White drupelet disorder (WDD) is a problem that occurs during the ripening stage in some blackber... more White drupelet disorder (WDD) is a problem that occurs during the ripening stage in some blackberry (Rubus subgenus Rubus) cultivars. Although berries affected with a few white drupelets may taste fine, they are unpleasant aesthetically, and this may lead to negative consumer perceptions and economic ramifications. During 2 years of observational studies and field trials (2016 and 2017), we evaluated changes in three susceptible cultivars in Mississippi affected by WDD. ‘Chickasaw’, ‘Kiowa’, and ‘Sweetie Pie’ berries were harvested twice per week and assessed for WDD. Weather conditions differed substantially during harvest in 2016 and 2017, with 2017 being cooler and rainier which resulted in a lower incidence of WDD. Compared with 2016, in 2017, the overall percentage of berries exhibiting WDD dropped from 22% to 12% for ‘Sweetie Pie’, 6% to 3% for ‘Chickasaw’, and 8% to 3% for ‘Kiowa’. The soluble solids concentration was highest in ‘Sweetie Pie’, 11.9% and 9.5% for 2016 and 2017...
The present study assessed the effect of photoperiod on budbreak of cuttings of three interspecif... more The present study assessed the effect of photoperiod on budbreak of cuttings of three interspecific hybrid grape (Vitis) cultivars that had received different chilling hours. Stem cuttings were collected at 100-hour intervals of chilling (200, 300, 400, 500, 600, 700, and 800 hours) from the vineyard and kept in three growth chambers with daylengths of 8, 16, and 24 hours. Another group of cuttings were maintained in a greenhouse with a natural daylength range of 10.5–13 hours [8 Dec. 2017 to 4 May 2018 (average = 12 hours)]. Chilling requirements, days to budbreak, and budbreak rate were determined after plants were exposed to different chilling hours and daylengths. Results of our study demonstrated that the chilling requirements of all three cultivars were adequately reached at 600 hours or more. Increasing chilling exposure from 600 to 800 hours shortened the time to budbreak in all cultivars. Overall, ‘MidSouth’ had an average budbreak rate of 90% when receiving at least 600 ho...
The effect of plant growth regulators (PGRs) on growth and flowering
of potted red firespike ( Odon... more The effect of plant growth regulators (PGRs) on growth and flowering of potted red firespike ( Odontonema strictum ) were examined in two experiments. In Expt. 1, foliar spray applications of daminozide, uniconazole, paclobutrazol, or flurprimidol or media drenches of paclobutrazol or flurprimidol were applied. In Expt. 2, foliar spray application of daminozide or media drenches of paclobutrazol or flurprimidol were further tested for efficacy of height control. Both studies included an untreated control. In Expt. 1, drench applications of paclobutrazol and flurprimidol resulted in plants 65% or 46% to 62% shorter than control, respectively. Paclobutrazol and flurprimidol drenches also decreased overall plant growth by 81% to 88% and 74% to 84%, respectively, compared with the control plants. PGRs did not affect number of inflorescences; however, paclobutrazol and flurprimidol delayed flowering 23 to 31 days. In Expt. 2, plants treated with flurprimidol or paclobutrazol drenches were shorter than the control. The greatest reduction in total plant growth occurred using a flurpri- midol drench at 0.47 mg/pot, which resulted in plants 78% smaller than the untreated control. Paclobutrazol and flurprimidol increased the time to flowering 11 to 27 days and 10 to 26 days, respectively. The most attractive and well-shaped plants were achieved with flurprimidol applied at 0.24 mg/pot or applications of paclobutrazol at 0.35 mg/pot.
White drupelet disorder (WDD) is a problem that occurs during the
ripening stage in some blackber... more White drupelet disorder (WDD) is a problem that occurs during the ripening stage in some blackberry (Rubus subgenus Rubus) cultivars. Although berries affected with a few white drupelets may taste fine, they are unpleasant aesthetically, and this may lead to negative consumer perceptions and economic ramifications. During 2 years of observational studies and field trials (2016 and 2017), we evaluated changes in three susceptible cultivars in Mississippi affected by WDD. ‘Chickasaw’, ‘Kiowa’, and ‘Sweetie Pie’ berries were harvested twice per week and assessed for WDD. Weather conditions differed substantially during harvest in 2016 and 2017, with 2017 being cooler and rainier which resulted in a lower incidence of WDD. Compared with 2016, in 2017, the overall percentage of berries exhibiting WDD dropped from 22% to 12% for ‘Sweetie Pie’, 6% to 3% for ‘Chickasaw’, and 8% to 3% for ‘Kiowa’. The soluble solids concentration was highest in ‘Sweetie Pie’, 11.9% and 9.5% for 2016 and 2017, respectively. For all cultivars examined, the soluble solids concentration of extracted white drupelets was substantially lower than regular drupelets. The value for skin break force for white drupelets was higher than that for black drupelets, 0.99 N vs. 0.29 N, respectively. In 2017, an about 30% shadecloth treatment had a significantly positive impact by decreasing WDD symptoms in all cultivars by 63% when compared with non-shaded plants, but soluble solids concentration was lower. Our results indicate that rain and shadecloth decrease symptoms of WDD. Therefore, growers may be able to use overhead irrigation and shade to reduce WDD symptoms.
Fruit splitting is a physiological disorder that produces surface cracks that promote disease and... more Fruit splitting is a physiological disorder that produces surface cracks that promote disease and insect damage. The spotted-wing drosophila (SWD), Drosophila suzukii (Matsumura), is a species of vinegar fly that attacks berry crops worldwide, including grapes, and reduces fruit quality and yield. In this study, we tested the susceptibility of various hybrid bunch grapes and muscadines to berry splitting and SWD attack. Ten grape culti- vars were harvested in 2016 and 2017, and Thompson Seedless (Vitis vinifera) was purchased locally. Fruit quality traits examined included Brix (soluble solids), total acidity (TA), pH, fruit firmness, and skin break force. Villard blanc and OK392 were the least susceptible to berry splitting (0%). Although muscadines showed the highest fruit firmness, they were also susceptible to splitting, especially Fry Seedless (88% splitting incidence). There were no significant correlations among soluble solids, firmness, and splitting; however, there was a negative correlation between splitting and TA. Pierce’s disease (PD)-resistant and PD-tolerant grapes also appear to be mostly resistant to or highly tolerant of SWD infestation. SWD females do not appear to be able to oviposit in fruit hosts that have a fruit firmness exceeding 300 g/mm. Wounds or splits in the grape epidermis increased reproductive success of SWD by 400%, suggesting that a well-managed vineyard will not host large SWD populations. Vineyards suffering from severe berry damage might provide SWD with a summer fruit host. Overall, PD-resistant hybrids and muscadines are highly adaptive to subtropical climates and are tolerant of this new invasive vinegar fly.
Rhizoctonia is a soil inhabitant fungus with many species and wide host range. As a facultative p... more Rhizoctonia is a soil inhabitant fungus with many species and wide host range. As a facultative parasite, Baiting is a shortcut for its isolation from soil. In current research, some soil samples were prepared from soils of cultivated fields and gardens of Golestan and Mazandaran provinces. Some sheath blight bearing symptom plant materials were subjected to sampling. Many Rhizoctonia isolates were isolated then cultures with orange to red soft sclerotes and orange mycelium were identified as R. zeae. Fifty seven from total of seventy had successful anastomosis with R.zeae CBS 384.34 as standard. Pathogenic ability of some isolates were tested on young seedling in petri plates On corn, wheat, cucumber, squash and radish. Pathogenicity tests had positive results as rot symptoms on emerged roots. This is the first report for pathogenicity of R.zeae on wheat sheath, cucumber, squash and radish from Golestan and Mazandaran provinces. Baiting is an easy and useful method on preliminary ecological and pathological studies of Rhizoctonia spp.
Purple firespike (Odontonema callistachyum), native to Central America, has
potential for use as a... more Purple firespike (Odontonema callistachyum), native to Central America, has potential for use as a new flowering potted plant. The effects of number of pinches (zero, one, or two) and number of cuttings (one, two, or three) per 6-inch pot were evaluated on the control of plant height. Plant height was suppressed as the pinch number increased. The greatest reduction was recorded with one cutting per pot and two pinches. The maximum number of branches per pot was recorded with two pinches and three cuttings per pot. In a second experiment, plant growth regulators (PGR) were also tested for efficacy of height control; 2 weeks after pinching, foliar sprays of paclobutrazol, flurprimidol, daminozide, chlormequat, and a tank-mix of daminozide D chlormequat or media drenches of paclobutrazol, uniconazole, or flurprimidol were applied. Plant height, leaf area, and leaf dry weight were recorded at 3, 6, and 9 weeks after PGR application. Maximum height control was obtained with uniconazole drench at 8 ppm, resulting in plants 22 cm tall, 61% shorter than the untreated control (56 cm); however, it resulted in severe leaf distortion. Plant height was 56% and 46% shorter than the control using drenches of paclobutrazol at 30 ppm and flurprimidol at 15 ppm, respectively. Daminozide spray at 2000 ppm and tank-mix of daminozide D chlormequat at 4500/1500 ppm suppressed stem elongation by 20.3% and 19%, respectively. Plants treated with paclobutrazol drench at 30 ppm reduced leaf area and leaf dry weight compared with other PGRs. Chlormequat spray at tested concentra- tions was ineffective for controlling firespike plant growth. The most attractive potted plants were produced using a drench application of paclobutrazol at 10 or 15 ppm.
Passiflora is a large genus in the family Passifloraceae Juss. ex DC. Many Passiflora
... more Passiflora is a large genus in the family Passifloraceae Juss. ex DC. Many Passiflora species are propagated by seed. However, seeds are often slow to germinate and have low germination rates due to seed dormancy factors. This study was conducted to evaluate four different pre-germination treatments on enhancing germination potential in seven Passiflora spp. Germination was monitored every 3 days for 90 days. Germination started after two weeks and then, a gradual increase was observed in germination in most species. Passiflora laurifolia L. showed maximal germination percentage (75%) with scarification plus fermentation; thus, it is the recommended treatment for this species. The highest germination rate was obtained for Passiflora maliformis L. at 0.23 in scarification plus GA 3 . For P. maliformis, scarification in combination with GA 3 was the most effective treatment, resulting in a germination percentage of 40%. Passiflora tripartita var. Mollissima showed highest germination percentage when soaked in water or scarified plus GA 3 (30%). Scarification alone resulted in the best germination percentage in Passiflora ligularis Juss. (30%). No unique pre-germination treatment resulted in complete germination for all species. When compared to results from previous research, Passiflora edulis f. edulis Sims. and Passiflora incarnata L. did not germinate at acceptable levels, whereas similar germination percentages in P. tripartita var. mollisima, P. maliformis, and P. ligularis depended on treatment. Further research is needed to determine dormancy types present in these species and the best treatment to overcome them.
Firespike (Odontonema callistachyum) is a tropical ornamental shrub native to Central America. It... more Firespike (Odontonema callistachyum) is a tropical ornamental shrub native to Central America. It is considered as a potential potted floriculture crop because of its beautiful crimson and brilliant red tubular flowers and shiny leaves. Five growth regulators, daminozide (Dazide), chlormequat (Cycocel), paclobutrazol (Bonzi), nniconazole (Sumagic), and flurprimidol (Topflor) at different rates and application methods (spray and drench) were tested on their efficacy on plant height control. Treatments were: daminozide spray (2000, 3000, 5000 mg.L-1), chlormequat spray (1000, 2000, 3000 mg.L-1), tank mix of daminozide and chlormequat spray (4500/1500, 3000/1000, 1500/500 mg.L-1), paclobutrazol spray (15 mg.L-1), paclobutrazol drench (10, 15, 20, 30 mg.L-1), uniconazole drench (2.5, 5, 8 mg.L-1), flurprimidol spray (15, 30, 45 mg.L-1), and flurprimidol drench (5, 10, 15 mg.L-1). Plant height, leaf area, and leaf dry weight were recored at 9 weeks after PGR application. Maximum reductio...
White drupelet disorder (WDD) is a problem that occurs during the ripening stage in some blackber... more White drupelet disorder (WDD) is a problem that occurs during the ripening stage in some blackberry (Rubus subgenus Rubus) cultivars. Although berries affected with a few white drupelets may taste fine, they are unpleasant aesthetically, and this may lead to negative consumer perceptions and economic ramifications. During 2 years of observational studies and field trials (2016 and 2017), we evaluated changes in three susceptible cultivars in Mississippi affected by WDD. ‘Chickasaw’, ‘Kiowa’, and ‘Sweetie Pie’ berries were harvested twice per week and assessed for WDD. Weather conditions differed substantially during harvest in 2016 and 2017, with 2017 being cooler and rainier which resulted in a lower incidence of WDD. Compared with 2016, in 2017, the overall percentage of berries exhibiting WDD dropped from 22% to 12% for ‘Sweetie Pie’, 6% to 3% for ‘Chickasaw’, and 8% to 3% for ‘Kiowa’. The soluble solids concentration was highest in ‘Sweetie Pie’, 11.9% and 9.5% for 2016 and 2017...
The present study assessed the effect of photoperiod on budbreak of cuttings of three interspecif... more The present study assessed the effect of photoperiod on budbreak of cuttings of three interspecific hybrid grape (Vitis) cultivars that had received different chilling hours. Stem cuttings were collected at 100-hour intervals of chilling (200, 300, 400, 500, 600, 700, and 800 hours) from the vineyard and kept in three growth chambers with daylengths of 8, 16, and 24 hours. Another group of cuttings were maintained in a greenhouse with a natural daylength range of 10.5–13 hours [8 Dec. 2017 to 4 May 2018 (average = 12 hours)]. Chilling requirements, days to budbreak, and budbreak rate were determined after plants were exposed to different chilling hours and daylengths. Results of our study demonstrated that the chilling requirements of all three cultivars were adequately reached at 600 hours or more. Increasing chilling exposure from 600 to 800 hours shortened the time to budbreak in all cultivars. Overall, ‘MidSouth’ had an average budbreak rate of 90% when receiving at least 600 ho...
The effect of plant growth regulators (PGRs) on growth and flowering
of potted red firespike ( Odon... more The effect of plant growth regulators (PGRs) on growth and flowering of potted red firespike ( Odontonema strictum ) were examined in two experiments. In Expt. 1, foliar spray applications of daminozide, uniconazole, paclobutrazol, or flurprimidol or media drenches of paclobutrazol or flurprimidol were applied. In Expt. 2, foliar spray application of daminozide or media drenches of paclobutrazol or flurprimidol were further tested for efficacy of height control. Both studies included an untreated control. In Expt. 1, drench applications of paclobutrazol and flurprimidol resulted in plants 65% or 46% to 62% shorter than control, respectively. Paclobutrazol and flurprimidol drenches also decreased overall plant growth by 81% to 88% and 74% to 84%, respectively, compared with the control plants. PGRs did not affect number of inflorescences; however, paclobutrazol and flurprimidol delayed flowering 23 to 31 days. In Expt. 2, plants treated with flurprimidol or paclobutrazol drenches were shorter than the control. The greatest reduction in total plant growth occurred using a flurpri- midol drench at 0.47 mg/pot, which resulted in plants 78% smaller than the untreated control. Paclobutrazol and flurprimidol increased the time to flowering 11 to 27 days and 10 to 26 days, respectively. The most attractive and well-shaped plants were achieved with flurprimidol applied at 0.24 mg/pot or applications of paclobutrazol at 0.35 mg/pot.
White drupelet disorder (WDD) is a problem that occurs during the
ripening stage in some blackber... more White drupelet disorder (WDD) is a problem that occurs during the ripening stage in some blackberry (Rubus subgenus Rubus) cultivars. Although berries affected with a few white drupelets may taste fine, they are unpleasant aesthetically, and this may lead to negative consumer perceptions and economic ramifications. During 2 years of observational studies and field trials (2016 and 2017), we evaluated changes in three susceptible cultivars in Mississippi affected by WDD. ‘Chickasaw’, ‘Kiowa’, and ‘Sweetie Pie’ berries were harvested twice per week and assessed for WDD. Weather conditions differed substantially during harvest in 2016 and 2017, with 2017 being cooler and rainier which resulted in a lower incidence of WDD. Compared with 2016, in 2017, the overall percentage of berries exhibiting WDD dropped from 22% to 12% for ‘Sweetie Pie’, 6% to 3% for ‘Chickasaw’, and 8% to 3% for ‘Kiowa’. The soluble solids concentration was highest in ‘Sweetie Pie’, 11.9% and 9.5% for 2016 and 2017, respectively. For all cultivars examined, the soluble solids concentration of extracted white drupelets was substantially lower than regular drupelets. The value for skin break force for white drupelets was higher than that for black drupelets, 0.99 N vs. 0.29 N, respectively. In 2017, an about 30% shadecloth treatment had a significantly positive impact by decreasing WDD symptoms in all cultivars by 63% when compared with non-shaded plants, but soluble solids concentration was lower. Our results indicate that rain and shadecloth decrease symptoms of WDD. Therefore, growers may be able to use overhead irrigation and shade to reduce WDD symptoms.
Fruit splitting is a physiological disorder that produces surface cracks that promote disease and... more Fruit splitting is a physiological disorder that produces surface cracks that promote disease and insect damage. The spotted-wing drosophila (SWD), Drosophila suzukii (Matsumura), is a species of vinegar fly that attacks berry crops worldwide, including grapes, and reduces fruit quality and yield. In this study, we tested the susceptibility of various hybrid bunch grapes and muscadines to berry splitting and SWD attack. Ten grape culti- vars were harvested in 2016 and 2017, and Thompson Seedless (Vitis vinifera) was purchased locally. Fruit quality traits examined included Brix (soluble solids), total acidity (TA), pH, fruit firmness, and skin break force. Villard blanc and OK392 were the least susceptible to berry splitting (0%). Although muscadines showed the highest fruit firmness, they were also susceptible to splitting, especially Fry Seedless (88% splitting incidence). There were no significant correlations among soluble solids, firmness, and splitting; however, there was a negative correlation between splitting and TA. Pierce’s disease (PD)-resistant and PD-tolerant grapes also appear to be mostly resistant to or highly tolerant of SWD infestation. SWD females do not appear to be able to oviposit in fruit hosts that have a fruit firmness exceeding 300 g/mm. Wounds or splits in the grape epidermis increased reproductive success of SWD by 400%, suggesting that a well-managed vineyard will not host large SWD populations. Vineyards suffering from severe berry damage might provide SWD with a summer fruit host. Overall, PD-resistant hybrids and muscadines are highly adaptive to subtropical climates and are tolerant of this new invasive vinegar fly.
Rhizoctonia is a soil inhabitant fungus with many species and wide host range. As a facultative p... more Rhizoctonia is a soil inhabitant fungus with many species and wide host range. As a facultative parasite, Baiting is a shortcut for its isolation from soil. In current research, some soil samples were prepared from soils of cultivated fields and gardens of Golestan and Mazandaran provinces. Some sheath blight bearing symptom plant materials were subjected to sampling. Many Rhizoctonia isolates were isolated then cultures with orange to red soft sclerotes and orange mycelium were identified as R. zeae. Fifty seven from total of seventy had successful anastomosis with R.zeae CBS 384.34 as standard. Pathogenic ability of some isolates were tested on young seedling in petri plates On corn, wheat, cucumber, squash and radish. Pathogenicity tests had positive results as rot symptoms on emerged roots. This is the first report for pathogenicity of R.zeae on wheat sheath, cucumber, squash and radish from Golestan and Mazandaran provinces. Baiting is an easy and useful method on preliminary ecological and pathological studies of Rhizoctonia spp.
Purple firespike (Odontonema callistachyum), native to Central America, has
potential for use as a... more Purple firespike (Odontonema callistachyum), native to Central America, has potential for use as a new flowering potted plant. The effects of number of pinches (zero, one, or two) and number of cuttings (one, two, or three) per 6-inch pot were evaluated on the control of plant height. Plant height was suppressed as the pinch number increased. The greatest reduction was recorded with one cutting per pot and two pinches. The maximum number of branches per pot was recorded with two pinches and three cuttings per pot. In a second experiment, plant growth regulators (PGR) were also tested for efficacy of height control; 2 weeks after pinching, foliar sprays of paclobutrazol, flurprimidol, daminozide, chlormequat, and a tank-mix of daminozide D chlormequat or media drenches of paclobutrazol, uniconazole, or flurprimidol were applied. Plant height, leaf area, and leaf dry weight were recorded at 3, 6, and 9 weeks after PGR application. Maximum height control was obtained with uniconazole drench at 8 ppm, resulting in plants 22 cm tall, 61% shorter than the untreated control (56 cm); however, it resulted in severe leaf distortion. Plant height was 56% and 46% shorter than the control using drenches of paclobutrazol at 30 ppm and flurprimidol at 15 ppm, respectively. Daminozide spray at 2000 ppm and tank-mix of daminozide D chlormequat at 4500/1500 ppm suppressed stem elongation by 20.3% and 19%, respectively. Plants treated with paclobutrazol drench at 30 ppm reduced leaf area and leaf dry weight compared with other PGRs. Chlormequat spray at tested concentra- tions was ineffective for controlling firespike plant growth. The most attractive potted plants were produced using a drench application of paclobutrazol at 10 or 15 ppm.
Passiflora is a large genus in the family Passifloraceae Juss. ex DC. Many Passiflora
... more Passiflora is a large genus in the family Passifloraceae Juss. ex DC. Many Passiflora species are propagated by seed. However, seeds are often slow to germinate and have low germination rates due to seed dormancy factors. This study was conducted to evaluate four different pre-germination treatments on enhancing germination potential in seven Passiflora spp. Germination was monitored every 3 days for 90 days. Germination started after two weeks and then, a gradual increase was observed in germination in most species. Passiflora laurifolia L. showed maximal germination percentage (75%) with scarification plus fermentation; thus, it is the recommended treatment for this species. The highest germination rate was obtained for Passiflora maliformis L. at 0.23 in scarification plus GA 3 . For P. maliformis, scarification in combination with GA 3 was the most effective treatment, resulting in a germination percentage of 40%. Passiflora tripartita var. Mollissima showed highest germination percentage when soaked in water or scarified plus GA 3 (30%). Scarification alone resulted in the best germination percentage in Passiflora ligularis Juss. (30%). No unique pre-germination treatment resulted in complete germination for all species. When compared to results from previous research, Passiflora edulis f. edulis Sims. and Passiflora incarnata L. did not germinate at acceptable levels, whereas similar germination percentages in P. tripartita var. mollisima, P. maliformis, and P. ligularis depended on treatment. Further research is needed to determine dormancy types present in these species and the best treatment to overcome them.
Firespike (Odontonema callistachyum) is a tropical ornamental shrub native to Central America. It... more Firespike (Odontonema callistachyum) is a tropical ornamental shrub native to Central America. It is considered as a potential potted floriculture crop because of its beautiful crimson and brilliant red tubular flowers and shiny leaves. Five growth regulators, daminozide (Dazide), chlormequat (Cycocel), paclobutrazol (Bonzi), nniconazole (Sumagic), and flurprimidol (Topflor) at different rates and application methods (spray and drench) were tested on their efficacy on plant height control. Treatments were: daminozide spray (2000, 3000, 5000 mg.L-1), chlormequat spray (1000, 2000, 3000 mg.L-1), tank mix of daminozide and chlormequat spray (4500/1500, 3000/1000, 1500/500 mg.L-1), paclobutrazol spray (15 mg.L-1), paclobutrazol drench (10, 15, 20, 30 mg.L-1), uniconazole drench (2.5, 5, 8 mg.L-1), flurprimidol spray (15, 30, 45 mg.L-1), and flurprimidol drench (5, 10, 15 mg.L-1). Plant height, leaf area, and leaf dry weight were recored at 9 weeks after PGR application. Maximum reductio...
Uploads
Papers by amir rezazadeh
of potted red firespike ( Odontonema strictum ) were examined in two experiments.
In Expt. 1, foliar spray applications of daminozide, uniconazole, paclobutrazol,
or flurprimidol or media drenches of paclobutrazol or flurprimidol were applied.
In Expt. 2, foliar spray application of daminozide or media drenches of
paclobutrazol or flurprimidol were further tested for efficacy of height control.
Both studies included an untreated control. In Expt. 1, drench applications of
paclobutrazol and flurprimidol resulted in plants 65% or 46% to 62% shorter than
control, respectively. Paclobutrazol and flurprimidol drenches also decreased
overall plant growth by 81% to 88% and 74% to 84%, respectively, compared with
the control plants. PGRs did not affect number of inflorescences; however,
paclobutrazol and flurprimidol delayed flowering 23 to 31 days. In Expt. 2,
plants treated with flurprimidol or paclobutrazol drenches were shorter than the
control. The greatest reduction in total plant growth occurred using a flurpri-
midol drench at 0.47 mg/pot, which resulted in plants 78% smaller than the
untreated control. Paclobutrazol and flurprimidol increased the time to flowering
11 to 27 days and 10 to 26 days, respectively. The most attractive and well-shaped
plants were achieved with flurprimidol applied at 0.24 mg/pot or applications of
paclobutrazol at 0.35 mg/pot.
ripening stage in some blackberry (Rubus subgenus Rubus) cultivars. Although
berries affected with a few white drupelets may taste fine, they are unpleasant
aesthetically, and this may lead to negative consumer perceptions and economic
ramifications. During 2 years of observational studies and field trials (2016 and
2017), we evaluated changes in three susceptible cultivars in Mississippi affected by
WDD. ‘Chickasaw’, ‘Kiowa’, and ‘Sweetie Pie’ berries were harvested twice per
week and assessed for WDD. Weather conditions differed substantially during
harvest in 2016 and 2017, with 2017 being cooler and rainier which resulted in
a lower incidence of WDD. Compared with 2016, in 2017, the overall percentage of
berries exhibiting WDD dropped from 22% to 12% for ‘Sweetie Pie’, 6% to 3% for
‘Chickasaw’, and 8% to 3% for ‘Kiowa’. The soluble solids concentration was highest
in ‘Sweetie Pie’, 11.9% and 9.5% for 2016 and 2017, respectively. For all cultivars
examined, the soluble solids concentration of extracted white drupelets was
substantially lower than regular drupelets. The value for skin break force for white
drupelets was higher than that for black drupelets, 0.99 N vs. 0.29 N, respectively.
In 2017, an about 30% shadecloth treatment had a significantly positive impact by
decreasing WDD symptoms in all cultivars by 63% when compared with non-shaded
plants, but soluble solids concentration was lower. Our results indicate that rain and
shadecloth decrease symptoms of WDD. Therefore, growers may be able to use
overhead irrigation and shade to reduce WDD symptoms.
damage. The spotted-wing drosophila (SWD), Drosophila suzukii (Matsumura), is a species of vinegar fly that
attacks berry crops worldwide, including grapes, and reduces fruit quality and yield. In this study, we tested the
susceptibility of various hybrid bunch grapes and muscadines to berry splitting and SWD attack. Ten grape culti-
vars were harvested in 2016 and 2017, and Thompson Seedless (Vitis vinifera) was purchased locally. Fruit quality
traits examined included Brix (soluble solids), total acidity (TA), pH, fruit firmness, and skin break force. Villard
blanc and OK392 were the least susceptible to berry splitting (0%). Although muscadines showed the highest fruit
firmness, they were also susceptible to splitting, especially Fry Seedless (88% splitting incidence). There were no
significant correlations among soluble solids, firmness, and splitting; however, there was a negative correlation
between splitting and TA. Pierce’s disease (PD)-resistant and PD-tolerant grapes also appear to be mostly resistant
to or highly tolerant of SWD infestation. SWD females do not appear to be able to oviposit in fruit hosts that have a
fruit firmness exceeding 300 g/mm. Wounds or splits in the grape epidermis increased reproductive success of SWD
by 400%, suggesting that a well-managed vineyard will not host large SWD populations. Vineyards suffering from
severe berry damage might provide SWD with a summer fruit host. Overall, PD-resistant hybrids and muscadines
are highly adaptive to subtropical climates and are tolerant of this new invasive vinegar fly.
potential for use as a new flowering potted plant. The effects of number of pinches
(zero, one, or two) and number of cuttings (one, two, or three) per 6-inch pot were
evaluated on the control of plant height. Plant height was suppressed as the pinch
number increased. The greatest reduction was recorded with one cutting per pot and
two pinches. The maximum number of branches per pot was recorded with two pinches
and three cuttings per pot. In a second experiment, plant growth regulators (PGR)
were also tested for efficacy of height control; 2 weeks after pinching, foliar sprays of
paclobutrazol, flurprimidol, daminozide, chlormequat, and a tank-mix of daminozide
D chlormequat or media drenches of paclobutrazol, uniconazole, or flurprimidol were
applied. Plant height, leaf area, and leaf dry weight were recorded at 3, 6, and 9 weeks
after PGR application. Maximum height control was obtained with uniconazole
drench at 8 ppm, resulting in plants 22 cm tall, 61% shorter than the untreated control
(56 cm); however, it resulted in severe leaf distortion. Plant height was 56% and 46%
shorter than the control using drenches of paclobutrazol at 30 ppm and flurprimidol at
15 ppm, respectively. Daminozide spray at 2000 ppm and tank-mix of daminozide D
chlormequat at 4500/1500 ppm suppressed stem elongation by 20.3% and 19%,
respectively. Plants treated with paclobutrazol drench at 30 ppm reduced leaf area and
leaf dry weight compared with other PGRs. Chlormequat spray at tested concentra-
tions was ineffective for controlling firespike plant growth. The most attractive potted
plants were produced using a drench application of paclobutrazol at 10 or 15 ppm.
species are propagated by seed. However, seeds are often slow to germinate and have low
germination rates due to seed dormancy factors. This study was conducted to evaluate four
different pre-germination treatments on enhancing germination potential in seven
Passiflora spp. Germination was monitored every 3 days for 90 days. Germination started
after two weeks and then, a gradual increase was observed in germination in most species.
Passiflora laurifolia L. showed maximal germination percentage (75%) with scarification
plus fermentation; thus, it is the recommended treatment for this species. The highest
germination rate was obtained for Passiflora maliformis L. at 0.23 in scarification plus
GA 3 . For P. maliformis, scarification in combination with GA 3 was the most effective
treatment, resulting in a germination percentage of 40%. Passiflora tripartita var.
Mollissima showed highest germination percentage when soaked in water or scarified plus
GA 3 (30%). Scarification alone resulted in the best germination percentage in Passiflora
ligularis Juss. (30%). No unique pre-germination treatment resulted in complete
germination for all species. When compared to results from previous research, Passiflora
edulis f. edulis Sims. and Passiflora incarnata L. did not germinate at acceptable levels,
whereas similar germination percentages in P. tripartita var. mollisima, P. maliformis, and
P. ligularis depended on treatment. Further research is needed to determine dormancy
types present in these species and the best treatment to overcome them.
of potted red firespike ( Odontonema strictum ) were examined in two experiments.
In Expt. 1, foliar spray applications of daminozide, uniconazole, paclobutrazol,
or flurprimidol or media drenches of paclobutrazol or flurprimidol were applied.
In Expt. 2, foliar spray application of daminozide or media drenches of
paclobutrazol or flurprimidol were further tested for efficacy of height control.
Both studies included an untreated control. In Expt. 1, drench applications of
paclobutrazol and flurprimidol resulted in plants 65% or 46% to 62% shorter than
control, respectively. Paclobutrazol and flurprimidol drenches also decreased
overall plant growth by 81% to 88% and 74% to 84%, respectively, compared with
the control plants. PGRs did not affect number of inflorescences; however,
paclobutrazol and flurprimidol delayed flowering 23 to 31 days. In Expt. 2,
plants treated with flurprimidol or paclobutrazol drenches were shorter than the
control. The greatest reduction in total plant growth occurred using a flurpri-
midol drench at 0.47 mg/pot, which resulted in plants 78% smaller than the
untreated control. Paclobutrazol and flurprimidol increased the time to flowering
11 to 27 days and 10 to 26 days, respectively. The most attractive and well-shaped
plants were achieved with flurprimidol applied at 0.24 mg/pot or applications of
paclobutrazol at 0.35 mg/pot.
ripening stage in some blackberry (Rubus subgenus Rubus) cultivars. Although
berries affected with a few white drupelets may taste fine, they are unpleasant
aesthetically, and this may lead to negative consumer perceptions and economic
ramifications. During 2 years of observational studies and field trials (2016 and
2017), we evaluated changes in three susceptible cultivars in Mississippi affected by
WDD. ‘Chickasaw’, ‘Kiowa’, and ‘Sweetie Pie’ berries were harvested twice per
week and assessed for WDD. Weather conditions differed substantially during
harvest in 2016 and 2017, with 2017 being cooler and rainier which resulted in
a lower incidence of WDD. Compared with 2016, in 2017, the overall percentage of
berries exhibiting WDD dropped from 22% to 12% for ‘Sweetie Pie’, 6% to 3% for
‘Chickasaw’, and 8% to 3% for ‘Kiowa’. The soluble solids concentration was highest
in ‘Sweetie Pie’, 11.9% and 9.5% for 2016 and 2017, respectively. For all cultivars
examined, the soluble solids concentration of extracted white drupelets was
substantially lower than regular drupelets. The value for skin break force for white
drupelets was higher than that for black drupelets, 0.99 N vs. 0.29 N, respectively.
In 2017, an about 30% shadecloth treatment had a significantly positive impact by
decreasing WDD symptoms in all cultivars by 63% when compared with non-shaded
plants, but soluble solids concentration was lower. Our results indicate that rain and
shadecloth decrease symptoms of WDD. Therefore, growers may be able to use
overhead irrigation and shade to reduce WDD symptoms.
damage. The spotted-wing drosophila (SWD), Drosophila suzukii (Matsumura), is a species of vinegar fly that
attacks berry crops worldwide, including grapes, and reduces fruit quality and yield. In this study, we tested the
susceptibility of various hybrid bunch grapes and muscadines to berry splitting and SWD attack. Ten grape culti-
vars were harvested in 2016 and 2017, and Thompson Seedless (Vitis vinifera) was purchased locally. Fruit quality
traits examined included Brix (soluble solids), total acidity (TA), pH, fruit firmness, and skin break force. Villard
blanc and OK392 were the least susceptible to berry splitting (0%). Although muscadines showed the highest fruit
firmness, they were also susceptible to splitting, especially Fry Seedless (88% splitting incidence). There were no
significant correlations among soluble solids, firmness, and splitting; however, there was a negative correlation
between splitting and TA. Pierce’s disease (PD)-resistant and PD-tolerant grapes also appear to be mostly resistant
to or highly tolerant of SWD infestation. SWD females do not appear to be able to oviposit in fruit hosts that have a
fruit firmness exceeding 300 g/mm. Wounds or splits in the grape epidermis increased reproductive success of SWD
by 400%, suggesting that a well-managed vineyard will not host large SWD populations. Vineyards suffering from
severe berry damage might provide SWD with a summer fruit host. Overall, PD-resistant hybrids and muscadines
are highly adaptive to subtropical climates and are tolerant of this new invasive vinegar fly.
potential for use as a new flowering potted plant. The effects of number of pinches
(zero, one, or two) and number of cuttings (one, two, or three) per 6-inch pot were
evaluated on the control of plant height. Plant height was suppressed as the pinch
number increased. The greatest reduction was recorded with one cutting per pot and
two pinches. The maximum number of branches per pot was recorded with two pinches
and three cuttings per pot. In a second experiment, plant growth regulators (PGR)
were also tested for efficacy of height control; 2 weeks after pinching, foliar sprays of
paclobutrazol, flurprimidol, daminozide, chlormequat, and a tank-mix of daminozide
D chlormequat or media drenches of paclobutrazol, uniconazole, or flurprimidol were
applied. Plant height, leaf area, and leaf dry weight were recorded at 3, 6, and 9 weeks
after PGR application. Maximum height control was obtained with uniconazole
drench at 8 ppm, resulting in plants 22 cm tall, 61% shorter than the untreated control
(56 cm); however, it resulted in severe leaf distortion. Plant height was 56% and 46%
shorter than the control using drenches of paclobutrazol at 30 ppm and flurprimidol at
15 ppm, respectively. Daminozide spray at 2000 ppm and tank-mix of daminozide D
chlormequat at 4500/1500 ppm suppressed stem elongation by 20.3% and 19%,
respectively. Plants treated with paclobutrazol drench at 30 ppm reduced leaf area and
leaf dry weight compared with other PGRs. Chlormequat spray at tested concentra-
tions was ineffective for controlling firespike plant growth. The most attractive potted
plants were produced using a drench application of paclobutrazol at 10 or 15 ppm.
species are propagated by seed. However, seeds are often slow to germinate and have low
germination rates due to seed dormancy factors. This study was conducted to evaluate four
different pre-germination treatments on enhancing germination potential in seven
Passiflora spp. Germination was monitored every 3 days for 90 days. Germination started
after two weeks and then, a gradual increase was observed in germination in most species.
Passiflora laurifolia L. showed maximal germination percentage (75%) with scarification
plus fermentation; thus, it is the recommended treatment for this species. The highest
germination rate was obtained for Passiflora maliformis L. at 0.23 in scarification plus
GA 3 . For P. maliformis, scarification in combination with GA 3 was the most effective
treatment, resulting in a germination percentage of 40%. Passiflora tripartita var.
Mollissima showed highest germination percentage when soaked in water or scarified plus
GA 3 (30%). Scarification alone resulted in the best germination percentage in Passiflora
ligularis Juss. (30%). No unique pre-germination treatment resulted in complete
germination for all species. When compared to results from previous research, Passiflora
edulis f. edulis Sims. and Passiflora incarnata L. did not germinate at acceptable levels,
whereas similar germination percentages in P. tripartita var. mollisima, P. maliformis, and
P. ligularis depended on treatment. Further research is needed to determine dormancy
types present in these species and the best treatment to overcome them.