April, ’24j 
WATSON: NEMATODE CONTROL 
227 
abandon the fields after the last truck crop was harvested to grass and 
weeds. Among these would be enough hosts of the nematodes to carry 
the infestation thru the summer. Furthermore, the heavy rains of 
the summer compact the soil to the exclusion of the optimum amount 
of air, as shown by the general acid reaction of such ground. These 
conditions tend to keep the nematodes in the encysted state so that 
they are carried over until trucking operations are begun again in the fall. 
One of our earliest attempts to control nematodes in infested land 
was by means of the summer fallow, the idea being to keep the soil 
constantly stirred and aerated so that the eggs would be forced to hatch, 
and at the same time to keep the land barren of all vegetation, in order 
to starve out the nematodes. The land was accordingly plowed and 
harrowed at itervals of ten days and after every heavy rain that packed 
the soil. A crust was never allowed to remain on the land. This kept 
the soil well aerated, and this in connection with the abundant moisture 
and high temperature of the summer season forced the eggs to hatch. 
As far as-nematode control is concerned this procedure has worked out 
very well, but as was to be expected the effect on soil fertility is very 
deleterious. The hot sun on the bare ground and the heavy rains cause 
the loss of a large part of the plant food and are very injurious to soil 
organisms. However, the method is still occasionally used by a number 
of truckers who regard their farms only as a site for growing crops, 
expecting to buy their soil from the fertilizer salesman. 
In an endeavor to avoid the injurious effects of the summer fallow 
we modified it by growing on the land some practically immune plant 
but maintained the constant cultivation and freedom from weeds, the 
idea being to shade the ground and thus prevent the injurious effects 
on the soil fertility; at the same time preserving the beneficial effects 
of constant cultivation. For a cover crop we turned to velvet beans for 
two reasons. In the first place they are practically immune to root- 
knot, being much more resistant than Brabham, or any other variety 
of cowpeas, and in the second place they make a rank growth during 
the summer time and completely shade the ground. It is to be observed 
that this method differs from the old method of crop rotation in that the 
land is kept under constant cultivation and a crust is never allowed 
to remain on the soil; also in the more careful elimination of weeds 
and grass. To secure this result, one or two hoeings when the velvet 
beans are young are necessary, and very frequently a hand weeding in 
the row as well. The results have been very satisfactory. Generally 
we have secured as thoro a control of nematodes in one summer from 
