Temperature


In East Africa and China, altitude and season are two factors that determine temperature.  In Australia, the season is the main factor in temperature.  Generally speaking Pyrethrum is intolerant of severe frosts, and an entire year’s yield can be wiped out.  If the crop is very young or recently transplanted, a relatively light frost can be equally detrimental and may result in near complete loss of crop.  At the same time, for a healthy mature pyrethrum crop, a light frost during the somewhat dormant stage of the crop seldom does much damage to the pyrethrum plant and or effect on future flowering.  While it is clear frost temperatures [0°C ( 32°F) and below] should be avoided, it is further noted that pyrethrum content is affected by changes in temperatures.  Tests have shown as the average temperature falls with no frost, the pyrethrum content rises, as long as there is no frost.  At the same time flower initiation can also be increased as temperatures fall during the onset of rains.