Vol. 15—1961 - NorthEastern Weed Science Society

177.
HUBICIDES roll YOUNGAPPLE TUES
, 'rank N. Hewetson
. fbePemasylvanla State University
Fruit Research Laboratory
Arendtsville, Pal
" Tbe .• ue~e.8ful· e8tabUs~t of an apple orchard is closely associated
,with the growth of the trees dul:1Dg tbeirfirst few years 10 the orchard.
After the trees have been planted, one of the 1mportant factors in ,t1mulatiog
growth 18 the adequate control of ~s around these young tree". The
1
use of chemicals for' this pUrPOse off~rs considerable, promise ap.d several'
advantages over the tedious and upensive 'atbod of hand hoeing in arCil8s
where machine hoeing is impossible or difficult. "
Previous work at Arendtsville and elsewhere has suggested the value
ol usiog ,certain' chemicals for weed control around young apple trees. This
,year a opportu.nity was availeb!e to test these suagestions on a larger
scale thaD had preViously been possible.' In the sprins of 1960, OIle hundred
ad thirty two 2-year-014 Delicious" apple tree. were set out for, the express
purPOse of testing herbicides around yoUDi, trees. These treesyere 'planted
S feet apart on April 19 in bo1•• dug by • i4 inch auger. Alltreesliere
cut back to 3 feet.
'
At ,the ,time the treatants were applied on Ju.ne 2, some weeds bad
grown up'aroundthe trees. In order t;~ have • more complete evaluation of
the 1II8ter1a1s used in this ezperiant, trees were pa1red. The first tree
in each pair was band hoed just pre~ous to ,being sprayed, so was' .weed free,
and is thus designate' as "clean" (C) in the table of results., The second
tree in the pair was left untouched, so that weeds were pres~~ at the
tia of treatment, and is therefore designated as "weedy"(W) 10 this' table.
No further cultivation was done around these trees. The materials used in
this exper1ment were applied with a s1ll811band operated pressure sprayer,
modified so that exactly one pint of spray could be applied per tree over
a area of 10 square feet. This amount per tree would be equivalent to SSO
gallons per acre, or about ten times the usual spray coverage foJ: field
applications. This relatively large amount of spray provided much better
coverage of the plot area than would have been possible with S1II811.r amounts
of spray. Treatment. were replicated four ttas. Hotes and pictures were
taken durins the season, and on Hoveuber 11 the trutants were evaluated
for weed control by estimating the percent weed control around each tree.
The results of this evaluation, together with the materials and rates used,
are shown in Table 1. Later in the month, tree height and tendnal growth
measureants were taken. These data are also shown in Table I ..
Under the conditions of this experiment, the use of Dalapan by itself
or in c01Dbination with Amitrol T gave Uttle if any weed control. Amitrol
1: by itself also gave negligible weed control. The predominant weeds around
these trees, howeveJ:, were bro.dleaf, which 'tlIOuldaccount for the poor
showing of Dalapon, a gra8s or narrow leaf herbicide. In contrast, SiJDszine
at the 2 and 3 lb. rate gave fair weed cont:.rol on the "clean" plotsI' but
. little on the "weedT'plot8. However, when Simuine and Amit:rol 1: were used