For low-volume, low-pressure type sprayers, the nozzle delivery rates
and speed of spray-rig travel are furnished by the manufacturer and may
be followed. If these are not available, the machine may be calibrated by
making a test run of a measured distance of, say, mile, and determining
the quantity of spray liquid applied. For example, let us suppose that
the following conditions prevailed: length of the test run was 1,320 feet
and width of spray swath was 16 feet, making a sprayed area of 21,120
square feet or about acre; quantity of spray liquid used in the test
run was 15 gallons. From these figures it can readily be determined that
about 30 gallons of spray was applied per acre. When the rate of spray
delivered per acre is ascertained, mix the required amount of 2,4-D amine
concentrate with this quantity of water so as to apply at the rate of
1 pound acid equivalent per acre.

 High volume, high pressure gun-type spray nozzles are supplied with
interchangeable discs with different size holes ranging from 3/64 to
3/16 inches in diameter. Accordingly, they deliver from 1 to 14 gallons
per minute at 400 psi. pressure when the gun is set for wide open,
distant stream delivery. The discharge is from 10 to 20 percent less in
medium fog position. The capacities for the different size discs are
supplied by the manufacturer. The size orifice and pressure selected
should deliver the largest possible droplet size consistent with the re-
quired coverage and effective killing range of the spray stream. When the
amount of spray solution required to cover an acre has been determined by
trial, mix the killing solution so as to put on the spray at the rate of
1 pound acid equivalent per acre. If in doubt, it is usually satisfactory
to mix at the rate of 1 pound 2,4-D acid equivalent to 100 gallons of
water and apply the spray so as to cover the plants adequately.

 COSTS

 The cost of controlling hyacinths with 2,4-D is cheap compared to
most of the manual or mechanical methods. Cost of 2,4-D amine concen-
trate, containing 4 pounds acid equivalent per gallon, varies from 3 to
4 dollars a gallon depending upon the quantity purchased. Thus, at the
recommended application rate the cost of the 2,4-D itself will run from
about 75 cents to a dollar an acre.

 The cost of application may vary greatly depending upon the experi-
ence of the applicators, the type and capacity of the spray equipment,
and the density and accessibility of the hyacinth cover. Normally, with
power equipment, a two-man crew can be expected to treat from 10 to 40
acres per day.

 A 90 to 95 percent kill can ordinarily be expected with the initial
application. If it is desired to eradicate the plants it will be necess-
ary to prevent reinfestation from other sources and to destroy the remain-
ing plants by removing them by hand or re-treating the remaining plants
with 2,4-D before they can repropagate.