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No. 11, March 2011
Cereal Cyst Nematodes: An unnoticed threat to global cereal
production
A. Dababat, S. Pariyar, J. Nicol, E. Duveiller
CGIAR Systemwide Program
on Integrated Pest
Management (SP-IPM) is a
global partnership that draws
together the diverse IPM
research, knowledge and
expertise of the international
agricultural research centers
and their partners to build
synergies in research outcomes
and impacts, and to respond
more effectively to the needs
of farmers in developing
countries.
SP-IPM Technical Innovation
Briefs present, in short, IPM
research findings and
innovations for the
management of pests, diseases,
and weeds in agricultural
production.
Global distribution and crop loss
Nematodes are among the earliest recognized parasites of
wheat that occur worldwide in nearly all environments. A loss of
10% of world crop production has been estimated as a result of
plant nematode damage (Whitehead 1998). The cereal cyst
nematodes (CCNs) are the most important group of plant
parasitic nematodes attacking temperate cereals, including
wheat and barley (Sikora 1988). CCNs are a group of several
closely related species which have been documented as causing
economic yield loss in rainfed wheat production systems in
several parts of the world including North Africa, West Asia,
China, India, Australia, the United States of America and
countries in Europe (Nicol and Rivoal 2008). The species most
Winter wheat affected by H. avenae combined
with lower soil fertility on a hilltop near
Palouse, Washington, USA. – R. Smiley
reported are Heterodera avenae, H. filipjevi and H. latipons
(Rivoal and Cook 1993) and each species consists of different
pathotypes. At least 12 pathotypes have been described for H.
avenae. Their worldwide distribution, predominance in areas
where cereal is grown, and their devastating yield loss rank them
as major pests affecting the world’s food supply. Their effects on
plant growth and yield are commonly underestimated by farmers,
agronomists, and pest management advisors because of
difficulties in detection (Bridge et al. 2002).
Irrigated winter wheat infested with Heterodera
avenae with tolerant (left) and intolerant (right)
cultivars growing in adjacent farmer’s fields in
Biology and damage symptoms
Xuchang, Henan, China. – I. Riley
CCNs are sedentary and monocyclic nematodes. The life cycle consits of the egg, four juvenile stages and the
adult stage. CCNs are characterized by the development of white females swelling to form resistant cysts which
may remain dormant in the soil for several years. The larvae of the nematodes emerge from eggs as second
stage juveniles, and migrates into the soil where they penetrate root tips.
The symptoms of nematode attack are more visible in seedlings than in the older plants. The symptoms appear
early in the season as pale green patches, with the lower leaves of the plant becoming yellow, and the plants
generally have few tillers. Infected plants grow poorly and in uneven patches. Symptoms can easily be confused
with those from other problems such as nitrogen deficiency and poor soil. Infected root systems show increased
root production, and have a `bushy-knotted´ appearance. This highly-branched root system is a characteristic
enabling CCNs to be diagnosed in wheat and barley. As the life cycle of CCNs progresses, several white
females in the form of cysts are usually visible at each knot.
This and other IPM Briefs are
available from
www.spipm.cgiar.org
AB
C
A) White female of Heterodera filipjevi on wheat root system. – H. Saglam. B) “Knotting” of wheat roots. C) Stunted wheat
plant with knotted roots heavily infested with Heterodera avenae (right) compared with uninfested plant (left). – H. Li