NORTHEASTERN FOREST EXPERIMENT STATION 

Upper Darby , Pennsylvania 

No. 30 

April 1954 

I 

Hm To Control The White Pine Weevil 

With A Nand Sprayer 

The white pine weevil is the most serious insect 

0 enemy of white pine in the Northeast, where more than 75 

percent of these valuable trees are weeviled. Weevil larvae 

feed just beneath the bark; this kills the leader, causing 

folks, crooks, and a subsequent degrade of timber. In fact, 

wideSpread damage by the weevil has reduced the demand for 

white pine planting stock considerably. 

During recent years an outstanding technique has been 

developed for protecting young trees. Concentrated lead 

arsenate is applied to the leader by means of a hand-operated knapsack sprayer. The method is particularly valuable 

for areas up to 10 acres. 

Blocks of 5,000 to 8,000 trees have been sprayed this 

way in Nerr Jersey, Connecticut, Massachusetts,Necr Hampshire, 

and Vermont; and i n a l l cases lass than 5 percent of the 

trees were weeviled the year the spray was applied. Costs 

have averaged $6 per 1,000 trees with labor at $1 per hour. 

Aircraft spraying, using DDT, appears promising for large 

areas, but is, of course, impractical for small ones. 

When To Spray 

Spraying with lead arsenate can be done aw time in 

late winter or spring before the adult weevils emerge from 

the duff and commence feeding. In Connecticut, spraying 

must be completed by the end of April. 

What Materials To Use 

Lead arsenate.-This is *the favored insecticide for 

several reasons: (1) It has consistently given perfect and 

near-perfect control; (2) it remains tdc to the weevil for 

at least several months; and (3) the white deposit is visible at a glance so there are fewer misses. To avoid clogging of the nozzle and too-rapid settling of the suspended 

material, use only the finest grades of lead arsenate. 

Chipman Standard and DuPont Nurex-form lead arsenate have 

given consistently excellent results Pre-season testing 

may be needed to find suitable brands of lead arsenate. 
hention of c-ercial products is not to be construed as endorsement of them by the Forest Service or 

Department of Agriculture. 

Spreader.or wetting agent.--A number of materials are 

satisfactory for this purpose. The preferred spreader is 

SantomerseS, produced by the Monsanto Chdcal Company. 

Any of the new detergents such as Tide, Dreft, etc., are acceptable and may be used dry or as a stock solution (made by 

dissolving 10 ounces in 1 quart of hot water) .I 

Oil.--The use of a drying oil makes the spray stick 

to the tree despite adverse weather. Either raw linseed or 

fish oil can be used; but linseed oil is preferred because 

it smells better. 

Formula And Mixing Procedure 

The formula for concentrated lead arsenate spray is 

as 40110~s: lead arsenate 1 part; water 10 parts; oil 0.3 

parts; spreader 0.02 to 0.03 parts. To prepare 5 gallons of 

spray mixture: 

1. Pour 1$ to 2 gallons water into mixing barrel. 

2. Add 2 ounces dry weight (or 6 fluid ounces) of spreader 

such as Dreft, Tide, or other wetting agent. Mix. 

3. Add 4 pounds lead arsenate. Mix. 

4. Add 20 fluid ounces linseed oil. Mix. 

5. Add water to make 5 gallons spray mixture. 

Equipment Needed 

Sprayer.--Concentrated sprays can be applied with a 

variety of equipment from a small hand atomizer to the knapsack sprayer. The knapsack sprayer made by D. B. Smith COP 

pany of Utica, N. Y., has been used almost exclusively in 

our tests and has proved highly satisfactorg. The backcarried sprayer is practically a necessity for plantation 

work, 

Strainer.--Concentrated sprays should be strained 

into the spray tank through 40-to-50-me~h metal cloth or six 

layers of cheesecloth to avoid clogging the spray nozzle. 

Spray rods .--A 4-f oot rod with 34 feet of hose attached is recommended for sprafing all trees up to 10 feet. 

Rods can be made up from 2-foot sections available from 

spray-equipment manufacturei%; or inexpensive *-inch aluminum tubing and standard &inch fittings can be used to make 
spray rods of any desired length. Bamboo should be bound to 

the tubing for support. 

Noqz1e.--Concentrated sprays demand a new type nozzle 

with an opening only one-third that of the older style noza zles. Under field conditions the delivery rate should be 

1 to 2 gallons per hour. The "IS" nozzle made by the Spray 

hgneering Company of 115 Central Street, Somerville, Mass., 

was used throughout our tests; the results recommend it 

strongly, The strainer should be removed from this nozzle 

when lead arsenate is used. 

How To Spray 

Thoroughness in treating each leader is essential. 

The sprayer should be swung sideways several times before 

pumping to insure adequate agitation of the lead arsenate. 

The nozzle should be held 2 to 4 inches from the tree, and 

the terminal bud cluster should be saturated from above, The 

upper two-thirds of the leader must be covered with spray; 

tho passes from opposite sides of the leader should suffice. 

If the tree has been weeviled, each of the new leaders must 

be sprayed. 

HOW Often To Spray 

Only two treatments should be needed to protect the 

stand until straight 16-foot butt logs are assured. Annual 

surveys must be made to determine weevil conditions. The 

first treatment should be made when 2 to 5 percent of the 

trees are weeviled in one year. In infested areas, the stand 

will probably be 2 to 3 feet high at this time. 

a After the initial knockdown it will take an average 

of 4 years before weeviling builds up to 10 percent in one 

season, the next critical time. The second spray should be 

applied when weeviUng reaches 10 percent. By the end of the 

second &-year period the stand should be 16 feet or more in 

height. ERtire blocks should be treated at one time to prevent rapid reinfestation from adjacent infested stands. 

Salvage Spraying 

Stands already heavily weeviled may be reclaimed or 

salvaged by removing all the heavily damaged trees, cutting 

back the lightly injured trees to one leader, and then following with a regular spray program. Dense stands will be 

improved by the thinning, and the spraying of the thinned 

stand is a much simpler operation. 

--DAVID CRrnBY 

3 

Agriculture-Forest Service-Upper Darby, Pa.