| Material Information
||Watermelon herbicide trial, spring 1982
||Bradenton AREC research report
||4 leaves : ; 28 cm.
||Gilreath, J. P ( James Preston ), 1947-
Everett, P. H ( Paul Harrison ), 1927-
Agricultural Research & Education Center (Bradenton, Fla.)
||Agricultural Research & Education Center, IFAS, University of Florida
||Place of Publication:
||Watermelons -- Diseases and pests -- Control -- Florida ( lcsh )
Plants -- Effect of herbicides on -- Florida ( lcsh )
Herbicides -- Testing -- Florida ( lcsh )
||government publication (state, provincial, terriorial, dependent) ( marcgt )
non-fiction ( marcgt )
||Statement of Responsibility:
||J.P. Gilreath and P.H. Everett.
||Florida Historical Agriculture and Rural Life
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c AGRICULTURAL RESEARCH & EDUCATION CENTER
IFAS, University of Florida
Bradenton AREC Research Report BRA1982-7 April, 1982
WATERMELON HERBICIDE TRIAL
/ J. P. Gilreath and P. H. Everett 1
A replica d herbicide trial was conducted on 'Charleston Gray' watermelon at
the Immokalee ARC on Irmokalee fine sand (f.s.) in the spring of 1981 to evaluate
herbicides for efficacy and phytotoxicity.
Herbicides evaluated were Sonalan, Surflan, Alanap, Hoelon, Prowl, Devrinol,
Bolero, Poast, S-734 and MK616. Watermelons werecplanted April 8, 1981. Preplant
incorporated (ppi) and preemnergence (pre) herbicide treatments-were applied April 8,
while posterergence over the top (post) and postemergence directed (post d) applica-
tions were made May 7, 1981. Experimental methods and conditions at time of herbi-
cide application are listed in Table 1.
Results and Conclusions: No significant differences in crop vigor were observed
early in the season (Table 2). Excellent ear f 1 asf provided
by all herbicides which had been applied at e1 4'f rating with ,te exception
of-a combination of Surflan and Devrinol. La e seawpps4' t control comparable to
the hoed check was obtained with all treatment s except Bolero and a combination of
Surflan and Alanap. Good early season broadle fpcAroU 3a r 4 y all herbi-
cide treatments, excluding Sonalan, Surflan, Hoe on and Poast, while only Alanap,
Surflan + Alanap, Surflan + Devrinol and MK616 gave acceptable late season broadleaf
There were no significant differences in yield among the various treatments due
to extreme variation between replications resulting, presumably, from a late season
infestation of downy mildew.(Pseudomonas cubensis) which defoliated the vines in the
last several weeks of the cropping season (Table 3).
The best overall herbicides based on crop vigor and grass and broadleaf weed
control were (in descending order) MK616, oryzalin (Surflan) + napropamide (Devrinol)
and naptalam (Alanap). Poast applied post emergence over the top of the vines gave
excellent control of established grass weeds and was not phytotoxic to the crop.
1Assistant Professor (Ueed Science) at the AREC-Bradenton, 5007-G0th Street East,
Bradenton, FL 33508 and Professor (Soils Chemist)at the ARC-Irmokalee, Rt. 1
Box 2G, Immokalee, FL 33934.
Table 1. Experimental methods and conditions for watermelon herbicide trial.
IrrTiokalee, FL. 1981.
ROW WIDTH 6 feet
PLOT SIZE 33 feet in length PLANT SPACING/SEEDING RATE 3 ft/10 plants/plot
DATE PLANTED 8 April 1981 SOIL TYPE AND pH Irmokalee f.s., 6.4
EXPERIMENTAL DESIGN RCB REPS 4
Preplant incorporated Post emergence Post emergence
& preemergence over the top directed
Type & Date 8 April 1981 7 Hay 1981 7 May 1981
Time of Day 10:00 AH 10:00 AM 11:00 AM
EQUIPMENT CO2 backpack sprayer CO2 backpack CO2 backpack
Nozzle Tips 11004 11004 TK-4 flood jet
Volume (gal/Acre) 26.6 26.6 42.9
Pressure (psi) 29 29 20
Speed (mph) 3 3 3
Sky conditions Clear Cloudy Cloudy
Air temperature 86F 850F 850F
Soil temperature 750F 800F 80F
Relative humidity 50% 98% 98%
Wind 5 mph 2 nph 2 mph
Soil Moisture field capacity field capacity field capacity
application -0- 1" after appl. k" after appl.
COMMENTS: Rating dates:
early season 7 Nay 1981
late season 24 June 1981
24 June 1981
7 April 1981 2800 Ibs/A of 5-8-8 + 30 Ibs/A FTE503 +
2 tons/A dolomite
Table 2. Effect of herbicide treatment on crop vigor and weed control. Inokalee, FL. 1981.
leed control rating
Rate Method of Crop Vigory Grass Broadleaf
Treatment (lb. a.i./A) Applicationx Early" Late" Early Late Early Late
Ueedy check 8.50 7.00D 5.37CD 1.500 4.25F O.OOCD
Hoed check 8.62 9.50AB 9.87A 9.62A 9.75A 8.87A
Ethalfluralin (Sonalan) 1.0 pre 6.25 9.25ABC 8.95AB 7.50ABC 6.87CDE 4.75BC
Oryzalin (Surflan) 1.0 ppi 8.37 8.75ABC 9.37AB 9.25A 8.62ABCD 4.75BC
Naptalam (Alanap) 3.0 pre 8.25 8.00CD 7.62AB 5.62ABC 9.00ABC 7.50AB
Oryzalin (Surflan) 1.0 pre 9.25 8.75ABC 7.87AE 6.25ABC 5.75EF 1.75CD
Diclofop (Hoelon) 1.1 pre 6.87 9.50AS 9.62A 9.75A 6.12DEF 3.50CD
Pendimethalin (Prowl) 0.75 pre 8.37 9.25ABC 8.50AB 8.00AB 7.12ABCD 1.75CD
Hapropanide (Devrinol) 2.0 pre 8.50 9.00ABC 8.25AB 7.37ABC 7.12ABCD 2.00CD
Thiobencarb (Bolero) 4.0 ppi 9.37 8.00CD 9.00AB 3.75CD 9.12ABC 3.25CD
Oryzalin + Naptalam
(Surflan + Alanap) 1.0 + 3.0 ppi 8.62 8.25BCD 8.45AB 4.50BCD 9.62AB 7.50AD
Oryzalin + naproparide post
(Surflan + Devrinol) 1.0 + 2.0 (directed) 9.12 9.00ABC 7.25BC 7.87AB 9.25ABC 7.50AB
Sethoxydir. + Atplus oil post /
(Poast) 0.3 (over top) 8.37 8.75ABC 4.7SD 9.00A 7.00BCDE 3.25CD
S-734 1.0 ppi 6.75 8..75ABC 8.62AB 6.62ABC 8.62ABCD 3.00CD
HiK-616 2.0 pre 8.50 9.75A 9.82A 9.25A 9.62AB 8.87A
ZWeed control rating of 10 = complete control; 0 = no control.
YVigor rating of 10 = no injury; 0 = dead.
^Pre = preemergence surface applied; ppi = preplant incorporation; post*= post emergence.
Early season and late season observations.
Vieans within a column followed by the same letter are not significantly different at the 5% level, as
determined by Duncan's new multiple range test.
Prir.ary grass species were goosegrass (Eleusine indica) and crabgrass (Digitaria ciliaris).
Primary broadleaf species were hairy indigo (Indqo-fera sp.) and purslane (Portulaca oleracea).
Table 3. Effect of herbicide treatment
Iranokalee, FL. 1981.
on yield of 'Charleston Gray' watermelon.
Rate Hethod of Number of fruity
Treatment (lb. a.i./A) Applicationx culls (Tons/A)
Weedy check 9.50" 1.29
Hoed check 8.00 6.59
Ethalfluralin (Sonalan) 1.0 pre 12.50 2.18
Oryzalin (Surflan) 1.0 ppi ".- 14.00 2.54
Naptalam (Alanap) 3.0 pre 10.0Q- 4.41
Oryzalin (Surflan) 1.0 pre 12.50 1.74
Diclofop (Hoelon) 1.1 pre 9.75 3.92
Pendimethalin (Prowl) 0.75 pre 13.75 1.38
Napropamide (Devrinol) 2.0 pre 12.00 1.69
Thiobencarb (Bolero) 4.0 ppi 11.00 2.63
Oryzalin + Naptalam
(Surflan + Alanap) 1.0 + 3.0 ppi 10.50 1.42
Oryzalin + Napropamide post
(Surflan + Devrinol) 1.0 + 2.0 (directed) 13.50 3.12
Sethoxydin + Atplus oil post
(Poast) 0.3 (over top) 13.25 2.18
S-734 1.0 ppi 11.75 3.07
MK-616 2.0 pre 10.25 4.23
ZFruit under 25 Ib apiece.
YAdjusted to a uniform plant population.
Xpre = preemergence surface applied; ppi
= preplant incorporation; post = post
WMeans not followed by letters are not significantly different at the 5% level.