Abstract

Seedlings of several annual and perennial bedding plant species were inoculated with an isolate of Phytophthora nicotianae (synonym = P. parasitica) and planted into field beds in a simulated landscape situation. Throughout the growing season, growth measurements and disease ratings of the inoculated plants were compared with those of non-inoculated control plants of the same species in identical beds. Phytophthora-inoculated plants that continued to thrive through most of the growing season included Ageratum houstonianum, Celosia ‘Apricot Brandy’, and ‘New Look’; Dahlia ‘Harlequin’; Eustoma grandiflorum (prairie gentian); Lobularia ‘Carpet of Snow’; Nicotiana ‘Alta Dwarf White’, ‘Domino Salmon’, and ‘Nicki Red’; Pelargonium (geranium) ‘Multibloom Scarlet Eye’; Petunia ‘Polo Salmon’, and ‘Sugar Daddy’; Portulaca ‘Sundial Peppermint’; Rudbeckia ‘Rustic Dwarf’; Salvia ‘Lady in Red’, and ‘Victoria Blue’; Tagetes (marigold) ‘Disco Mix’, ‘Inca Orange’, ‘Inca Yellow’, ‘Janie Harmony Improved’, and ‘Gold Fireworks’; and Zinnia angustifolia. Plants that performed poorly following inoculation with Phytophthora include Antirrhinum (snapdragon) ‘Liberty White’, and ‘Liberty Mix’; Catharanthus (vinca) ‘Little Bright Eye’, and ‘Tropicana Rose’; Hibiscus ‘Disco Belle Mix’; Impatiens ‘Accent Bright Eye’; Leucanthemum x ‘Alaska’; Melampodium ‘Medallion’; Salvia ‘Turkestanica’; Torenia ‘Clown Mix’; Verbena ‘Imagination’; and Viola (pansy) ‘Fama See Me’. This study identifies bedding plant taxa which will provide an acceptable display in landscape beds infested with Phytopthora nicotianae (synonym = P. parasitica).

ageratum (Ageratum houstonianum Mill.), snapdragon (Antirrhinum majus L. ‘Liberty White’, ‘Liberty Mix’), Madagascar periwinkle (vinca) (Catharanthus roseus (L.) G. Don ‘Tropicana Rose’, ‘Little Bright Eye’), celosia (Celosia argentea L. ‘Apricot Brandy’, ‘Castle Pink’, ‘New Look’), dahlia (Dahlia coccinea Cav. ‘Harlequin’), prairie gentian (Eustoma grandiflorum (Raf.) Shinn.), rose mallow (Hibiscus moscheutos L. ‘Disco Belle Mix’), garden balsam (Impatiens balsamina L.), impatiens (Impatiens walleriana Hook. f. ‘Accent Bright Eye’), shasta daisy (Leucanthemum x superbum (J. Ingram) Bergmans ex Kent.), alyssum (Lobularia maritima Desv. ‘Carpet of Snow’), melampodium (Melampodium cinereum DC. ‘Medallion’), flowering tobacco (Nicotiana x sanderae hort Sander ex Will. Wats. ‘Alta Dwarf White’, ‘Daylight Mix’, ‘Domino Salmon’, ‘Nicki Red’), geranium (Pelargonium x hortorum L. H. Bail. ‘Multibloom Scarlet Eye’, petunia (Petunia x hybrida hort. Vilm.-Andr. ‘Polo Salmon’, ‘Red Picotee’, ‘Sugar Daddy’), moss rose (Portulaca grandiflora Hook. ‘Sundial Peppermint’), black-eyed Susan (Rudbeckia hirta L. ‘Rustic Dwarf’), scarlet salvia (Salvia coccinea Juss. ex Murray. ‘Lady in Red’), mealy sage (Salvia farinacea Benth. ‘Victoria Blue’), clary sage (Salvia sclarea L. ‘Turkestanica’), African marigold (Tagetes erecta L. ‘Inca Orange’, ‘Inca Yellow’), French marigold (Tagetes patula L. ‘Disco Mix’, ‘Gold Fireworks’, ‘Janie Harmony’,‘Janie Harmony Improved’), wishbone flower (Torenia fournieri Lind. ex Fourn. ‘Clown Mix’), moss verbena (Verbena tenuisecta Briq. ‘Imagination’), pansy (Viola x wittrockiana Gams. ‘Fama See Me’), zinnia (Zinnia angustifolia Kunth.)
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Author notes

2Associate Professor and Agricultural Research Specialist, resp.