ICARDA annual report 2004

ICARDA Annual Report 2004
34
over-wintering sites in Azaz, Ariha,
Ksabia, and Tel Hadya, and from
wheat fields in Kamishly, Malkeia,
Hama, Ariha, Idlib, Sweida, and
Azaz. Researchers found four
species of Phasiine fly that attack
Sunn pest: Phasia subcoleoptrata,
Heliozeta helluo, Ectophasia oblonga,
and Elomyia lateralis. This is the first
time that these four species have
been reported to affect Sunn pest in
Syria.
In 2003, parasitism rates in all
the over-wintering sites sampled
were negligible. In early spring,
very low rates of parasitism were
found in wheat fields in Hama
(1.3%) and Sweida (2.7%); there
were no occurrences at the other
sites surveyed. Towards the end of
Project 2.2.
Successful chemical control
of Orobanche in
legumes
Orobanche spp. (broomrape) are parasitic
weeds which attack many cultivated
and wild plants. They mainly
parasitize legumes such as faba
bean (Vicia faba) and lentil (Lens
culinaris) and solanaceous crops
such as tobacco and tomato by
attaching themselves to the roots of
their hosts and absorbing the food
they gather. Orobanche produces
large numbers of small, easily-dis-
Larva of a parasitoid (Phasia sp.) emerging
from an adult Sunn pest.
the spring, however, parasitism
rates in wheat fields increased dramatically
to 6.5%, 4.0%, 5.9%, and
13.3% in Azaz, Idlib, Kamishly, and
Agronomic Management of Cropping Systems
for Sustainable Production in Dry Areas
T
o identify best practices for weed control, ICARDA
researchers have developed appropriate chemical methods
of controlling Orobanche, a damaging parasitic weed
that attacks legume crops. The most effective chemicals, doses,
and application times were identified for Orobanche control in
lentil, Vicia spp., Lathyrus spp., and faba bean.
seminated seeds that remain viable
for long periods, making this weed
difficult to control. It also spreads
through the planting of contaminated
crop seed.
Two types of Orobanche are
present in CWANA: O. crenata and
O. aegyptiaca-ramosa. Both attack
faba bean, vetch, winter chickpea,
lentil, safflower, and rapeseed,
although O. aegyptiaca-ramosa mainly
invades lentil and rapeseed
fields. Studies at ICARDA have
shown that lentil, narbon vetch
(Vicia narbonensis) and faba bean
Sweida, respectively. In 2004, parasitism
levels were negligible in all
over-wintering sites except Azaz
(1%). Parasitism was not detected
in wheat fields in early spring,
except in Malkeia where levels
reached 1.9%. However, in late
spring, rates reached 5.9% in
Kamishly and 12.5% in Malkeia.
Results showed that the parasitoids
are active in the spring about
two weeks after Sunn pest adults
migrate to cereal fields from their
over-wintering sites and start laying
eggs. However, the level of parasitism
varies from year to year.
These parasitoids could help reduce
Sunn pest populations if they are
not affected by the aerial spraying of
broad-spectrum insecticides.
Severe Orobanche infestation in a lentil
field.
are most susceptible to Orobanche.
The number of Orobanche shoots
per square meter in these three
crops reached 191, 226, and 226,
respectively. However, the pres-