Nitrogen and Flowering Dogwood. I. Impact of Nitrogen Fertilization Rate on the Occurrence of Spot Anthracnose, Powdery Mildew, and Cercospora Leaf Spot and Their Effect on Tree Growth

Abstract Impact of nitrogen (N) rate on spot anthracnose, powdery mildew, and Cercospora leaf spot as well as their impact on the growth of field-grown ‘Cloud 9’ and ‘Cherokee Chief’ flowering dogwood was assessed in 2003, 2004, and 2005. From 2001 to 2005, ammonium nitrate was applied at 4.1, 8.3, 16.5, 33.0 and 66.0 g N·m−2 (37.5, 75, 150, 300, 600 lb N·A−1). Heritage 50W fungicide was applied to one ‘Cherokee Chief’ and ‘Cloud 9’ flowering dogwood in each plot, while the second was untreated. Powdery mildew and Cercospora leaf spot were impacted by N rate more than spot anthracnose. In two of three years, powdery mildew intensified, particularly on the non-treated trees, as N rates increased. Cercospora leaf spot intensity (AUDPCI) and defoliation (AUDPCD) on the fungicide-treated and non-treated trees was influenced by N-rate in two of three and one of three years, respectively. Regardless of fungicide treatment, Cercospora leaf spot incited leaf spotting and defoliation was often lower at the two highest than the two lowest N rates. A reduction in the bract and leaf spot phases of spot anthracnose at the highest N rate was noted in 2004. While spot anthracnose was negatively correlated with trunk diameter in all three years and tree height in 2003 and 2004, Cercospora leaf spot intensity and defoliation were negatively correlated with tree height and trunk diameter in all three and two of three years, respectively. Powdery mildew had no impact on tree height or trunk diameter. Heritage 50W not only controlled spot anthracnose and powdery mildew but also slowed Cercospora leaf spot development sufficiently to enhance leaf retention and fall color.

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Synthetic and Biorational Fungicides Compared for the Control of Three Foliar Diseases of Flowering Dogwood

Journal of Environmental Horticulture ◽

10.24266/0738-2898-25.3.157 ◽

2007 ◽

Vol 25 (3) ◽

pp. 157-165

Author(s):

A.K. Hagan ◽

J.R. Akridge

Keyword(s):

Powdery Mildew ◽

Leaf Spot ◽

Tree Height ◽

Systemic Fungicide ◽

Cercospora Leaf Spot ◽

Foliar Diseases ◽

Trunk Diameter ◽

Flowering Dogwood ◽

Nursery Stock ◽

One Year

Abstract The biorational fungicides Neem Concentrate, SunSpray Ultra Fine Oil®, Rhapsody® were compared with the synthetic fungicides Eagle® 40W, Immunox®, Liquid Systemic Fungicide®, and 3336™ 50W for the control of spot anthracnose, Cercospora leaf spot, and powdery mildew on ‘Rubra’ flowering dogwood. In 2003, 2004, and 2005, fungicide treatments were applied at label rates at 1- and/or 2-week intervals over a period that coincided with the onset spot anthracnose and powdery mildew but before the appearance of Cercospora leaf spot. With few exceptions, the synthetic fungicides gave better control of the above diseases than biorational fungicides. Eagle 40W, Immunox, Liquid Systemic Fungicide, and 3336 50W gave equal control of the bract and leaf spot phases of spot anthracnose. Most notable was the carryover of control of the bract spot phase of spot anthracnose into the spring of the following year with the synthetic fungicides. While some control of spot anthracnose was seen in at least one year with the biorational fungicides, none was as effective as the synthetic fungicides. In 2003 and 2004, Neem Concentrate, SunSpray Ultra Fine Oil, and Rhapsody, when applied weekly controlled powdery mildew as effectively as the synthetic fungicides. Efficacy of the biorational fungicides declined under severe powdery mildew pressure in 2005. While Cercospora leaf spot development was slowed by the Eagle 40W, Liquid Systemic Fungicide, and 3336 50W, the biorational fungicides as well as the retail product Immunox also gave some control. An objectionable mottling of the leaves was noted on the flowering dogwood treated with SunSpray Ultra Fine Oil. Control of these diseases with the synthetic or biorational fungicides did not result in an increase in tree height or trunk diameter. While the biorational fungicides demonstrated sufficient efficacy for controlling powdery mildew on flowering dogwood in the landscape, they often failed to provide the level of control of this disease as well as spot anthracnose and Cercospora leaf spot needed to produce quality container- and field-grown nursery stock.

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Influence of Nitrogen Rate on Cercospora Leaf Spot and Growth of Crapemyrtle

Plant Health Progress ◽

10.1094/php-2009-1214-01-rs ◽

2009 ◽

Vol 10 (1) ◽

pp. 2 ◽

Cited By ~ 1

Author(s):

A. K. Hagan ◽

J. R. Akridge ◽

K. L. Bowen

Keyword(s):

Powdery Mildew ◽

Plant Growth ◽

Ammonium Nitrate ◽

Tree Growth ◽

Leaf Spot ◽

Spot Intensity ◽

Cercospora Leaf Spot ◽

Nitrogen Rate ◽

N Rates ◽

The Impact

The impact of N rate on development of Cercospora leaf spot on field grown ‘Carolina Beauty’ crapemyrtle and the impact of this disease, as well as N rate, on plant growth was assessed in Alabama. From 2002 to 2005, ammonium nitrate was applied at an N rate of 2, 4.1, 8.3, 16.5, 33.0, and 66.0 g/m2. Heritage 50W fungicide was applied to one tree in each plot, while the second tree was not treated. Powdery mildew was very sporadic and was not related to N rate. An N rate-related reduction in Cercospora leaf spot intensity and defoliation was noted on the non-fungicide and fungicide treated trees in 2005 but not in 2003 and 2004. In 2005, reductions in disease intensity and defoliation were obtained at the three highest N rates of 16.5, 33, and 66 g/m2 compared to the two lowest N rates of 2 and 4.1 g/m2. Regardless of N rate, Heritage 50W suppressed Cercospora leaf spot. Despite considerable leaf spotting and premature defoliation, Cercospora leaf spot did not impact crapemyrtle growth. Increasing N rates was less effective than Heritage 50W fungicide in controlling Cercospora leaf spot and also failed to enhance tree growth. Accepted for publication 10 September 2009. Published 14 December 2009.

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Nitrogen and Flowering Dogwood. II. Impact of Nitrogen Fertilization Rate on Flower Bud Set and Tree Growth

Journal of Environmental Horticulture ◽

10.24266/0738-2898-26.4.204 ◽

2008 ◽

Vol 26 (4) ◽

pp. 204-209

Author(s):

A.K. Hagan ◽

J.R. Akridge ◽

K.L. Bowen ◽

C.H. Gilliam

Keyword(s):

Tree Height ◽

Fertilization Rate ◽

N Fertilization ◽

Flower Bud ◽

Nitrogen Rate ◽

Trunk Diameter ◽

Flowering Dogwood ◽

Bud Set ◽

Optimum N Rate ◽

N Rates

Abstract Impact of nitrogen (N) fertilization rate on the growth of ‘Cloud 9’ and ‘Cherokee Chief’ flowering dogwood was assessed in a field planting from February 2001 until January 2006 in southwest Alabama (USDA Zone 8a). Starting at planting in 2001 and ending in 2005, ammonium nitrate was broadcast in a 0.3 m2 circle around the base of each tree at 4.1, 8.3, 16.5, 33.0 and 66.0 g N·m−2 (37.5, 75, 150, 300, 600 lb N·A−1) with the application of half of each N-rate in April and June of each year. In each year, disease control was maintained with approximately six applications of Heritage 50W fungicide made at 2-week intervals. Trunk diameter and tree height were recorded in early-winter from 2001 through 2006; flower bud counts were taken annually from 2003 to 2006. With the exception of 2004 when N rate had not influence on bud formation, highest flower bud counts were associated with elevated rates of 33 and 66 g N·m−2 (300 and 600 lb·N−2). Nitrogen rate had no influence on the height or trunk diameter of flowering dogwood until three and four years, respectively, after planting. Impact of N rates below 66.0 g N·m−2 (600 lb·A−1) per year on tree height was minimal. In 2005 and 2006, trunk diameter was greater for trees receiving the two highest than the two lowest N rates. Regression analysis was used to calculate optimum N rate for flower bud set, as well as change in trunk diameter and tree height.

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Disease Resistance and Adaptability of Stellar and Flowering Dogwood Cultivars at Two Alabama Sites

Journal of Environmental Horticulture ◽

10.24266/0738-2898-29.4.169 ◽

2011 ◽

Vol 29 (4) ◽

pp. 169-174

Author(s):

A.K. Hagan ◽

J.R. Akridge ◽

J. Ducar ◽

K.L. Bowen

Keyword(s):

Powdery Mildew ◽

Leaf Spot ◽

Ambrosia Beetle ◽

Insect Damage ◽

Cornus Florida ◽

Cercospora Leaf Spot ◽

Flowering Dogwood ◽

Southern States ◽

Synanthedon Scitula ◽

Dogwood Borer

Abstract Stellar® dogwood (Cornus florida × kousa) cultivars Aurora®, Constellation®, Celestial™, Ruth Ellen®, and Stellar Pink® were compared with selected flowering dogwood (Cornus florida) cultivars Cherokee Brave®, ‘Cherokee Princess’, ‘Cloud 9’, and ‘Rubra’ in a simulated landscape planting at sites in southwest (USDA Hardiness Zone 8a) and northeast Alabama (USDA Hardiness Zone 7a) for their reaction to the diseases spot anthracnose, powdery mildew, and Cercospora leaf spot. Tree longevity as influenced by the occurrence of the dogwood borer (Synanthedon scitula) and an ambrosia beetle (Xylosandrus sp.) was also assessed at both sites. All Stellar® dogwood cultivars generally proved resistant to the bract and leaf spot phases of spot anthracnose as well as powdery mildew and Cercospora leaf spot. While Cherokee Brave® was the only flowering dogwood with partial resistance to powdery mildew at both sites; this and the other flowering dogwood cultivars were equally susceptible to spot anthracnose and Cercospora leaf spot. Insect damage levels were higher at the southwest site than the northeast Alabama site. Within 3 years of establishment at the southwest Alabama site, incidence of tunneling damage attributed to dogwood borer and an ambrosia beetle was higher on the Stellar® dogwood than flowering dogwood cultivars, which also had higher values for tree longevity. In contrast, tree longevity was equally high and insect damage equally low at the northeast Alabama site for both the Stellar® and flowering dogwood cultivars. Superb resistance to the diseases spot anthracnose, powdery mildew, and Cercospora leaf spot translated into superior aesthetics and fall color for the Stellar® compared with the flowering dogwood cultivars at the northeast Alabama site. Hardiness of Stellar® dogwood cultivars in Alabama and possibly other southern states below USDA Hardiness Zone 7a is questionable due to tree vulnerability to the dogwood borer and ambrosia beetle.

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MGS Esmeralda: new large seed mungbean cultivar

Pesquisa Agropecuária Brasileira ◽

10.1590/s0100-204x2008000600015 ◽

2008 ◽

Vol 43 (6) ◽

pp. 781-782 ◽

Cited By ~ 1

Author(s):

Rogério Faria Vieira ◽

José Eustáquio Souza Carneiro ◽

Trazilbo José de Paula Júnior ◽

Roberto Fontes Araújo

Keyword(s):

Powdery Mildew ◽

Research And Development ◽

Leaf Spot ◽

Seed Mass ◽

Minas Gerais ◽

The State ◽

Cercospora Leaf Spot ◽

Large Seed ◽

Development Center

Mungbean cultivar MGS Esmeralda was developed by Asian Vegetable Research and Development Center (Shanhua, Taiwan), as a result of crossing between the lines VC 1973A and VC 2768A. In ten trials conducted in the State of Minas Gerais, Brazil, it produced 13.5% more grains than 'Ouro Verde MG-2' (control cultivar), and its highest yield was 2,550 kg ha-1. The cultivar MGS Esmeralda is more susceptible to lodging, and its pods mature more uniformly than Ouro Verde MG-2 pods. One hundred-seed mass of 'MGS Esmeralda' ranged between 5.5 and 6.8 g. Both cultivars are susceptible to powdery mildew and cercospora leaf spot.

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Growth of Three Shade Tree Genera as Influenced by Irrigation and Nitrogen Rates

Journal of Environmental Horticulture ◽

10.24266/0738-2898-1.1.5 ◽

1983 ◽

Vol 1 (1) ◽

pp. 5-6

Author(s):

R.D. Wright ◽

E.B. Hale

Keyword(s):

Shoot Growth ◽

Acer Rubrum ◽

Tree Height ◽

First Year ◽

Red Maple ◽

Trunk Diameter ◽

The Third ◽

Growing Seasons ◽

N Rates ◽

Nitrogen Rates

The influence of N rates and irrigation on shoot growth and trunk diameter were evaluated for red maple (Acer rubrum, L. ‘October Glory’), pin oak (Quercus palustris Muenchh) and dogwood (Cornus florida L. ‘Barton’). Irrigation increased shoot growth and trunk diameter for all 3 species during the first 2 growing seasons. Tree height and trunk diameter at the end of the third growing season were also greater for irrigated trees. Increasing the N levels from 168 to 329 Kg N/ha (150 to 300 lb N/A) resulted in a decrease in trunk diameter the first year and a decrease in shoot growth the second year in ‘October Glory’ maple. No significant differences in oak growth due to N rate were observed. Shoot growth and trunk diameter for dogwood were greater at 329 kg N/ha (300 lb N/A) than at 168 kg N/ha (150 lb N/A) only the first year. Neither height or trunk diameter at end of the third year were significantly increased from applying the higher level of N for any of the genera.

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Mulch Improves Pecan Tree Growth during Orchard Establishment

HortScience ◽

10.21273/hortsci.35.2.192 ◽

2000 ◽

Vol 35 (2) ◽

pp. 192-195 ◽

Cited By ~ 8

Author(s):

Michael W. Smith ◽

Becky L. Carroll ◽

Becky S. Cheary

Keyword(s):

Tree Height ◽

Carya Illinoinensis ◽

Split Application ◽

Single Application ◽

Trunk Diameter ◽

Leaf N Concentration ◽

K Concentration ◽

N Rates ◽

Leaf P ◽

Leaf N

`Giles' pecan [Carya illinoinensis (Wangenh.) K. Koch] seedlings were either not mulched or mulched with wood chips arranged in a 1- or 2-m-wide square that was 30 cm deep. Mulch treatments were in factorial combination with two N rates applied as either a single application at budbreak or as a split application at budbreak and 3 weeks later. Tree height was positively related to mulch width each year of the 3-year study, and trunk diameter was positively related to mulch width during the second and third years of the experiment. Leaf P and K concentration during 2 years and leaf N during 1 year of the study were positively related to mulch width. Trees receiving the higher N rate were taller during 2 of 3 years, but leaf N concentration was not affected by N rate. No differences in the parameters measured were observed whether N was applied as a single or as a split application.

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Impact of Application Rate and Interval on the Control of Powdery Mildew and Cercospora Leaf Spot on Bigleaf Hydrangea with Azoxystrobin

Journal of Environmental Horticulture ◽

10.24266/0738-2898-22.2.58 ◽

2004 ◽

Vol 22 (2) ◽

pp. 58-62 ◽

Cited By ~ 2

Author(s):

A. K. Hagan ◽

J. W. Olive ◽

J. Stephenson ◽

M. E. Rivas-Davila

Keyword(s):

Powdery Mildew ◽

Leaf Spot ◽

Application Rate ◽

Cercospora Leaf Spot ◽

Thiophanate Methyl ◽

Hydrangea Macrophylla ◽

Application Rates ◽

Erysiphe Polygoni ◽

Causal Fungus ◽

Paraffinic Oil

Abstract Efficacy of azoxystrobin (Heritage 50W™) was assessed over a range of application rates and intervals for the control of powdery mildew (Erysiphe polygoni) and Cercospora leaf spot (Cercospora hydrangea) on bigleaf hydrangea (Hydrangea macrophylla) ‘Nikko Blue’. Rooted hydrangea cuttings were transplanted in a pine bark/peat mixture. In 1998 and 1999, azoxystrobin at 0.16 g ai/liter and 0.32 g ai/liter, as well as 0.24 g ai/liter myclobutanil (Eagle 40W™) and 0.84 g ai/liter thiophanate methyl (3336 4.5F™), greatly reduced the incidence of powdery mildew compared with the untreated control where 75% of the leaves of were infected by the causal fungus. When applied at 1-, 2-, and 3-week intervals, both rates of azoxystrobin were equally effective in both years in preventing the development of powdery mildew on bigleaf hydrangea. In 1998, all fungicides except for thiophanate methyl protected bigleaf hydrangea from Cercospora leaf spot. In the last two trials, the incidence of powdery mildew increased significantly as the application rate for azoxystrobin decreased from 0.16 to 0.04 g ai/liter and the application interval was lengthened from 1 to 3 weeks. In general, all rates of azoxystrobin applied on a 3-week schedule failed to provide the level of powdery mildew control needed to produce quality bigleaf hydrangea for the florist and landscape market. When applied at 2-week intervals, myclobutanil was equally or more effective in controlling powdery mildew than any rate of azoxystrobin applied on the same schedule. When compared to the untreated controls, significant reductions in the incidence of powdery mildew on bigleaf hydrangea were obtained with weekly applications of paraffinic oil. No symptoms of phytotoxicity were associated with the use of any of the fungicides screened.

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