i Botany Circular No. 22
BRANCHED BROOMRAPE, OROBANCHE RA-
AN ECONOMICALLY IMPORTANT PARASITIC WEED NOT CURRI
Fla. Dept. Agric. & Consumer Serv.
r- 1- u T stry
ASA, Central Science
;NTLY KNOWN ItLAo yfpA
K. R. Langdon MA
Several species of Orobanche are important root parasites of cult vated crops. osof ese spec s are
native to the Mediterranean area and the Near or Middle East. )ne of these species, Orobanche ramosa
L., is established in the U.S. Here it is called branched broo rape,V*i( ti,!afsfjnMavariou wild
and cultivated plants, especially several economic plants in the ily Solana eae. ranched br mrape
(Fig. 1A and IB) is a small plant 4 to 12 inches (10-30 cm) ta ye ow, so0Lli .. Li l --lish,
without chlorophyll and with white to pale yellow or purplish to bluish small flowers. Leaves are
reduced to scales. It is often concealed beneath the host plant foliage.
Fig. 1. Orobanche ramosa. A) Plant with hosts. Some material removed to expose plant. B) Closeup
of flower spike. (Photos by C. A. Field, Texas Dept. Agric.)
DESCRIPTION: Plant annual, biennial, or perennial, depending mainly on host; stems 10-40 cm tall,
swollen at base, attached to host roots, simple or branched, glandular puberulent; leaves reduced to
scales, 3-10 mm, ovate to ovate-lanceolate, acute; inflorescence 2-25 cm, lax to moderately dense,
glandular pubescent; bracts 6-10 mm, ovate-lanceolate; bracteoles linear-lanceolate, about equalling
calyx; pedicels 0-8 mm; entire plant lacking chlorophyll, yellow or yellowish violet; calyx 6-8 mm; cor-
olla 10-22 mm; glandular-pubescent, suberect and inflated at base, white or yellow to violet or bluish,
usually pale; filaments inserted 3-6 mm above base of corolla; stigma white, cream or pale blue; capsule
6-10 mm containing numerous dust-like seeds. Plants highly variable where native; less so in introduced
DISTRIBUTION: Orobanche ramosa is native to the Mediterranean area of southern Europe but has been
spread to a number of other parts of the world. Present distribution includes southern Europe (occa-
sionally introduced farther north) to Russia and Siberia. It is also present in northern and southern
Africa and the Middle East (3,9,10,12). In the Americas, 0. ramosa has been introduced and is estab-
lished in the U. S., Mexico, and Cuba. It was reported at one time infesting hemp and tobacco in Ken-
Botanist, Office of Systematic Botany, P. 0. Box 1269, Gainesville, FL 32602.
It also has been reported (although some of these reports may be questionable or one-time reports) in
Illinois, Ohio, and Wisconsin. None of these infestations persisted (2,9). It was later found in New
Jersey and on Lo&Isfand, New YorI, These infestations apparently have since been eliminated (6,7).
An irfesta ion on tomato in California was first reported in 1929 and still remains a problem there
(6,9). In ,Lg rIB amosa was reported in Texas on various wild plants (4,7). An eradication campaign
has been initiated to eliminate this infestation.
HOSTS: Orobanche ramosa has a wide host range. Different populations appear to vary in their host
ranges, though the exact extent of variation is not known. Table 1 lists hosts reported for 0. ramosa
(1,2,7,9,12). A number of other plants have been reported as doubtful hosts (2), but since there is
uncertainty as to the correct identity of either the parasite or host species, these will not be re-
Table 1. Hosts of Orobanche ramosa
Amaranthus retroflexus L.
Ammi majus L.
Armoracia rusticana P. Gaertn., B.
Meyer & Schreb.
Artemisia biennis Willd.
Begonia semperflorens Link & Otto
Brassica napus L.
B. oleracea L.
B. rapa L.
Callirhoe leiocarpa R. F. Martin
Cannabis sativa L.
Capsella bursa-pastoris (L.) Medic.
Capsicum annuum L.
Chaerophytlum tainturieri Hook
Chenopodium album L.
Conium maculatum L.
Coreopsis basalis (A. Dietr.) Blake
Cucumis melo L.
C. sativus L.
Cucurbita pepo L.
Cuphea ignea A. DC.
Daucus carota L. Oxalis corniculata L.
Engelmannia pinnatifida Gray ex Nutt. Pelargoniumzonale (L.) L'Her. ex Soland.
Erigeron geiseri Shinners Penstemon gentainoides (H.B.K.) Poir.
Eryngium creticum Lam. Perilla frutescens (L.) Britton
Eupatorium ligustrinum DC. 'Crispa'
Galium tricornutum Dandy Petunia X hybrida Hort. Vilm.-Andr.
Gaura brachycarpa Small Salvia coccinea Juss. ex J. Murr.
Geranium texanum (Trelease) A. Heller S. splendens Sellow
Heliotropium arborescens L. Silene antirrhina L.
Lactuca sativa L. Solanum melongena L.
Lagenaria siceraria (Molina) Standl. S. nigrum L.
Lamium album L. S. pseudocapsicum L.
L. maculatum L. S. sarrachoides Sendtn.
L. purpureum L. S. tuberosum L.
Lepidium virginicum L. Taraxacum kok-saghyz Rodin
Leucas martinicensis R. Br. Tropaeolum majur L.
Lycopersicon esculentum Mill. Verbena sp.
Malva parviflora L. Veronica sp.
Melilotus alba Medic. Vicia faba L.
M. indica (L.) All. Vitis vinifera L.
M. officinalis (L.) Lam. Xanthium spinosum L.
Nicotiana tabacum L. X. strumarium L.
ECONOMICS: Orobanche ramosa parasitizes the roots of susceptible hosts, such as tomato, causing stunt-
ing and reducing yields as much as 51% (1). Some infested tomato fields in California have become
unprofitable as a result of branched broomrape infestations. It grows well in alkaline soils (5) and so
probably would be well adapted to the limestone and marl soils of South Florida where much of Florida's
winter tomato production occurs.
REPRODUCTION AND CONTROL: Each plant produced an average of around 100 seed capsules containing about
2,000 seeds each, or a total of 200,000 seeds per plant (11). These seeds are capable of lying dormant
in the soil in the absence of a suitable host for at least 13 years (2,9) and still germinate when host
roots are available. This makes control or eradication very difficult. An indication has been obtained
(4) that flax will cause germination of 0. ramosa seed but will not support growth or reproduction
(suicidal germination). This factor needs further study. Herbicidal treatments to prevent seeding
offer some promise.
SURVEY AND DETECTION: Look for small plants, often covered by host plant and other foliage, light
yellow or tinged purplish, with small tubular flowers white, light yellow, or pale purplish color. Many
situations can be checked, but a prime survey area would be tomato fields at around pink fruit stage.
Lift foliage and look underneath.
1. Abu-Irmaileh, B. E. 1979. Effect of various fertilizers on broomrape (Orobanche ramosa) infesta-
tion of tomatoes. Proc. Second Int. Symp. Parasitic Weeds, pp. 278-284.
2. Durbin, R. D. 1953. Hosts of the branched broomrape and its occurrence in California. Plant Dis.
3. Holm, L., J. V. Pancho, J. P. Herberger, and D. L. Plucknett. 1979. A geographical atlas of world
weeds. Wiley, New York. 391 pp.
4. Ivie, D. A. 1983. Orobanche ramosa (branched broomrape). Texas Dept. Agric. Mimeo. 2pp.
5. Kranz, J., H. Schmutterer, and W. Koch, editors. 1977. Diseases, pests and weeds in tropical
crops. Parey, Berlin. 666 pp.
6. Musselman, L. J. 1980. The biology of Striga, Orobanche, and other root-parasitic weeds. Ann.
Rev. Phytopathol. 18:463-489.
7. and K. C. Nixon. 1981. Branched broomrape (Orobanche ramosa) in Texas. Plant Dis. 65(9):
8. Reed, C. F. 1977. Economically important foreign weeds. U. S. Dept. Agric. Handbook 498. 746
9. Stout, G. L., and H. K. Wagnon. 1953. Branched broomrape, Orobanche ramosa L., a pest of tomato
and certain other crops. Bull. Calif. Dept. Agric. 42(2):45-51.
10. Tutin, T. G., V. H. Heywood, N. A. Burgess, D. M. Moore, D. H. Valentine, S. M. Walters, and D. A.
Webb, editors. 1972. Flora Europaea. Vol. 3. Cambridge Univ. Press, London. 370 pp.
11. Visser, J. 1981. South African parasitic flowering plants. Juta, Capetown. 177 pp.
12. Watson, T. R. 1971. Orobanche ramosa L. Calif. Dept. Agric. Detection Manual D. T. 4:24. 2 pp.