Belle Glade AREC iimeo Report EV-1972-4 Apr 1, 1972
JUN 2 9 1972
THE DEVELOPi ENT OF PENCIL STRI E IN CELERY
H. e ad R. F.A.S. Univ. of Florida
Hi. I'". urdine and R. D. B< rger ... "
Pencil stripe is a non-parasitic disorder in celery characterized by
longitudinal brown stripes running lengthwise along the petioles. It is most
obvious on the outward side of the petiole, although it is frequently seen as a
brown discoloration on the concave side of the petiole. Following the change
from Summer Pascal to the Utah types of celery in the Everglades, it was a threat
to the Florida celery industry during the 1958-1960 era.
After 1960, pencil stripe incidence was sporadic and seemed to occur most
frequently on celery growing in new areas. Pencil stripe incidence has been more
severe on winter harvested celery than that harvested in the spring, although
serious incidences have occurred in June.
During the 1965-66 season the use of an experimental fungicide on farms of
several growers was observed to resulted in the formation of the brown pigment
associated with pencil stripe. In many cases the discoloration was more of a
smear either on the outside or inside of the petiole, and was accompanied by leaf
distortion on many plants similar to that which might be caused by a hormone
or growth regulator. Experiments conducted before and after observations in
1965-66 season lead to the conclusion that there are at least two types of basic
causes of pencil stripe. These have been labeled by the authors as "External
induction' which results from material sprayed on the plant and 'Internal
induction' caused by nutritional factors. It is believed that much of the pencil
stripe occurring during the 1958-1960 period was by internal induction, and
most of that occurring since 1960 has been from external induction.
I. External and Internal Induction
An experiment was conducted on virgin Everglades peat, pl 5.8, in the
Gladeview area. Six weeks after fertilization, soil test P and K levels were
36 and 282 pounds per acre respectively. Treatments are summarized in Table 1.
Relative growth on the various micronutrient treatments is given in Table 2
as total weight in pounds per plot.
- Professor (Plant Physiologist), and Assistant Professor (Asst. Plant
Pathologist), respectively, University of Florida, IFAS, Agricultural Research
and Education Center, Belle Glade, Florida 33430.
Table 1. Experiment 1. ?icronutrient materials and rates applied to the soil
and as sprays to the foliage of 'Utah 52-70F celery grown on virgin
iiin plot materials applied to the soil in
Soil Soil pounds/A. .
treat treatment CuSO4 ZnSO iinSO4 FeSO4 Na B40
No. designation 4 4 4 2 247
.5H2 0 .7H20 .I!20 .7120 .10H20
1 None 0 0 0 0 0
2 iinus Cu 0 25 30 50 20
3 I-iinus Zn 75 0 30 50 20
4 ilinus i n 75 25 0 50 20
5 IHinus Fe 75 25 30 0 20
6 Minus B 75 25 30 50 0
7 All applied :75: 25 30 50 20
Subplot materials-- applied to the foliage in
Soil Soil 7 sprays
treat treatment Cu- Zn- n- Fe-
No. designation EDTAA EDTA EDTA EDTA H BO
1 None 7 7 7.52 7.52 12.0
2 Minus Cu 7 0 0 0 ,0
3 Minus Zn 0 7 0 0 0.
4 iMinus iMn: 0 0 7./ 0 2 0
5 i4inus Fe 0 0 0 7.5-2 0
6 ianus B 0 0 0 0 12.0
7 All applied 7 7 7.5-/ 7.5-/ 12.0
Salts of ethylenediaminetetra acetic acid (EDTA) supplied
Company, Ardsley, N. Y., as Sequestrene; 14.0 percent Cu,
Zn, 12.0 percent Mn, 12.0 percent Fe.
by Geigy Chemical
1.5 pounds Fe-EDTA and Mn-EDTA in 100 gal. H20 peracre were used in the
first application. Injury to plots receiving Fe-EDTA resulted in
reduction to 1.0 lb. in 100 gal. H 0 per acre for the next six sprays.
Other EDTA salts were rates of 1 1A. per 100 gal. per acre each application.
Boron was applied at 1.71 lbs. H3DO3 in 100 gal. per acre, per application.
Table 2. Experiment 1. Relative growth as total weight in pounds per plot,
with and without soil applied micronutrients.
WVithout With Significance
supplementary supplementary for spray or
Soil treatment spray spray no spray
None 58.7 70.81/ **
Minus Cu 86.3 96.3 **
Minus Zn 68.7 88.1 **
Minus i'!n 97.9 92.1 N.S.
ilinus B 99.5 94.81/ N.S.
Iiinus Fe 95.6 96.7-- N.S.
All applied 100.5 81.9-- **
1/ Plants in these plots were injured by 1.5 lbs. Fe-EDTA per acre in 100
gallons water on the first spray.
2/ ** Significantly different at the .01 level.
Table 3. Experiment 1. Percent of plants with pencil stripe on plots without
certain micronutrients applied to the soil, with and without the
missing elements) applied in seven supplementary foliar sprays.
Without With Significance
Soil supplementary supplementary for spray or Avg.
treatments spray spray no spray percent
1/ 2/ gc3/
None 20.3 17.31- N.S.2- 18.8b
Minus Cu 24.2 45.5 ** 34.8
Minus Zn 7.0 27.3 ** 17.1b
Iinus Inh 28.2 38.5 ** 33.3,
Minus B 34.2 25.2/ ** 29.7a
Hinus Fe 31.2 59.71 ** 45.4
All applied 42.4 38.5-! N.S. 40.4
Avg. 26.8 36.0 ++
1/ Plants on these plots were injured by the first spray carrying 1.5 Ibs.
Fe-EDTA per 100 gallons water per acre.
2/ ** Significantly different at the .01 level.
3/ Means carrying the same letter are not significantly different at the .05
Plants on unsprayed plots were divided into two groups, those without
pencil stripe and those with pencil stripe. Results of analysis for boron are
given in Table 4 and phosphorus in Table 5.
Experiment 1. Boron content of heart tissue (ppm, dry wt. basis)
of 'Utah 52-70H celery plants with and without pencil stripe
unsprayedd plots only).
Treat. Soil Plants without Plants with Sig.1or
No. Treatment pencil stripe pencil stripe PS- Average
1 None 37.4 29.5 **3/ 3.bc2/
2 Minus Cu 39.2 33.3 ** 6.cd
3 Minus Zn 32.5 31.6 N.S. 32.0b
4 Hinus iin 34.1 34.3 M.S. 34.2
5 Minus B 32.3 29.5 30.9d
6 Ilinus Fe 32.0 30.7 N.S. 31.4bc
7 All applied 34.9 31.6 33.2
Average 34.6 31.5 *
/ Difference significant at the .05 level.
** Differences significant at the .01 level.
2/ eans with the same letter are not significantly different at the .05
Table 5. Experiment 1 Phosphorus content (as percent of dry weight) of
heart petiole tissue of plants without and with pencil stripe
unsprayedd plots only).
Plants Plants Sig.
Treat. Soil without with for
No. treatment pencil stripe pencil stripe PS Average
1 None .83 .94 **/ .88-2/
2 Minus Cu .72 .78 .75
3 Ninus Zn .79 .91 ** .85b
4 Minus Hn .74 .78 N.S. .76
5 Minus B .71 .75 N.S. .73
6 iinus Fe .73 .77 N.S. ,76,
7 All applied .73 .78 .76
.75 .81 **
i and **: Significantly different at the .05 and .01
ieans carrying the same letter are not significantly
different at the .05
It is believed that pencil stripe occurring ir this experiment were fror
both types of cause. That from external induction, perhaps from fungicide sprays
and/or possibly from the Sequestrene sprays. All plots receiving these materials
alone showed greatly increased percentages of pencil stripe. Boric acid sprays
used alone reduced percentages of pencil stripe and when used in conjunction with
the EDTA sprays (treatments 1 and 7) pencil stripe differences between sprayed
and unsprayed plots were not significant. There were other evidences of boron
deficiency in most treatments, i.e. cracked stem and brown checking. All plots
sprayed with EDTA materials singly had significant increases in percentage of
II. Internal Induction.
Several greenhouse experiments were conducted in solution culture with
varying levels of boron, phosphorus, and other nutrients in attempts to re-
produce pencil stripe symptoms on plants. Significant effects were obtained at
times with boron at low levels and at times with high levels of phosphorus,
but the following results shown in Table 6 from a boron x phosphorus x ammonium
nitrogen level experiment may explain most of the pencil stripe occurring in the
Table 6. Experiment 2. Average pencil stripe incidence on 'Utah 52-70H'and
two other Utah cultivars in a greenhouse sand culture experiment.
Ratings 1 = none to 8 very severe.
Boron x NH N Interaction
ppm ppm N H Nitrogen Avg. for
B 0 28 56 84 B
0.1 1.6 3.1 4.9 5.5 4.0
0.2 1.1 1.1 1.0 1.0 1.1
Avg. for N 1.4 2.1 2.9 3.2
Phosphorus x NH N Interaction
ppm ppm NH Nitrogen Avg. for
P 0 28 56 84 P
46.5 1.6 2.1 3.0 2.8 2.4
93.0 1.2 2.1 2.9 3.7* 2.5
Avg. for N 1.4 2.1 2.9 3.2
No exchangeable ammonium data have been obtained from field plots involving
pencil stripe. Data from other plots indicate exchangeable ammonium may be
variable, depending on season, soil moisture, and pH. It may range from 30 to
more than 100 ppm, dry soil basis. Exchangeable ammonium would be expected to be
higher in the lower, wetter areas of a field.
The role of phosphorus is not understood. It is suspected that high levels
may increase susceptibility to pencil stripe from other causes.
III. External Induction
Following the 1958-1960 period, the authors believe-that most of the pencil
stripe appearing has been from externally applied materials, fungicides, possibly
insecticides, and nutritional chemicals that have been used in celery production
in the Everglades. After the 1956-66 observations of pencil stripe in commercial
trials with Difolatan, two experiments were conducted with various fungicidal
materials. Data from one experiment are reported here.
This experiment was conducted on plots at the Agricultural Research and
Education Center. Soil pH before fertilization averaged 5.9, but dropped to 5.6
at harvest. Two soil P levels were included as factors in the experiment. How-
ever, probably due to the drop in pH, water soluble P levels exceeded predicted
levels. Differences were generally not significant and this data is not included.
Seedlings were transplanted October 26. Fifteen applications of materials were
made beginning November 10 at rates designated in Table 8. Solutions were
applied at rates of 175 gallons per acre with pressures of 400 pounds psi. One
pint of Dibrom per 100 gallons was added to each of 11 sprays for insect control.
Table 8. Experiment 3. Common and chemical names of treatments and rates applied.
Treat. Proprietary/ Common Rate per
No. designation-" name Chemical name 5 formulation 100 gallons
1 Dyrene 2,4-Dichloro-6-o-chloroanilino-
2 Dyrene 2/
+ ZnSO4.H 20-M
3 Difolatan 4F
4 Difolatan 4F
+ ZnSO .H20
5 Difolatan 80
6 Difolatan 80
7 Dithane D-14
8 Dithane D-14
+ ZnSO 4H20
11 Dithane M-45
s-triazine (50% W.P.)
boximide (4 pounds per gallon)
See treatment 3
See treatment 3 (80% W.P.)
See treatment 3 (80% W.P.)
Nabam Disodium ethylene bisdithio-
carbamate (22% solution)
Nabam See treatment 7
-See treatment 1
See treatment 1
-Zinc ion manganese ethylene-bis
dithiocarbamate (2% Zn, 16% Hn)
/Proprietary names are used throughout this publication.
2/Supplied as 6% Zn spray grade inc sulfate.
Supplied as 36% Zn spray grade zinc sulfate.
Table 9 gives relative growth as trimmed weight per plot, average plant
height, percent and severity of plants with pencil stripe.
Table 9. Experiment
3. Effect of some fungicidal and nutritional chemicals
sprays on growth and pencil stripe incidence of 'Utah 52-70H'
Avg. wt. % of plants Avg. rated Avg.
per plot with pencil stype plant ht.
Spray material in pounds pencil stripe severity- in cm.
L. Dyrene 62.8a2/ 59.5d2/ 3.5d 66.8a2/
2. Dyrene + ZnSO4 59.1abc 60.9 4.0c 65.3ab
3. Difol. 4F 47.4e 98.2a 5.6a 55.6e
de ab a e
4. Difol. 4F + ZnSO 49.6 96.3 5.4 56.9
5. Difol. 80WS 47.8 94.2ab 5.2ab 56.1e
be bc b d
6. Difol. 80W! + ZnSO4 55.2c 89.2c 4.9 59.3d
7. Dithane D-14 56.1bc 27.5e 3.6d 62.1c
8. Dithane D-14 + ZnSO4 62.0a 15.6e 2.9e 64.0bc
9. Dyrene + NaIH2PO4 53.6c 82.2c 4.1c 63.2bc
10. Dyrene + NaH PO4 bc 83.1 c be
+ ZnSO 55.8 83.1 4. 64.
11. Dithane Ii-45 60.5ab 58.1d 3.0e 62.9bc
Rating for pencil stripe severity, 1 = none to 8 = very severe.
Means carrying the same letters are not significantly different
at the 5%
The surprising aspects of this data were the large percentage of plants
with pencil stripe in plots sprayed with Dyrene and Dithane M-45, although aver-
age severity was not great. Also the effects of monosodium phosphate mixed with
Dyrene increased both percentage of affected plants and severity of the disorder.
In general the addition of ZnSO did not have major effects. Difolatan 80W +
ZnSO4 plots seemed to have somewhat with higher yields and slightly less pencil
stripe incidence than Difolatan 80>W alone; Compared to other treatments Dyrene
seemed to have "stimulated" growth (i.e. plant height), if such a statement can
be made from plot data where there was no unsprayed check. The effects of
Difolatan were definitely toxic.
Some sprayed materials had effects on phosphorus content of plants as shown
in Table 10. There were no significant interactions with respect to boron con-
tent of heart petiole tissue, although hearts of plants with pencil stripe con-
tained higher boron content than plants without (Table 11).
Table 10 indicates that hearts of plants with pencil stripe on plots sprayed
with Dyrene and Difolatan contained larger amounts of phosphorus than plants from
the same plots without pencil stripe. Differences between groups on.the Dithane
plots were not significant.
Data in Table 11 may indicate that plants with pencil stripe may have
accumulated at least some of these inorganic nutrients because of a check in growth.
Experiment 3. Effects of various sprays on
phosphorus content of heart
2. Dyrene + ZnSO4
3. Difol. 4F
4. Difol. 4F + ZnSO4
5. Difol. 801O
6. Difol. 80i + ZnSO4
7. Dithane D-14
8. Dithane D-14 + ZnSO4
9. Dyrene + Nai2PO4
0. Dyrene + Nal2PO4 + ZnSO4
1. Dithane H-45
* Differences between plants with and without pencil stripe are significant at
the .05 level..
Table 11. Experiment 3. Nutrient content of heart tissue of plants with and
without pencil stripe.
% % % % ppm : ppm ppm
K P Ca B Fe Zn.
No PS 5.75 .46 .51 .34 46 24 46
PS 6.18 .49 .74 .25 53 28 53
Sig. ** ** ** ** ** ** **
The data indicate that a pencil stripe like condition may be the result of
two separate types of cause. One is a boron deficiency in the presence of size-
able amounts of exchangeable ammonium. This type was labeled internal induction.
It has not been predominant since 1960 as by this time growers learned that the
Utahs required higher levels of boron applied to the soil than the previously
grown Summer Pascals. It is believed that the recommendations of 2.3 pounds of
boron (7.2 pounds B 0 or 20 pounds borax equivalent) per acre on previously
cropped soil will prevent this type of pencil stripe.
This type of pencil stripe is easily recognizable as it is usually accompa-
nied by other symptoms of boron deficiency, i.e. cracked stem, excessive nodal
cracking, and brown checking.
The second type, external induction, seems to be a result of physiological
action by materials sprayed on the plant. With the many chemicals used in the
production of celery, this type of induction may be the result of interactions
with other chemicals. The increase in percentage and severity of pencil stripe
(Table 9) on plots sprayed with the simple mixture of Dyrene + monosodium
phosphate over that in plots sprayed with Dyrene alone is highly indicative of
the dangers of mixtures of pesticides with "shotgun" mixtures of nutritional
sprays. Enough is known about nutrition of celery on Everglades organic soils
to eliminate this practice.
The fact that surprisingly high pencil stripe incidence was found in plots
sprayed with Dyrene suggests several things. It might explain the sporadic,
but at times locally severe pencil stripe incidence, on growers' farms after
1960. It also suggests something else. The senior author used Dyrene for
several years to control blight in greenhouse experiments because it contains
only the element nitrogen that might be considered a plant food. At no time
was Dyrene associated with pencil stripe. The same holds true for fungicide
screening trials done usually in the late spring. The latter statement also
holds for trials with Difolatan. Only when these chemicals were used on winter
maturing celery did the association become unmistakably clear. This suggests
particular conditions or combinations of conditions for serious manifestations
of this type of the disorder. Whether the conditions are environmental,
chemical, or nutritional is not clear at this point.
Pencil stripe in celery seems to result from two separate types of cause.
One seems to be the result of a boron deficiency in the presence of sizable
amounts of ammonium nitrogen. This type has been labeled Internal Induction.
Symptoms have been reproduced in sand culture under such conditions. This
type is accompanied by other types of boron deficiency, i.e. cracked stem,
brown checking, and excessive nodal cracking. This type is believed to have
been predominant from 1958-1960. Recommended rates of boron in the fertilizer
mixture eliminate this type on previously cropped soil.
The other type seems to be the result of physiological action by some
organic pesticides and has been labeled External Induction. This type has
been predominant since 1960. Only a few fungicides have been critically
examined. The role of certain insecticides has not been determined.
High soil P levels have a ro4eexactly what is not clear, but it may increase
plant susceptibility to the induced type.
Over a long period of observations of pencil stripe occurrence, two associa-
tions have been formed. One is that since 1960, most pencil stripe observed
has occurred in midwinter; the other is soil test phosphorus levels above 30
pounds water soluble P per acre.
These are two conditions that might be considered in screening chemicals to
be used in celery production. It may be that either of these two conditions, or
a combination of the two, in some way precondition susceptible cultivars to