Greengram and blackgram are grown either as pure stands
or mixed with cotton, maize, upland rice, sorghum, pearlmillet, fingermillet,
etc. throughout India.
They are also grown as summer crops throughout the country
under irrigated conditions.
In southern and eastern states, they are grown in rabi
succeeding rice with the available residual soil moisture.
The varieties under cultivation are late-maturing and
Greengram and blackgram are mainly grown during kharif.
But these crops happen to be highly vulnerable to yellow-mosaic
virus which is prevalent during this season.
It has been estimated that about 30 to 70 % of losses
in production occur due to this disease.
As a result these crops have the lowest mean productivity
of around 3.8q/ha on the national basis.
The situation with reference to mothbean and cowpea is
in no way different.
Whereas yellow-mosaic virus is more serious in the north-
central plains and coastal regions, Cercospora leaf-spot and powdery-
mildew diseases occur both in rainy and winter seasons almost all over
the country but are more serious in the central and peninsular zones.
The improved varieties also to these diseases.
In blackgram , greengram , mothbean and cowpea, the stem-fly
causes serious problem at the seeding stage , while pod-borers cause
considerable damage at the reproductive stage.
Although insecticides have been suggested, they have
only limited use at the farmersí level.
Unfortunately, varieties resistant to insect pests have
yet to be evolved.
Greengram and blackgram suffer from waterlogging.
In areas, where these crops are grown during the rainy
season, even temporary waterlogging in the field adversely affects the
If water is not drained out of the fields promptly,
it causes severe plant mortality. Varieties of greengram and blackgram
traditionally grown by farmers and which have been developed recently
show excessive vegetative growth and do not attain maturity at the same
time, thus calling for a number of pickings.
This amounts to heavy labour cost at harvesting.
The problems and their solutions regarding greengram
and blackgram are common to mothbean also.
The genetic modifications of the plant type would go
a long way in augmenting the productivity of all these crops.
The determinate growth habit, if induced in these crops
varieties, would results in synchronous fruiting and possibly short-duration
The determinate habit will specially be useful for summer