If and when spraying is necessary depends very much on the individual case and this can only be decided by the farmers or the appointed adviser. In general, it may be said that in areas of vegetable cultivation, where pests are a great problem, weekly spraying is necessary. If, on the other hand, infestation is only slight, treatments in intervals of 10 to 14 days are adequate. Often a single treatment of the plants is sufficient. Just as with chemical insecticides, the insect species and crop are important factors in deciding how often spraying should occur. According to scientific research the extract is not poisonous for humans, thus, it is not necessary to wait long between final spraying and harvesting.