Control Of Bitter Pit Research Articles

Control of bitter pit in apple achieved with reduced calcium inputs

Control of bitter pit in apple achieved with reduced calcium inputs

Short-term storage of ‘Honeycrisp’ apples at 0.5 oC does not improve control of bitter pit without increasing low temperature-induced physiological disorders

‘Honeycrisp’ apples are conditioned at 10 °C for 7 d before storage at 3 °C to reduce development of low temperature disorders such as soft scald. Conditioning, however, can result in greater risk of bitter pit development. A strategy to compromise between two types of disorder by storing fruit for short periods at 0.5 °C before being transferred to 3 °C showed promise in earlier research. Here, this strategy has been investigated over three years. Fruit were conditioned or not conditioned for 1 week at 10 °C before being stored at 0.5 or 3 °C. Fruit stored at 0.5 °C were moved to 3 °C after 1, 2, 3, 4, or 6 weeks in year 1; 5 weeks in year 2; and 1, 2, 3, 4, 6, or 8 weeks in year 3. Fruit quality and incidence of physiological disorders assessed after 16 weeks in years 1 and 2, and 20 weeks in year 3, plus 4 d at 20 °C. Internal ethylene concentration (IEC) and concentrations of acetaldehyde, ethanol and ethyl acetate of the fruit were measured during storage in year 3. Storage at 0.5 °C for different durations before transferring fruit to 3 °C in different years did not inhibit bitter pit or soft scald development compared with 0.5 or 3 °C with or without conditioning for 1 week at 10 °C. Fruit quality was not affected by storage temperature manipulation in any year. Bitter pit incidence correlated negatively with that of soft scald, and positively with IEC. Acetaldehyde, ethanol and ethyl acetate concentrations reached a maximum at 6–8 weeks of storage, but were not consistently related to treatment differences on soft scald incidence. However, volatile accumulations were associated with increasing severity ratings when fruit were categorized by disorder severity. Cavities and vascular browning of fruit were increased by short-term periods at 0.5 °C in year 3. Previous research suggesting that temperature manipulations could be used to manage soft scald and bitter pit incidence was not supported by this study.

Pulverização de fontes de cálcio em pré-colheita para o controle de "bitter pit" em maçãs 'Catarina'

Este trabalho teve como objetivo avaliar os efeitos de fontes de cálcio (Ca), aplicadas em pré-colheita, no controle de "bitter pit" e na qualidade físico-química de maçãs 'Catarina'. Os experimentos foram conduzidos durante três safras (2004/2005, 2005/2006 e 2006/2007) em um pomar comercial localizado em São Joaquim, SC. O delineamento experimental utilizado foi em blocos casualizados, com quatro repetições. As fontes de Ca testadas foram CaCl2, Calboron, Sett, Aminolom Floración, Max Fruit, S-CaB, Cal Super, Wuxal Cálcio, Orgasol Ca, CalSOL 15, Coda-Ca-L e CodaSal-Plus 2000. As pulverizações foram iniciadas do estádio J (frutos verdes) e finalizaram 30 dias antes da colheita dos frutos. Avaliaram-se a incidência e severidade de "bitter pit" na colheita (safras 2005/2006 e 2006/2007) e após três (safra 2005/2006) e cinco meses (safra 2006/2007) de armazenamento refrigerado. A incidência de "bitter pit" no tratamento controle (sem fonte de Ca) foi 24% e 46% nas safras de 2005/2006 e 2006/2007, respectivamente. Somente na safra 2004/2005, os tratamentos CaCl2, Calboron+CaCl2, Sett, Calboron e S-CaB aumentaram o teor de Ca nos frutos. Pulverizações em pré-colheita de CaCl2, Calboron e Sett na safra 2005/2006, e de CaCl2 e CalSOL 15 (10 e 15 aplicações) na safra 2006/2007, reduziram a incidência de "bitter pit", sem ocasionar alterações significativas nos teores de Ca, N e K nos frutos em relação ao controle. Os resultados obtidos mostram que as fontes de Ca testadas foram pouco efetivas para aumentar o teor deste elemento no fruto e controlar o "bitter pit"em maçãs 'Catarina', havendo uma tendência do cloreto de cálcio ser mais efetivo em controlar este distúrbio fisiológico. Nas três safras, a pulverização pré-colheita com diferentes fontes de Ca não afetou o rendimento, o peso médio e a qualidade físico-química dos frutos.

Evaluating the Effectiveness of Pre-Harvest Calcium Applications for Bitter Pit Control in ‘Golden Delicious’ Apples Under South African Conditions

ABSTRACT Pre-harvest foliar applications to increase fruit calcium (Ca) content and reduce bitter pit incidence, is a standard practice world wide. We re-evaluated the effectiveness of early season applications versus late applications of calcium nitrate (Ca(NO3)2) to reduce bitter pit in ‘Golden Delicious,’ under the present environmental conditions of the Western Cape, South Africa. Two periods of efficient uptake of external Ca were identified, viz., during cell division and the last few weeks before harvest. Foliar Ca applications during mid season (from 40 d after full bloom) were more effective in increasing fruit Ca content and reducing bitter pit incidence, than later applications. Thus, it is important to apply the bulk of the Ca(NO3)2 during the first few weeks after cell division to maximize the Ca content of ‘Golden Delicious’ apples.

Controlling Bitter Pit in `Honeycrisp' Apples

Control of bitter pit in `Honeycrisp' apples (Malus ×domestica) from trees treated during the growing season with foliar sprays of trifloxystrobin fungicide and calcium was evaluated in four replicated trials over 2 years. All trials were in commercial orchards of `Honeycrisp' trees that were 3 to 6 years old. The effectiveness of combining boron with foliar applications of calcium chloride (CaCl2) was evaluated in two trials, and effectiveness of harpin protein, used either alone or in alternating sprays with CaCl2 was assessed in one trial. Trifloxystrobin applied twice during the 30 days before harvest reduced bitter pit incidence at harvest in one of the four trials, but the reduction was transitory, no longer being evident when fruit were re-evaluated after 63 days of cold storage. Harpin protein did not affect disorder incidence. Calcium sprays failed to control bitter pit in treatments where the total elemental calcium applied was less than 2.7 lb/acre (3.03 kg·ha–1) per year for tree canopies that were sprayed to drip using 100 gal/acre (935.4 L·ha–1) of spray solution. In the two trials where some treatments involved application of at least 2.9 lb/acre (3.25 kg·ha–1) of elemental calcium per season, the incidence of fruit with bitter pit at harvest was reduced by 76% to 90%. Effectiveness of calcium sprays for bitter pit control was not enhanced by superimposing trifloxystrobin, boron, or harpin protein treatments. Flesh firmness at harvest was lower in calcium-treated than in non-treated fruit, and fruit maturity was more advanced on trees receiving boron sprays than on trees receiving no boron. In one trial, where the first calcium application was made approximately 2 weeks after petal fall and 4 days prior to a fruit thinning spray, crop load of trees that received calcium sprays, measured as number of fruit per cm2 trunk cross-sectional area, was 38% greater than on trees that received no calcium sprays. CaCl2 provided better control of bitter pit in `Honeycrisp' than any of the other materials tested.

Boron Maintenance Sprays for Apple: Early-season Applications and Tank-mixing with Calcium Chloride

The recommendations for boron (B) sprays in deciduous tree fruit orchards have changed little over the past 50 years. We conducted two 3-year field studies evaluating the effect of two modifications to the existing recommendation for B maintenance sprays on apple (Malus ×domestica) tree nutritional status. A widely recommended Na polyborate-based commercial B spray product was used as the B source. Postbloom sprays of B applied at the recommended annual B maintenance rate of 0.56 kg·ha-1 to `Scarlet Gala' apple trees consistently increased fruit B concentration but had a weaker effect on leaf B concentration in early August, the recommended timing for sampling leaves for mineral element analysis. Applying half or all of the annual B maintenance rate in a spray at the pink flowering stage increased flower cluster and early-season leaf B concentrations as well as having positive effects on fruit and leaf B concentrations. The pink sprays increased flower cluster Na concentration but had no effect on leaf and fruit Na concentrations. In the second study, one-quarter of the annual B fertilizer requirement was tank-mixed with each of four biweekly CaCl2 sprays applied starting in early June for bitter pit control. This treatment consistently increased `Scarlet Gala' fruit B concentration but had a lesser effect on August leaf B concentration. It did not interfere with fruit Ca status, and increased both fruit and leaf Na concentrations. Leaf Na concentration in all treatments was substantially lower than levels associated with specific Na toxicity of deciduous fruit trees. The results of these experiments indicate that applying B sprays at the pink flowering stage timing and tank-mixing B with CaCl2 sprays applied for bitter pit control are useful practices to enhance B spray efficacy and convenience of application.

Number and concentration of calcium nitrate plus Kelpak® sprays for control of bitter pit in 'Braeburn5 apple fruit

In a spray trial to test the effects of calcium nitrate and a kelp extract (Kelpak®), fruit calcium (Ca) concentrations in ‘Braeburn’ apples peaked between 7.6 and 9.5 mg 100 g−1 fresh mass (FM) on 19 December 2000, then declined to between 2.3 and 3.2 mg 100 g−1 FM at harvest (22 March 2001). Fruit Ca concentrations on 19 December were highest where 12 sprays, each containing 117 g Ca per 100 I water were applied, without Kelpak®, at weekly intervals from 42 days after full bloom to 30 January. At harvest, fruit Ca in this treatment was no greater than where 12 sprays containing either 117 or 58.5 g Ca per 100 I water were applied with Kelpak®. Incidences of bitter pit in these treatments were, respectively, 1.0%, 1.3% and 3.4%. Where six half-strength sprays were applied, with Kelpak®, over the same time period, bitter pit increased to 9.3%. At harvest, fruit Ca concentrations were 0.25 mg Ca per 100 g−1 FM lower in pitted, than in bitter pit-free fruit. Total soluble solids and starch conversion were lower where 12 full-strength sprays were applied without Kelpak® than where 12 half-strength sprays were applied with Kelpak®. Starch conversion was greatest where six half-strength sprays were applied with Kelpak®. The effects on fruit colour of calcium nitrate, alone or with Kelpak®, were inconclusive

Effect of calcium spray materials, rate, time of spray application, and rootstocks on fruit quality of ‘red’ and ‘golden delicious’ apples

Calcium (Ca) spray materials improved fruit quality as measured by control of bitter pit, fruit finish (appearance), increased red skin color, reduced incidence of scald, increased juiciness, texture, and fruit firmness of ‘Red’ and ‘Golden Delicious’ apples (Malus domestica, Borkh.). Concentrations of Ca in leaf and fruit tissues were increased by Ca sprays, especially calcium chloride (CaCl2)‐containing spray materials. Improved fruit firmness and control of bitter pit occurred for either standard recommended or high rates of Ca spray materials. At high rates of application, the only significant difference that occurred between early and late applications of Ca spray materials was that less leaf injury occurred with the early applications. Unsprayed ‘Red Delicious’ fruit from M.7 rootstocks had greater fruit peel Ca concentrations and a lower incidence of bitter pit but smaller fruit than fruit from trees on M.26 rootstocks. The above information is strong evidence that Ca sprays are important for the improvement of apple quality.

Bitter Pit Control by Sprays and Vacuum Infiltration of Calcium in `Cox's Orange Pippin' Apples

The incidence of external and internal bitter pit in `Cox's Orange Pippin' apple (Malus domestics Borkh.) fruit sprayed with normal therapeutic sprays either with or without Ca salts at 2-week intervals during the growing season was determined after 6 weeks of storage over 7 consecutive years. Following harvest, fruit was either vacuum-infiltrated with CaCI2 or received no further treatment. Although there was a tendency for fruit that had been sprayed and vacuum-infiltrated with Ca to exhibit the greatest degree of bitter pit control, this treatment was not significantly superior to Ca sprays alone. Vacuum infiltration alone reduced the disorder to a lesser extent than Ca sprays and was more effective in reducing external than internal bitter bit. The results suggest that Ca applications over the growing season are superior to postharvest vacuum-infiltration with Ca in the prevention of bitter pit.

The effects of high CO2pre-storage treatments and rate of establishment of controlled atmosphere conditions on bitter pit and bruise susceptibility of ‘Bramley’s Seedling’ apples

SummaryBitter pit incidence in Bramley apples that were cooled prior to either slow (three weeks) or rapid (one day) establishment of controlled atmosphere (CA) conditions (9% CO2, 12% O2) was 14.7 and 3.2% respectively. Bruise susceptibility was also reduced by rapid CA establishment although the rate of fruit softening was unaffected. The control of bitter pit by pre-storage treatment with 15–25% CO2 for one to three weeks was no better than by rapid establishment of CA, although bruise susceptibility was further reduced by some treatments. Some pre-storage treatments caused injury to the apple skin and flesh (brownheart). The extent to which fruits were injured was dependent on CO2 concentration and the duration of CO2 treatment. There was some evidence that early picked fruit not cooled prior to CO2 treatment was more severely injured both internally and externally by CO2 than that harvested later and cooled prior to treatment.

Effects of water rinses after calcium chloride dips, with and without additives, on the control of bitter pit of apples

Studies on the control of bitter pit in apples after harvest were conducted during two seasons in Tasmania and New Zealand. The cultivars, Cox's Orange Pippin, Sturmer Pippin, Golden Delicious, Delicious and Cleopatra, which are susceptible to bitter pit on overseas markets, were examined. Bitter pit was reduced and calcium content of the fruit increased, by dipping the fruit in calcium chloride solutions (1-3% w/v). The addition of diphenylamine or the non-ionic wetting agent, Agral 60 (ICI Australia), had little effect on the control of bitter pit or on the calcium content of the treated fruit. Rinsing in water even 1 or 2 days after dipping did not significantly increase the incidence of bitter pit or lower the calcium content of the fruit. There was no difference in the incidence of bitter pit between fruit stored at ambient temperature (15-20�C) or at 3-5�C during the interval between dipping and rinsing. Dipping apples in calcium chloride followed, after 1 or more days, by a water rinse may be suitable commercially for reducing bitter pit in a number of cultivars.

Bitter pit reduction in ‘Cox's Orange Pippin’ apples by controlled and modified atmosphere storage

Controlled and modified atmospheres reduced bitter pit in New Zealand ‘Cox's Orange Pippin’ apples stored for 5 weeks at 2°C. Fruit from orchards that had received calcium sprays during the season were stored in an integral container maintained with a gas atmosphere of 3% CO 2 plus 3% O 2, and had less than 6% bitter pit. In comparison, air-stored fruit from the same orchards had up to 26% bitter pit. Polyethylene bags containing different numbers of 9-mm holes were tested for their effectiveness in influencing bitter pit development. The incidence of bitter pit that developed during storage was progressively reduced from 50% to less than 5% as the number of holes per bag decreased. Fruit in polybags had less weight loss, higher firmness and improved quality compared with air-stored fruit. Practical problems relating to commercial use of polybags for bitter pit control are discussed.

Cation distribution and balance in apple fruit in relation to calcium treatments for bitter pit

Calcium (Ca), magnesium (Mg) and potassium (K) concentrations and distribution have been measured in apple fruit treated with Ca sprays during the growing season, and in stored fruit after post-harvest vacuum-infiltration of Ca or Mg, for bitter pit control. The highest concentrations of each cation occurred in the skin and core, the lowest in the outer cortex. Ca sprays increased Ca levels in each tissue segment; K levels were lower in Ca-sprayed fruit, but effects on Mg were variable. Concentrations of all 3 cations in the outer cortex increased during storage. Vacuum-infiltration of Ca substantially increased Ca levels in the outer 12 mm of cortical flesh after 2 weeks in storage, but did not affect Mg or K concentrations. Vacuum-infiltration of Mg resulted in an increase in Mg concentration in the outermost segment of flesh, but had little effect on levels elsewhere in the tissue, or on the concentrations of other ions. Ca added to fruit, either by spray or vacuum-infiltration, could easily leak from tissue in experiments with tissue disks. This leakage reduced tissue Ca concentrations to a level common to all treatments, indicating that Ca externally applied was probably located in the free space, and not involved with maintaining cell structure and function.

The Action of Lecithin and Calcium Dips in the Control of Bitter Pit in Apple Fruit1

Abstract Addition of 1% lecithin (phosphatidyl choline) to 4% Ca dips increased internal CO2 levels and decreased O2 levels in fruit of apple (Malus domestica Borkh.) stored at 3°C. This effect was greater than that found with lecithin alone. At 18°, respiration and ethylene production by the fruit were reduced slightly by Ca, but to a much greater extent by lecithin. A further reduction of the production of both gases was found with Ca and lecithin. The climacteric rise was also delayed by lecithin treatments. At 3°, ethylene production was both delayed and reduced by lecithin treatments, but no influence on CO2 production was detected. Although differences in Ca concentration of the fruit caused by the addition of lecithin to Ca could not be detected when bulked samples of fruit were analysed, use of 45Ca showed that both the initial rate of Ca uptake and the final Ca content of the fruit flesh after 6 weeks at 3° were increased by lecithin. The beneficial effects of lecithin plus Ca in bitter pit control probably result from rapid modification of gas exchange together with increased Ca uptake.

Prediction and control of bitter pit in apples. II. Control by summer pruning, fruit thinning, delayed harvesting and soil calcium dressings

SummaryVarious orchard treatments were investigated as alternative or supplementary measures to routine spraying with Ca(NO3)2 solutions for the control of bitter pit in stored Cox’s Orange Pippin and James Grieve apples. The leaf/fruit ratio was modified by summer pruning and fruit thinning, and picking date was delayed while, in orchards on sandy soils, Ca was applied either as CaCO3 or CaSO4 directly to the soil. Summer pruning produced a slight improvement in the storage quality of larger fruits from unsprayed trees. Spraying lowered the incidence of both bitter pit and breakdown, and reduced external bitter pit to such an extent that no additive effect of pruning was discerned. Fruit thinning at the end of June or in early July did not seriously affect fruit storage quality and there was some evidence that late picking decreased bitter pit incidence. In four trials in Cox orchards on sandy soils liming lessened the incidence of bitter pit slightly after several successive years of treatment. Although...

Prediction and control of bitter pit in apples. I. Prediction based on mineral leaf composition, cropping levels and summer temperatures

SummaryEarly prediction of the probable incidence of bitter pit is required to enable growers to identify, at harvest time, fruit with a high risk of the disorder so that it may be excluded from long-term storage. Data were collected over four years from 28 orchards to investigate the factors related to its incidence. The mineral composition of leaves sampled in August was unsuitable for forecasting bitter pit, unless the fruit/leaf ratio of the tree and regularity of cropping between trees were also taken into consideration. Bitter pit in stored apples increased with the (K+Mg)/Ca ratio in leaf and fruit, and decreased with a higher fruit/leaf ratio and more regular cropping. Clear differences in the incidence of bitter pit were recorded between years, even where cation ratios and yield levels were comparable. Part of these differences could be attributed to the unfavourable effect of high temperatures in August. However, factor analysis from trials over a 15-year period failed to show any marked association between bitter pit and the weather during August and September.

Effects of vacuum and pressure infiltration of calcium chloride and storage temperature on the incidence of bitter pit and low temperature breakdown of apples

Post-harvest treatment of apples with calcium chloride markedly reduced bitter pit and breakdown in several cultivars during three seasons in Australia and New Zealand. Infiltration of calcium chloride at pressures above or below atmospheric pressure improved the control over that obtained by simple immersion of the fruit in the calcium chloride solution, and was effective in the absence of the usual field sprays of calcium nitrate. These new treatments retained much of their effectiveness when the fruit were afterwards rinsed with water to reduce the risk of injury to the fruit or the grading equipment. The treatments were effective whether the fruit had open or closed calyces, but there were problems of excessive uptake and internal damage with some fruit having an open calyx. Commercial development of the process for closed calyx varieties such as Cox's Orange Pippin or Granny Smith is in progress. For the 3–4 month period required for export, the use of a lower temperature (0° instead of 3°C) improved the control of bitter pit, and a post-harvest calcium treatment reduced the incidence of low temperature breakdown.

Post‐harvest chemical treatments for the control of storage disorders of apples

SUMMARYImmersion of apples of the varieties Cox's Orange Pippin and James Grieve for 1 min in solutions of calcium chloride or nitrate reduced the incidence of bitter pit and senescent breakdown that developed during air storage at 3 °C. Calcium nitrate treatments decreased the severity of superficial scald in both Bramley's Seedling and Cox apples probably by slightly delaying the rate of senescence. Calcium chloride caused unacceptable levels of damage when applied to Cox and Grieve at concentrations above 0.125 M; this injury was enhanced in Cox when benomyl was added to this strength of solution. Bramley's Seedling apples were more sensitive to calcium injury than Cox, especially in the presence of benomyl and the scald inhibitor, ethoxyquin; diphenylamine did not increase calcium injury. Calcium nitrate caused more damage to Cox than equimolar concentrations of the chloride without improving the control of bitter pit. Virtually no damage occurred when Cox and Grieve apples were immersed for 10 min in 0.125 M calcium nitrate at 45 °C. The incorporation of calcium in warm water treatments to control rotting and scald may delay sensecent breakdown in heat‐treated apples.

Control of bitter pit in apples with lecithin and calcium

Abstract The incidence of bitter pit in ‘Cox’s Orange Pippin' apples was halved when the apples were dipped after harvest in solutions containing 2.5% CaCl2 or Ca(NO3)2. Addition of egg lecithin to the dips further reduced the incidence of the disorder (to less than one quarter of that in water-dipped controls). Lecithin addition also alleviated the damage often associated with calcium dips and improved control of two other physiological disorders, breakdown and water core. A dip containing lecithin alone was relatively ineffective. It is suggested that lecithin may assist the movement of applied calcium into apples.

Calcium sprays for control of bitter pit and other disorders in apples

Abstract Calcium nitrate sprays were applied to ‘Cox's Orange’ apples over four different periods between fruit set and harvest. Four sprays applied early, from 8 October to 2 December, gave no control of bitter pit. With the other three periods (II days, 27 days, and 64 days pre-harvest) there was good control of pit. The relative values of these three later spraying periods for pit control were difficult to assess, but the 64-day period gave slightly less pit in one season. The highest levels of fruit calcium were with the 27-day pre-harvest period. Over 64 days pre-harvest, 6 sprays of 0.6% calcium nitrate doubled the total calcium in apples, whereas in unsprayed apples total calcium remained practically constant. Over this period the apples gained in weight fourfold, thereby reducing the percentage of calcium in sprayed apples to one-half, and in unsprayed apples to near one-quarter. Calcium sprays reduced internal breakdown in ‘Cox's Orange’ and ‘Red Delicious’ apples. Colour development on ‘Red Deli...