 250 gal/acre was applied to the entire block in Test 1. In addition to the treatment application in Test 2 on 25 Jun, 6 lb tribasic copper sulphate in 250 gal of water/acre was applied with an airblast sprayer to the entire block on 8 and 9 Aug. Twenty fruit were examined at random around the canopy perimeter of each sample tree at various time intervals before and after spraying of test materials. Live motile citrus rust mites were counted within a 1 cm2 area using a 10X hand lens on 2 shaded fruit surfaces. The combined 2 cm2 count per fruit of living CRM was recorded as 1 observation. The percentage of surface russeting due to CRM feeding injury was estimated by examining 50 fruit at random around the canopy perimeter of each sample tree (N = 600) in Aug and Nov for both tests.