Download Burr Ragweed: Information Booklet

The Israel Ministry of
Environmental Protection
Ambrosia confertiflora
Burr Ragweed
Ecological Paper
Information booklet
www.sviva.gov.il
The Ministry of Environmental Protection,
the Ministry of Agriculture, the Israel Nature
and Parks Authority, Drainage Authorities and River
Authorities have come together to prevent further
proliferation of Ambrosia confertiflora and the other
non-native species of this genus; the most urgent threat
posed by the plant is its potential spreading in the
Galilee, particularly in the Sea of Galilee watershed
area and in the valleys region the Galilee.
Invasion
of the burr
ragweed in
these regions
will cause
extensive
damage to:
Agriculture crops,
riparian habitats,
the shores of
the Sea of Galilee,
gardens and parks,
outdoor recreational
and leisure areas
Ambrosia confertiflora Invasion
of agricultural land in the Emek Hefer
Region (central coastal plain)
Production | Israel Ministry of Environmental Protection – Publications, Information and Internet Department
Ambrosia trifida
Four non-native species
of Ambrosia were
introduced to Israel in
recent years:
Ambrosia artemisiifolia
Ambrosia tenuifolia
Ambrosia confertiflora
This species poses
an immediate
threat to
agriculture and to
natural systems
The burr ragweed
causes damage to:
Agriculture
Humid habitats
Infrastructures
Spreads
quickly
in groves,
orchards and
fields
Ambrosia confertiflora
creates dense cover
that displaces the
local plant species
and completely
changes the features
of the ecosystems
The plant spreads
along roadsides
and infrastructure
networks
Gardens
and parks
The plant
invades
gardens and
disrupts their
maintenance
Health
It is liable to
cause allergies
in humans,
similar to other
species of
ambrosia
The original source of infestation
of Ambrosia confertiflora was the Shechem
(Nablus) area in the central Samaria region.
Today, the plant is common in the Samaria,
the Northern Jordan Valley, wadi Tirza,
Emek Hefer and the Sharon areas.
Additional foci were discovered in wadi
Qana, the Yarkon River, the Haifa region, at
the Ahihud junction, near Gadera and in the
Ashdod area.
Haifa
Em
ek H
it is crucial to prevent
further infestations.
efer
Yarkon River
Ashdod
Since it is very difficult to
eradicate the plant after
it has established itself
(a perennial species that
also uses vegetative
reproduction),
Sharon
Gedera
Ahihud
junction
ria
a
am
S
Qana River
Northern alley
Jordan V
Wadi Tirza
Ambrosia confertiflora DC
Compositae (Asteraceae)
Basic description: An upright perennial
herb, 75-250 cm tall. Its grayish green
leaves are 12-16 cm long and 10-15 cm
across. The leaves have a short petiole
and are bipinnate into long lobes; their
margins have sparse short hairs. The
leaves are opposite at the base of the
stem and alternate on the upper part
of the plant. The plant is monoecious
and has male and female yellow or
greenish flowers. The male flowers are
numerous and small (diameter about
1 cm), and are borne on erect clusters.
The female flowers lack petals and are
concentrated in the leaf axil, in a cupshaped involucre. In Israel the species
blooms from September to October.
The seeds are brown and their diameter
is 3-4 mm.
Geographic origin: Semi-arid valleys in
the southern United States and Mexico.
Invasion elsewhere in the world:
Ambrosia confertiflora is invasive in
Western Australia since the 1950’s.
General view
Southern
United States
and Mexico
Leafs
Inflorescence
Israel
Australia
On the banks of the
Alexander River
Background to the burr ragweed
invasion in Israel: the plant was first
recorded in 1990 on the Carmel coast.
A massive invasion began along the
Alexander River banks between the
late 1990s and the early 2000s. It is not
clear how the plant was introduced
into Israel. One possibility is that
seeds were introduced in seed mixes
imported from the United States for
feeding birds and pond fish.
Biological and ecological features: Ambrosia confertiflora forms very dense
stands that displace local plant species. The root system is shallow and very dense,
concentrated in the upper soil layers extending down to a depth of only 30 cm.
The plant reproduces from seeds as well as vegetatively by adaptive buds found
on horizontally spreading roots. The prevalent reproduction mode of the plant in
Israel is still unclear, but both reproduction modes were recorded in the field in
Israel. The plant resilience is very high: the plants renew themselves within just five
weeks of mowing. Seasonal domination of native annual ruderals during winter
months, such as the white mustard, milk thistle and Syrian thistle, does not displace
the burr ragweed.
Methods of dispersal: the plant is dispersed naturally as well as by humans. Natural
dispersal: the dispersal unit (the fruit) is a bur with 10-20 hooked spines enveloping a
single seed. The spines cling to the fur of animals, and thus the seeds are dispersed.
Dispersal also occurs by flowing water, especially during floods. Dispersal by
humans results mainly from seeds or plant parts unintentionally removed from
place to place by vehicles or agriculture machinery. Seeds or plant parts falling
off tools are liable to create infestations in new locations. In this way, for example,
new foci were established along Highway No. 1. And this is why new infestations
are likely to first appear along roadsides.
Along roadside in
the Sharon region
Along roadside
in Samaria
Along Highway No. 1
The current status of the invasion in Israel: the latest burr
ragweed survey showed that the plant first established itself
in the area of Shekhem (Nablus) in Samaria. From there the
plant spread, westwards, along the banks of the Shekhem
stream down to the banks of the Alexander River. At the
same time the plant spread eastwards along wadi Tirza,
where large stands were formed and recently the plant
reached the Jordan Valley.
Ahihud Junction
Kishon River
Alexa
nder R
iver
Na
blu
sR
Dror River
Qana River
A survey conducted by the Sharon Drainage Authority
found that the plant had infested 480 ha along the banks
of the Shekhem stream and the Alexander River, and from
there, it infested nearby fields and orchards. At the end of
2008, Ambrosia confertiflora was reported on the banks
of wadi Qana, in the wadi Qana Reserve in the western
Samaria Mountains. Since 2009, several new small foci were
reported in the central coastal plain, on the banks of the
Dror stream, and on roadsides along Road No. 3 and Road
No. 4. At the end of the summer of 2009, a foci was found
in the Petza’el Reserve in the eastern Samaria region. In
April 2011, a small foci was reported for the first time in the
Galilee, in a site adjacent to the Kishon River, near Haifa.
ive
r
Tirz
aR
Shechem
(Nablus)
iver
Petza'el Reserve
Kibbutz
Palmachim
Kibbutz
Revadim
The burr ragweed spreading rate is the fastest among land
invasive plants in Israel.
The impact on local species: Ambrosia
confertiflora forms very dense units that displace
all other plant species, so that the understory
at infested sites is almost completely lacking
native species. Ambrosia confertiflora is a serious
nuisance in cultivated fields where it spreads
rapidly. The plant also makes its way into orchards
and avocado groves.
irza
Along wadi T aria
a
Sm
in the eastern
An infested orchard in the
Sharon (photographed in
winter)
Control methods
Mowing is pointless as the plant regenerates quickly.
Uprooting may be effective against very young individual plants.
Uprooting of established individual plants (over 10 cm high) is not effective
as roots remain in the soil.
Herbicides authorized for use in Israel such as Glyphosate (Roundup),
Triclopyr (Garlon) and Fluroxypyr (Tomahawk) are not very effective since
the plant recovers shortly after the spraying. Moreover, these herbicides as
well as 2,4-D, are not registered for use in wetlands and riparian habitats
since they are hazardous to aquatic organisms.
A trial is currently in progress with an herbicide registered for use in humid
habitats. The trial is being conducted in collaboration with the Plant
Protection and Inspection Services in the Ministry of Agriculture, the
Ministry of Environmental Protection, the Sharon Drainage Authority and
the Israel Nature and Parks Authority. The final conclusions from the trial
are expected by the end of 2013.
At the same time, a study conducted along the Alexander River since
2008, is testing the efficiency of natural vegetation restoration along banks
in order to prevent Ambrosia confertiflora establishment. The experiment
in made with Arundo donax and Arundo mediterranea, two native
reed species. The first results of the study show that the restoration of the
natural and dense vegetation cover along river banks prevents Ambrosia
confertiflora establishment.
No biological control has been developed so far, against this species of
Ambrosia.
Report any foci of Ambrosia
confertiflora to the the Ministry
of Environmental Protection:
call *6911
In a palm tree
pla
in the Jordan ntation
Valley
ds
ricultural fiel
g
a
in
n
o
si
a
Inv
Hefer region
in the Emek
Invasion in agricultural fields
in the Jordan Valley
Author:
Dr. Jean-Marc Dufour-Dror
Dr. Tuvia Yaakobi
Photography by:
Dr. Jean-Marc Dufour-Dror