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Kausar (1960) discussed the reasons for the blight epidemic of 1956-57 and
pointed out that the varieties which had remained resistant showed high susceptibility.
C 612, a local cultivar, almost failed along with other selected and promising
hybrids. Infection of blight started on early-sown crop in late November in
Attock, Rawalpindi, Jhelum and most of the Thal area. However, dry weather
during January-February-March arrested further spread of the disease. Early
infection of the disease and the subsequent check in its development by dry
weather resulted in the regrowth of most of the blighted plants, which is a
characteristic feature of blight epiphytotics (Kausar 1958 a).
Blight broke out again in 1957-58 in epidemic form in Peshawar, Dera Ismail
Khan, Rawalpindi, and in Thai. High rains during November and December
1957 provided suitable conditions for initial infection and later development of
the disease (Kausar 1958 b).
The epidemic of 1958-59 was followed by a relatively wet summer which
provided sufficient moisture, good germinatio, and early growth of chickpea.
Blight infection was initiated in the wake of heavy rains by mid-December and
blight developed severely during January and February, which were months of
high rainfall. Rains at the end of March and early April helped the development
of infection on pods of surviving and dying plants and this resulted in high seed
infection (Kausar 1960). Sattar and Hafiz (1952) reported that the critical
period of rainfall from February to April had a lot of influence on the development
of the disease. This period relates to the flowering and fruiting stages in
chickpea. Disease was reported to appear in epidemic form in those years only
when the rianfall during that period was about 150 mm or more.
Recently, I surveyed the chickpea growing area of the Punjab to assess the loss
suffered by the crop due to blight. The intensity of attack was not as severe as
during 1979-80. The primary infection of the crop had taken place in almost all
locations, even in no-blight areas of Faisalabad, as a result of almost continuous
cloudy weather, light drizzle and low temperatures in March. Almost dry weather
after March 22 coupled with higher temperature did not let the infection
increase in intensity. The result was that whereas highly susceptible cultivars
were killed, C 727 - a susceptible type - escaped and did not show more than a
few loci of primary infection.
The data on daily maximum temperature and rainfall for January, February,
March and April for 1979, 1980 and 1981 are provided in Tables 1-4. It is
apparent that severe blight epidemics of 1979 and 1980 were due to well spread
and well spaced rainfall during the crucial months of Feburary and March.
Intervening dry spells and high day temperatures reduce overall humidity to an
extent that spores do not germinate. In this connection a continuous wet spell for
2-3 days with cloudy, overcast and light drizzle is much more conducive for the
spread of the disease than a heavy shower on a single day followed by a dry spell.