-7- 
Paris green dusts 
Result ° indicate that paris green is more effective as a dust than as a 
spray when us d at a dilution of 1 pound to 9 pounds of hydrated lime, applied 
at a rate of 20 pounds per acre, per application, until the plant begins to 
head, provid J the headed cabbage is stripped to four loose outer or wrapper 
leaves when being prepared for market. If the marketed product is to bear a 
greater number of loose outer leaves than those allowed in the above grade, 
paris green should not be used after the plants have been thinned or trans- 
planted. 
Cryolite (sodium fluoaluminate) dusts 
Both synthetic and natural cryolite prepared for insecticidal purposes 
have given favorable results when mixed with from 1 to 2 parts of the diluents 
mentioned for derris dusts. The same care should be exercised to avoid harmful 
residues from cryolite, as has been prescribed for arsenicals. 
Calcium arsenate dusts 
Results with commercial calcium arsenate, for cabbage worm control, have 
shown a varia ion in the toxicity of various brands of this arsenical. Calcium 
arsenate, in the undiluted form, gave fairly satisfactory results when applied 
at the rate of 15 to 20 pounds per acre per application. On account of the 
harmful residue hazard, this materia] is subject to the same limitations 
mentioned for paris green and cryolite. 
CABBAGE WORMS ON CAULIFLOWER, BROCCOLI, KALE, AND COLLARDS 
The Bureau has not yet had an opportunity to conduct any extensive ex- 
periments on the control of cabbage worms on cauliflower, broccoli, kale, or 
collards. In general, it is believed thai the derris and pyrethrum compounds 
should give the same results on these crops as when used on cabbage, provided 
a good coverage of the affected parts of the plant can be obtained. 
Preliminary experiments in California have shown that derris, or cube, 
or pyrethrum dust mixtures, at the same dilutions as have been mentioned for 
cabbage, gave as satisfactory results in the control of the three more common 
species of cabbage worms on cauliflower as they did on cabbage. It was found 
to be e^rec i" lly importan t , however , to start the treatments early in the 
developmen t of the cauliflower , while the plant s we re small , since it was not 
possible to rbtain a good coverage of the insec t icides over the heav y foliag e 
of nearly mature cauliflower plants . Good results were also obtained against 
cabbage worms on cauliflower with sprays of derris root powder containing from 
0.02 to 0.025 percent of rotenone (viz, 2 to 2£ pounds of derris root powder 
containing 4 percent of rotenone per 50 gallons of water) . 
The experiments of 1934 on collards indicate that each of the three more 
common species of cabbage worms may be controlled satisfactorily with a derris 
dust mixture containing 0.5 percent of rotenone. Less satisfactory results were 
obtained with pyrethrum powder containing 0.9 percent total pyrethrins, diluted 
