LONCHOCARPUS, DERRIS, AND PYRETHRUM CULTIVATION ao 
prepared on a well-drained, neutral, or sightly alkaline sandy loar 
soil which has been spaded, or plowed, to a depth of at least 6 inches. 
Well-rotted manure or some commercial fertilizer, such as 2 er 3 
pounds of a 4-8-4 mixture per 100 square feet of bed surface, may be 
incorporated in the soil if its fertility is low. 
Weeds are likely to be a nuisance in the seedling nurseries; it is 
desirable therefore to choose a site on newly cleared ground or on 
freshly plowed sod land where the weed problem may be minimized. 
Steam sterilization, such as is sometimes practiced in preparing 
tobacco seedbeds, is a useful method of killing weed seeds in nursery 
beds where equipment is available. Before planting, the soil should 
be worked until finely pulverized and the surface made smooth. It 
is recommended that the beds be boxed in with side boards 12 to 14 
inches high and that they be covered with cheap muslin to prevent 
wind drying of the soil during the germination period. 
Between 40 and 50 percent of an average lot of heavy, well-cleaned, 
properly stored seed may be expected to germinate if planted within 
3 years after harvest. The seeds are so small and light that nearly 
30,000 of them are required to weigh an ounce. Even though half of 
them may germinate, a grower should not calculate on obtaining more 
than 3,000 to 5,000 thrifty seedlings worth transplanting to the field 
for each ounce of seed sown. Between 3 and 5 ounces of seed should 
be broadeast over 150 square feet of nursery bed for each acre of field 
planting desired. Some growers prefer to soak their seed in water for 
several hours previous to sowing in order to hasten germination. After 
_ broadcasting, the seed should be lightly raked into the soii or else 
covered to a depth of about an eighth of an inch with mixture of soil 
and sand; then the ground should be gently tamped or rolled. 
The seed will germinate within 1 to 3 weeks, and during this period 
the soil should be kept damp and protected either by a muslin cover 
or a light mulch of straw or grass. If mulch is used, it should be re- 
moved as germination begins. Muslin need not be taken off until the 
plants are 0.5 to 1 inch in height. In temperate climates seed should 
be sown in the early spring or midsummer, and the plants ought to be 
' 3 to 5 inches tall within 6 to 10 weeks. At this stage they may be dug 
up and set in the field or left in the nurseries over winter. Spring-sown 
plants should be transplanted by early summer. Those sown in mid- 
summer are set out early the following spring. In the Tropics, where 
wet and dry seasons may be pr onounced, seedlings should be sown in 
time to allow the transplants 3 or 4 months of rainy weather to become 
well established in the field before a period of prolonged drought is to 
be expected. 
Field Planting 
Pyrethrum grows well on soils ranging from sandy loams to clays; 
good drainage conditions are more important than a specific texture. 
Pot-culture work by Martin and Tattersfield (27) indicates that the 
total yields of flowers and of pyrethrin extracts are determined more 
by the inherent gualties of individual plants than by soil fertility. 
Gnadinger, Evans, and Corl (7) made field-plot studies of the effect. of 
fertilizers or yieids of flowers and pyrethrins and also concluded that 
there were no significant differences either as between controls and 
treate? plots or between plete receiving various fertilizers, with the 
