Vol. 16—1962 - NorthEastern Weed Science Society

170
Yie.s of U.S. #1 Delus potatoes ranged from3~a, bushels to 491 bushels
per acre; and those of Kennebec',fran 508 to 646bu~helS per acre. The variability
of the individual yields was such that no statistically significant
differences between treatments ~' ,found. Th, sPCIP'11:1c gravity of the Kennebec
potatoes averaged 1.078 and,the,Delus 1.083~:'
Procedure
Post-hilling and layby herbicide applications, 1961
These tests were randomized in blocks which alternated with the pre-emergent
blocks. They were planted ,at the same time ancf:Ileaeived the same fertilization
and managementexcept that they were CUltivated on May31, June 6, 16,
and 20, with preliminary hilling on June 26 and final hilling on June 30.
Ladysthumband ragweed were eliminated from the tops of the hills by the cultivating
process. The field was overseeded with millets but the heavy fOliage
cover and dry weather minimized the stand.
The post-hilling herbicide sprays were applied June 26 with a calibrated
sprayer at 'the rate of 40 gallons to the acre. The granular materials were
weighed out individually and mixed with sand befo" spreading by hand. A few
plots received vine-down applications on August 15. The vines were green and
leafy but had opened up enough so herbicides COuldreach the soil. Trietazine
spray prod~ced a little yellowing on the older leaves but this effect disappeared
within two week$.
Results
The materials used, stands of weeds and yields of U.S. #1 Kennebecand
Delus potatoes are shown in table 3. The yieldS of Kennebecs ranged from 500
bushels per acre where the double application of t1'ietazine was used to 631 on
the falone plots. The controls averaged 590 bushels. The maximumand minimum
yields of Oelu6 potatoes were 481 and 341 bushels per acre for these same two
treatments, respectively. The check plots of Delus produced 438 bushels per
acre. Unfortunately, the variation within blocks was such that significance
could not be established at the 5%level. It is suspected, however, that the
lowest average yields obtained from the combined application of trietazine at
layby and vine-down is in part due to the heavy application of this herbicide.
Whentubers of the, Kennebecvariety were dug in ~9ust for trietazine analysi~,
smaller potatoes than in the check plots were found. ~ext season it is
planned to' harvest potatoes at several periods to see whether the post-hilling
spray retards tuber development.
The weed stand was rather light. Proper CUltivation in June produced a
nearly weedfree area. Ladysthumb(Polygonvmgersicaria) and some of the
annual millets were present. '"
The data in table 3 show that granular falone, alanap, zytron, eptam,
dalapon, and amiben were effective in reducing the stand of annual grasses.
Falone spray and trietazine spray were also effective.
Repeating'the application of falone or trietazine at vine-down was no more
effective than the post-h~lling treatment alone. The repeat application of