Download Iva axillaris

EUROPEAN AND MEDITERRANEAN PLANT PROTECTION ORGANIZATION
ЕВРОПЕЙСКАЯ И СРЕДИЗЕМНОМОРСКАЯ ОРГАНИЗАЦИЯ ПО КАРАНТИНУ И ЗАЩИТЕ РАСТЕНИЙ
ORGANISATION EUROPEENNE ET MEDITERRANEENNE POUR LA PROTECTION DES PLANTES
02/9187
Point 7.8
Iva axillaris
IDENTITY
Name:
Iva axillaris Pursh.
Taxonomic position: Asteraceae
Common name: Poverty weed, Poverty sumpweed (English); бузинник пазушный, ива
многолетняя (Russian).
Bayer code: IVAAX
GEOGRAPHICAL DISTRIBUTION
North America: Canada, Mexico, USA.
Oceania: Australia.
ON WHICH CROPS
All kinds of agricultural land may be infested by Iva axillaris, especially spring cereals, pastures,
meadows, orchards and gardens, as well as uncultivated land.
BIOLOGY
Iva axillaris is a perennial weed. It reproduces mainly by its spreading rhizomes, but may also
reproduce by seeds. The weed has a very well developed underground system, the main root
going deep into the soil (more than 2 m). A mass of spreading rhizomes develops at a depth of
20-60 cm in the soil and produces above-ground shoots. In years of drought, deeply situated
rhizomes grow up to the depth of 5-10 cm, then grow horizontally, developing several shoots and
a new main root. This helps the weed to survive in dry conditions when all other plants die. Each
year, new shoots appear late in spring, flowers appear in July, seeds in September.
DETECTION AND IDENTIFICATION
Iva axillaris grows 15-60 cm tall depending on conditions. The stem is upright, glabrous, with
many branches. The leaves are opposite (except at the shoot tips), small (not more than 2.5 cm
long), and silvery-grey because they are covered by whitish hairs. The flowers are small,
greenish, in axillary heads 4-7 mm in diameter, on short pedicels. The inflorescence is
surrounded by a toothed involucre. The outer flowers (1-6) of the head are female, with tubular
corolla (sometimes absent) and a bifid style. The inner flowers (15-25) of the head are male, with
tubular corolla, 5 stamens and a reduced sterile gynaecium. The seed is flattened, grey to almost
black, ovate, up to 5 mm long, about 2 mm large and 1 mm thick. Each head usually produces 1
or 2 seeds.
MEANS OF MOVEMENT AND DISPERSAL
Iva axillaris seeds are carried with seeds of many crops harvested late in the season, and also
with other plant products.
2
PATHWAYS
Contaminated seeds and grain, fodder, soil and growing media, soil accompanying plants. Seeds
of Iva axillaris have been detected many times in wheat grain imported into Russia from Canada
and the USA.
DAMAGE
Iva axillaris is a perennial weed, reproducing by seeds and by rhizomes which strongly compete
with crops for water and nutrients. It can seriously reduce the yield and quality of harvested
crops, especially cereals. The plants are toxic for livestock, have a strong disagreeable smell and
much reduce the quality of pastures.
PHYTOSANITARY RISK
Iva axillaris is an invasive weed, which continues to spread in areas where it has been introduced
(it is classified as a noxious weed in Victoria, Australia). Its control is difficult. Its drought
resistance is particularly significant. It could present a risk for the Mediterranean region and
Central Europe.
PHYTOSANITARY MEASURES
The movement of agricultural seeds, grain, forage, fodder and other materials infested with seeds
of Iva axillaris into pest-free areas should be restricted. Eradicative treatments with herbicides
are possible.
BIBLIOGRAPHY
Best KF (1975) The biology of Canadian weeds. 10. Iva axillaris Pursh. Canadian Journal of
Plant Science 55, 293–301.
Pritchard GH (1987) Poverty weed (Iva axillaris Pursh): its distribution and control. Plant
Protection Quarterly 2, 69-73.
Savotikov YuF, Smetnik AI (1995) Guide on pests, plant diseases and weeds of quarantine
significance for the Russian Federation. Arnika, Nizhnii Novgorod (in Russian).
Shutova NN (ed.) (1970) Guide on quarantine and other dangerous pests, diseases and weeds.
2nd edition. Kolos, Moscow (in Russian).
Vasyutin AS, Smetnik AI, Mordkovich YaB, Zinchenko VN, Yudin BI, Smirnov SA,
Moskalenko GP, Shakhramanov IK, Maslyakov VYu (2001) Plant Quarantine in the Russian
Federation. Kolos, Moscow (in Russian).
Whitson TD et al. (1996) Weeds of the West. Western Society of Weed Science, Newark (US).
Entry date 2001-11
Fig. 1. Iva axillaris : 1-4) seeds; 5) rhizome; 6) above-ground of the plant with flowers (Shutova,
1970).