I - --ii

56
Later Nene et al. (1978) published an annotated bibliography on diseases of
chickpea, including ascochyta blight.
Mycosphaerellarabiei Kovacevski, the perfect state of Ascochyta rabieihas
been reported from Bulgaria by Kovacevski (1936) and from Greece by Zachos
et al. (1963). It has not been reported from any other country, either in nature or
in culture. This is probably the reason that we have relatively less variability in
this pathogen.
Luthra et al. (1941) tested 392 lines and found three lines from USA, namely,
Pois chich Nos. 4732, 199 and 281, which showed a high degree of resistance to
A. rabieiunder varying environmental conditions. For easy reference these lines
were named F 8, F 9 and F 10, respectively. Infection was observed in traces on F
8 with faint, superficial lesions without pycnidia. Line f-0, Deing high yielder and
blight resistant, was distributed to the farmers for cultivation in blight-affected
areas. However, F 8 was susceptible to wilt. Therefore, Ahmad et al. (1949)
released a cultivar C 12-34 (progeny of a cross between F 8 X Pb 7)as resistant to
blight and tolerant to wilt. Cultivar C 12-34 los, "ts resistance to blight in 1950­
51. A new cultivar C 235 (cross between F 8 and a high-yielding local chickpea
cultivar) was developed and distributed to farmers (FAO 1963). This cultivar
also lost resistance to blight in the epiphytotic year of 1968, probably due to the
appearance of a new race of the pathogen (Grewal 1969). Keeping in view the
variation in A. rabieiand breakdown of resistance in cultivar C 235, investigations
were undertaken to determine the existence of physiologic races in the
pathogen.
Experiments on Physiological Races
Two hundred and sixty-eight isolations were made from diseased leaves, stems
and pods of chickpea collected from different lines and cultivars from many
localities of the northern states of India during the epiphytotic of 1968. The
isolates were purified and maintained on Potato-dextrose agar (potato 250g; agar
20 g; water 1000 ml) at 25°C, and were named according to the locality from
where they were collected. They were grown on Richards's agar in culture tubes.
On the basis of growth and sporulation, the isolates were grouped into 13 forms.
One representative isolate from each form was taken and its pathogenicity
confirmed on susceptible cultivar Pb 7. The above 13 forms were then grown on
sterilized Richards's agar in Petri dishes (25 ml per plate). They were inoculated
in the center with 5-mm disc of A. rabieiculture (15-day old) and incubated for 3
weeks at 25°C. The data on growth rate, colony color, pycnidial formation and
size of pycnidia are given in Table 1.
Isolates G-31, G-51, G-52, L-24, L-60 and R-21 were relatively fast growing
with fair amount of sporulation (Table 1). Colony color was light pink and the
size of pycnidia relatively smaller than in isolates J 101, G-5, D-30, L-l, L-I 1,