Bulletin 151, Truck and Garden Insects


cause of its tendency to burn tender foliage. One can diminish
this danger by adding to the solution hydrated lime or the milk
obtained from slaking quick lime. A good formula is:
 Paris green ................................. .. .... ......... 5 ounces
 Lim e ............................... ..................... ..... 2 pounds
 W ater .................... .......................... ............50 gallons
 Lead Arsenate.-The poison now commonly used on truck
crops is lead arsenate. It is not as likely to burn as paris
green. One pound of the powder or 2 of the paste to 50 gal-
lons of water, makes a liquid about as strong as it is ordinarily
necessary to use. On very tender plants, such as beans, it is
well to add 2 pounds of lime as in the paris green mixture.
The powdered form of lead arsenate is cheaper than the paste
and but little more troublesome to make up. By joining with
other truckers and ordering in 100 pound drums, lead arsenate
can be had for about twenty cents a pound and can be used
either as a dust or in water.
 Zinc Arsenite.-This is a new but promising insecticide.
It is less poisonous to stock or man than lead arsenate and
should be sold at about the same price, making it somewhat
cheaper as a less quantity is required. It is much lighter than
lead arsenate and works better as a dust. It has the disad-
vantage that it is not yet as generally on the market as the
other arsenicals and consequently is harder to get. Like lead
arsenate, it comes in both powder and paste forms.
 Calcium Arsenite.-A still newer arsenical is calcium ar-
senite. It is the cheapest of all the arsenicals and does not
scorch ordinary truck crops. It is lighter than zinc arsenite.
 LIQUID SPRAYS.-These are generally more efficient than the
dusts in their results as they cover the plant more thoroly and
require less of the poison to the acre, but are usually more ex-
pensive to apply on account of the labor involved, particularly
if water is not handy.
 Mixing.-In making up any of these substances in sprays,
 the proper amount should be mixed first in a few gallons of
 water until all lumps have disappeared and then be added to
 the bulk of the water. It is better to put some substance into
 the solution that will act as a spreader so that the spray will
 wet the surface of the plants more evenly, and also stick better.
 In spraying glossy plants like cabbage, this is imperative. For
 a list of these spreaders and directions for making them see
 under cabbage butterflies, page 141.