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Pierce ARC Research Report RL-12- ISeptember, 1979
Comparing flat fan and hollow cone spray-patterns Ait-controlling
diseases of Morgan melon planted at one month int vals
R. M. Sonoda and N. C. Hayslip
Abstract OCT 199
There were no significant differences in disease seveifyMkWitAiv. of Florida
between plots sprayed with nozzles forming a flat fan or hllow tone
pattern in each of three plantings of Morgan melon made at one month
intervals at the Agricultural Research Center, Fort Pierce. Plots
sprayed with flat fan SS8002 nozzles appeared to be the least affected
in each of the three plantings, however. The diseases noted were
downy mildew, powdery mildew, and gummy stem blight.
Sprays of fungicide with nozzles producing a flat-fan spray
pattern were more effective in controlling foliar diseases of several
crops in Ohio (5) and Florida (2, 3, 4). The flat-fan pattern was
more effective than hollow cone patterns in controlling foliar diseases
of Morgan melon where fungicide concentration, nozzle size and tractor
speed were varied (2). The following tests were conducted to determine
whether control of Morgan melon diseases would be influenced by time of
planting of the crop.
Materials and Methods
'Morgan' melon was plug-mix seeded (1) into plastic-mulch-covered
beds on February 22, March 22, and April 22, 1979 on Oldsmar fine sand
at the Agricultural Research Center, Fort Pierce (ARC-FP). The soil
was fertilized with 4-16-4 analysis fertilizer prior to bedding. Two
bands of 32 lb/00 ft (47.6 kg/100 m), 21 in (0.53 m) apart were applied
at the time the beds were covered with the 1.5 mil white on black
plastic. Fifteen plants, two feet (0.61 m) apart, were planted in a
single row down the middle of the bed. The plots were separated by a
15 ft (4.6 m) buffer downrow and by 12 ft (3.7 m) space between rows.
There were five replicates of each treatment in a randomized complete
block. The three plantings were all in the same block. The first
planting was made in the northwest corner of the block, the second in
the northeast, and the third in the southeast corner. The prevailing
winds during the experiment was from the southeast.
The melons were sprayed at one week intervals with a tractor-
drawn spray-rig, beginning 3-4 weekds after seeding. There were four
treatments; two nozzle types and two sizes per nozzle type. Nine flat
fan (SS8002 or SS8003) or seven hollow cone (Tee Jet D4-25 or D5-25)
were arranged on a spray boom as previously described (2). Tractor
speed was adjusted to apply 5.3 g active ingredient of mancozeb per
100 ft2 (9.3 m2) at 200 psi (1.4 x 105 Pa). The order in which the
nozzles were used each spray day was randomly determined. When heavy
rains fell before a scheduled spray was completed or immediately after
spraying was completed, all plots were re-sprayed when weather cleared
on that day or the following day.
Plants were rated for disease severity on May 23 for planting 1,
June 14 for planting 2, and July 7 for planting 3. The disease severity
ratings were 1 = no disease to 10 = plants completely difoliated.
Results and Discussion
All three plantings were affected by downy mildew, powdery mildew,
and gummy stem blight. Severe defoliation occurred when the melon
fruit were nearing maturity in all three plantings. Of the three diseases,
downy mildew appeared to be the primary defoliator. It was difficult to
separate the effect of one disease from that of another. Disease severity
ratings for all three plantings (Table 1) were based on condition of
plants rather than on the internsities of individual diseases.
Although plots treated with SS8002 flat fan nozzles appeared to be
less affected than plots treated with the other nozzles in each of the
three plantings (Table 1), no significant differences in the means of
the disease severity indices were observed in any of the plantings.
Although results have not been consistent during the past three
seasons (Table 1, and ref. 2, 3, and 4) Morgan melon plots sprayed with
flat fan nozzles have generally been less affected by the foliar disease
complex than plots sprayed with hollow cone nozzles. Further tests are
needed to determine whether flat fan nozzles do give better control than
hollow cone nozzles on foliar diseases of Morgan melon.
Table 1. Severity ratings for downy mildew, powdery mildew, and gummy
stem blight disease complex on 'Morgan' melons planted at
one month intervals at the Agricultural Research Center,
Fort Pierce, and sprayed with nozzles producing a hollow
cone or flat fan pattern.
Disease Severity Index 1/
Spray Nozzle Planting Planting Planting
Pattern Size 1 2 3
flat fan SS8002 4.4 3.4 3.6
flat fan ss80o3 5.2 4.6 3.3
hollow cone D4-25 5.3 4.0 4.4
hollow cone D5-25 5.5 4.4 4.5
NS NS NS
1/ Rating system: 1 = no disease to 10 = plants completely defoliated.
Disease severity ratings made on May 23, planting 1; June 14, planting
2; and July 7, planting 3.
Planting dates 1 = February 22, 1979, 2 = March 22, 1979, and 3 =
April 22, 1979. Each planting consisted of five replications of
each treatment in a randomized complete blocks.
1. Hayslip, N. C. 1979. Plug-mix seeding guide for small farms and home
gardens. Ft. Pierce ARC Res. Rept. RL-1979-7.
2. Sonoda, R. M. and N. C. Hayslip. 1978. Comparison of flat fan and
hollow cone spray patterns on 'Morgan' melon diseases. Ft.
Pierce ARC Res. Rept. RL-1978-7.
3. Sonoda, R. M. and N. C. Hayslip. 1977. Comparison of two spray
nozzle arrangements for control of 'Morgan' melon diseases,
1976. Fungicide and Nematocide Tests, Results of 1976. 32: 87.
4. Sonoda, R. M. and N. C. Hayslip. 1977. Flat fan vs. hollow cone
spray patterns against fungus diseases of three vegetable
crops. Ft. Pierce ARC Res. Rept. RL-1977-5.
5. Wilson, J. D., 0. K. Hedden, and J. P. Sleesman. 1963. Spray
droplet size as related to disease and insect control on row
crops. Ohio Ag. Exp. Sta. Res. Bul. 945. 50 pp.