Etiology, Biology and Management of Diseases of Ornamental Plants and Turfgrasses

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
212	2199	1160	100%

Progress 10/01/01 to 09/30/06

Outputs
During the life of this project, cultivars of woody and herbaceous plant species (ageratum, crape myrtle, daylily, dianthus, Madagascar periwinkle, marigold, mimosa, pansy, phlox, rose, viola, zinnia) were evaluated for their resistance/susceptibility to common diseases that occurred in landscape plantings. Some crape myrtle, daylily and rose cultivars consistently showed very good disease resistance to Cercospora leaf spot/powdery mildew, rust and black spot diseases, respectively. New diseases were discovered, pathogens identified and findings published that included diseases on azalea, coleus, Madagascar periwinkle, garden petunia, Mexican petunia, Osteospermum, Gazania and phlox. Other new diseases were also found on ageratum, Marguerite daisy, crape myrtle, and cassia. Sodium and potassium carbonates and bicarbonates were found to efficiently kill ball moss at a minimum rate of 2% (17 lbs/100 gal water). An unidentified virus disease of Ligustrum japonicum was found infecting 98% of over 1000 landscape plants surveyed. The virus disease was transmitted to L. lucidum by grafting. Pine bark leachates significantly reduced mycelial growth of the camellia flower blight fungus in vitro which suggests it might be beneficial to use pine bark mulches beneath camellia bushes. Four isolates of the unique plant pathogenic green algae Cephaleuros virescens and C. parasiticus were deposited in the American Type Culture Collection (ATCC) and the University of Texas Algal Culture Collection. Observations on occurrence of azalea powdery mildew for the first time in Louisiana suggests the disease could be a potential problem on susceptible cultivars. Likewise, downy mildew disease of coleus has the potential of becoming an important new disease in the United States on greenhouse and landscape coleus plants. The latter disease is believed to have entered the United States on imported cuttings. Fifty seven (57) publications were produced during the term of this project that included 8 refereed articles, 31 cultivar evaluation reports in the on-line journal Biological and Cultural Tests for the Control of Plant Diseases, 6 articles in Louisiana Agriculture and 12 abstracts and articles in published proceedings.

Impacts
Information on plant cultivar resistance/susceptibility is of considerable value to production and retail nurseries, landscape businesses, extension personnel and homeowners. Using disease resistant cultivars reduces production costs and losses to producers, landscape services and homeowners. Information on new disease problems, their potential and management, is also important to all the previously mentioned clientele. Deposition of new or unique organisms in culture collections insures their availability to researchers now and in the future.

Publications

Holcomb, G. E., Valverde, R. A. and Gutierrez, D. L. 2006. A disease of Phlox paniculata caused by Alfalfa Mosaic Virus. HortScience 41:474-476.
Holcomb, G. E. 2006. First report of crown rot of Gazania rigens caused by Sclerotinia sclerotiorum in Louisiana. Plant Disease 90:1114.
Holcomb, G. E. and Ferrin, D. M. 2006. First report of powdery mildew on azalea caused by Erysiphe azaleae in Louisiana. Plant Disease 90:1263.
Daughtrey, M., Holcomb, G., Eshenaur, B., Palm, M., Belbahri, L. and Lefort, F. 2006. First report of downy mildew on greenhouse and landscape coleus caused by Peronospora sp. in Louisiana and New York. Plant Disease 90:1111.
Holcomb, G. E., Owings, A. D., Witcher, A. L. and Broyles, C. A. 2006. Reaction of crape myrtle cultivars to powdery mildew and Cercospora leaf spot, 2005. Report 21:O008. DOI:10.1094/BC21. The American Phytopathological Society, St. Paul, MN.
Holcomb, G. E., Owings, A. D., Witcher, A. L. and Broyles, C. A. 2006. Reaction of daylily cultivars to natural rust infection, 2005. Report 21:O009. DOI:10.1094/BC21. The American Phytopathological Society, St. Paul, MN.
Holcomb, G. E., Owings, A. D., Witcher, A. L. and Broyles, C. A. 2006. Reaction of pansy and viola cultivars to Cercospora leaf spot, 2005. Report 21:O012. DOI:10.1094/BC21. The American Phytopathological Society, St. Paul, MN.
Holcomb, G. E., Owings, A. D., Witcher, A. L. and Broyles, C. A. 2006. Reaction of vinca (Madagascar periwinkle) to Alternaria leaf spot, 2005. Report 21:O011. DOI:10.1094/BC21. The American Phytopathological Society, St. Paul, MN.
Holcomb, G. E., Owings, A. D., Witcher, A. L. and Broyles, C. A. 2006. Reaction of budded and own-rooted rose cultivars to black spot disease. Report 21:O010. DOI:10.1094/BC21. The American Phytopathological Society, St. Paul, MN.

Progress 01/01/05 to 12/31/05

Outputs
Seven ornamental plants species that included 304 named cultivars, 160 of them daylilies, were evaluated for resistance/susceptibility to various diseases during 2005. Crape myrtle cultivar Miami again was the most susceptible to Cercospora leaf spot but showed very good resistance to powdery mildew. Those showing very good resistance to Cercospora leaf spot again included Acoma, Catawba, Twilight and Tonto. Most crape myrtle cultivars showed very good resistance to powdery mildew except for Country Red which was very susceptible. Daylily cultivars Bitsy and Lullaby Baby have shown no rust disease for the third year in a row. Black Eyed Stella, rust-free for two years, showed moderate infections for the first time this year. Daylily cultivars Leebea Orange Crush and Judith were the most susceptible to rust for the third year in a row. One hundred and thirty eight (138) other daylily cultivars, including Pardon Me, were rated highly susceptible to rust. It was again confirmed that late-season (November) daylily rust ratings are very reliable from year to year in comparison to ratings made in August or earlier in the season. Two of 10 rose cultivars, Artistry and Climbing America, were more resistant to black spot disease when grown on their own roots as compared to being grafted to other root stock. Vinca (Madagascar periwinkle) cultivars varied in their susceptibility to Alternaria leaf spot with Cooler Hot Rose and Cooler Red being very resistant and Victory Lavender and Sunstorm White/Eye being very susceptible. Pansy Patiola series cultivars were more resistant to Cercospora leaf spot than were Colossus series cultivars. Viola Rocky series cultivars ranged from very resistant to very susceptible to Cercospora leaf spot disease. An Alternaria sp. isolated from young poinsettia plants was not pathogenic when inoculated to plants of the same cultivar that were mature with colored bracts. Axenic cultures of the plant pathogenic green algae Cephaleuros virescens and C. parasiticus were deposited with the American Type Culture Collection and the Algae Culture Collection of the University of Texas. The Louisiana isolate of Alfalfa mosaic virus (AMV) from phlox was identified as a distinct strain that is more closely related to AMV strains from the U.K. and France than to strains from the U.S. and Italy.

Impacts
Information on ornamental plant cultivar resistance and susceptibility is of great value to production and retail nurseries, landscape businesses, homeowners and extension personnel. The use of disease resistant cultivars reduces production costs and losses to producers, landscape services and homeowners. Information on daylily cultivar resistance/susceptibility to rust is particularly important because the disease is so new to the United States (5 years) and there are over 30,000 named cultivars. The deposition and preservation of Cephaleuros species isolates (two of C. parasiticus and four of C. virescens) in the ATCC and Texas culture collections is important because of the uniqueness of this plant pathogenic genus and because of the dearth of other deposits of this genus. The identification of a new and distinct strain of Alfalfa mosaic virus in phlox in the U.S. is important to the ornamental plant industry and for floriculture disease management.

Publications

Holcomb, G. E. 2005. Reaction of crape myrtle cultivars to Cercospora leaf spot, 2004. Biological and Cultural Tests for Control of Plant Diseases (online). Report 20:O008. DOI: 10.1094/BC20. The American Phytopathological Society, St. Paul, MN.
Holcomb, G. E., and Raiford, T. 2005. Reaction of rose cultivars to black spot disease, 2004. Biological and Cultural Tests for Control of Plant Diseases (online). Report 20:O005. DOI: 10.1094/BC20. The American Phytopathological Society, St. Paul, MN.
Holcomb, G. E., Owings, A. and Witcher, A. 2005. Evaluation of crape myrtle cultivars for reaction to Cercospora leaf spot, 2004. Biological and Cultural Tests for Control of Plant Diseases (online). Report 20:O009. DOI: 10.1094/BC20. The American Phytopathological Society, St. Paul, MN.
Holcomb, G. E. 2005. First report of Sclerotinia stem rot and death of Osteospermum spp. hybrid cultivars caused by Sclerotinia sclerotiorum in Louisiana. Plant Disease 89:911.
Holcomb, G. E. 2005. Ball moss and the alga Cephaleuros: one a pest on landscape trees, the other a leaf spot pathogen on magnolia. Proceedings Southwide Forest Disease Workshop.
Holcomb, G. E., Owings, A. and Witcher, A. 2005. Reaction of vinca (Madagascar periwinkle) cultivars to Choanephora flower spot/blight, 2004. Biological and Cultural Tests for Control of Plant Diseases (online). Report 20:O003. DOI: 10.1094/BC20. The American Phytopathological Society, St. Paul, MN.
Holcomb, G. E., Owings, A. and Witcher, A. 2005. Reaction of vinca (Madagascar periwinkle) cultivars to Alternaria leaf spot, 2004. Biological and Cultural Tests for Control of Plant Diseases (online). Report 20:O004. DOI: 10.1094/BC20. The American Phytopathological Society, St. Paul, MN.
Holcomb, G. E., Owings, A. and Witcher, A. 2005. Reaction of marigold cultivars to Choanephora flower blight, 2004. Biological and Cultural Tests for Control of Plant Diseases (online). Report 20:O006. DOI: 10.1094/BC20. The American Phytopathological Society, St. Paul, MN.
Holcomb, G. E., Owings, A. and Witcher, A. 2005. Reaction of daylily cultivars to natural rust infection, 2004. Biological and Cultural Tests for Control of Plant Diseases (online). Report 20:O007. DOI: 10.1094/BC20. The American Phytopathological Society, St. Paul, MN.
Holcomb, Gordon E. and Owings, Allen D. 2005. Daylily rust problem continues. Louisiana Agriculture 48(2):13.
Owings, Allen D., Holcomb, Gordon E., Witcher, Anthony L. and Broyles, C. Allen. 2005. Rose research continues to expand at the LSU AgCenter. Louisiana Agriculture 48(2):11.
Owings, Allen D., Holcomb, Gordon E., Witcher, Anthony L. and Broyles, C. Allen. 2005. 2003-2004 Landscape Performance: Bedding plants and herbaceous perennials. Louisiana Agriculture 48(2):18-19.
Owings, A., Holcomb, G., Witcher, A. and Broyles, C. 2005. Initial performance of Texas Earth Kind roses in Louisiana. Proc. Southern Nursery Assoc. Res. Conf. 50:481-483.
Owings, A. D., Holcomb, G. E., Witcher, A. L., Broyles, C. A. and Bush, E. W. 2005. Landscape plant observations from the LSU AgCenter, 2004. (Abstr.) HortScience 40(3):893.
Owings, Allen D., Holcomb, Gordon E., Bush, Edward W., Witcher, Anthony L. and Broyles, C. Allen. 2005. All American Daylilies: Performance and the rust threat. Louisiana Agriculture 48(2):12-13.
Owings, A. D., Witcher, A. L., Holcomb, G. E., Broyles, C. A. and Bush, E. W. 2005. All-America daylilies: Landscape performance and rust observations. (Abstr.) HortScience 40(4):1040.

Progress 01/01/04 to 12/31/04

Outputs
Seven ornamental plant species and 239 cultivars were evaluated for resistance/susceptibility to leaf spot, flower blight and rust diseases during 2004. Crape myrtle cultivar Miami was very susceptible to Cercospora leaf spot defoliation at two different sites while cultivars Acoma, Basham's Party Pink, Tuskegee and Tonto showed only minor defoliation at both sites. Rose cultivars Carefree Delight and Knock Out again showed good resistance to black spot whereas cultivars Friendship, Tropicana, Arkansas and Bewitched were severely defoliated. Madagascar periwinkle cultivar Victory Blue was the most severely affected by Choanephora flower spot/blight and Titan Polka Dot was least affected. Alternaria leaf spot was most severe on Madagascar periwinkle cultivar Victory Lavender and least severe on cultivar Titan Polka Dot. Marigold cultivars Inca II Orange and Primrose were severely infected with Choanephora flower blight, but cultivars Aspen Flame and Aspen Orange showed only minor disease. For the second year in a row, daylily cultivars Judith and Leebea Orange Crush were severely infected with leaf rust while Bitsy, Black Eyed Stella and Lullaby Baby were free of rust. In south Louisiana, daylily rust ratings should not be taken until November to obtain the most accurate results regarding cultivar susceptibility. It was found that several Earth Kind Rose cultivars were highly susceptibile to powdery mildew (Clotilde Soupert, Souvenir de St. Anne's, Georgetown Tea and Sarah Jones) and should not be grown in south Louisiana. Tests were conducted, at the request of Monrovia Nursery, that showed mimosa cultivar Bourbi (a recent introduction from Monrovia) to be susceptible to Fusarium wilt. Fresh weight of the green alga Cephaleuros virescens, grown in vitro, was greater when grown with sucrose than with dextrose and doubled when sucrose was increased from 10 to 40 g/L. Commercial pine bark leachates (30-day-old) significantly reduced mycelial growth of Ciborinia camelliae (camellia flower blight pathogen) at concentrations of 12.5 to 100% when added to the growth medium. After 82 days, these leachates were no longer effective in reducing mycelial growth except at 50% concentration and when filter sterilized (vs. steam sterilization).

Impacts
Plant cultivar susceptibility information is of great value to production and retail nurseries, landscape businesses, homeowners, and extension and research personnel because the planting of resistant materials reduces production costs and losses. Information on daylily cultivar resistance to rust is currently of great interest since the disease has been in the United States for only about 4 years, but already occurs over the entire U. S. Daylily growers are anxious for any information on cultivar susceptibility. Pathogenicity tests with the alga Cephaleuros have never been accomplished, because the alga has never been induced to sporulate in culture. Growth studies cited here are directed toward that goal. The negative effects of pine bark leachates on mycelial growth of the camellia flower blight fungus suggests that pine bark used as a mulch may reduce inoculum levels of this important pathogen.

Publications

Holcomb, G. E. 2004. First report of southern blight of Ruellia brittoniana caused by Sclerotium rolfsii in Louisiana. Plant Disease 88:770.
Holcomb, G. E., Owings, A. and Witcher, A. 2004. Reaction of Viola spp. cultivars to Botrytis flower spot/blight, 2003. Biological and Cultural Tests for Control of Plant Diseases (online.) Report 19:O006. DOI: 10.1094/BC19. The American Phytopathological Society, St. Paul, MN.
Holcomb, G. E., Owings, A. and Witcher, A. 2004. Reaction of vinca Madagascar periwinkle) cultivars to web blight, 2003. Biological and Cultural Tests for Control of Plant Diseases (online.) Report 19:O005. DOI: 10.1094/BC19. The American Phytopathological Society, St. Paul, MN.
Holcomb, G. E., Owings, A. and Witcher, A. 2004. Reaction of rainbow pink cultivars to Alternaria leaf spot, 2003. Biological and Cultural Tests for Control of Plant Diseases (online.) Report 19:O003. DOI: 10.1094/BC19. The American Phytopathological Society, St. Paul, MN.
Holcomb, G. E., Owings, A. and Witcher, A. 2004. Reaction of daylily cultivars to natural rust infection, 2003. Biological and Cultural Tests for Control of Plant Diseases (online.) Report 19:O002. DOI: 10.1094/BC19. The American Phytopathological Society, St. Paul, MN.
Holcomb, G. E., Raiford, T. and Witcher, A. 2004. Reaction of rose cultivars to black spot disease, 2003. Biological and Cultural Tests for Control of Plant Diseases (online.) Report 19:O004. DOI: 10.1094/BC19. The American Phytopathological Society, St. Paul, MN.
Holcomb, G. E. 2004. SAD and Palmetto. Louisiana Turfgrass Bulletin 4(2):1.
Owings, A., Holcomb, G. Witcher, A. and Bush, E. 2004. All America daylilies: Landscape performance and rust observations. Proc. Southern Nursery Assoc. Res. Conf. 49:414-417.
Owings, A., Holcomb, G., Bates, D. and Witcher, A. 2004. Fall and spring landscape performance of African marigold varieties. La. State Hort. Soc. J. 1:1-2.
Owings, A., Bush, E., Bates, D. and Holcomb, G. 2004. Landscape performance of miniature and dwarf crape myrtle cultivars. La. State Hort. Soc. J. 1:11-12.

Progress 01/01/03 to 12/31/03

Outputs
Five ornamental plant species were evaluated for resistance/susceptibility to leaf spots, rust, flower blight and web blight. Rainbow pink (Dianthus) cultivars ranged from slightly susceptible (Amazon Mix and Bouquet) to highly susceptible (several cultivars of Floral Lace and Ideal series) to Alternaria leaf spot. Rose cultivars Knock Out and Carefree Delight have shown good resistance to black spot disease during four test seasons. The Mediterranean series cultivars (prostrate growth habit) of Madagascar periwinkle (vinca) were again the most susceptible to web blight caused by Rhizoctonia solani. Viola spp. cultivars, of pansy panola and viola, ranged from slightly susceptible (Sorbet Yellow Delight, Baby Face Ruby Gold) to highly susceptible (all panola cultivars) to Botrytis flower spot/blight. Daylily cultivars Black Eyed Susan, Lullaby Baby and Bitsy remained free of rust disease during the growing season, whereas Judith, LeeBea Orange Crush and Star Struck were highly susceptible to the disease. Two fungus diseases, both new for Louisiana and the United States, were discovered in a wholesale nursery and identified. Downy mildew, caused by Peronospora radii, was identified on Argyranthemum frutescens (Marguerite or Paris daisy). Southern wilt, caused by Sclerotium rolfsii, was identified on Ruellia brittoniana (Mexican petunia). Both diseases were introduced into the state on infected nursery stock. A new virus disease on perennial phlox also was found and has been partially characterized. A virus disease survey of landscape Ligustrum japonicum found 98% of over 1000 plants infected. In contrast, only 4% of 400 plants in retail nurseries showed symptoms. This virus was graft transmitted from L. japonicum to L. lucidum, however, L. lucidum has never been observed to be naturally infected. The commercial SAR inducer Messenger failed to give any disease control in greenhouse trials on Alternaria leaf spot of zinnia and Fusarium wilt of mimosa. The commercial St. Augustinegrass cultivar Palmetto, advertised as resistant to SAD virus disease, was shown to be susceptible in inoculation tests. Both 2% and 5% sodium bicarbonate was effective in killing Spanish moss 5 to 7 days after treatment.

Impacts
Plant cultivar susceptibility information is of value to production and retail nurseries, landscape businesses, extension personnel and homeowners because the use of these materials reduces production costs and losses. Identification of new disease problems and their causes is necessary before effective management practices can be developed and implemented. The use of SAR inducers for disease control has the potential for reducing pesticide use.

Publications

Holcomb, G. E. 2003. First report of petunia blight caused by Choanephora cucurbitarum in the United States. Plant Disease 87:751.
Holcomb, G. E. 2003. Reaction of crape myrtle cultivars to Cercospora leaf spot, 2002. Biological and Cultural Tests for Control of Plant Diseases (online.) Report 18:O007. DOI: 10.1094/BC18. The American Phytopathological Society, St. Paul. MN.
Holcomb, G. E. 2003. Control of ball moss (Tillandsia recurvata) with bicarbonate and carbonate salts of sodium and potassium. (Abstr.) Proc. Pan American Plant Disease Conference 2003:238. April 5-10, 2003. South Padre Island, Texas.
Holcomb, G. E. and Cox, P. 2003. Reaction of petunia cultivars to Botrytis flower spot and blight, 2002. Biological and Cultural Tests for Control of Plant Diseases (online.) Report 18:O009. DOI: 10.1094/BC18. The American Phytopathological Society, St. Paul. MN.
Holcomb, G. E. and Cox, P. 2003. Reaction of pansy, panola and viola cultivars to Cercospora leaf spot, 2002. Biological and Cultural Tests for Control of Plant Diseases (online.) Report 18:O014. DOI: 10.1094/BC18. The American Phytopathological Society, St. Paul. MN.
Holcomb, G. E. and Hollier, C. A. 2003. Daylily rust: A new disease for Louisiana. Proc. Louisiana Plant Protection Assoc. and Louisiana Assoc. of Agronomists 2003:35.
Holcomb, G. E., Owings, A. and Witcher, A. 2003. Reaction of dwarf crape myrtle cultivars to powdery mildew and leaf spot, 2002. Biological and Cultural Tests for Control of Plant Diseases (online.) Report 18:O008. DOI: 10.1094/BC18. The American Phytopathological Society, St. Paul. MN.
Holcomb, G. E., Raiford, T. and Witcher, A. 2003. Reaction of rose cultivars to powdery mildew, 2002. Biological and Cultural Tests for Control of Plant Diseases (online.) Report 18:O011. DOI: 10.1094/BC18. The American Phytopathological Society, St. Paul. MN.
Holcomb, G. E., Raiford, T. and Witcher, A. 2003. Reaction of rose cultivars to black spot disease, 2002. Biological and Cultural Tests for Control of Plant Diseases (online.) Report 18:O012. DOI: 10.1094/BC18. The American Phytopathological Society, St. Paul. MN.
Holcomb, G. E. and Witcher, A. 2003. Evaluation of perennial phlox cultivars for reaction to powdery mildew and leaf spot, 2002. Biological and Cultural Tests for Control of Plant Diseases (online.) Report 18:O010. DOI: 10.1094/BC18. The American Phytopathological Society, St. Paul. MN.
Holcomb, G. E. and Witcher, A. 2003. Reaction of vinca cultivars to web blight, 2002. Biological and Cultural Tests for Control of Plant Diseases (online.) Report 18:O013. DOI: 10.1094/BC18. The American Phytopathological Society, St. Paul. MN.
Owings, A., Holcomb, G. and Witcher, A. 2003. Landscape performance of warm season annual bedding plants. Louisiana Agriculture 46(1):10-11.
Owings, A., Holcomb, G., Witcher, A., Ellis, W. and Raiford, T. 2003. Landscape performance of dianthus cultivars. Southern Nursery Assoc. Res. Conf. Proceedings 48:370-372.
Owings, A., Holcomb, G., Witcher, A., Ellis, W. and Raiford, T. 2003. Landscape performance of viola and panola cultivars. Southern Nursery Assoc. Res. Conf. Proceedings 48:373-376.

Progress 01/01/02 to 12/31/02

Outputs
Eight ornamental species, that included herbaceous and woody plants, were evaluated for susceptibility to fungal leaf spots, powdery mildew and web blight during 2002. Among 93 rose cultivars, Knock Out, Brass Band and Carefree Delight showed very good black spot resistance. Rose cultivars Touch of Class and Perfume Delight were the most susceptible to powdery mildew. Delta series pansy cultivars were less susceptible to Cercospora leaf spot than were Majestic series cultivars. All Mediterranean series Madagascar periwinkle (vinca) cultivars (10) were susceptible to web blight and all Stardust series (3) and Heat Wave (5) series cultivars were resistant. Among 24 perennial phlox cultivars, Snow White was very susceptible to both powdery mildew and Septoria leaf spot, but Rosalinda showed good resistance to both diseases. Dwarf crape myrtle cultivar Purple Velvet was very susceptible to both powdery mildew and Cercospora leaf spot, but Orlando showed good resistance to both diseases. Crape myrtle cultivar Biloxi (tree form) was again the most susceptible among 41 cultivars evaluated for Cercospora leaf spot and should not be recommended for south Louisiana. Tests were conducted to determine the lowest concentration of potassium and sodium bicarbonate that was effective for controlling ball moss. Ammonium bicarbonate did not give effective control at the highest (5%) rate. Web blight of Madagascar periwinkle, caused by Rhizoctonia solani AG 1, was reported for the first time from Louisiana. This was only the second reported incidence of the disease in the United States. A new anthracnose disease of crape myrtle was observed, the pathogen isolated and initial pathogenicity tests performed. Preliminary research was initiated on a previously unreported fungal disease on petunia that caused heavy losses in a commercial nursery. Daylily rust is now widespread in south Louisiana. The disease is active whenever temperatures are warm and daylilies are growing (including during the months of December and January).

Impacts
Plant cultivar susceptibility information is valuable to homeowners, landscape businesses, and to production and retail nurseries. The use of known disease resistant cultivars reduces production costs and losses to homeowners, nurseries and landscape businesses. Identification of new disease problems in retail and production nurseries and landscape plantings is necessary before effective management practices can be developed and recommended.

Publications

Holcomb, G. E. and Owings, A. 2002. Reaction of dwarf crape myrtle cultivars to powdery mildew, 2001. Biological and Cultural Tests 2002:O05.
Holcomb, G. E., Bates, D. and Owings, A. 2002. Reaction of vinca cultivars to web blight, 2001. Biological and Cultural Tests 2002:O21.
Owings, A., Bates, D., Holcomb, G. and Bush, E. 2002. Miniature and dwarf crape myrtles for Louisiana. Louisiana Agriculture 45(1):24-25.
Holcomb, G. E. 2002. Control of ball moss with carbonate and bicarbonate salts of sodium and potassium. Proc. La. Plant Protection Assoc. and La. Assoc. of Agronomists 2002:20.
Holcomb, G. E. 2002. Reaction of crape myrtle cultivars to powdery mildew, 2002. Biological and Cultural Tests 2002:O04. (online journal)
Holcomb, G. E. and Carling, D. E. 2002. First report of web blight caused by Rhizoctonia solani on Catharanthus roseus in Louisiana. Plant Disease 86:1272.
Holcomb, G. E.and Bates, D. 2002. Reaction of phlox cultivars to Septoria leaf spot, 2001. Biological and Cultural Tests 2002:O17.
Holcomb, G. E. and Bates, D. 2002. Reaction of rose cultivars to black spot disease, 2001. Biological and Cultural Tests 2002:O20.

Progress 10/01/01 to 12/31/01

Outputs
Tests were conducted to compare several bicarbonate and carbonate compounds for their effectiveness in controlling ball moss when applied as aqueous sprays. Potassium and sodium bicarbonate and their carbonates were found equally effective in causing desiccation and death. Neither ammonium bicarbonate nor ammonium carbonate gave effective control when used at the same concentrations as used for potassium/sodium bicarbonate/carbonate. In comparison with controls, potassium and sodium bicarbonate and their carbonates caused 50% water loss in ball moss plants and resulted in their death 5 days after treatment. Final dry weights of treated and nontreated plants were not significantly different in these tests. It was also found that sodium bicarbonate rates previously used for ball moss control could be reduced by half and still get effective control.

Impacts
Ball moss has now become an established pest on crape myrtle and live oak trees in Baton Rouge after spreading from its center of introduction on the Louisiana State University campus. Information developed on the use of sodium bicarbonate will give municipal agencies and homeowners a cheap and effective method for controlling this pest plant.

Publications

No publications reported this period