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GULF COAST RESEARCH & EDUCATION CENTER
IFAS, UNIVERSITY OF FLORIDA
5007 60th Street East
Bradenton, FL 34203

Dradenton GCREC Research Report BRA1986-23 December 1936

EFFECT Oil NITROGEN SOURCE AND LLidIG PROCEDURE
ON SEVERITY OF FUSARIUHi WILT OF YELLOW
DELAWARE CHRYSANIhEMiUil

S. S. IOLTZ AND A. H. EHIGEiLAARD1

Liming procedure and nitrogen source have been shown to be of importance
in reducing the severity of the Fusarium wilt disease of Chrysanthemum (1,
2, 3). The present report represents an effort to extend the research
area to include additional liming procedures tested in concert with two
nitrogen sources, namely armoniur sulfate (NH4)2SO4 and calcium nitrate
Ca(N03)2

Single yellow Delaware rooted cuttings were planted in 6 inch plastic pots
in the greenhouse April 14, 1936, five replications per treatment,
randomized block design. The potting medium employed was 1:1 Eau Gallie
fine sand: Florida sedge peat. The medium was amended as shown in Table
1. Plants were root wounded with a knife and inoculated with 50 million
Fusarium wilt spores per pot Hay 12. Disease development was less than
desired and plants were inoculated a second time with 300 million spores
per pot on June 4. Following this inoculation, severe disease developed
in many of the experimental treatments.

The (HH4)2 SO4 series (#I) had very low pH values whereas most of the
Ca(N03)2 series (#II) had pH levels elevated somewhat by the nitrate
source. Fusarium wilt disease ratings were generally higher with the
ammonium source than with the nitrate source. With the all-ammonium
regime there was relatively little difference among the various lime
regimes. Treatment #9, high level of calcium hydroxide, Series II with
nitrate-nitrogen, had the lowest disease rating. With all-nitrate
nitrogen there was as pointed out above, less disease and with the higher
rates of soil pH elevating chemicals there'was an additive benefit from
the combination of all-nitrate nitrogen with upward pH adjustment. The
combination of nitrate and Portland cement appears especially beneficial
in disease reduction. Calcium hydroxide was also beneficial when combined
with the high nitrate regime with the exception of treatment #8 which
deviated from the other calcium hydroxide-nitrate treatments in having a
higher Fusarium wilt disease rating.

iPlant Physiblogist and Plant Pathologist, respectively.

-2-

In summary, it appears that pH elevation by an all-nitrate regime
(furnished as calcium nitrate) together with adequate admixture of liming
materials to raise pHI levels will considerably reduce the severity of
chrysanthemum Fusarium wilt. This conclusion was reached with a very high
inoculum potential. Lower, more realistic, levels of inoculation should
show greater benefit from high lime all-nitrate regimes.

Literature Cited

1. Jones, J. P. and Woltz, S. S. 1981. Fusarium incited diseases of
tomato and potato and their control. pp 157-168. In: Nelson, P. E.,
T. A. Tousson and R. J. Cook. Fusarium: Diseases, Biology and
Taxonomy. The Pennsylvania State University Press, University Park,
PA.

2. Nelson, P. E., R. K. Horst and S. S. ioltz. 1981. Fusarium diseases
of ornamental plants. Ibid.

3. Woltz, S. S. and J. P. Jones. 1981. nutritional requirements of
Fusarum oxysporum : Basis for a disease control system. Ibid.

Table 1. Media pH and Fusarium wilt disease ratings for yellow Delaware chrysanthemums grown with
varied lime and nitrogen treatments.

Nitrogen sourceY
Liming amendment Ammonium Nitrate
grams per liter of media (Series I) (Series II)
Portland Sodium iedia Disease Hedia Disease
CaCOq Ca(OIH) Dolomite cement bicarbonate pH ratings pH ratings

1 0 4.1 2.6 a-e" 4.5 2.4 a-f
2 1.125 4.2 3.0 a-c 4.6 1.6 b-f
3 2.25 4.2 2.8 a-d 5.5 1.4 b-f
4 4.5 4.3 2.4 a-f 5.9 2.0 a-f
5 9.0 6.0 2.2 a-f 7.0 1.4 b-f
6 0.3 4.3 2.4 a-f 4.6 2.4 a-f
7 1.6 4.3 3.2 ab 5.0 1.0 c-f
8 3.2 4.4 2.3 a-d 5.7 2.2 a-f
9 6.4 5.1 1.6 b-f 7.4 0.4 f
10 1.125 4.2 1.0 b-f 4.7 2.4 a-f
11 2.25 4.2 2.2 a-f 5.1 2.6 a-e
12 4.5 4.3 3.0 a-c 5.8 2.0 a-f
13 9.0 5.6 2.2 a-f 6.2 1.2 b-f
14 2.25 0.56 4.4 2.0 a-d 5.3 1.8 b-f
15 2.25 1.125 4.4 4.0 a 5.5 1.4 b-f
16 2.25 2.25 4.4 3.0 a-c 5.8 0.8 d-f
17 2.25 4.5 4.4 2.6 a-e 6.5 0.6 ef
18 2.25 1.125 4.2 4.0 a 5.4 1.0 c-f
19 2.25 2.25 4.2 2.4 a-f 5.7 1.0 c-f

ZAlso amended with Osmocote 14-14-14,
H20, 0.75 grams per liter.
YSeries I received N as (NHi4)2 SO4.
of 500-0-450 (ppm N-P-K) solutions.

2.0 grams per liter, iiicromax 0.7 grams per liter and igS04.7

Series II received N as Ca(N03)2 with weekly drenches of 200 ml

XDisease ratings: 0 = healthy; 1 = very slight disease; 2 = slight; 3 = moderate; 4 = severe, 5 =
dead plants.

"leans followed by different letters differ significantly at the 5% level of probability.