California Pest Rating for
Egyptian broomrape | Orobanche aegyptiaca Pers.
Pest Rating: A | Proposed Seed Rating: P
PEST RATING PROFILE
Egyptian broomrape was found for the first time in North America in Solano County, California in July, 2014.
History & Status:
Egyptian broomrapes are annual plants that grow from seed and require a host to survive. They are a parasitic plants that grow on the roots of Broad-leaf hosts and obtain all of their nutrients and water from these plants. As such, they can seriously reduce the yield of infected crops. Seeds germinate in response to chemicals released by host plant roots. The broomrape seedling root then attaches itself to the host plant root and remains underground until flowering. The plant has no chlorophyll and no photosynthetic leaves. Flowering stems emerge about 6 weeks after germination, then flower and begin to set seed within 2–3 weeks. Seed capsules dry and shatter in summer. One plant can produce over 100,000 seeds per year and seeds may lay dormant in the soil for more many years. Broomrape seed can be spread by footwear, livestock, machinery, vehicles, flooding, as well as by contaminated fodder, seed and soil. Egyptian broomrape is a relative of branched broomrape and belongs to a species group that is among the world’s worst crop weeds. Most authorities treat Orobanche ramosa and Orobanche aegyptiaca as distinct species, and in most keys there is a clear differentiation between them on the basis of corolla length and hairiness of anthers; in practice many specimens fall on the borderline and are difficult to place with certainty. Some authorities segregate this species group of Orobanche as the genus Phelipanche, in which case the species in question is known as Phelipanche aegyptiaca Pomel. Nevertheless, as a broad approach to Orobanche is followed in the Jepson Manual and will be followed in Flora North America, the species will be recognized as Orobanche aegyptiaca here. In the wild in Europe, Egyptian broomrape attacks annual composites (members of the aster family, Asteraceae), although it occasionally attacks members of the legume family (Fabaceae) and other broad-leaved plants. Egyptian broomrape attacks a broad array of field crops and some ornamentals. Tomato, potato, tobacco, eggplant, peppers, peas, carrot, celery, mustard, spinach, and chrysanthemum are among the susceptible plants. In areas such as southern Russia melons are also potential hosts. Established broomrape infestations can reduce crop yields by up to 70%, threaten export markets, and they are extremely difficult to eradicate.
Egyptian broomrape has been a “Q” listed noxious weed in California since it was recently found. Although the species has not yet been given a permanent official pest designation in the United States, it is included as a federal listed noxious weed under the genus Orobanche (all species that are not native or already widespread).
California Distribution: One site in Solano County.
California Interceptions: Egyptian broomrape has been detected only in eastern Solano County, California.
United States: The finding of Egyptian broomrape in California is the first detection for North America.
International: Egyptian broomrape is native to the Middle East and is also found as a crop weed in Eastern Europe, at least 3 countries in Africa and in the warmer parts of Asia. Before this detection in California, its only Western Hemisphere report was in Cuba.
This risk Egyptian broomrape would pose to California is evaluated below.
Consequences of Introduction:
1) Climate/Host Interaction: The plant has attacked crops in many countries in the Eastern Hemisphere. It is more adapted to warmer climates than its close relative branched broomrape. This makes it well adapted to the regions of California where most row crops are grown. Therefore, Egyptian broomrape scores as High (3) in this category.
Evaluate if the pest would have suitable hosts and climate to establish in California. Score:
– Low (1) Not likely to establish in California; or likely to establish in very limited areas.
– Medium (2) may be able to establish in a larger but limited part of California.
– High (3) likely to establish a widespread distribution in California.
2) Host Range: Risk is High (3) as Egyptian broomrape is documented to attack at least 23 crops grown in California. Important crops it is known to attack include tomato, olive, melons, cucumbers, eggplants, and carrot. Therefore, Egyptian broomrape scores as High (3) in this category.
Evaluate the host range of the pest. Score:
– Low (1) has a very limited host range.
– Medium (2) has a moderate host range.
– High (3) has a wide host range.
3) Pest Dispersal Potential: Egyptian broomrape produces numerous seeds that seem to last for years and be able to spread via equipment and on animals (including humans). The seed bank is highly persistent. Egyptian broomrape receives a High (3) in this category.
Evaluate the natural and artificial dispersal potential of the pest. Score:
– Low (1) does not have high reproductive or dispersal potential.
– Medium (2) has either high reproductive or dispersal potential.
– High (3) has both high reproduction and dispersal potential.
4) Economic Impact: Egyptian broomrape can lower crop productivity in susceptible row crops by up to 70%. This can make profitable crops unprofitable, affect land value, and result in quarantine. Furthermore, the weed may also be present on broadleaf weeds in fields when non-host crops are grown, affecting marketability of additional crops due to potential seed contamination. Egyptian broomrape receives a High (3) in this category.
Evaluate the economic impact of the pest to California using the criteria below. Score:
A. The pest could lower crop yield.
B. The pest could lower crop value (includes increasing crop production costs).
C. The pest could trigger the loss of markets (includes quarantines).
D. The pest could negatively change normal cultural practices.
E. The pest can vector, or is vectored, by another pestiferous organism.
F. The organism is injurious or poisonous to agriculturally important animals.
G. The organism can interfere with the delivery or supply of water for agricultural uses.
– Low (1) causes 0 or 1 of these impacts.
– Medium (2) causes 2 of these impacts.
– High (3) causes 3 or more of these impacts.
5) Environmental Impact: Egyptian broomrape is likely to trigger new treatments by land managers. The plant has not yet spread to the wild in California. However, certain native plants such as our annual composites (Asteraceae) and legumes such as clovers (Trifolium) are likely susceptible to attack from Egyptian broomrape. These include such rare or endangered species such as Contra Costa goldfields (Lasthenia conjugens), Suisun aster (Symphyotrichum lentum), Delta tule pea (Lathyrus jepsonii jepsonii), and showy Indian clover (T. amoenum). Egyptian broomrape receives a High (3) in this category.
Evaluate the environmental impact of the pest on California using the criteria below.
A. The pest could have a significant environmental impact such as lowering biodiversity, disrupting natural communities, or changing ecosystem processes
B. The pest could directly affect threatened or endangered species
C. The pest could impact threatened or endangered species by disrupting critical habitats
D. The pest could trigger additional official or private treatment programs
E. Significantly impacting cultural practices, home/urban gardening or ornamental plantings.
Score the pest for Environmental Impact. Score:
– Low (1) causes none of the above to occur
– Medium (2) causes one of the above to occur
– High (3) causes two or more of the above to occur
Consequences of Introduction to California for Branched broomrape: High (15)
Add up the total score and include it here.
– Low = 5-8 points
– Medium = 9-12 points
– High = 13-15 points
6) Post Entry Distribution and Survey Information: Egyptian broomrape has been found in 1 county in California, and may be eradicable. It receives a Low (-1) in this category.
Evaluate the known distribution in California. Only official records identified by a taxonomic expert and supported by voucher specimens deposited in natural history collections should be considered. Pest incursions that have been eradicated, are under eradication, or have been delimited with no further detections should not be included.
-Not established (0) Pest never detected in California, or known only from incursions.
-Low (-1) Pest has a localized distribution in California, or is established in one suitable climate/host area (region).
-Medium (-2) Pest is widespread in California but not fully established in the endangered area, or pest established in two contiguous suitable climate/host areas.
-High (-3) Pest has fully established in the endangered area, or pest is reported in more than two contiguous or non-contiguous suitable climate/host areas.
The final score is the consequences of introduction score minus the post entry distribution and survey information score: High (14)
The experience in the Middle East shows the potential of this species to disrupt crop systems. Its potential effects on the environment are more speculative and necessarily more uncertain.
Conclusion and Rating Justification:
Egyptian broomrape is a bad agricultural weed because of its ability to reduce yields, produce large numbers of long-lived seeds, and its ease of spread. Therefore, its advent into California can be viewed as a significant event in North American agriculture. It should be included in regulations such as the California Code of Regulations Section 4500 list of noxious weeds as it is already included on the USDA noxious weed list.
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Dean G. Kelch, Primary Botanist; California Department of Food and Agriculture; 1220 N Street, Sacramento, CA 95814; Tel. (916) 654-0312; plant.health[@]cdfa.ca.gov.
Pest Rating: A | Proposed Seed Rating: P
Posted by ls