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C5s

^ GULF COAST RESEARCH & EDUCATION CENTER
IFAS, UNIVERSITY OF FLORIDA
5007 60th Street East
Bradenton, FL 34203
Bradenton GCREC Research Report BRA1986-21 December 1936

EFFECT OF LIiING i-MATERIALS, LIiNE RATES AND MEDIA
ON FUSARIUM WILT IN ROYAL TROPHY CHRYSANTHE1iUiUi

S.S. WOLTZ AND A. W. ENiGELHARD1

There have been many reports (2, 3, 4) that higher versus lower soil pl
levels depress the incidence and severity of Fusarium wilt disease of
chrysanthemum incited by Fusarium oxysporum f. sp. chrysanthemi as well as
Fusarium wilt of other horticultural crops. The experiment reported herein,
initiated Aug. 19, 1935, was carried out with 2 media, EauGallie fine sand
and a 1:1 mix with EauGallie and Florida sedge peat. In addition to common
liming materials, a novel amendment was employed, namely Portland cement.
Cement was used as a commercial source of calcium metasilicate which has
been reported to be useful as a soil amendment with benefits attributed to
the soluble silicate content (1).

Liming amendments and rates used for the 2 media are given in table 1.
Higher rates were employed with the 1:1 mix of EauGallie fine sand: Florida
sedge peat to compensate for the acidity of the peat. Media pH values
ranged from 4.3 to 7.5. iledia calcium levels measured in a 1:1 volume mix
of water: Hedia ranged from 17 to 97 ppm calcium in the extract which had
been shaken 30 minutes. Calcium ion determination was found to be a rapid
procedure that was indicative of the current calcium supply available in
media. The values are relative ionic values and reflect the ionized or
active portion of soluble calcium in the media, Further work is planned to
establish the correlation of the rapid test with plant response and current
soil chemistry methods.

Ionic calcium content in extracts was reduced in both media by increasing
levels of dolomitic limestone. The other lime treatments appeared to
maintain adequate levels of the element. EauGallie soil (treatments 1-4)
appeared less responsive than the mix (treatment 14-17) to CaCO3 effects in
adjusting ionic calcium supply.

All lime treatments were effective in partially neutralizing soil acidity
(treatments 1 and 14 were unlimed). Liming was more effective with the mix
than with the EauGallie, probably because of greater acidity. With
EauGallie fine sand the unlimed treatment (No. 1) had more disease than

1Plant Physiologist and Plant Pathologist.

treatments 3,9 and 13 CaCO3, Ca(OH)2 + Portland cement and dolomite,
respectively. There was a visible trend, however, for reduced disease with
most of the lime treatments, especially at higher rates of application.
lith the EauGallie + Florida peat mix, unliimed (trt. 1) had more disease
than all other treatments except Hos. 13 and 24. In the case of the mix as
with the soil there was much less disease with the higher rates of lime
usage. An inspection of data for the Portland cement + Ca(OH)2 treatments
suggests that the cement amendment is worthy of further trial to elucidate
the benefits, if any, of soluble silicates in Fusarium wilt control for
chrysanthemums.

In summary, liming practices for chrysanthemum production should be adjusted
to effectively and uniformly raise the media pH to reduce problems with
Fusarium wilt. "Effective" and "uniform" effects are functions of the
timing of application, fineness of grind of liming materials, speed of
reaction and thoroughness of mixing of living materials with media.
Moisture control is essential in the media, the living material and during
the reaction period to permit rapid, uniform adjust-eint of media pH (5).

Literature Cited

1. Gascho, G. J. 1978. Response of sugarcane to calcium silicate slag.
I. i:echanisms of response in Florida. Proc. Fla. State Hort. Soc.
37:55-53.

2. Jones, J. P. and Joltz, S. S. 1981. Fusarium incited diseases of
tomato and potato and their control, pp. 157-163. In: Nelson, P. E.,
T. A. Tonsson and R. J. Cook. 1931. Fusarium: Diseases, biology and
taxonomy. The Pennsylvania State University. Press University Park,
PA.

3. Nelson, P. E., R. K. Horst and S. S. tioltz. 1931. Fusarium diseases
of ornamental plants. Ibidem.

4. IJoltz, S. S. and J. P. Jones. 1981. i.utritional requirements of
Fusarium oxysporum: Basis for a disease control system. Ibidem.

5. tIoltz, S. S. 1976. Speed of reaction of finely ground dolomitic
limestone. Bradenton AREC Research Report GC1976-14, November 1975.

Table 1. Liming amendments effects on soil pH soil calcium and Fusarium wilt ratings for
Royal Trophy chrysanthemums.

Treatment io. Liming Amendments EauGallie Fine Sand
grams per liter of media
I- .-

CaCO3 Ca(OH)3

Dolomite

1.5
3.0
6.0
1:1 mix

2.25

mieia
pH

4.8
5.5
6.1
6.7
4.8
5.9
7.0
5.0
6.4
7.0
4.8
5.5
6.1
EauGallie
4.3
4.5
6.0
5.7
4.6
5.5
7.0
4.9

1 e i a
Calcium
ppm

60
50
71
71
49
55
665
54
70
62
50
28
24
fine sand:
17
53
64
97
55
78
74
83

ilt ing
rating

4.0
3.3
2.2
3.0
3.4
2.3
2.3
2.6
1.8
2.4
3.4
3.2
2.2
Fla.
5.0
3.4
3.0
2.2
4.6
2.6
3.2
2.4

abcdd
abcde
efg
cdefg
bcdef
cdefg
cdefg
cdefg
fg
defg
bcdef
bcdefg
efg
peat
a
bcdef
cdefg
efg
ab
cdefg
bcdefg
defg

'ort land
Cement

1.5
3.0
6.0

2.25
4.5
9.0

1.0
2.0
4.0
0.5
1.0
2.0

1.5
3.2
6.4
0.0

Table 1 (cont.). Li;ning amendments effects on soil pH soil calcium and Fusarium wilt
ratings for Royal Trophy chrysanthemums.

Treatment No. Liming Amendments EauGallie Fine Sand
grams per liter of media

Portland hedia iledia Fus.
CaCO3 Ca(OH)3 Cement Dolo:mite pH Calcium i ilt
ppm* Rating 'i
22 1.6 4.5 6.4 36 2.5 cdefg
23 3.2 9.0 7.5 64 2.6 cdefg
24 2.25 4.7 50 4.2 abc
25 4.5 5.4 34 2.6 cdefg
26 9.0 5.0 29 2.6 cdefg

Concentration of calcium ion measured with a selective
water extract, shaken 30 minutes.

ion electrode in 1:1 media:

Fusarium wilt rating scale: 1=no disease; 2=very slight disease; 3=slight; 4=medium;
5=severe; 6=very severe; 7=plant dead.
iiumbers followed by different letters are significantly different at the 51 l4vel of
significance.