BACTERIAL WILT OF CUCURBITS. 11 
larger and larger number of beetles have the opportunity to feed on 
diseased plants and so to become possible wilt carriers. Thus the 
maximum number of actual wilt carriers comes not simultaneously 
with the maximum beetle prevalence, but after that maximum; that 
is, at some time during the downward progress of the beetle-prevalence 
curve. 
STOMATAL INFECTION. 
Since the last publication on the subject by the writers 1 further 
attempts at stomatal infection have given uniformly negative results. 
Unless the epidermis is wounded and the wilt organism introduced, 
infection apparently never takes place. 
SOIL INOCULATIONS. 
As reported in a previous article, 2 the only cases in which we have 
been able to transmit wilt through the soil have been those where heavy 
tap-water suspensions of virulent bacteria had been poured directly 
around the roots of potted plants. In these cases sufficient water 
was used so that it would immediately percolate through the soil 
to the roots, and some of the plants were root pruned on one side. 
Only a small percentage, even of the root-pruned plants, became 
infected, and examination of the roots of nonroot-pruned plants 
which had wilted usually showed injuries from transplanting, from 
nematodes, or from other causes. 
During 1916 and 1917 several further series of soil inoculations 
on potted cucumber plants were carried out in a similar manner. 
The virulence of the heavy tap-water suspensions of the bacteria 
was established in each case by needle-puncture inoculations made 
just before pouring into the soil. Briefly, the results are as follows: 
March 31, 1916. All had been recently transplanted. (1) Not root pruned, 36 
pots, 2 plants to a pot; 22 per cent wilted. (2) Root pruned, 24 pots, 2 plants to a 
pot; 25 per cent wilted. 
April 19, 1916. All had been transplanted. (1) Not root pruned, 30 pots, 2 plants 
to a pot, 23 per cent "wilted. (2) Root pruned, 18 pots, 2 plants to a pot; 39 per cent 
wilted. 
April 19, 1916. All these plants were grown in the pots without transplanting. 
(1) Not root pruned, 36 pots, 2 plants to a pot, 2.8 per cent wilted. (2) Root pruned, 
24 pots, 2 plants to a pot, 29 per cent wilted. 
December 7, 1916. All these were old plants and not recently transplanted. 
(1) Not root pruned, 4 pots, 1 plant to a pot, no wilt. (2) Root pruned, 4 pots, 1 
plant to a pot, 50 per cent wilted. 
December 7, 1916. All these were young plants recently transplanted. (1) Not 
root pruned, 27 plants, 3.7 per cent wilted. (This plant showed the roots badly 
gnawed. Examination of the roots of 8 of the non wilted plants failed to show any 
root injury.) (2) Root pruned, 9 plants, 55 per cent wilted. (Examination of the 
roots of the 4 nonwilted plants failed to show root injury. In running a knife into 
the soil the main roots at least must have been missed.) 
1 Rand, F. V., and Enlows, Ella M. A., 1916. Op. cit., p. 425. 
2 Band, F. V. ; and Enlows, Ella M. A., 1916. Op. cit., p. 423. 
