Studies were conducted to evaluate potential chemical disease management tools for Alternaria fruit rot on navel oranges and Coniophora brown wood rot on lemon trees, to investigate the possible effect of branch diameter on development of Coniophora wood rot on lemon trees and to summarize our evaluations of citrus rootstocks with respect to relative resistance to root rot and stem canker development when challenged with Phytophthora citrophthora and P. parasitica. We were unable to reduce the level of Alternaria fruit rot on navel oranges with single applications of Abound or copper hydroxide following significant rainfall events. Wood decay in lemon branches inoculated with Coniophora eremophila was significantly suppressed by Abound and a thick formulation of sodium tetrathiocarbonate. The degree of Coniophora brown wood rot in lemon branches of different diameters was variable, although the level of disease in 10 mm diameter branches was significantly smaller than the amount of wood decay in 30 mm diameter branches. Root loss due to Phytophthora citrophthora and P. parasitica in Citrus macrophylla, rough lemon, C. volkameriana and Troyer citrange was lower than most of the 36 different rootstocks tested. On the other hand, root loss on Carrizo citrange, C-35 citrange and sour orange was among the higher values of disease recorded. Stem canker development due to both species of Phytophthora on Troyer citrange, Carrizo citrange, sour orange and Citrus macrophylla was lower than most of the 36 rootstocks tested. Stem cankers on rough lemon and Citrus volkameriana were among the higher values of disease recorded.

A field survey of mature lemon trees showed an average of 30% of trees with symptoms of brown heartwood rot caused by Coniophora sp. In vivo growth of Coniophora inoculated into branches of different types of citrus (Valencia orange, Marsh grapefruit, Orlando tangelo or Lisbon lemon) on rough lemon rootstock was significantly higher in lemon while Coniophora inoculated into Lisbon lemon wood branches on trees established on rough lemon, volkameriana, macrophylla, Cleopatra mandarin, sour orange or Troyer citrange rootstocks showed no significant differences in growth. Vegetative incompatibility trials from one mature orchard demonstrated that isolates from different trees are incompatible. In vitro fungicide trials showed that only NECTEC paste effectively reduced decay on lemon blocks 15 weeks after inoculation with Coniophora. Field fungicide trials showed that NECTEC P paste as well as the blank paste without fungicides, propiconazole at 10,000 μg /ml, imazalil at 20, 000 μg /ml or propiconazole plus imazalil in combination at 10,000 and 20,000 μg/ml, respectively, significantly inhibited the advance of fungus 7 mo. after inoculation. A second fungus isolated from brown rot in branches in younger orchards was identified as Antrodia sinuosa, a native decay fungus on conifers in Arizona.

The incidence and severity of Alternaria fruit rot on navel oranges has increased in Maricopa County. The objectives of this study were to test the efficacy of two fungicides, Kocide 101 and Rovral, for disease control and to determine an application schedule that will result in optimum control of disease. In 1994, compared to nontreated trees, a significant reduction in the number of dropped oranges occurred on trees sprayed one to five times with Rovral at monthly intervals from April through August. In the same year, monthly applications of Kocide 101 from April through August were no better than leaving trees untreated. In 1995, Rovral treatments from March through August provided no apparent beneficial effects on control of Alternaria fruit rot, while a single application of Kocide 101 in December, January, or February resulted in significantly less dropped oranges compared to nontreated frees. Because of the inconsistent activity of Kocide 101 and Rovral in these two studies, an additional trial is in progress during 1996. The additional data from 1996 may help identify when and what fungicide(s) could provide significant control ofAlternaria fruit rot of navel oranges in Arizona.

A physiological characterization has established that vascular changes in Macrophylla decline affected trees are not similar in character to xyloporosis affected trees. In addition, a survey of Macrophylla decline affected citrus did not establish any genetic similarity between Macrophylla decline and xyloporosis. We report diagnosis of either CCV or CEV by reverse transcription-polymerase chain reaction (RT-PCR), as well as diagnosis of Macrophylla decline or xyloporosis by Zn-distribution, water conductivity, accumulation of decline- specific proteins and examination of phloem morphology in lemon trees on the Macrophylla rootstock.

Experiments were initiated to evaluate chemical disease management tools for Alternaria fruit rot on navel orange and Coniophora brown wood rot on lemon trees, examine the possible effect of branch diameter on development of Coniophora wood rot on lemon trees and continue evaluations of relative resistance of rootstocks to root rot and stem canker development when inoculated with P. citrophthora and P. parasitica. Rovral or Kocide did not significantly reduce the amount of Alternaria fruit rot on navel orange trees occurring in late summer and early autumn when applied during the preceding winter or spring months. Of several chemical treatments tested, only Nectec paste inhibited the development of Coniophora brown wood rot on inoculated lemon branches. The size of wood decay columns on branches 10 mm (0.5 inch) in diameter were significantly smaller than those developing on branches 50-70 mm (2.0-2.75 inches) in diameter. In extensive trials evaluating root rot caused by Phytophthora citrophthora and P. parasitica, some relatively tolerant rootstocks were found among the group of new potential rootstocks as well as currently used rootstocks such as rough lemon, C. macrophylla and Troyer citrange. C. volkameriana was relatively tolerant to the development of root rot by P. citrophthora but demonstrated variable tolerance to P. parasitica. Comprehensive evaluation of stem canker development on citrus rootstocks inoculated with P. citrophthora or P. parasitica revealed that rough lemon is usually highly susceptible to both pathogens, while C. volkameriana was at times less susceptible (more tolerant) than rough lemon to both pathogens. Some of the new potential rootstocks were highly tolerant or resistant to infection of stem tissue by P. citrophthora or P. parasitica.

Seasonal flight of beet leafhopper vectors of stubborn disease was monitored at wholesale nurseries in Yuma County, and at young citrus groves in Maricopa County using yellow sticky traps exposed at successive two-week intervals. Trapped leafhoppers were removed and assayed for presence of the citrus stubborn agent by PCR. Leafhoppers were collected live from weed plants in groves and nurseries using an insect vacuum and both leafhoppers and tissue from weed plants were assayed by PCR for the stubborn agent. Selected trees in groves in Yuma and Maricopa Counties were visually inspected for stubborn symptoms.

published_or_final_version / Ecology and Biodiversity / Master / Master of Philosophy

Bibliography: leaves 204-211. / v, 211 leaves : ill. (chiefly col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This study investigates the effects of a number of petroleum and vegetable oils against citrus pests. / Thesis (Ph.D.)--University of Adelaide, Dept. of Applied and Molecular Ecology, 2000

Made available in DSpace on 2014-06-11T19:26:08Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-02-22Bitstream added on 2014-06-13T18:29:32Z : No. of bitstreams: 1 santos_m_me_jabo.pdf: 333325 bytes, checksum: 9f90954b7831d0ab7d554fea50c99a27 (MD5) / O huanglongbing (HLB ou greening) é uma doença altamente destrutiva que ataca a maioria das espécies de citros. Trabalhos e observações recentes sugerem que os porta-enxertos podem ter influência na incidência e severidade da doença. O presente projeto teve como objetivo monitorar a reação de 16 variedades de porta-enxertos sob laranjeira „Valencia‟ frente ao Candidatus Liberibacter asiaticus por meio da técnica de q-PCR, e suas respostas biométricas, tais como: diâmetro 2 cm a baixo e a cima da linha da enxertia, altura do colo da planta ao enxerto e do enxerto a poda, comprimento do lançamento, peso fresco da parte aérea e do sistema radicular, volume do sistema radicular, e análise foliar de macro e micronutrientes. Os porta-enxertos empregados foram os principais em uso comercial: trifloliateiro „Flying Dragon‟, limoeiro „Cravo‟, „Poncirus trifoliata’, tangerineira „Sunki‟ e citrumelo „Swingle‟, testados experimentalmente com bons resultados: citrangeiros „Troyer‟ e „Carrizo‟ tetraplóides, HRS 643, HRS 702, HRS 849 e HRS 812, em fase de experimentação: „Clementina x trifoliata‟ (1615), „Cleópatra x Swingle‟ (1614), „Cleópatra x Rubidoux‟ (1600) e „Changsha x English Large‟, além de um híbrido „Rhode Red + Volkameriano‟, também em fase experimental. O experimento foi conduzido no Centro de Citricultura Sylvio Moreira, em Cordeirópolis. Cada associação copa e porta-enxerto apresentaram sete plantas, cinco delas foram inoculadas e duas não inoculadas. Para analisar a evolução da bactéria nas plantas foram realizadas três amostragens (8, 12, 16 meses após a inoculação), de pecíolos e nervuras centrais... / The Huanglongbing (HLB or greening) is a highly destructive disease that affects most citrus cultivars, species and hybrids. Recent works and researches suggest that rootstock variety influenced disease severity and incidence. This work aimed to characterize variation in the reaction of 16 cultivars of rootstocks grafted with a sweet orange „Valência‟ scion in response to Candidatus Liberibacter asiaticus by q-PCR and biometric characteristics such as: stem diameter 2 cm above and below the grafting, collar height of the plant to the graft, collar height of the graft to the pruning, length of the first bud after pruning, fresh weight of aerial part of the plant, fresh weight of root system, root volume and leaf analysis of macro and micronutrients. The rootstocks used in the work were the major commercial cultivars: trifoliate orange „Flying Dragon‟, Rangpur lime, „Poncirus trifoliata‟, mandarin „Sunki‟ and citrumelo „Swingle‟, tested experimentally with good results, citrange „Troyer‟ and „Carrizo‟ tetraploid, HRS 643, HRS 702, HRS 849 and HRS 812, in experimental stage, „Clementina x trifoliata‟ (1615), „Cleópatra x Swingle‟ (1614), „Cleópatra x Rubidoux‟ (1600) and „Changsha x English Large‟, plus a hybrid „Rhode Red + Volkameriano‟. The experiment was conducted at Centro de Citricultura Sylvio Moreira in Cordeirópolis. Each cultivar had seven plants, five were inoculated and two were used as control plants. To evaluate the growth of bacteria in plants, three sampling were done at (8, 12, 16 months after inoculation) by visually infected... (Complete abstract click electronic access below)

Orientador: Eduardo Sanches Stuchi / Coorientador: Helvécio Della Coletta Filho / Banca: Antonio Baldo Geraldo Martins / Banca: Simone Rodrigues da Silva / Resumo: O huanglongbing (HLB ou greening) é uma doença altamente destrutiva que ataca a maioria das espécies de citros. Trabalhos e observações recentes sugerem que os porta-enxertos podem ter influência na incidência e severidade da doença. O presente projeto teve como objetivo monitorar a reação de 16 variedades de porta-enxertos sob laranjeira „Valencia‟ frente ao Candidatus Liberibacter asiaticus por meio da técnica de q-PCR, e suas respostas biométricas, tais como: diâmetro 2 cm a baixo e a cima da linha da enxertia, altura do colo da planta ao enxerto e do enxerto a poda, comprimento do lançamento, peso fresco da parte aérea e do sistema radicular, volume do sistema radicular, e análise foliar de macro e micronutrientes. Os porta-enxertos empregados foram os principais em uso comercial: trifloliateiro „Flying Dragon‟, limoeiro „Cravo‟, „Poncirus trifoliata', tangerineira „Sunki‟ e citrumelo „Swingle‟, testados experimentalmente com bons resultados: citrangeiros „Troyer‟ e „Carrizo‟ tetraplóides, HRS 643, HRS 702, HRS 849 e HRS 812, em fase de experimentação: „Clementina x trifoliata‟ (1615), „Cleópatra x Swingle‟ (1614), „Cleópatra x Rubidoux‟ (1600) e „Changsha x English Large‟, além de um híbrido „Rhode Red + Volkameriano‟, também em fase experimental. O experimento foi conduzido no Centro de Citricultura Sylvio Moreira, em Cordeirópolis. Cada associação copa e porta-enxerto apresentaram sete plantas, cinco delas foram inoculadas e duas não inoculadas. Para analisar a evolução da bactéria nas plantas foram realizadas três amostragens (8, 12, 16 meses após a inoculação), de pecíolos e nervuras centrais... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The Huanglongbing (HLB or greening) is a highly destructive disease that affects most citrus cultivars, species and hybrids. Recent works and researches suggest that rootstock variety influenced disease severity and incidence. This work aimed to characterize variation in the reaction of 16 cultivars of rootstocks grafted with a sweet orange „Valência‟ scion in response to Candidatus Liberibacter asiaticus by q-PCR and biometric characteristics such as: stem diameter 2 cm above and below the grafting, collar height of the plant to the graft, collar height of the graft to the pruning, length of the first bud after pruning, fresh weight of aerial part of the plant, fresh weight of root system, root volume and leaf analysis of macro and micronutrients. The rootstocks used in the work were the major commercial cultivars: trifoliate orange „Flying Dragon‟, Rangpur lime, „Poncirus trifoliata‟, mandarin „Sunki‟ and citrumelo „Swingle‟, tested experimentally with good results, citrange „Troyer‟ and „Carrizo‟ tetraploid, HRS 643, HRS 702, HRS 849 and HRS 812, in experimental stage, „Clementina x trifoliata‟ (1615), „Cleópatra x Swingle‟ (1614), „Cleópatra x Rubidoux‟ (1600) and „Changsha x English Large‟, plus a hybrid „Rhode Red + Volkameriano‟. The experiment was conducted at Centro de Citricultura Sylvio Moreira in Cordeirópolis. Each cultivar had seven plants, five were inoculated and two were used as control plants. To evaluate the growth of bacteria in plants, three sampling were done at (8, 12, 16 months after inoculation) by visually infected... (Complete abstract click electronic access below) / Mestre