Title: Weed control trials on potatoes at Hastings, Florida, 1970
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 Material Information
Title: Weed control trials on potatoes at Hastings, Florida, 1970
Physical Description: Book
Creator: Shumaker, J. R.
Publisher: Potato Investigations Laboratory,
Copyright Date: 1970
 Record Information
Bibliographic ID: UF00076343
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: 144610465 - OCLC

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POTATO INVESTIGATIONS LABORATORY
Hastings, Florida

Mimeo Report POL 71-5 October 1970

WEED CONTROL TRIALS ON POTATOES AT HASTINGS, FLORIDA 1970
J. R. Shumaker, Asst. Horticulturist

METHODS AND MATERIALS:

Seventeen chemical treatments and two nontreated checks (noncultivated and
mechanically cultivated) were tested for effectiveness of weed control in
potatoes during the 1970 season at Hastings, Florida. Chemical and noncul-
tivated treatments were replicated 4 times in a randomized block field design.
The mechanically cultivated treatment was not incorporated into this design.
Instead, these operations were performed on 9 adjacent potato plots. This
insured that chemical treatments would not be disturbed during the tractor-
implement(s) cultivations performed periodically until lay-by. The soil type
used for these tests was Rutledge fine sand containing approximately 2 per
cent organic matter. A 6-8-8 fertilizer was banded on each side of the row
at the rate of 2500 pounds per acre at planting. Sebago seed pieces were
machine planted approximately 10 inches apart in the rows on February 18.
Plots were 4 rows wide and 20 feet long. There were 40 inches between rows.
Chemicals were broadcast via 4-row sprayer -- 40 gpa per acre, 2 flat-tip
nozzles per row, and 35 psi. Vernolate was applied preplant, disk incorporated
on February 16. EPTC was applied as a postplant preemergence, bedder-
incorporated treatment on March 5. The remaining compounds were surface
applied after final bedding on March 6. At this time, metaburon, alachlor,
and linuron were superimposed on previously treated EFTC plots to complete
herbicide combinations. Subsurface irrigation was used. Recommended
insect and disease control practices were followed. Data for each variable
were collected from the two inside rows of the 4-row plots. Tubers were
harvested, graded May 29, and their specific gravities were determined May 30.
Rains recorded over the duration of these trials follow: February 17 0.68",
February 26 0.19", March 9 1.12", March 13, 0.01", March 22 0.09",
March 29 2.60", March 30 0.20", April 6 1.48", April 12 0.53", and
May 18 0.19" for a total of 7.09".

RESULTS:

Chemical injury to the crop was not observed nor were the differences among
plant emergences and vigor ratings significant (Table 1). Broadleaf and
grass weed control ratings were taken separately on April 6. In order to
evaluate the treatments further, a composite rating of all weeds was taken
just prior to harvest. The predominate weeds were pigweed, Amaranthus
lividus, and crabgrass, Digitaria sanguinalis. Crabgrass interferred most

HUME UBRARY'




10-8-70 .F.A.S. Univ. of Florida
250 copies.. ....













with harvesting operations. While good weed control was maintained in
mechanically cultivated plots until lay-by, control was considered poor
at harvest. Best control was obtained from treatments consisting of
herbicide combinations. Commercially acceptable weed control (a rating
of 7 or better) was obtained by: (a) EPTC + metaburon at 2 + 2 AI/A
(lb.), (b) EPTC + alachlor at 2 + 2 AI/A (lb.), (c) EPTC + linuron at
2 + 1 AI/A (Ib.), (d) alachlor at 2 and 4 AI/A (lb.), (e) linuron at 2
AI/A (lb.), and (f) EPTC at 2 AI/A (lb.). Total and USIA potato yields
from these plots were greater than from those which were mechanically cul-
tivated (Table 2). All chemically treated plots produced greater yields
than the noncultivated ones. There was no significant response associated
with tuber specific gravities.

RECOMMENDATIONS:

At this date: (a) DNBP (Premerge, Sinox, P etc.), (b) EFTC (Eptam ,
and (c) metaburon (Patorar) are the only herbicides reported herein which
are approved for use on potatoes under local conditions. DNBP and EPTC
are recommended and have been used quite extensively by local growers.
Metaburon has not been thoroughly tested under local conditions and there-
fore can only be suggested for trial purposes. Growers are urged to proceed
with caution when applying herbicides. Always check the container label
for recent changes regarding crop, rate, time schedule, and soil type
approved for use.


POL 71-5 Page 2






Table 1. Crop emergence and ratings of 1970 potato weed control trials at Hastings, Florida.
Potato Weed Control Ratings37
Broadcast Plants Vigor Total
Rate Emerged Rating 2 Broadleaf Grass Weeds
Treatment Lb. AI/A!/ 4-2-70 4-2-70 4-6-70 4-6-70 5-28-70
EPTC 7E + Metaburon 50W 2.0+2.0 43 9.3 10.0 10.0 9.1
EPTC 7E + Alachlor 4E 2.0+2.0 42 8.3 10.0 10.0 8.6
EPTC 7E + Linuron 50W 2.0+1.0 44 9.Q 9.8 10.0 8.9
Alachlor 4E 4.0 42 8.8 9.8 8.8 8.9
Alachlor 4E 2.0 41 8.5 8.8 9.8 7.3
Linuron 50W 2.0 4 9.3 8.8 7.5 7.5
EPTC 7E 2.0 42 8.8 8.0 9.8 8.0
Metaburon 50W 3.0 42 9.0 7.5 6.8 5.1
VCS-438 75W 3.0 41 9.2 7.5 8.3 4.8
Metaburp 50W 2.0 44 9.3 7.3 5.8 5-3
Malorar 50W 1.0 43 8.3 7.0 6.3 3-5
Malorai 50W 2.0 42 7.8 7.0 6.5 4.1
vcs-438 75w 2.0 42 8.8 5.5 6.3 3.3
Vernolate 7E 3.0 45 9.3 5.3 7.5 5.5
Linuron 50W 1.0 43 8.0 5.3 7-3 3.3
Nitrofen 2E 4.0 42 8. 3.8 5.5 4.3
DNBP 3E 4.0 42 8.8 2.3 4.3 2.0
Noncultivated -- 41 8.3 1.0 1.0 1.0
LSD .05 NS NS 1.2 2.8 2.1

Mechanically cultivated, mean of 9 plots 43 8.1 "- 3.7
+ + + +

Standard error 1.6 0.3 0.5


1/ Rates of all applications are given as broadcast active ingredient pounds per a
the bedder incorporated method associated with EPTC treatments, this compound a:
application of 4 AI/A lb.
2/ Vigor ratings are on the basis of 1 = complete kill, 10 = normal crop vigor.
3/ Weed control ratings are on the basis of 1 = no control, 10 = complete control.


cre (AI/A lb.). BE
pproximates a band


cause of


PCL 71-5 Page 3









Table 2. Yield and specific gravity
at Hastings, Florida.


data from 1970 potato weed control trials


Broadcast t/A
Rate wt/A Specific
Treatment Lb. AI/A-/ USIA US1B Total- Gravity

EPTC 7E + Metaburon 50W 2.0+2.0 214.6 27.1 266.5 1.0673
Alachlor 4E 2.0 214.6 22.5 259.4 1.0659
EPTC 7E 2.0 211.9 22.1 262.7 1.0669
Vernolate 7E 3.0 208.8 28.4 262.2 1.0669
EFTC 7E + Alachlor 4E 2.0+2.0 204.6 22.9 255.0 1.0670
Alachlor 4E 4.0 200.3 23.8 252.9 1.0652
Linuron 50W 2.0 199.2 25.7 249.2 1.0659
Nitrofen 2E 4.0 198.7 21.0 241.3 1.0654
EPTC 7E + Linuron 50W 2.0+1.0 197.0 22.9 246.5 1.0632
Malora~ 50W 1.0 192.3 27.0 240.3 1.0647
MalorarO50W 2.0 186.5 21.3 234.9 1.0650
vcs-438 75W 3.0 184.7 20.6 228.2 1.0661
Metaburon 50W 3.0 183.9 20.7 232.1 1.0643
Metaburon 50W 2.0 181.4 27.3 235-9 1.0654
Vcs-438 75W 2.0 178.1 21.3 226.9 1.0635
Linuron 50W 1.0 176.0 23.9 223.0 1.0632
DNBP 3E 4.0 160.3 28.7 212.6 1.0660
Noncultivated -- 144.1 26.9 196.4 1.0684

LSD .05 36.5 5.4 31.4 NS


Mechanically cultivated, mean of 9 plots 181.6


Standard error


7.1


25.2
+


227.1
+


1.0617
+


.001


1/ Rates of all applications are given as broadcast active ingredient pounds
per acre (AI/A lb.). Because of the bedder incorporated method associated
with EPTC treatments, this compound approximated a band application of
4 AI/A lb.
2/ Includes pick-outs.


POL 71-5 Page 4


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