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العنوان
BIOLOGY AND CONTROL OF BROWN ROT FUNGI ON SOME STONE FRUITS.
المؤلف
ABO EL WAFA, THAURIA MABRUOK MOHAMED.
هيئة الاعداد
باحث / ثرية مبروك محمد أبو الوفا
مشرف / أحمد أحمد أحمد موسى
مشرف / مدحت كامل على السيد
مشرف / صلاح السيد يوسف
تاريخ النشر
2019.
عدد الصفحات
434 p. :
اللغة
الإنجليزية
الدرجة
الدكتوراه
التخصص
علوم النبات
تاريخ الإجازة
24/2/2018
مكان الإجازة
جامعة عين شمس - كلية الزراعة - أمراض النبات
الفهرس
Only 14 pages are availabe for public view

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from 434

Abstract

The stone fruit crops are subject to attacked by many fungal diseases during various stages of fruit development where the brown rot is considered the most destructive disease. The brown rot fungus, Monilinia spp., may attack blossoms, fruit spurs (flower and fruit bearing twigs), small branches as well as the fruit itself causing serious losses. The disease development is most important on fruits just before ripening, and during and after harvest. Under favorable conditions, fruits got decayed on the trees in stone fruit orchards, mainly peach and apricot, where the entire crop can be completely lost. Peaches and apricots that not kept in cool storage may be rotted within two to three days by Monilinia spp. resulting in significant economic losses, and also reduce the value of marketing fruits and make them undesirable to the consumer, in addition to the loss of the value of food and the inability to export them to foreign markets. Due to the importance of this disease, this study was conducted to characterize species of Monilinia causing brown rot of peach, apricot and nectarine in different areas in Egypt, during the years 2013-2014 using traditional and molecular techniques. Also, to study the effect of some chemical treatments or safe biological alternatives, either as before-or after-harvest treatments to reduce disease and reduce post-harvest losses while preserving quality of fruits.
The main findings of the study could be summarized as follows:
1. Survey of brown rot disease were carried-out at different phenological stages of peaches, nectarines and apricots, at flowering stage, in different growing locations at four governorates (Qalyubia, Ismailia, Menoufia, Beheira) during seasons, 2013-2014. Peaches produced in Beheira governorate showed the highest infection with brown rot on all examined twig and floral parts except when comparing twig canker observed on peaches cultivated in Qalyubia. Nectarine produced in Beheira showed brown rot and twig canker with Monilinia spp. infection comparable to that found on peaches at relatively higher percentage.
2. A total of 300 isolates of Monilinia species were isolated from diseased samples, including flowers, flower holder, immature green fruits, branches and mature fruits of peach, apricot, and nectarine trees grown in orchards in different governorates. Monilinia fructigena was the most dominant fungus (90.66%) where 272 isolates were obtained from flowers, peduncle, twigs and branches, immature and ripe fruits, followed by 21 isolates of M. laxa (7.0%), six isolates of M. fructicola (2.0%) and an isolate of M. polystroma (0.44)
3. The number of obtained Monilinia spp. isolates varied according to orchards locations, where 77 isolates were obtained from El-Nobaria, 68 isolates from El-Qanater, 61 isolate from Wady El-Natron, 32 isolates from El-Tahrir, 30 isolates from El-Khatatba, 24 isolates from El-Sadat, and 8 isolates from Ismailia, representing different geographical distribution.
4. Molecular identification of Monilinia isolates divided these isolates into four main clusters depending upon the determined morphological features for Monilinia species. To facilitate molecular characterization of Monilinia isolates, 10 isolates represent the main clusters and groups were selected and coded ARC1 to ARC10 and subjected to RAPD-PCR testes using 2 primers; and thereafter four isolates were selected for further molecular analysis. Four selected isolates were allocated on lanes and named as ARC1, ARC4, ARC5 and ARC7. Internal transcribed spacer regions (ITS) and a genomic sequence with unknown function were analyzed and compared with sequence data from other Monilinia species in an international database (NCBI GeneBank).
5. The ITS1-5.8S-ITS4 sequences of isolates ARC5 and ARC7 were identical with M. fructigena (Genbank accession nos FJ515296, and Z73781), and isolate ARC4 was identical with M. laxa (Genbank accession nos Z73784, EF153015) while isolate ARC1 was identical with M. fructicola (Genbank accession nos JN001480 ). Within each species, the ITS sequences of M. fructigena, M. fructicola, and M. laxa isolates were 100% identical to one another Genbank. Between the three species, there were considerable nucleotide variations.
6. Representative isolates of three Monilinia species, i.e. M. fructigena, M. laxa and Monilinia fructicola, were tested for their pathogenic capability and aggressiveness on peach and apricot fruits. All Monilinia isolates tested were pathogenic to peache and apricot fruits in fast tests,however the isolates varied in aggressiveness.
7. Certain salts and acids showed in vitro inhibitory effect to mycelial growth of Monilinia laxa, M. fructigena and Monilinia fructicola. Sodium bicarbonate and salicylic acid were the most effective treatments to suppress M. fructigena and M. fructicola growth. Meanwhile, several compounds (sodium bicarbonate, potassium sorbate, boric acid and salicylic acid) were effective against M. laxa. The calculated IC50 values of sodium bicarbonate, potassium sorbate and salicylic acid on M. fructigena were less than 1000 ppm. On M. laxa, only sodium bicarbonate showed IC50 less than 1000 ppm, while the IC50 values of potassium sorbate and boric acid were less than 2000 ppm.
8. The fungicide Swimex (Cyprodinil + fludioxonil formulation) was the most effective treatment to suppress in vitro mycelial growth of M. laxa and M. fructicola isolates, while cyprodinil+fludioxonil formulation and pyraclostrobin+boscalid formulation were the most effective treatments on M. fructigena. Iprodione was only effective on M. laxa, when used at 0.5 ppm or 1.0 ppm. Calculated IC50 values showed that all four fungicides were effective at tested concentrations against the three Monilinia spp. up to 1.0 ppm except for Reynoutria extract on M. fructigena. While, Iprodione, Reynoutria extract and cyprodinil+fludioxonil formulation showed high inhibitory effect against M. laxa, where the IC50 values were less than 0.025 ppm. pyraclostrobin+boscalid formulation was less effective with IC50 of 0.127 ppm, referring to high sensitivity of M. laxa toward all tested fungicides.
9. Essential oils of cinnamon, thyme and carnation were highly effective to suppress in vitro growth of M. fructigena, M. laxa and Monilnia fructicola isolates.
10. Potassium sorbate, boric acid and sodium bicarbonate were significantly the most effective treatments, as three times pre-harvest spray, to reduce incidence and severity of brown rot on FlordaPrince peaches grown at Qalyubia and Ismailia. On the other hand, calcium chloride achieved more brown rot control on peaches. High firmness and relatively low total soluble solids were determined for FlordaPrince peach fruits at harvest time. Among salt and acid preharvest treatments, calcium chloride almost showed highest firmness of peaches stored for 15 days or 30 days.
11. The fungicide Cyprodinil+fludioxonil formulation, as preharvest spray 3 times, was the most effective fungicide as well as biological treatments to reduce brown rot incidence and severity on peaches produced in Qalyubia and Ismailia governorates. Relatively high firmness and low total soluble solids were determined for FlordaPrince peach fruits at harvest time. Among fungicide and bioagent preharvest treatments, cyprodinil+fludioxonil formulation almost showed the highest firmness of peaches stored for 15 days or 30 days in Qalyubia and Ismailia governorates in seasons 2015 and 2016.
12. When Canino apricots preharvest-sprayed with certain salts and acids, sodium bicarbonate, calcium chloride, potassium sorbate and boric acid resulted in total suppression of brown rot incidence when apricots cold stored for 15 days, where no brown rot symptoms appeared on apricot of Qalyubia governorate. Cold storage at 0oC for 15 days of apricots from Ismailia which preharvest-sprayed with different salts and acids did not show any incidence of brown rot. Firmness of apricots from preharvest sprayed trees in Qalyubia and Ismailia governorates with tested salts and acids was reduced with cold storage than it at harvest time. Calcium chloride was the most effective treatment to maintain highest firmness during cold storage in seasons 2015 and 2016. Pre-harvest treatment with boric acid resulted in higher firmness than salicylic acid treatment along the experiments, particularly with longer cold storage.
13. On Apricot, prehatvest-sprayed three times, with fungicide and bio-agents during seasons 2015 and 2016 at Qalyubia and Ismailia and kept after harvest at 0oC during cold storage up to 30 days, Pyraclostrobin+boscalid formulation, iprodione, cyprodinil+ fludioxonil formulation and T. harzianum (Th5), Bacillus amyloliquefaciens (Ba) and Bacillus cereus (Bc) highly suppressed brown rot incidence. Firmness of apricots was varied according to treatments, season and produced location. However, some treatments showed high firmness after 15 days at cold storage, but this firmness was deteriorated rapidly except for the effective treatment that maintain the firmness high after 30 days of cold storage such as cyprodinil+fludioxonil formulation.
14. Postharvest treatments of apricot and peach with salts and acids during season 2016 resulted in significant reduction of brown rot disease in the naturally infected fruits during cold storage for 15 days, but without significant differences among disease severity of all treatments and the control. Prolonged storage period to 30 days at 0oC magnified the positive effect of salts and acids to control brown rot on natural infected apricot and peach. However, potassium sorbate and boric acid totally controlled brown rot on naturally infected apricots and peaches during cold storage for 15 days. Artificial inoculation of apricots and peaches resulted in 100% disease incidence in the control treatment, with 10% and 20% disease severity for both types of fruits respectively, during the 15 days cold storage. sodium bicarbonate, calcium chloride, potassium sorbate and boric acid completely inhibited brown rot incidence on postharvest treated apricots and peaches. Regarding the firmness of naturally infected and artificially inoculated peaches, no significant differences were obtained among all salt and acid treatments and the control, except for the long cold storage of naturally infected ones. Calcium chloride, potassium sorbate and sodium bicarbonate showed significant higher fruit firmness when naturally infected peaches were cold stored for 30 days. TSS values of both naturally and artificially inoculated apricots and peaches postharvest treated with salts and acids did not show any significant differences.
15. Postharvest treatments of peaches with essential oils during seasons 2015- 2016 significantly reduced brown rot disease in naturally infected fruits during cold storage for 15 days. Thyme, camphor and carnation at 1% were the most effective treatments to control brown rot on naturally infected peaches during cold storage for up to 30 days in season 2015. Similar results for the efficacy of thyme, camphor and carnation oils at 1% followed by cinnamon oil at 1% to control naturally infected peaches with brown rot disease in season 2016 were observed. On artificially infected fruits, oils at 1% concentration showed more effectiveness to control brown rot than at 0.5%. During the short cold storage for 15 days in season 2015, camphor at 1% was the most effective treatment that reduced disease incidence and disease severity, followed by thyme and carnation at 1%. While cinnamon at 1% and camphor at 0.5% showed higher disease incidence than above mentioned essential oils, which caused the least disease severity. Prolonged storage of artificially inoculated peaches revealed that camphor and carnation at 1% were the most effective natural oils to reduce brown rot incidence and its severity.
16. Quality of FlordaPrince peaches postharvest treated with certain essential oil during cold storage; i.e.thyme, camphor, cinnamon and carnation as postharvest treatments at 0.5% and 1% concentration showed higher firmness of both naturally infected and artificially inoculated peaches cold stored for 15 days than when stored for 30 days. TSS values of both naturally infected and artificially inoculated peaches postharvest treated with natural oils did not show significant differences than the control treatment, which showed the highest TSS values. However, thyme and camphor at 0.5% showed as high TSS as the control treatment in the season 2015. Cinnamon also showed high TSS with prolonged cold storage of naturally infected peaches. In season 2016, thyme at 0.5% showed as high TSS as the control in naturally infected fruits stored for 15 days and in artificially inoculated peaches stored for 30 days.
17. Postharvest treatments of apricots with essential oils, i.e. thyme, camphor, cinnamon and carnation at 0.5% and 1%, during the two seasons (2015 and 2016) totally reduced brown rot disease in the naturally infected fruits during cold storage for 15 day except for carnation at 0.5% in season 2015. Prolonging cold storage up to 30 days showed that the most effective treatments to control brown rot concerning disease incidence and disease severity were carnation, cinnamon and thyme, at 1% in 2015. While carnation, cinnamon and thyme at 1% concentration were the best in 2016. So, in both seasons, carnation and cinnamon at 1% were the most effective treatments to control brown rot of naturally infected apricots during cold storage at 0oC for up to 30 days. On artificially inoculated apricots, thyme and camphor at both concentrations of 0.5% and 1% in season 2015 totally inhibited brown rot on apricots during cold storage at 0oC for 15 days. Camphor at 1% was the most effective treatment to control brown rot disease on artificially inoculated apricots during cold storage up to 30 days.
18. Quality of apricot, cv. Canino, postharvest treated with certain natural oils during cold storage: non-significant differences were determined among tested natural oils, i.e. thyme, camphor, cinnamon and carnation as well as between oil concentrations in the seasons 2015 and 2016. All tested postharvest treatments with essential oils at 1% resulted in higher firmness in seasons 2015 and 2016. On artificially inoculated apricots, almost most oils adopted at 1% showed high fruit firmness and could be concluded that cinnamon and carnation at 1% were the most effective treatments to maintain highest fruit firmness in both seasons 2015 and 2016.