YAM CULTURE IN PORTO RICO. 7 
A small-rooted type of the Potato variety and a large-rooted kind 
of the St. Vincent were used in this test. The yams were harvested 
15 davs before treatment, and after treatment were stored in a 
room having a high humidity and temperature of probably 80° F. 
Such conditions favor the rapid decay of the roots. 
Two weeks after the treatment was applied the roots were exam- 
ined. It was found that where the lime had been applied 40 per 
cent of the pieces were decayed, although none of them was entirely 
destroyed. Where Bordeaux mixture was applied to freshly cut 
surfaces only 16 per cent of the pieces showed decay, and all could 
be planted. The application of Bordeaux mixture to the lot that had 
been previously dried resulted in little improvement over the check. 
In the untreated lot more than three-fourths of the pieces were con- 
siderably impaired and a few were entirely consumed by disease, 
while only 12 per cent were in normal condition. In all cases a per- 
centage of the decay on the cut surfaces developed from bruises on 
other parts of the roots, and in some instances from infections re- 
ceived after the roots were cut. The Potato variety was slightly less 
injured than the St. Vincent. 
DISTANCE APART TO PLANT. 
The distance oetween the seed yams in planting depends much 
upon the normal growth of the variety. One foot apart in the ridges 
is sufficient for varieties producing small roots, but the larger- 
rooted kinds require a distance of 1 to 2 feet. In Porto Rico it is the 
practice to plant much farther apart than this, sometimes twice the 
distance. This is hardly wise, because a given area will produce 
much more when close planting is practiced. The cost will be lower, 
too, since the only cultivation required after planting is occasional 
weeding and maintaining well-formed ridges. The expense involved 
in cultivation consists mainly in plowing the land, securing suitable 
vegetable matter or manure for the ridges, building the ridges, and 
placing poles for the support of the vines. Any decrease in area 
prepared for planting results in a proportional decrease in expense, 
equally good preparation being necessary for planting at any distance. 
Where hill planting is practiced the hills should be from 3 to 4 feet 
apart each way, depending upon the type of soil. The wider dis- 
tance is necessary in heavy soils because the hills must be made 
higher than in more open soil to insure good aeration and drainage. 
The closest planting will be found convenient in light soils. The seed 
should be covered with 2 or 3 inches of earth to prevent it from 
drying in case drought follows, or from being washed out by heavy 
rains. 
