The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
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site maintained by the Florida
Cooperative Extension Service.
Copyright 2005, Board of Trustees, University
Gulf Coast Experiment Station Mimeo Report 62-5
SOIL PREPARATION FOR GLADIOLUS BULB PRODUCTION
A. J. Overman
Gulf Coast Experiment Station
Clean soil is essential to production of quality gladiolus bulbs for the
commercial cut-flower industry. It is the purpose of this report to chart the
procedures by which bulb growers in Florida may insure their crops against loss
by nematodes. aoil-borne diseases and weeds. This information should be co-
ordinated with the seasonal scheduling of operations illustrated in Mimeo Report
62-4 which deals with the handling of bulblets prior to planting.
The hot-water treated bulblets planted by the grower must be set in clean
soil. Though land may be "new" to gladiolus and free of Fusarium and Sclero-
tinia disease fungi, previous crops or the native cover may have contributed
populations of weeds, diseases and nematodes that complicate bulb production.
Soil pests must be eliminated as a problem before planting because there is little
that can help a crop after it has become infected with soil-borne diseases and
nematodes. Even though bulb production may proceed normally during the season,
rootknot nematodes may invade the tissue of the new bulb and be carried through
curing and storage to affect the flower grower's crop the following season.
Therefore, some type of preplanting soil fumigation is generally necessary.
Regardless of whether chemical soil treatment is to be used, growers should
control soil conditions of the field for as long before the planting date as
possible. Certain management practices can preserve the production value of
gladiolus land. Plowing and disking to keep the field clean-fallow for at least
2 months prior to planting starves out many organisms that attack gladiolus.
Moisture should be maintained in the soil during this period to germinate weeds
which are then killed by cultivation. Moisture and cultivation also assist in
rotting old plant debris which harbors many plant pests.
Where soil fumigation is to be used, all handling of the soil should be com-
pleted before time to treat. Drainage, irrigation and roadways should be estab-
lished. Soil amendments should be applied several months before planting time and
seedbed tilth and moisture should be maintained consistently for at least two
weeks before fumigation. At the time the fumigant is applied, fertilizer may be
included as the bed is formed. The bed should not be disturbed after placement
of the fumigant. This is important in order to obtain maximum benefit from the
At the time that the need for fumigating the soil is established, growers
must make several decisions: (1) which pests must be controlled; (2) which
chemical to use; (3) which planting pattern is to be used for the crop, since
the placement of the chemical depends on how gladiolus are to be planted and
(4) which method of application is suitable, Choice can be made from the
,., ** -'' '
Soil Fumigation Procedures
r _A j -1
_ _ i- I-
1 1/2 pt.
a drench in
1/4 inch over-
bands 6 inches
apart 5 inches
ned crop row.
er; 3 week
S-- S--- S; S-- -
depth of 6
ed by 1/4 inch
_ l___ .7
crop row 6
In hot weath-
er more de-
Broadcast as Short waiting
Fungi, Allyl 25 gal. a drench in period. Leaves
7eeds alcohol per acre 1-200 dilut- 3 days no toxic re-
ion. sides in soil
Injected in 10 days
Ethylene bands 12 in warm,
Nematodes dibromide 6 gal. inches apart dry wea- Low in cost.
(EDB/W-85) per acre 8 inches be- their; 3 Excellent
low compact- weeks in nematode
ed soil sur- wet, cold control.
* The benefits derived from Vapam, Mylone and EDB should be insured in warm weather by
daily overhead irrigation with 1/8 inch water for the first 3 days following soil
treatment. Weed control with Vapam and Mylone can be improved by covering the soil
for 5 days with a plastic sheet.
ontrolled- .Material ea
-- ------- --- --- '
n.rnfnAd I dA
ronnre l nd
UDisaLvantages p ___
hazardous to handle.
cannot be used at
ow 500 F. Expensive
because hand labor
s required unless Yes
s available to
control of soil
critical to pre-
scape of gases
rom the soil.
n hot weather
to fumigate. Not
Does not kill
!Hazardous to Yes Yes
handle; it is
gowth of Yes Yes Yes
nj _-J..-_ ^d
Since so many factors influence the results obtained with any fumigant a table of
precautions to be observed.during preparation of'the soil. for treating
and planting is included for the growers convenience-
--- --- Lj t I J
S--I /l /
i i i i
1. By one or a combination of the following opera-
tions keep populations of soil pests as low as
possible between gladiolus crops:
(1) clean cultivation, (2) crop rotation,
(3) alternate flooding and drying.
2. Recognize the pests which must be controlled
(fungi, nematodes, weeds).
3. Choose the proper fumigant for the job.
4. Prepare soil in advance so old plant debris will
be well rotted at treatment time.
5. Add fertilizers and soil conditioners before or
at the same time as the fumigant.
6. Maintain a good soil moisture for at least 2
weeks prior to treatment,
7. Test the soil temperature at a 4 inch depth to
be sure it is above 600 F.
8. Choose the proper method of application.
9. Use recommended rates of fumigants for the
method of application to be used.
10. Observe proper waiting period before planting.
11. Plant disease and nematode-free bulblets and
12. Retain the treated soil volume during and after
WITH IN-THE-ROW TREATMENT:
WITH BROADCAST TREATMENT:
- -- ---
DO DO NOT
1, Do destroy plants after harvest, Do remove Do not expect these short term cul-
infected plant parts from the field where tural operations to replace fumiga-
2. Do consult your County Agent, State Bureau Do not assume that abandoning "old"
of Plant Industry or Experiment Stations land infested with nematodes or dis-
for diagnosis of problems, ease organisms to weeds for several
seasons eliminates the problem.
3. Do base choice on pests to be controlled, Do not expect elimination of soil
cost related to crop value, method of appli- pests with present day fumigants,
cation and equipment available. Do consid- rather an economic degree of tempo-
er desirability of controlling as many pests rary control. Do not repeatedly use
as possible in one operation: ie., money a material which permits accumula-
invested in nematode control can be lost if tion in soil of phytotoxic residues,
crop is destroyed by Stromatinia disease. ____
4, Do establish uniform porosity to 8-10 inch Do not expect fumigant to penetrate
depth to permit uniform passage of fumigant deeply into masses of unrotted plant
vapors through soil. debris.
5. Do complete all operations except planting Do not mulch area with untreated ma-
by time of treating, trials after initial treatment. Do
not combine fumigants with other
6. Do wet to surface to encourage germination Do not water-log the soil.
of weed seed,spores, sclerotia, and hatch-
ing of nematode eggs.
7. Do not fumigate when soil is below
8. Do use in-the-row for widely spaced crops. Do not treat in-the-row shallower
Do use broadcast for bulblets. than 5 inches or deeper than 8 in-
Do use drenches where feasible when maxi- ches.
mum control of disease organisms and weeds
9. Do insure maximum benefit of dose by employ- Do not increase recommended dosage
ing a water seal, with compaction or plastic expecting double benefits; toxic res-
cover. dues may Inlure crop.
10. Do increase waiting period if soil is con- Do not plant as long as odor of chem-
sistently below 650 F., or if excessive ical remains in soil. Do not till
rainfall follows treatment. Do check soil soil to dissipate fumigant vapors,
for odor of chemical before planting. _
11. Do dip diseased and nematode-infested Do not contaminate treated area at
stocks, planting with plant containers, con-
rtaminated tools or workers' feetetc.
12. Do recognize boundaries of zone of con- Do not mix untreated soil into treat-
trol so that recontamination can be held ed soil by breaking up beds or cul-
to minimum, tivating deeply.
Do plant over injection point. Do press a Do not plant between 2 lines of fum-
bulb furrow in the bed and press bed back igant. Do not throw untreated soil
together to cover bulbs. on top of the bed.
Do construct beds at time of treatment. Do not expect maximum control if
Sbeds are constructed after treatment.