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Proceedings ofthe Workshop on Ascochyta Blight and Winter Sowing ofChickpeas (Saxena, M.C
and Singh. K.B.. eds.), ICARDA. 4-7 May 1981, Aleppo. Syria
Epidemiological Aspects of Chickpea Ascochyta
Blight
H.C. WELTZIEN and H.J. KAACK
Deputy Director General (Research) and Visiting Research Associate,
ICARDA, Aleppo, Syria, respectively
A devastating plant disease such as the one caused by Ascochyta rabiei on
chickpeas has to be thoroughly understood if control is to be achieved with a
reasonable degree of certainty. Within the framework of the ICARDA/ICRI-
SAT effort to study and control ascochyta blight, we have tried to understand
some of the epidemiological aspects of this disease.
Taking into account the massive epiphytotics as the ones reported from Pakistan
in the last two seasons or those noted on susceptible winter-planted chickpeas
in Syria, the question arises as to how such massive outbreaks are biologia!ly
achieved and how they can be manipulated by changing the genetic resistance
and the planting date. In this paper we discuss some findings on four different
aspects of the disease cycle:
(1) the epiphytotic spread of the disease on growing plants,
(2) the climatic conditions for infection,
(3) the role of contaminated plant debris for disease initiation, and
(4) the role of infected seeds for disease initiation.
Methods and Material
A disease assessment key was developed, based on nine grades between I and
100% leaf and stem area infected. Conditions for infection were studied in
growth chambers and the saturated atmosphere required was maintained under
plastic bags. Plants were dried with afan after the required times and placed in a
plastic greenhouse for 14 days to allow disease development. All field trials
mentioned here were conducted at the Tel Hadya Research Station near Aleppo,
Syria. All seeds were supplied by th, Food Legume Improvement Program of
ICARDA.
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