HOWARD AND HOWARD 13 
plants grew next to next with interlocking root systems and in no single 
instance did wilt spread to the late sown plants. Since 1912, many similar 
examples have been noted which prove conclusively that wilt is neither a 
disease in the ordinary sense, nor is it caused by any deficiency in the soil 
Solution. 
Not only may wilted and healthy plants exist side by side, but it is easy to 
produce a wilted branch as well as vigorous growth on the same plant at the 
same time. This phenomenon occurs if a branch is left at the first cut in June 
to maintain the transpiration current. The result of this is that the damage 
to the fine roots and nodules (as shown by root washings) is less than if the 
plant is completely cut back while the new shoots are formed much more 
quickly. It often happens in such cases that after the new growth is well 
established near the ground, the old branch left begins to show signs of wilt 
which, however, does not spread to the new shoots. This is probably due 
to the utilization of the crude sap by the new growth near the ground level 
and the consequent slow starvation of the upper branch. 
Both during the early and the late rains, deep cultivation has the effect of 
producing wilt. Two well-marked cases of this have occurred at Pusa recently. 
In 1918, Java indigo, sown in double lines to admit of interculture during 
the monsoon, steadily lost in vigour compared with the broadcast crop side 
by side and also developed more wilt. In the present season, 1919, the experi- 
ment was repeated with four types of indigo and on different classes of land. 
In most cases, the indigo grown in double lines with interculture yielded less 
green plant and also developed more wilt than the neighbouring broadcast 
plots. The effect of the cultivation was found to destroy the lateral roots near 
the surface and to stimulate root formation in the deeper soil layers. The 
lower roots were destroyed by poor soil aeration and the plants therefore 
developed wilt. 
Wilt is easily produced after the rains during October and November 
by the cultivation of old indigo which has hitherto managed to survive at 
this period, the only active roots are close to the surface and the indigo plants 
are dependent on these. Cultivation or the natural drying of the surface 
soil destroys the surface roots and wilt occurs. It can be prevented by 
mulching such plants with straw or dried grass after the sowing rains in 
October. The mulch preserves the moisture and so assists the surface roots 
to maintain the indigo till growth ceases during the cold whether. 
In 1919, a comparison was made between mulched and non-mulched 
plants. The former held their leaves and resisted wilt while the latter were 
affected by the trouble. 
