Vol. 16—1962 - NorthEastern Weed Science Society

308
Results
.~' ;,,~, .
July 1961 was considerably@-l..-than thep:revj,ous July, particularly the
first 3 weeks after the post-emergent atrazine. ComParative accumulative rainfall
for these seasons is shown Jin,U,ure 1.
Nutgrass in four randOlllon'!'_~!J?9-t..square areafl.2!l.plot wlls~ounted on June
19 indicating a range of 1000 to 6000 plants per plot. All plots were cultivated
on June 20,27 and July .3 1;()·~:?>.9sen soil.and '.~ the later date to incorporate
the atraz1ne. After layby,:aconsiderable infestation of crabgrasses
occurred and lTI06tp10ts receivinga1;~azine at la)'bll._11J,.well as the checks .. had
heavy' stands of redrooted pigweed. The pigweed grew as rapidly and as tall as
the ceen,
The corn was harvested on August 15 at the' fUll pollen-shed stage in order
to prevent further development of weeds. As seen as weed estimates were made,
the area was plowed.
Because of the tangle of n.ut,grllS.Sand crabgUIlS.J it did not seem feUible
to try to count every nutgrass pl:ant' on each of the 72 plots. Weed estimates
were made by cutting nutgrass, crabgrass and pigweed;.at ground level frOlll:lIt1
area 3 feet wide (1.5 feet on either side a corn row) and 7 feet long. These
weeds were separated by genera and the grams of oven-dry weights per sample
area are presented in table 2. Analysis of varianee of the oven-dry weights
showed that the 602A corn produced significantly more yield than the dwarf corn.
The average yield for all treatments'was 3.01T/A of Penn. 602A and 2.72 rIA
of Penn. 602 dwarf. .1'he analysis ,~owed there was no significant interaeUon
between treatlnente and varieties u>!.r as dry matter' wasconcerned. Therefore
only the average dry weight f,or t;he;.,2 varieties is shown in table 2. It