Controlled Atmosphere Cold Storage Research Articles

First report of Didymella macrostoma causing calyx-end rot of pear (Pyrus communis) in The Netherlands.

Pear (Pyrus communis) is an important fruit crop in the Netherlands, with a total production of 400,000 tons in 2020, and 'Conference' is the main pear cultivar that comprises 80% of total pear production area. In the Netherlands, pears are kept in controlled atmosphere cold storage (-0.5°C) up to 11 months after harvest. Calyx-end rot incidences of 1% to 5% were observed on 'Conference' pears from different orchards in surveys from 2019-2021 in packing houses in the Netherlands. Infections showed 1 to 3 cm brown necrosis. Lesions were round, slightly sunken and next to or including part of the calyx. To isolate the causal agent, fruit were rinsed with sterile water, lesions were sprayed with 70% ethanol until droplet runoff, the skin was removed aseptically with a scalpel, and tissue under the lesion was isolated and placed onto Potato Dextrose Agar (PDA) (Oxoid, UK). The PDA plates were incubated at 20°C in the dark, and hyphal tip isolates were transferred to fresh PDA plates. Colonies on PDA were rosy-whitish to peach-colored. Colonies grown on oat meal agar (OA) under UV light were peach to red color, aerial mycelium sparse, and produced a pink to salmon colored conidial matrix. Conidia were irregular-ellipsoidal to allantoid, smooth, hyaline and usually with one or several gutulles. Conidia were sometimes one septate and measured 15.2±2.8 x 4.0±0.7 μm (n =14), but mostly aseptate and measured 7.9±1.7 x 3.2±0.6 μm (n =100). The fungus was morphologically identical to Didymella macrostoma (syn. Phoma macrostoma) (Boerema et al. 2004; Hou et al. 2020). The identity of four representative isolates, WURR-206, WURR-223, WURR-227 and WURR-308, from affected pears from four orchards in the Netherlands, was determined by multilocus gene sequencing. To this end, genomic DNA was extracted using the LGC Mag Plant Kit (Berlin, Germany) in combination with the Kingfisher method (Waltham, MA). Sequences of the internal transcribed spacer (ITS) region of ribosomal DNA, the large-subunit rRNA (LSU) region, partial sequences of beta-tubulin (TUB) and the translation elongation factor 1-alpha (TEF1) gene region were amplified with primers ITS1/ITS4 (White et al. 1990), LROR/LR5 (Vilgalys and Hester 1990), Btub2Fd/Btub4Rd (Woudenberg et al. 2009) and EF1-983F/EF1-1567R (Rehner and Buckley 2005), respectively. Sequences were deposited under GenBank accession numbers ON077588-ON077591 (ITS), ON113487-ON113490 (LSU), ON098515-ON098518 (TUB) and ON098519-ON098522 (TEF1). MegaBLAST analysis revealed that the ITS, LSU, TUB sequences matched with 100% identity to culture collection sequences of Didymella macrostoma in GenBank MH854841 (ITS), MH866341 (LSU), MN983895 (TUB). The TEF1 sequences matched with 99.7% identity to TEF sequence of Didymella macrostoma MT454020. Subsequently, Koch's postulates were performed on 10 'Conference' pears per isolate (WURR-206, WURR-223, WURR-227 and WURR-308). Fruits wiped with 70% ethanol were inoculated in pathogenicity tests with an agar disk (5 mm diameter) of D. macrostoma prepared from the actively growing edge of 14-day-old cultures grown on PDA. Inoculated fruits were sealed in plastic bags and were incubated in darkness at 20°C. Typical symptoms appeared 7-10 days after inoculation on all pears. PDA-only controls remained symptomless. Fungal colonies isolated from the lesions and cultured on PDA morphologically resembled the original isolate from the infected pears. The identity of the re-isolations was confirmed as D. macrostoma by sequencing, thus completing Koch's postulates. To the best of our knowledge, this is the first report of D. macrostoma causing calyx-end rot of pears. The identification of this causal agent is important knowledge necessary for developing control measures for postharvest diseases of pear.

Persistence of Listeria innocua on Fresh Apples during Long-Term Controlled Atmosphere Cold Storage with Postharvest Fungal Decay

Recent apple-related recall and outbreak events have exposed a need for better food safety controls along the supply chain. Following harvest, apples can be stored under a controlled atmosphere for up to 1 year after harvest before packing and distribution, making the crop susceptible to many opportunities for contamination that increase the quantity of postharvest losses. Botrytis cinerea and Penicillium expansum cause significant rot-associated losses to the apple industry. These fungi can colonize and destroy apple tissue as storage duration increases, which may also impact the growth of saprophytic foodborne pathogens like Listeria monocytogenes. Thus, the objective of this study was to observe population changes of Listeria innocua as a surrogate for L. monocytogenes on apples inoculated with B. cinerea or P. expansum under long-term controlled atmosphere cold storage conditions to identify the effect of postharvest mold growth on growth patterns of a microorganism relevant to food safety. 'Gala' and 'WA 38' apples (n = 1,080) were harvested, treated with pyrimethanil, and inoculated with L. innocua only or with L. innocua and one of the mold species on wounded and unwounded portions of the apple equator. Apples were treated with 1-methylcyclopropene and stored at a controlled atmosphere (2 kPa O2, 1 kPa CO2, 1°C) for 1 week and 1, 3, 6, 9, and 11 months before enumeration. After 3 months, L. innocua consistently fell below the limit of detection (2.35 Log CFU/g), and samples were enriched following a modified Bacteriological Analytical Manual method with PCR confirmation. Listeria persistence was dependent on the storage duration and type of fungal contamination (P ≤ 0.05). Surface wounding may impact these trends, depending on the apple variety. Prevalence of L. innocua was greater in Gala apples. Future studies should more closely examine the interactions on the fruit surface that occur during the seemingly critical time frame of 3 to 6 months in storage.

Comparison of fruit maturation and quality of ‘Gala’ apple strains at harvest and after storage

Abstract Strains of ‘Gala’ apples with highly red-colored skins have been planted in new orchards based on consumer interest and financial returns to the producers. The effect of somatic mutation may not be limited to change in fruit skin appearance. In this study, six ‘Gala’ strains were compared regarding fruit maturity and quality attributes at commercial harvest time and after 210 days in controlled atmosphere cold storage plus seven days shelf-life. Experimental orchards were established in three regions and fruit assessed over four seasons. The fruit skin red color area was highest in ‘Baigent’ and ‘Galaxy’, and lowest in ‘Royal Gala’ and ‘Imperial Gala’. Fruit of ‘Maxi Gala’ and ‘Gala Real’ had intermediate skin coloration among the six strains. There was no difference among the strains regarding the fruit weight, starch index, flesh firmness, soluble solid content (SSC), and titratable acidity (TA) at harvest, and flesh firmness, SSC and TA after storage. Fruit of the six ‘Gala’ strains were equally affected by physiological disorders (flesh browning, fruit cracking, calcium deficiency disorders and shrivel) and fungal diseases (external decay, core rot and Glomerella cingulata spot) during storage, indicating that they have similar storability. Only ‘Imperial Gala’ and ‘Royal Gala’ exhibited superficial scald, an unusual disorder for ‘Gala’ cultivar. Harvest management and potential economic impacts of highly red colored fruit of ‘Gala’ strains are discussed.

First Report of Neofabraea kienholzii Causing Bull’s Eye Rot on Pear (Pyrus communis) in the Netherlands

Pear (Pyrus communis L.) is an important fruit crop in the Netherlands, with a total production of 349,000 tons in 2014, and ‘Conference’ is the main cultivar. In the Netherlands, pears are kept in controlled atmosphere cold storage up to 11 months after harvest. Symptoms of bull’s eye rot were observed in 2015 on ‘Conference’ pears in storage in the Netherlands. Bull’s eye lesions on apple and pear fruits are generally caused by four Neofabraea species: N. alba Jacks, N. malicorticis Guthrie, N. perennans Kienholz, and N. kienholzii Seifert, Spotts & Levesque (Gariepy et al. 2005). N. alba is the major pathogen causing bull’s eye rot on pear fruits in the Netherlands. Independent of the species, the symptoms appear as flat or slightly sunken lesions, which are brown, often lighter brown in the center (Spotts et al. 2009). To isolate the causal agent, fruit were rinsed with sterile water, lesions were sprayed with 70% ethanol until droplet runoff, the skin was removed aseptically with a scalpel, and tissue under the lesion was isolated and placed onto potato dextrose agar (PDA). PDA plates were incubated at 20°C in the dark, and single spores were transferred to fresh PDA plates. The isolates produced colonies with white-yellowish to brownish mycelium. Microconidia were produced on feathery fascicles of aerial mycelium, with a white, powdery, or sugary appearance on the surface of the agar colony. Microconidia were 2.5 to 6.5 × 1.5 to 2.5 µm, ellipsoidal, slightly asymmetrical to a curved form. The identity of a representative isolate (PPO 45010) was confirmed by means of multilocus gene sequencing. To this end, genomic DNA was extracted using the LGC Mag Plant Kit (Berlin) in combination with the Kingfisher method (Waltham, MA). Segments of the internal transcribed spacer region (ITS), 28S ribosomal RNA (28S rRNA) and beta-tubulin (TUB2) loci were amplified, sequenced with primers ITS1/ITS4, LR0R/LR5, and Btub2Fd/Btub4Rd (Chen et al. 2016), and deposited in GenBank under accession nos. KX424942 (ITS), KX424941 (28S rRNA), and KX424940 (TUB2). MegaBLAST analysis revealed that the ITS, 28S rRNA, and TUB2 sequences matched with 99 to 100% identity to N. kienholzii isolates in GenBank (KR859082 and KR859083 [ITS], KR858873 and KR858874 [28S rRNA], KR859288 and KR859289 [TUB2]). Alcohol surface sterilized fruits were inoculated in pathogenicity tests in two ways: (i) with an agar disk (10 mm diameter) with actively growing mycelium of N. kienholzii prepared from a 14-day-old culture grown on PDA; and (ii) with 20 μl of a spore suspension (105 conidia ml-1) prepared from a 21-day-old PDA culture after wounding with a needle. Both experiments were performed on 10 ‘Conference’ pears. Inoculated fruits were sealed in plastic bags and were incubated in darkness at 20°C. Typical symptoms appeared between 7 and 14 days. Mock-inoculated controls with water and PDA-only controls remained symptomless. Fungi isolated from the lesions had morphological characteristics that resembled the original isolates from infected pears. The identity of these isolates was confirmed as N. kienholzii by sequencing, thus completing Koch’s postulates. Bull’s eye rot of apple and pear is an important postharvest disease, occurring in major fruit growing areas of North America, Chile, Australia, and Europe (Henriquez et al. 2004; Spotts et al. 2009). N. kienholzii was reported twice on apple in Europe (Michalecka et al. 2016). To the best of our knowledge, this is the first report of N. kienholzii causing bull’s eye rot of pear in Europe.

Study of controlled atmosphere cold storage

Major cold storages existing in India are all having 50 years old technology. These are basically refrigeration units with no or minimum control on hhumidity, let aside aatmosphere ccontrol ssystems. As a result the aapples stored in it gets non-crispy and freshness is gone, India is a ssecond llargest pproducer of ffruits & vvegetables in the world but there is great loss by spoiling them worth Rs 40000 crores every year. Invest in apples is not like in gold but put up in a controlled atmosphere cold storage (CACS) and it will earn gold, this only way to keep fruit and vegetable as farm fresh. Have you ever wondered how the apples & other fruits from Australia & China come to Indian market and still fresh and crispy? And we define the non-crispy (Bhus-Bhus) apples a Cold Storage Apple.

First Report of Fusarium avenaceum Causing Postharvest Decay on ‘Conference’ Pears in the Netherlands

Pear (Pyrus communis) is an important fruit crop in the Netherlands, with a total production of 349,000 tons in 2014. ‘Conference’ is the main pear cultivar that occupies 75% of the total pear production area in the Netherlands. In the Netherlands, pears are kept in controlled atmosphere cold storage for 9 to 11 months after harvest. Lesions were observed on pears of the cultivar Conference in a survey carried out from 2012 to 2014 in packing houses in the Netherlands. In general, low incidences of 1 to 5% were recorded. Lesions showed brown and watery circular necrosis, were slightly sunken, often with visible whitish, yellowish, or pink mycelia covering the lesions. Fruits were rinsed with sterile water, and lesions were sprayed with 70% ethanol until droplet runoff. The skin was removed aseptically with a scalpel, and tissue under the lesion was isolated and placed onto potato dextrose agar (PDA). The PDA plates were incubated at 20°C in the dark, and single spore isolates were propagated on fresh PDA plates. These isolates produced fast-growing colonies with extensive aerial mycelium which was initially white, then turning yellow to pink and a dark pink to red reverse. Macroconidia were slightly falcate, thin-walled, usually 5 septate, with a tapering apical cell, and measured 40 to 80 × 3.5 to 5 μm. Both cultural and morphological characteristics of the pathogen were similar to those described for Fusarium spp. The identity of two representative isolates (Fu5-44261 and Fu6-44280) from different pear lots was confirmed by means of multilocus gene sequencing. Genomic DNA was extracted using the LGC Mag Plant Kit (Berlin) in combination with the Kingfisher method (Waltham, MA). Sequences of ITS region, translation elongation factor 1-alpha (TEF1), and histone H3 (HIS3) loci were amplified and sequenced. The sequences have been deposited in GenBank under accession numbers KT350588 and 89 (ITS), KT350605 and 06 (TEF1), and KT935569 and 70 (HIS3). MegaBLAST analysis revealed that our ITS sequences matched with 99.8 to 100% identity to Fusarium spp. belonging to the Fusarium tricinctum species complex. The TEF1 sequences of both isolates were 99 to 100% identical with F. avenaceum culture collection sequences in GenBank (JQ429374 and GQ915502). The HIS3 sequences of both isolates were 97 to 99% identical with the sequences of accessions JQ435857 and GQ915469, confirming the identity of these isolates as F. avenaceum. Koch’s postulates were performed on 15 ‘Conference’ pears per isolate. Surface sterilized fruit were inoculated with 20 μl of a suspension of 105 macroconidia ml–1 prepared from a 15-day-old PDA culture, after wounding with a needle. Inoculated fruits were sealed in a plastic bag and incubated in darkness at 20°C. Symptoms appeared after 4 to 6 days on 100% of the fruits while mock-inoculated controls with water remained symptomless. Fungal colonies isolated from the lesions and cultured on PDA morphologically resembled the original isolate from the infected pears. Symptoms observed on artificially inoculated ‘Conference’ pear fruit were identical to the decay observed on ‘Conference’ pears that were obtained from cold storage. Only few reports describe symptoms associated with F. avenaceum on apple in Europe and the United States (Kou et al. 2014; Sever et al. 2012; Sorensen et al. 2009), while F. avenaceum infections of pears have not been reported. Thus, this is the first report of storage decay caused by F. avenaceum on pear. F. avenaceum infections may constitute a safety issue due to the potential production of mycotoxins such as moniliformin (Sorensen et al. 2009).

First Report of Neonectria candida Causing Postharvest Decay on ‘Conference’ Pears in the Netherlands

Pear (Pyrus communis) is an important fruit crop in the Netherlands, with a total production of 349,000 tons in 2014, and ‘Conference’ is the main pear cultivar that occupies 75% of the total pear production area. In the Netherlands, pears are kept in controlled atmosphere cold storage up to 11 months after harvest. Occasionally, storage rots are observed when storage crates are contaminated with orchard soil. In a storage trial (2012 to 2013), boxes with ‘Conference’ pears were amended with soil particles from the same orchard from which the pears were harvested (four orchards), and stored for 11 months. Boxes without amended soil were included as controls. In contrast to the control boxes, up to 15% of the pears stored in boxes with soil particles showed typical rot symptoms (lesions) of an unknown causal agent. The lesions showed brown and watery circular necrosis, were slightly sunken, and displayed whitish to yellowish mycelia covering the lesions. To isolate the causal agent, fruit were rinsed with sterile water, lesions were sprayed with 70% ethanol until droplet runoff, the skin was removed aseptically with a scalpel, and tissue under the lesion was isolated and placed onto potato dextrose agar (PDA). The PDA plates were incubated at 20°C in the dark, and single spore isolates were transferred to fresh PDA plates. These isolates produced fast-growing colonies with white-yellowish mycelium. Conidia were hyaline, cylindrical, 1 to 3 septate, and 15.8 to 26.4 × 5.3 to 7.9 µm. The fungus was morphologically identical to Neonectria candida (syn. N. ramulariae; anamorph Cylindrocarpon obtusiusculum) (Lombard et al. 2015). The identity of a representative isolate (VTN10Bs3) was confirmed by means of multilocus gene sequencing. To this end, genomic DNA was extracted using the LGC Mag Plant Kit (Berlin, Germany) in combination with the Kingfisher method (Waltham, USA). Sequences of the ITS region, translation elongation factor 1-alpha (TEF1), and actin (ACT2) loci were amplified, sequenced, and deposited in GenBank under accessions KU588183 (ITS), KU588186 (TEF1), and KU588184 (ACT2). MegaBLAST analysis revealed that our ITS, TEF1, and ACT2 sequences matched with >99 to 100% identity to N. candida isolates in GenBank (KM249079 and JF735314 [ITS], JF735791 and HM054091 [TEF1], and KM231146 [ACT2]). Subsequently, Koch’s postulates were performed on 15 ‘Conference’ pears. Surface sterilized fruits were inoculated with 20 µl of a suspension of 105 conidiospores ml–1 water, prepared from a 15-day-old PDA culture, after wounding with a needle. Inoculated fruits were sealed in a plastic bag and incubated in darkness at 20°C. Symptoms appeared after 7 days on 100% of the fruits while mock-inoculated controls with water remained symptomless. Fungal colonies isolated from the lesions and cultured on PDA morphologically resembled the original isolate from the infected pears. Moreover, symptoms observed on artificially inoculated ‘Conference’ pear fruit were identical to the decay observed on ‘Conference’ pears that were obtained from the cold storage experiment. The identity of the reisolations was confirmed as N. candida by sequencing. N. candida (syn. N. ramulariae) is known as a globally distributed soilborne fungus (Domsch et al. 2007), but only few studies have identified the fungus as plant pathogen (Hirooka 2012). This is the first report of N. candida causing storage rot of pears. Importantly, we note that the occurrence of storage rots may be enhanced by contamination of storage crates or fruit with orchard soil.

First Report of Fusarium avenaceum Causing Postharvest Decay of 'Gala' Apple Fruit in the United States.

Apples are kept in controlled atmosphere cold storage for 9 to 12 months and are highly susceptible to postharvest decay caused by various fungi. Fusarium avenaceum is a wound pathogen that has been shown to account for the majority of Fusarium rot on apple fruit in Croatia (1). F. avenaceum produces an array of mycotoxins including moniliformin, acuminatopyrone, and chrysogine, which are of primary concern for the apple processing industry (2). In February 2013, 'Gala' apple fruits with soft, circular, brown, watery lesions with characteristic abundant whitish mycelium covering the surface of the colonized fruit were obtained from bins from a commercial storage facility located in Pennsylvania. Several samples were collected and prepared for pathogen isolation. Apples were rinsed with sterile water, and the lesions were sprayed with 70% ethanol until runoff. The apple skin was aseptically removed with a scalpel, and asymptomatic tissue was placed onto full strength potato dextrose agar (PDA) petri plates without antibiotics and incubated at 25°C under natural light. Two single-spore isolates were propagated on PDA and permanent cultures were maintained as slants and stored in a cold room at 4°C in the dark. Fungal colonies initially formed abundant fluffy white mycelium and produced a golden orange pigment on PDA at 25°C. Isolates were identified as Fusarium based on cultural and conidial morphology as macroconidia were slightly falcate, thin-walled, usually 3 to 5 septate, with a tapering apical cell that was on average 23.6 μm long × 5.0 μm wide (n = 50). Microconidia were produced on PDA plates while chlamydospores were not evident. Identity of the isolates was confirmed through DNA extraction followed by amplification and sequencing of the translation elongation factor (EF-1α, 350 bp) gene region. The amplicons were sequenced using the forward and reverse primers and assembled into a consensus representing 2X coverage. MegaBLAST analysis revealed that both isolates were 100% identical with many other culture collection F. avenaceum sequences in Genbank (Accessions JQ949291.1, JQ949305.1, and JQ949283.1), which confirms their identification in conjunction with the morphological observations. Koch's postulates were conducted to determine pathogenicity using organic 'Gala' apple fruit that were surface sanitized with soap and water, sprayed with 70% ethanol, and wiped dry. The fruit were wounded with a finishing nail to 3 mm depth, inoculated with 50 μl of a conidial suspension (1 × 104 conidia/ml) using a hemocytometer, and stored at 25°C in 80-count boxes on paper trays for 21 days. Water-only controls were symptomless. Ten fruit composed a replicate for each isolate, and the experiment was repeated. Symptoms observed on artificially inoculated 'Gala' apple fruit were identical to the decay observed on 'Gala' apples that were obtained from cold storage. Decay caused by F. avenaceum may represent an emerging problem for the apple storage and processing industry. Therefore, it is important to monitor for this pathogen to prevent future losses and mycotoxin contamination of processed fruit products caused by this fungus. To the best of our knowledge, this is the first report of Fusarium rot caused by F. avenaceum on apple fruit from cold storage in the United States.

THE EFFECT OF CALCIUM TREATMENTS ON ASPECTS OF CELL WALL METABOLISM IN APPLE CV. ´BRAEBURN´

'Braeburn' apple is appreciated because of its 'crispy' texture and acid taste but it is very susceptible to several storage disorders, mealiness included, because of its low calcium content. Many attempts are in progress to improve calcium flesh concentration and thus its keeping quality. Aim of the present work is to study the capability of both field and posthavest treatments in keeping fruit quality during cold storage. 'Braeburn' apples field or postharvest treated with diverse calcium formulae and additives, were examined for quality (total soluble solids, titratable acidity, flesh firmness and starch content), calcium content and cell wall composition (cellulose, total, soluble and insoluble pectins and neutral sugars) at harvest and after seven months of controlled atmosphere cold storage (ULO). Field and postharvest calcium treatments did not affect quality traits both at harvest and after storage, nevertheless they influenced calcium contents in fruit flesh and they modified cell wall composition. All field treatments increased fruit calcium content up to 10-60% and the effects lasted until the end of storage. Postharvest treatments increased cation level (8-60%) at the end of storage. Cellulose content increased for both treatments and the effect lasted during storage. Field supplies seemed to stimulate pectin biosynthesis also after harvest for long time, while postharvest treatments did not increase pectin biosynthesis but were very effective in preventing pectin solubilization. Field treatments reduced rhamnose content in stored fruits, thus reducing the side chain number of polygalacturonic acid with the consequent increase of the pectic matrix cohesion to which ascribe the flesh crispness of this apple cultivar. Galactose, a basic component of pectin chains, was positively affected by field supplies and its high level was maintained through the storage period. Postharvest calcium treatments did not increase galactose content, but were very active in keeping its level. This results confirmed the influence of calcium on cell wall metabolism.

Mortality responses of the brownheaded and blacklyre leafrollers to controlled atmosphere and air cold storage treatments for kiwifruit

The mortality responses of the brownheaded leafroller (Ctenopseustis obliquana) and the blacklyre leafroller (Cnephasia jactatana) to controlled atmosphere cold storage (CACS) and air cold storage (CS) treatments for kiwifruit were investigated CACS (2 O2 5 CO2 at 0C) killed both leafrollers faster than CS (at 0C) The brownheaded leafroller was more tolerant of both storage treatments than the blacklyre leafroller Third and 5th instars were generally more tolerant of storage treatments than 1st instars which in turn outlived eggs This work predicts both brownheaded and blacklyre leafrollers should be completely controlled by 4 weeks CACS or 9 weeks CS

Pre- and Postharvest Effects of Lufenuron on <I>Epiphyas postvittana</I> (Lepidoptera: Tortricidae)

First-, third-, and fifth-instar Epiphyas postvittana (Walker) were exposed to a range of lufenuron concentrations (0-200 ppm) incorporated into synthetic diet and their subsequent development and mortality responses were determined. For all instars the greatest change in mortality response occurred over lufenuron concentrations < or = 3 ppm. However, third and fifth instars displayed an increase in mortality earlier than first instars, and were more sensitive to the lower lufenuron concentrations in this range. Only first and third instars subjected to < or = 2.5 ppm lufenuron survived the 26-d exposure trial. No larvae first exposed to lufenuron as first or third instars survived to pupation if ingesting concentrations of > or = 1 and > or = 3 ppm, respectively. Consumption of lower lufenuron concentrations by these larvae delayed pupation and resulted in pupal deformity. In contrast, fifth instars subjected to 100 ppm were capable of surviving the 26-d trial period and displayed a slower progressive reduction in survival to pupation with increase in lufenuron concentration. Also in contrast to more immature stages, fifth instars exposed to lufenuron developed more rapidly to pupation than larvae not exposed to the insect growth regulator (IGR), and all resulting pupae were normal. Third instars were exposed to sublethal lufenuron concentrations (0-3 ppm) for 4 d and the fourth-instar survivors subjected to a controlled atmosphere cold storage treatment (2% O2, 2% CO2, 0.6 degree C). Larvae ingesting diet containing 0.5 ppm (and to a lesser extent 1 ppm) lufenuron required longer exposure to the postharvest treatment to achieve > or = 95% mortality than larvae not ingesting the IGR. However, the analogous mortality response of larvae exposed to 3 ppm lufenuron was comparable to the control.

Mortality response of lightbrown apple moth to a controlled atmosphere cold storage treatment for apricots

The mortality response of lightbrown apple moth, Epiphyas postvittana (Walker), to a controlled atmosphere (CA) cold storage treatment for apricots was investigated. The mean estimated times for 99% mortality (LT99) of 1st and 5th instar larvae inoculated onto apricots and exposed to 1.5% O2, 3% CO2 (CA) at 0°C, were 19.9 ± 0.13 and 22.4 ± 0.24 d, respectively. The treatment time for 50% mortality (LT50) was similar for the two life stages. However, 5th instar larvae required longer treatment times than 1st instar larvae to achieve 99 and 99.9968% mortality (LT99.9968). A 28 d treatment resulted in complete mortality of both life stages tested.

Effects of ethephon on ripening, red colour, and storage performance of Jonathan and Delicious apples

Ethephon, at concentrations of 125- 1000 ppm, was applied to Jonathan and Delicious apple trees 3-4 weeks before the anticipated harvest date for untreated apples. Ripening of Jonathan, as measured by increases in red colour and flavour score, was advanced by 6, 10, and 15 d by 250,500 and 1000 ppm ethephon respectively. Softening was not affected. Fruit drop was increased by 1000 ppm only, to 14% of the crop. In Delicious, red colouring and flavour development were advanced by up to 6 d with 1000 ppm ethephon, but yellowing and softening were advanced more, by 7- 14 d with 250 ppm and up to 10- 17 d with 1000 ppm. Softening did not reach unacceptable levels, but three weeks after treatment, yellowing and water core reached unacceptable levels. Red colouring, as measured by anthocyanin concentration or area of red skin, was increased up to two-fold in Jonathan with 1000 ppm, and by up to 50% in Delicious with 1000 ppm. Ethephon also advanced the rise in susceptibility of both cultivars to storage disorders, breakdown and brownheart, in air or controlled atmosphere cold storage. However, if the treated apples were harvested when ripe, 7- 15 d before the controls, their quality after storage was the same as that of controls harvested later.