Summer squash and broccoli nematicide trials

Material Information

Summer squash and broccoli nematicide trials
Series Title:
Research Report - University of Florida Institute of Food and Agricultural Sciences , Central Florida Research and Education Center ; 88-04
Rhoades, H. L.
Place of Publication:
Sanford, FL
University of Florida, Institute of Food and Agricultural Sciences, Central Florida Research and Education Center
Publication Date:


Subjects / Keywords:
Broccoli ( jstor )
Squashes ( jstor )
Roundworms ( jstor )

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Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
122260858 ( OCLC )


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L- Central Science
3-I Library
University of Florida
Institute of Food and Agricultural Sciences DEC 04 1987
2700 East Celery Avenue University of Florida
Sanford, FL 32771-9608

Research Report SAN -04 November 1987


H. L. Rhoades

Squash (Cuourbita jpeo L.) is an important commercial vegetable
crop in Florida. Approximately 6,400 ha were harvested in the 1985-86
growing season, having a total value of $40.2 million. Broccoli
(Brassica oleracea L.) is much less important commercially, but is
becoming more popular and is grown more extensively each year. Both of
these crops are produced primarily on fine sandy soils where plant
nematodes frequently cause serious reductions in vegetable yields. The
sting nematode, Belonolaimus lonicaudatus Rau, and root-knot nematodes,
Meloidogyne spp., are particularly injurious to vegetable crops in
Florida. When concomitant populations of B. longicaudatus, I. incognita
(Kofoid & White) Chitwood, and the lance nematode, Hololaimus galeatus
(Cobb) Thorne, were found in experimental fields of Myakka fine sand at
the Central Florida Research and Education Center, Sanford, nematicide
efficacy trials were planned and conducted during the late winter and
spring of 1987.

Two experiments were conducted on broccoli and one on summer
squash. The experimental design was a randomized complete block with
five replicates for all treatments. Each broccoli plot consisted of two
rows 76 cm apart and 12.2 m long and each squash plot one row (152 cm
spacing) 12.2 m long.

Soil fumigants used In the experiments were 1,3-dichloropropene
(1,3-D) applied at 56 L/ha on broccoli and 28 L/ha-on-squash, and
metam-sodium applied at 140 and 280 L/ha on broccoli and 93.5 and 187
L/ha on squash. The soil fumigants were applied as in-row treatments
with a hand injector set to deliver the fumigant 20 cm deep 2 wks before
transplanting broccoli or seeding squash. 1,3-D was applied in a single
line of injections spaced 25 cm apart and metam sodium was applied in a
double line of injections spaced 15 cm apart per plot row.

Nonfumigant granular formulations of carbofuran, ethoprop, and
fenamiphos were applied in a 38-cm-wide band in-row and incorporated 6-8
cm deep with spiked rotary cultivator wheels one day before planting.
Application rates were 2.24 and 3.36 kg ai/ha over the experimental area
for each nematicide on broccoli and 1.12 and 2.24 kg ai/ha on squash.

Transplanting dates for 'Atlantic' broccoli were 17 February for
the first experiment and 2 March for the second. 'Early Prolific
Straight Neck' squash was seeded on 9 March. Normal fertilization and
*cultural practices for the area were followed. Broccoli was harvested
when the diameter of heads was 10 cm or greater; there were 6 harvests
between 3 March and 5 May for the first experiment and 5 harvests
between 28 April and 25 May for the second. Eight harvests of squash
(fruit 10 cm or longer) were made between 4 May and 25 May.

Soil samples were collected at the first harvest of each experiment
for nematode population assays. The samples'consisted of five random
cores 2.5 x 18 cm taken from the plot rows. Processing was done by
centrifugal-flotation. Root-knot nematode galling indices were recorded
after the final harvest by examining 6 random root systems from each
plot and rating them on a 1-5 scale: 1=no galling, to 5=severe galling.

In the squash experiment, stunting, uneven growth, and restricted
root systems with typical sting nematode symptoms of discoloration,
lesions, and stubby roots occurred in control plots during early growth,
and root-knot galling developed as the season progressed. Both soil
fumigants and fenamiphos significantly reduced D.. longicaudatus
populations, but ethoprop and carbofuran did not (Table 1). Both soil
fumigants also significantly reduced f. galeatus, but none of the
non-fumigants were effective against this nematode. All of the
nematicides significantly reduced root-knot galling with 1,3-D being the
most effective. Yields were higher for alltreatments, except ethoprop
applied at 2.24 kg ai/ha, when compared with control plots. The greater
yields were obtained from plants in plots treated with the soil
fumigants and fenamiphos, all of which reduced populations of f.

There was a distinct improvement in plant growth and vigor of
broccoli plots treated with nematicides in both experiments, and
symptoms of sting nematode injury were evident on roots in control
plots. As in the squash experiment, the soil fumigants and fenamiphos
were more effective than carbofuran or ethoprop for controlling ..
longicaudatus and only the fumigants reduced .. galeatus populations
(Table 2). Only minor root galling developed on the broccoli plants,
indicating that the population of 1J. incognita was too low to be a
factor in the experiment or that broccoli is a poor host of this
nematode. Plants in all plots treated with nematicides had
significantly higher yields than in the untreated control plots.

The results of these experiments demonstrate that the soil
fumigants, 1,3-D and metam-sodium, were highly effective nematicides
that significantly reduced populations of D. longicaudatus, B. galeatus,
and 1. incognita, and increased yields of broccoli and squash.
Fenamiphos significantly reduced populations of _. longicaudatus and M.
incognita, but was not effective against 11. galeatus; however, yields
were increased and were similar to those obtained from the soil
fumigants. This indicates that Ii. galeatus was probably not a factor in
yield reduction. Carbofuran and ethoprop significantly reduced
populations of B. longicaudatus in the first experiment on broccoli, but
did not in the second broccoli experiment or the experiment on squash.
Neither chemical affected 1. Raleatus populations, but both
significantly reduced root galling from 1. incognita. Yields of both
broccoli and squash were significantly higher for treatments with
carbofuran and ethoprop when compared with those from untreated control
plots. This indicates that, although nematode control was not as good
for carbofuran and ethoprop as for the fumigants-or fenamiphos, the
nematodes had been effectively managed by these chemicals.

Table 1. Effects of fumigant and nonfumigant nematicides on nematode
populations, root galling indices, and yield of summer squash.

Nematodesz Yield
Treatment Rate BL HG MI (kg/ha)

Control --- 117 158 3.00 17,788

1,3-D 28.0 L/ha 3 2 1.08 26,892

Metam-sodium 93.5 71 14 2.00 26,219

187.0 52 8 2.04 27,048

Fenamiphos 1.12 kg ai/ha 56 158 2.16 26,448

2.24 35 155 1.92 26,580

Ethoprop 1.12 121 176 2.16 22,911

2.24 107 137 2.20 20,740

Carbofuran 1.12 168 109 2.36 23,726

2.24 161 140 2.40 22,906

LSD 0.05 52 61 0.51 3,542

0.01 70 82 0.68 4,750

ZAverage number of Belonolaimus lonaicaudatus (BL) and Hoplolaimus

galeatus (HG) extracted from 100 cm3 of soil at harvest. The root

galling index from Meloidogyne incognita (MI) was based on a 1-5 scale:

1=no galling to 5=severe galling.

Table 2. Effects of fumigant and nonfumigant nematicides on nematode populations and yield of


First experiment .Second experiment
Nematode populationsz Yield Nematode poDulations Yield
Treatment Rate BL HG (kg/ha) BL HO (kg/ha)

Control --- 129 337 4,147 230 217 3,640

1,3-D 56 L/ha 0 4 8,606 3 9 10,899
Metam-sodium 140 L/ha 92 90 7,465 141 92 10,362

280 L/ha 59 42 7,825 101 88 10,304

Fenamiphos 2.24 kg ai/ha 35 297 6,069 70 198 9,640
3.36 31 275 7,094 67 197 11,036

Ethoprop 2.24 107 329 5,952 282 174 7,240

3.36 67 281 5,952 271 224 7,777

Carbofuran 2.24 n 69 216 6,069 287 188 7,533

"3.36 72 294 6,820 330 180 6,733

LSD 0.05 44 132 1,733 124 88 2,202
0.01 59 177 2,324 167 118 2,953

ZAverage number of Belonolaimus lonaioaudatus (BL) and Hoplolaimus Raleatus (HG) extracted from

100 cm3 of soil at harvest.