This section is from the book "Commercial Gardening Vol1", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
This powder is obtained by grinding the dried flowerheads of Chrysanthemum coccineum and G. cineraricefolium. The powder obtained from unopened flowerheads is considered better, although more expensive. The powder is used in various ways: (i) Simply by dusting over plants affected with aphides, &c; (ii) as a spray, 2 1/2 lb. powder to 10 gal. hot water; (iii) as a fumigant, by sprinkling the powder over hot cinders in a greenhouse; and (iv) mixed with flour in the proportion of 1 part to 10 to 30, and dusted over the foliage.